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Memory Improvement Elements Of Memory

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Comparative neuroanatomy of the dentate gyrus

The comparative neuroanatomy of the dentate gyrus is covered in detail in Chapter 2. However, we would like to raise a few issues for which there remains substantial confusion in the literature. First, the basic trilaminar structure of the dentate gyrus is common across all species studied. And, Unfortunately, many of the connections of the monkey and human dentate gyrus have yet to be investigated. One example of a projection that has been studied in both species is the commissural connection. While cells of the polymorphic layer (mainly the mossy cells) give rise to a very robust commissural projection to the molecular layer of the contralateral dentate gyrus in the rat, this projection does not exist in the nonhuman primate brain or in the human brain. As connections of the primate and human dentate gyrus are better studied, it is undoubtedly the case that there will be other fundamental differences that will affect not only normal function but also pathological processes. This...

Anatomy and physiology of the developing human brain

Density Synapse Ages

Although a thorough review of the structural, chemical, and physiological development of the human brain is beyond the scope of this chapter, this section aims at summarizing the state of knowledge on postnatal human development from infancy to adulthood. months. In contrast, synaptogenesis in the middle pre-frontal cortex takes longer, reaching a maximum synap-tic density at about 3.5 years of age. Furthermore, the time course for synapse elimination occurs significantly later in the middle frontal gyrus (until age 20) than in the primary visual cortex (converged on adult levels by age 4 see figure 7.1 Huttenlocher and Dabholkar, 1997). Recently, Huttenlocher and colleagues have described developmental changes in synaptic density for different cortical areas important in language processing-primary auditory cortex, the angular gyrus (Broadman's area 40), and Broca's area (Huttenlocher, 1994 Huttenlocher and Dabholkar, 1997). At birth synaptic development (as measured by the time...

Neuroanatomy of Maternal Behavior

In a review of the neural structures and circuits that regulate the occurrence of maternal behavior in mammals, this chapter will begin with an analysis of the sensory basis of maternal behavior, and will then move to a discussion of central neural mechanisms. This chapter's emphasis will be on presenting a functional neuroanatomy of maternal behavior. We will be interested in determining the neural circuits that are influenced by hormones and by sensory stimuli from infants, and in determining the functions served by these circuits so that maternal responsiveness is altered. This functional analysis will take place within the context of the motivational models that were presented in the previous chapter. In short, we will present evidence that there are dual neural mechanisms regulating maternal behavior an inhibitory one that promotes avoidance and withdrawal from infant stimuli, and an excitatory system that promotes approach and interaction with infants. Maternal behavior occurs...

Trying a Different Tool

The human brain and its diverse capacities are so complex, and so costly to grow and maintain, that they must have arisen through direct selection for some important biological function. To date, it has proven very difficult to propose a biological function for human creative intelligence that fits the scientific evidence. We know that the human mind is a collection of astoundingly complex adaptations, but we do not know what biological functions many of them evolved to serve.

Sexual Selection and Other Forms of Social Selection

Scientists became excited about social competition because they realized that it could have become an endless arms race, requiring ever more sophisticated minds to understand and influence the minds of others. An arms race for social intelligence looks a promising way to explain the human brain's rapid expansion and the human mind's rapid evolution.

Characteristicallyhuman behaviors

Now ask a neuroscientist what the brain is doing during language- or tool-usage. Again, there are many things to consider, fashionable and unfashionable topics, new and old methodologies, and personal research interests of various kinds, but let us start at the top What is the single, most-outstanding fact about brain function during speech or goal-directed manual activity The answer is unambiguous and no longer controversial the left hemisphere is dominant. It is dominant for most people most of the time for the most basic language functions, and it controls the hand favored for undertaking precise manual manipulations of the external world. Issues concerning left-handers, special bimanual skills and the language-related functions of the right hemisphere must be addressed in any complete account of human brain functions, but the first and most firmly established fact is that the left hemisphere is the dominant work-horse for motor control during these crucial, quintessentially human...

B A brief history of laterality

Many discussions in the 1970s went well beyond the facts - as hemisphere differences were invoked to explain, in one fell swoop, all of the puzzles of human psychology, including the subconscious mind, creativity, and parapsycho-logical phenomena - but the inevitable backlash was also exaggerated. Within academic psychology, Efron's The Decline and Fall of Hemispheric Specialization (1990) was an attempt to turn a critical eye on the methodologies of lat-erality research and to reject those claims for left-right differences that could be as easily explained by response biases as by differences in cognition of the cerebral hemispheres. Unfortunately, the title of Efron's book was taken too literally as a rejection of not only some cases of poor methodology, but also of several core ideas in neuropsychology. Today, a surprising number of psychologists - from Department Chairmen to best-selling authors - consider the entire issue of laterality to be a meaningless Age of Aquarius...

Genesis of an Individuals Genes

To return to our developing embryo, at five days after fertilization about a hundred cells, all derived from a clonal cellular process known as mitosis, make up the individual. Within four weeks of conception, a human brain begins to take form (from ectoderm), and a tiny heart begins to pulsate. At about thirty-six weeks, an infant is ready to begin an existence outside of its mother's nurturing body.

The contribution of cerebral functional imagery

The results revealed a clear difference in the metabolism of the primary and secondary visual areas in the three populations, whereas cortical activity of the other areas remained similar in the different groups. Metabolism of the primary and secondary visual areas in the late-blind is lower than that for blindfolded sighted people. Moreover, the cortical activity of visual areas is higher in the early-blind than in sighted and late-blind people. This hypermetabolism of the visual areas is observed in the early-blind whether they are resting or carrying out the various haptic tasks (a similar hyperactivity of visual areas is also present in tasks of auditory location Wanet-Defalque et al. 1998). All these results are similar in both hemispheres. Taken together, they suggest that early lesions of peripheral visual pathways bring about lasting modifications in the functional organization of the human brain.

Neurons Synapses and Neurotransmitter Molecules

By definition, neurons are brain cells that are involved in communication of information. There are an estimated 100 billion neurons in the human brain at the time of birth 72 . The actual number could vary by an order of magnitude or more. Using unbiased stereology, a rigorous sampling method, 13-23 billion neurons are estimated in the human neocortex 9, 97 . Sex and age appear to be factors affecting cell number.

Hemispheric Laterality

One of the oddest facts about the brain is that its two hemispheres carry out somewhat distinct functions, at least in certain domains. Why the human brain In sum, principles and discoveries from behavioral genetics (genetics and intelligence) and cognitive neuroscience (neurogenesis, brain plasticity, frontal lobe functioning, and hemispheric laterality) have begun to shed light on the structure and function of the human brain in general and even somewhat on scientific and mathematical thought in specific. Indeed, a few principles of the genetics of intelligence are now in place about 80 percent of the variance in intelligence is genetic brain structures are more similar in people who are more genetically alike and genius-level ability appears to be the result of multiplicative rather than additive genetic influences. It is also increasingly clear from neuroscientific evidence that specific regions of the brain are predominantly active in thought, reasoning, and problem solving...

Elements of Functional Neuroimaging

There has been explosive interest in the use of brain imaging to study cognitive and affective processes in recent years. Examine Figure 2.1, for example, to see the dramatic rise in numbers of publications using positron emission tomography (PET) and functional Magnetic Resonance Imaging (fMRI) from 1985 to 2004. A recent surge in inte-grative empirical work that combines data from human performance, neuroimaging, neuropsychology, and psy-chophysiology provides a more comprehensive, but more complex, view of the human brain-mind than ever before. Because the palette of evidence from which researchers draw is larger, there is an increasing need to for cross-disciplinary integration and education. Our goal in this chapter is to provide an introduction to the growing field of neuroimaging research, including a brief survey of important issues and new directions.

Runaway Produces Large Sex Differences

Another problem with the runaway brain theory is that runaway is supposed to produce large sex differences in whatever trait is under sexual selection. Peacock tails are much larger than peahen tails. If the human brain tripled in size because of runaway sexual selection, we might expect that increase to be confined to males. Men would have three-pound brains, and women would still have one-pound brains like other apes. This has not happened. Male human brains average 1,440 grams, while female brains average 1,250 grams. If one measures brain size relative to body size, the sex difference in human brain size shrinks to 100 grams. This 8 percent difference is larger than would be predicted by a sexblind theory like E. O. Wilson's cultural feedback loop, or the

Formation Elimination and Stabilization of Synapses in the Primate Cerebral Cortex

The cerebral cortex contains by far the largest proportion of synapses in the human brain (Szenthagothai, 1978). Although the timing and status of synaptic connections form the basis of all theories of human psychological development, quantitative information on synap-togenesis has been lacking. To provide insight into mechanisms of development and maintenance of cortical synapses in primates, we have examined the course of synaptogenesis in the macaque monkey under normal and experimental conditions. The cellular organization and functional parcellation of cerebral cortex in this Old World monkey is remarkably similar to that of the hu-

Microscopy and Particle Morphology

Inclusion bodies containing ribonucleoprotein (RNP) were observed by electron microscopy (Fig. 1A) of infected bat, mouse and human brain, and infected cultured cells (Gould et al. 1998 Hooper et al. 1997 Samaratunga et al. 1998). These were composed of crescent-shaped tri-laminar membranes and associated with electron-dense material and RNP filaments. In infected mouse brain, these membranes were also associated with an electron-dense granular material. In addition, ring-shaped inclusions were observed in the dendritic processes or cytoplasm of large neurons, or associated with inclusions.

Thyroid Hormone and Brain Development

Among the most dramatic actions of thyroid hormone are those exerted on brain development and function. In the adult human brain, a deficiency or excess of thyroid hormone may lead to various psychiatric manifestations, but it is during development when thyroid hormone exerts its most varied and critical actions on neural tissue. In humans, a deficiency of thyroid hormone taking place during a critical period of development may lead to severe mental retardation and also to neurological defects (1). This critical period may extend from the start of the second trimester of pregnancy to the first few months after birth. During this period, the absence of thyroid hormone, if not corrected by early postnatal treatment, leads to irreversible damage with mental retardation. While in utero, the fetal brain is protected from thyroid deficiency by the maternal hormone. Severe thyroid hormone deficiency in the pregnant woman, especially if combined with fetal deficiency, leads to severe...

Towards Experimental Tests of Quantum Effects in Cytoskeletal Proteins

The consciousness experiments belonging to the tissue-cell scale frequently utilize apparatus such as electroencephalographs (EEG) or magnetic resonance imaging (MRI) to track responses of brains to stimuli. The best example of such is the excellent work undertaken by Christoff Koch's group at Caltech 61 sometimes in collaboration with the late Francis Crick 22 , tracking the activity of living, conscious human brain neurons involved in visual recognition. These experiments are designed to elucidate the multi- and single-cellular substrate of visual consciousness and awareness and are likely to lead to profound insights into the working human brain. Because of the large spatial and long temporal resolution of these methods, it is unclear whether they can reveal possible underlying quantum behavior (barring some unlikely inconsistency with classical physics such as, for instance, nonlocality of neural firing).

Concurrent synaptogenesis in the cortical mantle

Although the rate of decline to adult levels in phase 4 varies in different areas, this phase of high synaptic density also exhibits an overlap in timing across the cortical regions (Rakic, Bourgeois, and Goldman-Rakic, 1994). We have suggested that this overlap may be essential for competitive interactions and the validation of synaptic connections during experience-dependent development. It should be pointed out that not all evidence is supportive of concurrent synaptogenesis, however. In particular, Huttenlocher and Dabholkar (1997) have reported that during the ascending phase of synaptogenesis in the human brain (phase 3 in macaque), the prefrontal association cortex appears to acquire synaptic junctions more slowly than in the primary visual and auditory cortices. This finding has appeal in its concordance with the general notion that executive functions based on language appear to mature latest in development. We have discussed the technical issues related to this conclusion in...

Global Anatomy Of Longterm Memory

Currently, most models of memory disorders are still based on extreme simplifications of the neuroanatomy, typically focusing on the hippocampus and adjacent temporal lobe structures (e.g. entorhinal and perirhinal cortices, parahippoampal gyrus, etc.). Figure 5.3a gives a partial view of the neuroanatomical hierarchy derived by Felleman & Van Essen (1991), who position the hippocampus at the top of the neuroanatomical hierarchy of interconnected brain areas, with the sensory and motor organs at the bottom. Squire (1992) and Squire & Zola-Morgan (1991) give a similar hierarchy (see Figure 5.3b). Figure 5.3 Schematic overview of neuroanatomy. (A) How the hippocampus is located at the top of the neuroanatomical hierarchy illustration by Felleman & Van Essen (1990). Shown is a small part of a combination of the maps of the visual and somatosensory areas. (B) Similar hierarchy according to Squire (1992 Squire & Zola-Morgan, 1991), but simplified even further The two hypotheses...

Anatomical asymmetries in perisylvian regions

Brain lateralization may be indexed in a variety of ways, two of the most common being dichotic listening, in which different syllables are presented simultaneously to each ear and the subject usually reports the syllable presented directly to the hemisphere that is dominant for language, and handedness, in which the most useful classification has consisted of separating subjects into consistent right-handers and nonconsistent right-handers rather than into dextrals and sinistrals (Witelson, 1995). There is an important relationship between functional lateralization (hereafter referred to as lateralization) and anatomical asymmetry (hereafter referred to as asymmetry) in the human brain, which will be reviewed in the next section. Next, we will analyze in some detail the relationship between brain asymmetry lateralization and interhemispheric connectivity. Only after Geschwind and Levitsky's (1968) classic paper did the concept that the human brain is structurally asymmetrical become...

The Brain as a Target for Mutation

For simple traits that depend on just a few genes, selection is pretty good at eliminating mutations. Each mutation is likely to cause such dramatic change that natural selection rapidly eliminates it But for very complex traits, like human brains, that grow through the interaction of many genes, mutations are harder for selection to eliminate. There are more genes vulnerable to mutation in the first place, and selection's effects get diluted across more genes. This decreases selection's power to eliminate mutations on any one gene. With mutation stronger and selection weaker, complex traits are less likely to be perched on the peak of perfection. Genetic variation is more likely to be manifest in complex traits. This makes complex traits like the human brain better fitness indicators. Imagine all the DNA in our 23 pairs of chromosomes laid end to end in a single strip. The DNA from a single human cell would be about six feet long, and contain about 80,000 genes. Imagine that the...

In vivo studies relating anatomical asymmetry and functional laterality

Certain visuospatial functions in the right (Bradshaw and Rogers, 1993). An interesting finding is that, among lefthanders, those who have an inverted writing posture tend to show leftward asymmetry of the planum temporale, while those with noninverted writing have a right-ward asymmetry (Foundas, Leonard, and Heilman, 1995). Using MRI, Habib and colleagues (1995) found two leftward asymmetric parameters the size of the planum temporale and the distance between the central sulcus and the end of the Sylvian fissure. These two asymmetries were not correlated that is, in a given individual, presence of asymmetry in one region does not predict that the other region will be asymmetric. Although each of these asymmetry measures correlates with handedness, the two combined showed a much stronger correlation with manual preference. This is consistent with a recent report (Ide et al., in press) showing several anatomical asymmetries in different surface regions of the human brain even though...

Safe Sex Tips For Sperm

Hurst explains this by raising once again the matter of disease.2* Organelles are not the only genetic rebels inside cells bacteria and viruses are there as well. And exactly the same logic applies to them as to organelles. When cells fuse, the rival bacteria in each engage in a struggle to the death. If a bacterium living happily inside an egg suddenly finds its patch invaded by a rival carried by a sperm, it will have to compete, and that might well mean abandoning its latency and manifesting itself as disease. There is ample evidence that diseases are reawakened by other rival infections. For example, the virus that causes AIDS, known as HIV, infects human brain cells but lies dormant there If, however, cytomegalovirus, an entirely different kind of virus, infects a brain cell already infected with HIV, then the effect is to reawaken the HIV virus, which proliferates rapidly. This is one of the reasons HIV seems more likely to go on to cause AIDS if the infected person gets a...

Is the wafl dpi gene altered in cancer

Reported in colorectal cancer and somatic mutations have not been found in codons 9 through 139 that were screened (Li YJ et al., 1995). Multiple polymorphisms were seen in human brain tumours, most frequently of codon 31 - again there were no somatic mutations (Koopmann et al, 1995). Codon 31 polymorphism occurs also in normal individuals (Li YJ et al, 1995 Marchetti et al, 1995c) and, in the brain tumour study, the polymorphisms did not relate to histological type (Koopmann et al, 1995). Jung et al (1995b) also investigated gliomas for wafl cipl abnormalities. Surprisingly, wafl cipl protein levels were low in normal brain tissue and in reactive gliosis, but were highly elevated in gliomas irrespective of grade. Glioblastoma multiforme showed elevated protein levels, in tumour samples carrying either wild-type or mutated p53- No elevation of protein occurred in anaplastic astrocytomas carrying mutant p53-Jung et al (1995b) also stated that wafl cipl gene is not deleted in gliomas....

Mental Traits as Fitness Indicators

If we make an inventory of what the human brain can do, we find two general themes very few of the ancient mental abilities that we share with other apes look like fitness indicators, but many mental abilities unique to humans do look like fitness indicators. There are probably thousands of psychological adaptations in the human mind. The vast majority are shared with other species. Some evolved hundreds of millions of years ago and are shared with thousands of species. Some evolved only a few million years ago and are shared only with other great apes. We have exquisitely efficient mechanisms for regulating our breathing, controlling our limbs, keeping our balance, seeing colors, remembering spatial locations, learning foraging skills, being kind to offspring, feeling pain when injured, remembering faces, making friends, punishing cheats, perceiving social status, estimating risks, and so forth. Steven Pinker has explored many of these mechanisms in his book How the Mind Works. When...

The Hominid That Wasted Its Brain

To sum up the last few sections, I think that the handicap principle casts a new light on the human brain. Everyone who proposes a theory about the brain's evolution mentions its costs. Our brains are only 2 percent of our body weight, but they consume 15 percent of our oxygen intake, 25 percent of our metabolic energy, and 40 percent of our blood glucose. When we spend several hours thinking really hard, or just conversing with people whose opinion matters to us, we get hungry and tired. Our brains cost a lot of energy and effort to run. Usually, theorists argue that these costs must have been balanced by some really large survival benefits, otherwise the brain could not have evolved to be so large and costly. But that survivalist argument holds only as long as one ignores sexual selection. If we view the human brain as a set of sexually selected fitness indicators, its high costs are no accident. They axe the whole point. The brain's costs are what make it a good fitness indicator....

Evolutionary speculations based on postmortem anatomy in the human

The results presented in this chapter support the concepts of regional variation and of individual diversity in callosal fiber composition in the human. The first class of findings unveiled a difference between commissural connections of primary and secondary sensorimotor versus higher-order cortical areas in terms of the requirements of interhemispheric transfer time. On the basis of these results, we will propose a phylogenetic scenario for the origin of callosal function that is based on the emphasis in midline fusion tasks. This process is not well developed in the telencephalon of other vertebrates, as they lack a major telencephalic commissure, but also because most topographical sensory information is processed at lower brain levels, that is, in the midbrain. Next, a tentative scenario for the evolution of callosal connectivity both in placental mammals and in the lat-eralized human brain will be proposed.

Inflammationdependent Oxidative Stress In The

Figure 6 presents in simplified form the rationale of why brain is considered to be susceptible to oxidative stress (12). Brain is enriched in the more easily peroxidizable fatty acids (20 4 and 22 6), consumes an excessive fraction (20 ) of the total oxygen consumption for its relatively small weight (2 ) and is not particularly enriched in antioxidant defenses. In fact, brain is low in catalase activity containing about 10 of liver catalase. Additionally, human brain has higher levels of iron (Fe) in certain regions and in general has high levels of ascorbate. Thus, if tissue organizational disruption occurs, the Fe ascorbate mixture is expected to be an abnormally potent pro-oxidant for brain membranes (12).

The Space of All Possible Stimulation

The entertainment industry can be viewed as an attempt to explore the space of all possible stimulation that can excite the modern human brain. Every movie, every book, every painting, every music CD, and every computer game is a set of potential stimuli that may or may not work. The human brain is fickle it responds much more positively to some stimulation than to other stimulation. Nobody knows in advance what stimulation will work, though some can make some good guesses. If evolutionary psychologists like me could make solid predictions about exactly what stimulation patterns would optimally excite the human brain, we could just move to Hollywood and become highly paid entertainment industry consultants. But we cannot do much better than ordinary film producers, because a general understanding of typical human reactions to ancestrally normal events does not allow us to predict the human brain's exact reactions to any possible novel stimulation. Modern human culture is a vast,...

Sexual Selection Natural Selection and Innovations

It remains to be seen how important the human brain is as an evolutionary innovation. If we became extinct tomorrow, it would count as a micro-innovation characteristic of just one species. If our descendants succeeded in colonizing the galaxy and splitting apart into a hundred thousand species millions of years from now, it would count as a macro-innovation. But an innovation's ability to trigger an adaptive radiation millions of years after its origin cannot explain why it evolved. This raises a serious problem that has remained unsolved ever since Darwin how can innovations emerge through a gradual process like natural selection This question has three variants of increasing difficulty.

Carboxy terminus See cterminus

Carboxyl-terminal Src kinase homologous kinase CHK Csk homologous kinase A negative regulatory kinase of the Src tyrosine kinase family generally believed to inactivate Src-family tyrosine kinases (SFKs) by phosphorylating their consensus C-terminal regulatory tyrosine. Has been reported to regulate the expression of the chemokine receptor, CXCR4. CHK overexpression in neuroblastoma and astrocytoma cells inhibits their growth and proliferation and loss of CHK expression is associated with human brain tumours.

The Biological and Cognitive Hierarchies

Division between possible futures is much older in geography there is a divide (or watershed), where water runs either east to one sea or west to another, and in mathematics, such a sharp dividing line is called a separatrix. Less formally, politicians and social scientists speak of a tipping point and of the straw that broke the camel's back, and we are all familiar with a light switch - which is either on or off - and a coin toss. Such switches are the essential elements of modern electronics, and a computer can be viewed as a system of many interconnected switches. Some believe that the human brain can be similarly described as it parses the future in unanticipated ways.

The Evolution of the Brain

Of all the unsolved mysteries of the history of the universe, none is more enigmatic than the evolution of the human brain. The fact that organic life emerged from the inert planet is, in the minds of many, a miracle of (truly) biblical proportions. The earth, the only life planet of which we have any knowledge, spun lifeless for over a billion years before the first glimmer of blue-green algae appeared it was three billion years (3,000,000,000 years) later that shellfish and sea corals emerged, and it took another 350 million years for mammals to evolve. Another 345 million years would pass before the first humans walked the earth, and only 125,000 years ago Human brains, like some dogs, can't hunt beyond those borders set by physiologically and psychologically determined limits. We cannot know what we cannot know. We even have difficulty asking questions to which we couldn't understand answers

Production Studies and Findings

Of course, widening the database also broadens the questions Why are utterance-final particles preserved in Japanese aphasia but not so well in Chinese (Paradis, 2001b) Why does canonical word order make comprehension and elicited production easier across languages, even those that have ''free'' word order, and why is some noncanonical order occasionally used as a production default Cross-linguistic psycholinguistic and computational-linguistic approaches seem to be the most promising avenues to further understanding of aphasia, and, more generally, to the question of how language is represented in the human brain.

Comparison to Denenberg and colleagues factor analysis model

In both the human and rat analyses, a total of eight factors resulted, of which seven comprised intercorre-lated clusters of CC widths. CC area did not correlate uniquely with any cluster, and brain size was associated with an eighth factor. Among the many implications of this factor analytic model to CC and brain anatomy, the one most relevant to Jancke and Steinmetz's model is that CC area and the seven width clusters were not strongly related to measures of brain size in humans or rats.

Helen J Neville And Daphne Bavelier

Cognitive neuroscience has rapidly expanded during the decade of the brain. Progress in cognitive science and in the development of techniques that permit nonin-vasive monitoring of the human brain have permitted extensive, ongoing mapping and differentiation of sensory and cognitive systems in the mature human mind brain. The burgeoning literature on the normal adult brain serves as the point of departure for a major opportunity and challenge for the coming decade and cen-tury-the characterization of the processes that lead to the development and differentiation of the mature brain (developmental cognitive neuroscience).

Epilepsy Patient and Family Guide Second Edition

Summary Epilepsy Patient and Family Guide is an updated resource that addresses all aspects (psychosocial, financial, legal, and medical) of epilepsy to help adult patients with epilepsy or parents of children with epilepsy understand the disorder and to enable them to better cope with the problems it causes. It is written in a style that the general reader can easily follow. The first section is entitled Medical Aspects of Epilepsy and consists of six chapters that cover topics including (1) brain anatomy and epilepsy, (2) seizures and epileptic syndromes, and (3) seizure provoking factors. The second section is entitled Diagnosis and Treatment of Epilepsy and is divided into seven chapters that (1) describe the health care team for a patient with epilepsy, (2) discuss how epilepsy is diagnosed, (3) discuss providing first aid for seizures, (4) summarize the

The Complete Neurologic Examination

If you like using your hands to solve clinical puzzles, if you enjoy playing with reflex hammers and tuning forks, this specialty may be the perfect choice. In addition to the necessity of a thorough knowledge of neuroanatomy and accurate history taking, neurology is famous for its savvy methods of physical diagnosis. After conducting a complete physical examination, good neurologists pride themselves on knowing the exact localization of the problem prior to any laboratory or imaging studies.

Generating New Neurons

The rise in blood flow to an active part of the brain can be measured and is the basis for certain imaging techniques, including positron emission tomography (PET) scanning and functional magnetic resonance imaging (fMRI), that enable neuroscientists to observe which parts of the brain are especially active when a subject is carrying out a task. These noninvasive imaging techniques are adding enormously to our understanding of human brain function.

Understanding Seizure Disorders

Summary understanding Seizure Disorders, an 11-minute video produced by the Epilepsy Foundation of America, examines the human brain and uses testimonials from persons with epilepsy and videotapes of persons having seizures to explain epilepsy. Epilepsy is defined as seizures that are not related to an explained cause and which tend to recur over time in an unpredictable fashion. There are two types of seizures Generalized and partial. In a generalized seizure, the electrical disturbance affects the entire brain all at once. In a partial seizure, only one part of the brain is affected at the start the electrical disturbance may remain localized or spread throughout the brain. Partial seizures may be characterized by strange changes in sense of taste or smell or feeling of movement outside the body or back in time. Some people experience only one kind of seizure, while others experience several kinds. Doctors can attempt to determine the cause and treatment for seizures by (1) taking...

Development of the corpus callosum

Embryonic Period Growth of the normal human brain occurs in a highly regular and well-defined manner. Anatomical neuronal development progresses in a posterior-to-anterior fashion as well as a ventral-to-dorsal fashion. Growth of the corpus callosum also occurs in an orderly manner. The development of the corpus callosum is initiated between 8 and 17 weeks of gestation (Rakic and Yakovlev, 1968). A thickening of the telencephalon, along the rostral wall, forms the lamina reuniens, which is the precursor to the white matter bundles of the anterior commissure and corpus callosum. As cells from the lamina reuniens migrate superiorly, they form the massa, which will form the bed for the extension of the crossing fibers of the corpus callosum (Barkovich and Norman, 1988). The corpus callosum does not develop homogeneously, and axons of the genu develop first, followed by the body and sple-nium. One exception to this anterior to posterior growth pattern is the rostrum. This is the last...

Gene Isolation and Identification

The key steps in this strategy are to hook random messenger RNA (mRNA) molecules from the pool of molecules in a particular tissue of interest such as the human brain, and then reverse-transcribe them to their complementary DNAs (cDNAs). Recall that mRNA molecules in effect are miniature transponders whose intracellular job is to relay the coded information in particular genes to direct the construction of proteins. A partial reversal of this process, carried out in the laboratory under the auspices of an enzyme known as reverse transcriptase, permits the in vitro (outside a living system) recovery of coding portions of genes from their more easily isolated mRNAs. Each stretch of DNA caught in this fashion is known as an expressed sequence tag, or EST. One advantage of this approach is that each EST came from a protein-coding gene, as opposed to the surrounding genomic sea of non-coding junk DNA. A disadvantage is that the identity of the gene recovered and its cellular...

ASynuclein And The Proteasome In Cellular And Animal Models

Transgenic for A30P mutant a-synuclein. The model includes neuritic pathology and astrogliosis without loss of nigral neurons (24). These authors also examined the steady state levels of well-characterized proteasome substrates and the expression patterns of protein components of the proteasome (23). Such in vivo data might suggest that many of the observations from in vitro systems have little or no relevance to the in vivo situation. However, one difficulty in comparing the different models is that it is hard to assess the aggregation state of a-synuclein in these situations. As Martin-Clemente et al. have pointed out, it is not merely the presence of a-synuclein that causes damage, as the protein probably needs to aggregate as well (23). The aggregation is most often and most obviously seen in human brain. Recently, we have seen increased expression of this a-synuclein in blood samples from patients with increased gene dosage but only saw aggregation and deposition into insoluble...

Tactile exploration and manual lateralization

Neuroanatomical and functional asymmetries of the human brain are well documented (Bradshaw 1989 Corballis 1991 Hellige 1993). One of the most obvious expressions of cerebral lateralization in humans is manual laterality, with more than 90 of individuals being right-handed (Corballis 1991). The bias toward the right hand is associated to a left hemispheric specialization for the comprehension and production of language More than 95 of right-handers have a left hemisphere specialization for language function (Ras-mussen & Milner 1977). Because of this possible association between hemispheric asymmetry and language, manual laterality was thought to be a marker of human uniqueness. We know today that numerous animal species present neuroanatomical and functional asymmetries comparable to those of humans (Bradshaw & Rogers 1993 Bisazza, Rogers, & Vallortigara 1998 Fagot et al. 1997 Ward & Hopkins 1993). Whether these asymmetries are homologous and simply analogous to those of...

RQNNbased Eye Tracking Model

There are certain aspects of brain functions that still appear to have no satisfactory explanation. As an alternative, researchers 36, 37, 21, 28 are investigating whether the brain can demonstrate quantum-mechanical behavior. According to a current hypothesis, microtubules, the basic components of neural cytoskeleton, are very likely to possess quantum-mechanical properties due to their size and structure. The tubulin protein, which is the structural block of microtubules, has the ability to flip from one conformation to another as a result of a shift in the electron-density localization from one resonance orbital to another. These two conformations act as two basis states of the system according to whether the electrons inside the tubuline hydrophobic pocket are localized closer to a or 3 tubulin. Moreover, the system can lie in a superposition of these two basis states, that is, being in both states simultaneously, which can give a plausible mechanism for creating a coherent state...

Atlasbased pathology detection

Probabilistic Atlasing Probabilistic atlasing is a research strategy whose goal is to generate anatomical templates that retain quantitative information on inter-subject variations in brain architecture (Mazziotta et al., 1995 Thompson et al., 1997 Thompson and Toga, 1998). A digital probabilistic atlas of the human brain, incorporating precise statistical information on positional variability of important functional and anatomical interfaces, may help to address many of the methodological difficulties that we have observed in detecting alterations in callosal anatomy. As the database of subjects on which probabilistic atlases are based increases in size and content, the digital electronic form of the atlas provides efficiency in statistical and computational comparisons between individuals or groups. In addition, the population on which probabilistic atlases are based can be stratified into subpopulations by age, gender, handedness, or other demographic factors by stage of...

A bilateral neural network simulation

To begin to fill this gap, a rather simple simulation of object recognition will be outlined in the present chapter, in which the bilaterality issue is considered. The computational capabilities of the simulation are in fact modest, but represent one way in which the functional asymmetry of the human brain might be addressed in an artificial system.1

The Ups In Huntingtons Disease

Testing the UPS hypothesis of neurodegeneration has been difficult due to paucity of available experimental techniques (22,23). Some studies have approached this issue of potential UPS impairment in HD by assaying the pro-teolysis of small fluorogenic substrates specific for each of the three catalytic activities of the 20S proteasome. This has been done in homogenates from cell models such as cell lines transfected with the mutant forms of huntingtin (24), from mouse models of HD (25) and, more recently, from postmortem human brain tissue from HD patients (26). A drawback of exploring UPS activity by assaying proteolysis of these small fluorogenic substrates is that they are degraded by the 20S proteasome in an ubiquitination independent manner. Therefore, these assays can detect alterations in the catalytic activity of the 20S proteasome, but will fail to detect, alterations at any other level of the UPS such as availability of free ubiquitin, polyubiquitination, recognition by the...

How To Be An Excellent Pmr Physician

A superb understanding of neuroanatomy, neurophysiology, and the muscu-loskeletal system serves as the basis for your daily practice when evaluating patients and discussing rehabilitation plans with colleagues. All physiatrists can execute the neurologic examination as well as any neurologist and the musculoskeletal examination as skillfully as any orthopedic surgeon or rheuma-tologist. As directors of an interdisciplinary team, good physiatrists are also adept at coordinating people and tasks.

Source Localization Techniques

In recent years, substantial progress has been made to extend the original dipole fitting approach implemented using simplified spherical head models to more realistic geometry head model constructed from single subject's MRI images, in particular using boundary element methods (BEM) or finite element methods (FEM). Not surprisingly, simulation and experimental studies have shown that a more accurate localization can be achieved by using realistic head models (e.g., Fuchs, Wagner, & Kastner, 2001). In a recent study (Cuffin, Schomer, Ives, & Blume, 2001), the best average localization that could be achieved with spherical head model was 10 mm. In addition to improved localization capability, co-registration with MRI images can be used to visualize the dipole location coordinates relative to brain anatomy, facilitating comparisons with other functional imaging modalities. Studies combining electrophysiological and hemodynamic measures have further extended dipole source...

Why Do we Need a Theory of Consciousness

The next clue to the nature of consciousness is the fact that it is associated with living flesh in particular configurations that we call brains. The type of brain that most clearly exhibits the phenomenon is a subtype of the basic design, called the human brain. We can (for the reasons discussed above) be pretty sure that our own brain and other people's brains are conscious (ignoring, because it is too unspeakably dull to even discuss, the solipsism argument) and most would make a case for the brains of higher animals, such as chimps, sharing that property, at least in some form. But not all living flesh is conscious. Our livers aren't conscious. Neither is our colon nor our kidneys. Only brains are conscious. So it must be something about the structure of brains that generates the phenomenon of consciousness. This fact requires an explanation. But even living human brains aren't always aware. Our brain remains very active in the state we call unconsciousness, and even when we are...

Inferences to Cognitive Architecture from Individual Case Studies

Neuropsychology has relied on a variety of methods to obtain information about human cognitive architecture from the profiles of capacities and incapacities presented by normal and abnormal subjects. The nineteenth-century neuropsychological tradition associated with Broca, Wernicke, Meynert, and Lichtheim attempted to correlate abnormal behavior with loci of brain damage, and thus to found syndrome classification ultimately on neuroanatomy. At the same time, they aimed to use the data of abnormal cognitive incapacities to found inferences to the functional architecture of the normal human cognitive system. Contemporary work in neuropsychology involves statistical studies of the correlation of behavior with physical measures of brain activity in both normal and abnormal subjects, statistical studies of the correlations of behavioral abnormalities in groups of subjects, and studies of behavioral abnormalities in particular individuals, sometimes in conjunction with information about...

The Basicranium as a Template for Facial Growth

Human craniofacial growth and development is basically not different from that in other mammalian species. In mammals the neurocranium (brain) determines in a phylogenetic relationship the development and growth of the viscerocranium (face),with the basi-cranium (cranial base) as a template in between. The enormous expansion of the human brain led to expansion (Fig. 8.1) and bending (so-called basicranial flexure Fig. 8.2) of the basicranium. This process resulted in an inferior and posterior rotation of the human face with forward rotation of the orbits. Therefore, the architectonic morphologic plan of the human face is wide and vertically flattened, in contrast to the narrow and long viscerocranium of phylogenetically lower mammalian species (e.g. sheep Figs. 8.3,8.4).

Cortical excitation and inhibition by the corpus callosum

Doty says that very little is known about the neural signals that pass between the hemispheres, and the same could be said of the effects of these signals on their target neurons in the human brain. In the analysis of in-terhemispheric interactions, it is often claimed that one hemisphere may wholly inhibit or facilitate the other hemisphere in a multitude of sensory, motor, and cog-

Stem Cell Transplants

The discovery that the mature human brain possesses neuronal stem cells that yield new neurons into advanced age was groundbreaking and has provided major impetus to research into the potential of stem cells to definitively treat degenerative disorders, including Alzheimer's disease. Researchers hope that stem cells might be able to restore damaged brain functions by replacing cells that were destroyed. Stem cells might also be able to slow or stop 190, further damage by helping to bathe neurons in protective chem

Collective Unconscious

Jung called this deeper unconscious (symbolized by the deeper cellar) the collective unconscious. This collective unconscious is the core of Jung's mysticism and is the concept least accepted by mainstream psychology. Jung described the collective unconscious as inherited, contained in human brain structure and not dependent on personal experience to develop. It can be described as prewired circuits in our brain, to use an electrical metaphor, or ROM (read-only memory) chips, to use a computer metaphor content that is built into the machine at the factory and not changed by the user. The collective unconscious can also be illustrated with imagery from science fiction. Human beings, no matter how far they might travel to distant galaxies, bear the imprint of ancestors who originated on a planet with seasons and with 24-hour days, even if they have been born in a spaceship somewhere in space and have never personally experienced life on Earth. The collective unconscious is shaped by the...

The Cognitive Blueprint

Like an ever-brachiating network growing exponentially, the human brain became by far the most complicated entity known to man. With more profusely arborized neurons working in parallel synchrony, the computational powers of the human The relative indifference to the environment springs, I believe, from deep within human nature. The human brain evidently evolved to commit itself emotionally only to a small piece of geography, a limited band of kinsmen, and two or three generations into the future . . . because it is a hardwired part of our Paleolithic heritage. For hundreds of millennia, those who worked for short-term gain within a small circle of relatives and friends lived longer and left more offspring. Our conscious AWAREness engages only a tiny fraction of the psychological activity that may be found just below the level of conscious thoughts. The human brain is aglow with untold millions of neural circuits flashing their electrochemical messages from one module to another....

Neuropsychological Dissociations Between Visual Working Memory And Spatial Working Memory

Corsi Block

In summary, the behavioural data from the literature indicate a clear dissociation in performance of the visual pattern memory and immediate memory for location or mental spatial manipulation, but there is no clear lateralization of function for movement sequence memory or for visual pattern memory. This again suggests that a simple mapping of well-established behavioural dissociations onto neuroanatomy might be too simplistic.

Historical Developments

The soul or mind squeezed the pineal gland this way and that, nudging the animal fluids in the human brain into the pores or valves, 'and according as they enter or even only as they tend to enter more or less into this or that nerve, they have the power of changing the form of the muscle into which the nerve is inserted, and by this means making the limbs move.' (Jaynes, 1973, p. 172, paraphrasing and quoting from Descartes, 1824, p. 347)

Assessment Of Receptorg Protein Interactions Using [35SGTPyS Autoradiography

G-protein-coupled receptor complexes are functional in brain tissue sections (30). Therefore, 35S GTPyS autoradiography can be used to localize and quantify activated G proteins while preserving brain anatomy (1,4). Because 35S GTPyS autoradiography labels functionally active receptor-G protein complexes, this method can be used for receptor desen-sitization studies (31). For example, chronic in vivo drug treatment decreases agonist-stimulated G-protein activation in brain regions known to be involved in the development of physical dependence and drug tolerance (32). G-protein-coupled receptors comprise 30 of small-molecule drug targets (33). Therefore, 35S GTPyS autoradiography can be used to analyze functional changes at the level of G proteins as a direct result of drug administration. A recent example is provided by a study using 35S GTPyS autoradiography to demonstrate that chronic consumption of ethanol in rats uncouples 5-opioid receptors from G proteins (34).

Corpus Callosum Morphology in Relation to Cerebral Asymmetries in the Postmortem Human

Abstract In this chapter we present data of fine callosal structure in postmortem humans revealing regional differences in fiber composition that indicate differences in interhemi-spheric transfer between primary secondary sensorimotor areas, on the one hand, and higher-order cortical regions, on the other. In addition, we review evidence from studies concerning a negative relation between interhemispheric communication and brain lateralization in the human as indexed by anatomical asymmetry in the Sylvian fissure and on individual differences in this relation. Since the topic of anatomical asymmetry in perisylvian regions is now a debated issue, it is necessary to delve into some details about the morphology of the Sylvian fissure. Therefore, the chapter begins with a review of callosal anatomy in the postmortem human at both the macroscopic and microscopic levels, continues with a critical review of the current status of anatomical asymmetry in the posterior language region and its...

The CEMI Field Theory

The CEMI field theory 34, 35 suggests that processing information through the wave-mechanical dynamics of the CEMI field provided a significant advantage to our ancestors that was captured by natural selection to endow our minds with the capability to process information through fields. MacLennan 32 has proposed that the brain is capable of field computing (which has many of the attributes of quantum computing) that may perform some operations with greater efficiency, or with fewer resources, than can be achieved in a digital system. In a similar way, optical holograms can perform convolution, deconvolution and Fourier transforms, at the speed of light, acting on massively parallel data sets. Sending information through the electromagnetic field may similarly confer novel information processing capabilities on the human brain that have been captured by our conscious mind.

The Problem Of Detecting Brain Plasticity

Given this orderly map of the hand (and other body parts) in the cortex, we can ask the following question Does it change as a result of sensory experience or deprivation The organization of the normal map can be determined in great detail by recording receptive fields for neurons at many places in the map (hundreds of places) with penetrating microelectrodes, and using this information to reconstruct the map. All of the neurons recorded in the territory of digit 3, for example, will have receptive fields centered on digit 3, and even have most or all of each receptive field on digit 3. After any manipulation that might alter the organization of the map, microlectrode recordings can be used to characterize the potentially altered map, and the results can be compared with previously obtained maps from normal or inexperienced monkeys, a map from the same monkey before the manipulation, and even the unchanged morphological map from the manipulated monkey. Prolonged, intense stimulation...

Homotopic callosal connectivity

Homotopic Connectivity

The anatomy of the human corpus callosum has been intensively studied (Reeves 1985) and it is known that primary sensory and motor cortical regions characteristically lack callosal fibers, while most of the other parts of human cerebral cortex send and receive commissural fibers (Figure 5-5). The absence of callosal fibers in early sensory cortex is presumably due to the fact that there is no advantage in mixing the sensory stimuli from both the left and right sensory fields at an early stage of processing. In contrast, at higher-level cortical regions, a comparison of the sensory data obtained from the left and right can be a valuable means determining the nature and location of the stimulus. This is known to be the case both for depth perception in vision, where the slightly different images at the left and right retinas allow for an estimation of the distance of the object from the observer, relative to the distance between the eyes. Similarly, the slight differences in the...

Overview of the Contributions

Must devise to test hypotheses that quantum effects have a fundamental place in the phenomenon of consciousness. These authors astutely identify that the three different scale ranges to address are (1) tissue-to-cell, (2) cell-to-protein and (3) protein-to-atom. The authors exclude experiments that aim to detect quantum effects at larger levels arguing negative results and inconsistencies. Mershin and coauthors pay particular attention to those consciousness experiments belonging to the tissue-to-cell scale frequently utilizing techniques such as electroencephalography (EEG) or magnetic resonance imaging (MRI) to track the activity of living, conscious human brains. They point to experiments by Christoff Koch's group, for example, designed to elucidate the multi-and single-cellular substrate of visual consciousness and likely to lead to profound insights into the working human brain. Nonetheless, because of the large spatial and long temporal resolution of these methods, Mershin et...

Mapping Structural Alterations of the Corpus Callosum During Brain Development and Degeneration

Abstract In this chapter we review current neuroimaging research on the structure of the corpus callosum. The corpus callosum is the main fiber tract connecting the two brain hemispheres, consisting of approximately 200-350 million fibers in humans. Given the corpus callosum's importance in communicating perceptual, cognitive, mnemonic, learned, and volitional information between the hemispheres, it has not surprisingly been a focus of many studies examining structural and functional neuropathology. We and other groups have investigated callosal abnormalities in Alzheimer's disease, multi-infarct dementia, schizophrenia, attention deficit hyperactivity disorder, and multiple sclerosis and during normal and aberrant development. Nonetheless, extreme variations in brain structure make it difficult to design computerized strategies that detect and classify abnormal structural patterns. Intense controversy exists on the question of whether different callosal regions undergo selective...

Multiplicity of GABAa Receptors

As other members of the superfamily of ligand-gated ion channels that also include the nicotinic acetylcholine (nACh) receptor, the 5-hydroxytryptamine type-3 receptors, and the glycine receptors, GABAa receptors are made up of five subunits that can belong to different subunit classes (a, P, y, 5, e, n, 0, p). Within each class the subunits exhibit a 60-70 homology In between the classes the homology is only 30-40 (1,3). So far, a total of six a-, three P-, three y-, one 5-, one e-, one n-, one 0-, and three p-subunits of GABAA receptors as well as alternatively spliced isoforms of several of these subunits have been cloned and sequenced from the mammalian nervous system (1,3). At least for the human brain this subunit set seems to be final. In a recent study, by applying search algorithms designed to recognize sequences of all known GABAA-receptor type subunits in species from man down to nematodes, no new GABAA-receptor subunits were detectable in the human genome (4). However, in...

For the Seven Clues to the Nature of Consciousness

The only place in the known universe where electromagnetic fields occur that are capable of communicating self-generated irreducibly complex concepts like self (and thereby persuading an observer that they are indeed conscious) is in the human brain. Artificially generated electromagnetic fields, such as the electromagnetic fields that communicate radio and TV signals, are only capable of communicating the information encoded and transmitted within their fields. They have nothing else to say. To question whether they are either aware or conscious is meaningless.

Magnetic resonance imaging MRI Also called

Magnetite A natural magnetic material, commonly known as lodestone, magnetite is found in the brains of certain animals, from homing pigeons to whales the animals use the internal magnets to help orient their sense of direction. Recently, scientists at the California Institute of Technology in pasadena have found magnetite crystals in tissues of the human brain as well.

The Neurobiology of Dyslexia

Examination Health Boys

Figure 1 shows a diagram of the eyes and brain. Defects at every stage from the retina (Grosser & Spafford, 1989, 1992 Stordy, 2000) through the midbrain to the cerebral cortex and the cerebellum have been said to be involved in dyslexia. Figure 2 shows the main features of the human brain which are referred to in this chapter.

The central dogma of human neuropsychology

Since most mammalian species show few, weak or simply no indications of lateral specialization, why would the human brain show such unmistakable and pervasive functional asymmetry Why are we so different Speculations about mechanisms abound, but most suggestions about the origins of laterality suffer from over-prediction. If human left-right asymmetry has its origins in the parity of fundamental particles, the directionality of DNA twisting, the unequal importance of molecular stereoisomers, the off-center position of the heart, or something asymmetrical about fetal life, then the functional asymmetry of the human brain should certainly have analogs in the brains of a great many animal species, primitive and advanced. That is simply not the case.

Bihemispheric Dissonance

Alivisatos, B., & Petrides, M. (1997). Functional activation of the human brain during mental rotation. Neuropsychologia, 35, 111-118. Binder, J., Frost, J., & Hammeke, T. (1997). Human brain language areas identified by functional magnetic resonance imaging. Journal of Neuroscience, 17, 353-362. Cook, N. D., Callan, D. E., & Callan, A. (2002a). Frontal areas involved in the perception of harmony. 8th International Conference on Functional Mapping of the Human Brain. Sendai, June 2-6. Heun, R., Klose, U., Jessen, F., Erb, M., Papassotiropoulos, A., Lotze, M., & Grodd, W. (1999). Functional MRI of cerebral activation during encoding and retrieval of words. Human Brain Mapping, 8, 157-169. Kiehl, K. A., Liddle, P. F., Smith, A. M., Mendrek, A., Forster, B. B., & Hare, R. D. (1999). Neural pathways involved in the processing of concrete and abstract words. Human Brain Mapping, 7, 225-233. Price, C. J., Wise, R. J. S., Warburton, E., Moore, C. J., Patterson, K., Howard, et...

Exploring the Three Pound Universe

Liver Cell Tem Microscope

The human brain has been described as the three-pound universe 46 because, along with some other mammalian brains, it is the single most complex system so far discovered in the entire cosmological realm. It is also the most mysterious. Although we have developed supercomputers, their architecture remains that of a simplistic deterministic automaton by comparison with the brain. Despite the vast increases of speed and memory capacity of modern computers, they remain trivial by comparison. Few have more than a few processing units and the communication protocols for parallel processing, outside simple matrix calculations, remain simple procedural farming out. The notion that a computer may some day also become subjectively conscious is at this point a science fiction fantasy. Fig. 13.7. Human brain showing key underlying structures (Sci. Am. Sep 92) indicate a massively parallel organization with feedback loops linking major cortical and limbic areas and interfacing them with midbrain...

The Cognitive Big Bang and the Emergence of

That points to plausible answers to this central ques- There are more synaptic connection. A critical mass of cortical neurons of vari- tions in the human brain than ous types is essential to understanding terrestrial there are stars in our galaxy. intelligence. The human brain evolved over millions of years for adaptive purposes. One important component of adaptation was the facility to image and respond to things not present. One did not need, for example, to feel the sting of an angry snake in

General Features of the Brain

Cerebro Ntico

The human brain is larger than brains of most other species, particularly animals of similar or smaller size. Recent studies using magnetic resonance imaging (MRI) verify earlier research that the typical human brain is approximately 1100 cm3 in volume and has a surface area averaging 1700 cm2 67 . Fig. 3.1. Areas of the human brain drawn according to the scheme of Brodmann 10 . The colors refer to areas of the same (visual, somatosensory, auditory or motor) modality. Prefrontal and limbic (cingulate and parahippocampal) areas are shown in white. Olfactory area is shown in black Two features of the human brain are believed to account for its elevated cognitive capabilities increased number of modules in association areas and more convolutions compared to lower animals. The cerebral cortex is hierarchical in nature. Higher association areas receive projections from lower levels of sensory cortex, as well as from thalamic regions specifically supplying those regions. These higher...

Microtubules and Quantum Entanglement A Possible Basis for Memory and Consciousness

In summary, the human brain defines a volume of space (on average 1100cm3) in which many types of interaction are possible. Space has a minimum nonzero volume of approximately 10 99 cubic centimeters (one cubic Plank length) this translates into 10102 cubic Planck lengths in the human brain. Since quantum states of entanglement in the human brain would be influenced by all possible factors - including electrophysiological (membrane potentials, action potentials), mechanical (transport along micro-tubules), biochemical (phosphorylation of MAP2 detyrosination, acetylation and polyglutamylation of microtubules), biophysical (microtubule polymerization), metabolic (energy utilization), electromagnetic and gravitational -one can argue that it can only be the state of brain-wide quantum coherence that corresponds with the cognitive state. Since tubulin and MAP2 compose a sizable percentage of brain protein, microtubules would be expected to contribute greatly to the equation. The presence...

The Human Mind as a Set of Fitness Indicators

We could call this the healthy brain theory, in contrast to the runaway brain theory The healthy brain theory suggests that our brains are different from those of other apes not because extravagantly large brains helped us to survive or to raise offspring, but because such brains are simply better advertisements of how good our genes are. The more complicated the brain, the easier it is to mess up. The human brain's great complexity makes it vulnerable to impairment through mutations, and its great size makes it physiologically costly. By producing behaviors such as language and art that only a costly, complex brain could produce, we may be advertising our fitness to potential mates. If sexual selection favored the minds that seemed fit for mating, our creative intelligence could have evolved not because it gives us any survival advantage, but because it makes us especially vulnerable to revealing our mutations in our behavior.

Brown Sequard Charles Edouard

The heaviest known normal human brain belonged to the Russian writer Ivan Turgenev, who died in 1883. His brain weighed 4.43 pounds, more than a pound heavier than the average male brain. The smallest known normal brain belonged to a woman who died in 1977 her brain weighed just 2.41 pounds.

Environment and Neurodegenerative Diseases

The situation with regard to stress and the aging human brain is by no means clear, but some studies on aging people suggest a relation between stress hormones and difficulties with memory tasks. In one study, 11 healthy subjects in their sixties or seventies were followed for four years. Of these, six showed increased levels of cortisol, one of the main glucocorticoids released from the adrenal gland in stress. The other five had stable or decreased levels of cortisol. The six whose cortisol levels increased over the four years had difficulty with certain memory tasks such as navigating a maze or remembering a list of words. Those whose cortisol levels remained low or even decreased somewhat performed these tests with no difficulties. A subsequent fMRI study showed that the hippocampi of subjects with higher cortisol levels were smaller by about 14 percent.

The effects of callosal damage

In cortical regions where the nature of the information is known, callosal functions can be quantitatively studied, but in many frontal and associations areas, the nature of cortical processing itself is uncertain, and the added effects of callosal activity remain unknown. On the one hand, the exchange of sensory hemifield information certainly occurs via the corpus callosum, but the number of callosal fibers increases remarkably from primary to secondary to tertiary sensory cortical regions. Low-level sensory functions are thus apparently not the main chore of this nerve tract. The explosive evolutionary growth of the corpus callosum is strong indication that it serves useful purposes in the mammalian brain and, in the human brain, it is the largest nerve tract present. Firm conclusions concerning the callosal code are not yet possible, but the comments of Creutzfeldt (1995) after a lifetime of study of the cerebral cortex are worth noting

List of contributors

Bechmann, Institute of Clinical Neuroanatomy, J.W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt Main, Germany D. Del Turco, Institute of Clinical Neuroanatomy, J.W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt Main, Germany T. Deller, Institute of Clinical Neuroanatomy, J.W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt Main, Germany T.G. Ohm, Institute of Integrative Neuroanatomy, Department of Clinical Cell and Neurobiology, Charite CCM, 10098 Berlin, Germany A. Rappert, Institute of Clinical Neuroanatomy, J.W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt Main, Germany

Conclusion

The metaphor of the human mind as computer software on a discrete personal computer and the brain the hardware on which this software runs dominated psychology and the cognitive sciences in the latter half of the twentieth century. Interestingly, the notion of a computer disconnected from others is already passe, as mobile computers that are linked through ubiquitous broadband wireless connections have produced remarkable capacities in the form of the Internet. Although access and deposits to the Internet are achieved through the operation of a discrete computer, the study of the software alone of that computer would not reveal its functional capacities given its connectivity and the presence of the Internet. The human brain, of course, has long been mobile and connected to others through broadband telereceptors. A hallmark feature of psychophysiology is the longstanding attention not only to physiological correlates of cognitive or behavioral states but to the elucidation of the...

Physical Context

Another structural scanning technique is diffusion tensor imaging. This technique allows one to identify white-matter tracts (such as corpus callosum) in the human brain and changes in these structures as a function of some variable, such as age or training. Although not a technique to image brain function, tractography, most often performed using diffusion tensor imaging (DTI) in MRI, is a technique that allows the investigator to map the white matter tracts that connect regions of the brain and hence determine the physical connectivity network underlying brain activity (Peled, Gudb-jartsson, Westin, Kikinis, & Jolesz, 1998). MR images can

Future Directions

Pathophysiological changes at the level of G proteins may occur as a result of neurotox-ins, hypoxic ischemic damage, pathogens, and secondary to trauma. Human narcolepsy is a neurodegenerative disease thought to be caused, in part, by a loss of hypocretinergic neurons (57). The effects of diminished hypocretin peptide levels on the plasticity and function of hypocretin receptor-G protein complexes in brain tissue from narcoleptic patients have not been investigated. Agonist-stimulated 35S GTPyS binding can be measured in postmortem human brain samples (58), suggesting future experiments using 35S GTPyS autoradiography to test the functional activity of hypocretin receptor-G protein complexes in brains from nar-coleptic patients. Cell lines expressing hypocretin 2 receptors from narcoleptic dogs showed no G-protein activation upon treatment with hypocretin (36), consistent with the known receptor defect (59) and demonstrating the utility of 35S GTPyS binding for evaluating normal...

The central dogma

In the discussion of the hemispheric contributions to language processing, a remarkable similarity between the effects due to RH damage and callosal damage was noted (Sections A and B) that similarity suggests that normal RH contributions to language are realized through transmission of RH information to the LH across the corpus callosum. Moreover, the most obvious possibility for explaining HERA (Section C) was that the RH contributes to language-processing by communicating callosally with the LH, rather than using its information for direct control over the relevant somatic musculature (the organs of speech). The HERA effect is a clear illustration of hemispheric cooperation that would not be predicted by a simple LH-dominance model of language processing. This pattern of information processing in the human brain can be summarized in what I have referred to as the central dogma of human neuropsychology (Cook 1986,1989,2002a, b) It is central because it involves truly fundamental...

Retrograde Amnesia

Distinction between episodic and semantic memory. However, a difficulty arises in the case of past memory, especially remote autobiographical memory, because it is not easy to agree as to when an individual is engaged in episodic retrieval of specific events and when an individual is drawing on a well-rehearsed base of semantic knowledge. This point was developed in some detail by Cermak (1984). Consequently, caution is merited when trying to interpret the facts of retrograde amnesia in terms of episodic and semantic memory. Regardless of uncertainties about definition, it remains important to assess the quantitative and qualitative features of remote memory for facts and events in amnesic patients. Is remote memory intact Or is there some aspect of remote remembering that is lost after medial temporal lobe lesions or restricted hippocampal lesions The question of interest, then, is how the capacity of amnesic patients to recollect past facts and events compares with the capacity of...

Diazepam

Dimethylaminoethanol (DMAE) This naturally occurring nutrient is found in some types of seafood and in the human brain. Studies suggest this substance may improve memory and learning, elevate mood and increase physical energy, and act as both a mild stimulant and a sleep enhancer. it is believed to improve the brain's production of acetylcholine, which plays an important part in

Hebbian Learning

Several computational models of amnesia introduce some level of modularity to shape the learning process and the formation of long-term memory. Unfortunately, at this point our knowledge of the neuroanatomy of memory is very incomplete, which forces modellers to use a global approach with only a few modules or systems. Before discussing some models in more detail, we will first review some of the neuroanatomical considerations that are pertinent to most computational models of memory disorders.

Conclusions

It has been fashionable at times to highlight the simple neuroanatomy of the dentate gyrus and to claim that it provides a heuristic for studying and understanding the much more complicated neo-cortex. This is probably a misguided strategy. There are numerous features of the dentate gyrus that make it absolutely unique from a neuroana-tomical point of view and thus presumably from a functional point of view as well. The largely unidirectional nature of its inputs and outputs is one distinctive feature. The distinctive mossy fibers that give rise to massive synaptic endings that have as many as 40 active sites onto postsynaptic neurons is another. Our view is that the distinctive neuroanatomy of the dentate gyrus has been sculpted by evolution to play a precise and unique role in the hippocampal information processing that ultimately leads to the production of declarative memories. Whatever computations the dentate gyrus executes will undoubtedly be different from, and will work in...

Scientific Enigmas

A pregenetic version of a directed mutation evolutionary hypothesis originally was advanced by Jean-Baptiste Lamarck nearly two hundred years ago.33 Lamarck suggested that organisms acquire heritable adaptations during their lifetimes through the continual exercise of particular organs or other body parts. By stretching their necks to reach higher branches, giraffes acquire greater neck musculature and length, a disposition transmitted directly to progeny.34 If true, the inheritance of favorable characteristics acquired during the lifetime of an individual would at once alleviate the enigma of adaptive randomness of mutations under traditional Darwinian evolution, and perhaps explain more readily the perceived levels of perfection in adaptive features such as the giraffe's neck or the exercised human brain.

The Ornamental Mind

Our discussion of sensory bias theory and pleasure leads to a different view. Perhaps we can do better by picturing the human brain as an entertainment system that evolved to stimulate other brains brains that happened to have certain sensory biases and pleasure systems. At the psychological level, we could view the human mind as evolved to embody the set of psychological preferences our ancestors had. Those preferences were not restricted to the surface details of courtship like the iridescence of a peacock's tail they could have included any preferences that lead us to like one person's company more than another's. The preferences could have been social, intellectual, and moral, not just sensory.

Studying Memory

Today, new imaging methods such as x-ray computerized tomography and magnetic resonance imaging (mri) allow more precise views of these damaged animal brain sections. pet scans (positron emission tomography) have allowed scientists to study the human brain as it functions for clues to the relationship between brain structure and function.

Patricia E Cowell

The investigation of regional neuroanatomy along dimensions of interest such as male-female differences is a complex task. It might seem at first glance a simple job to compare the size of a brain region in one group of research subjects to the size of the same region in another group. However, even the most straightforward comparisons of neurobiological measures can be contaminated or influenced by variability in the data that is related to factors outside the purview of the particular research in question. For example, a comparison of temporal lobe size in men and women to examine anatomical sex differences in this part of the brain may be affected by other aspects of the subjects' biographies (e.g., age, medical history) or neurobehavioral profiles (e.g., brain size, hand preference) even though these were not the original or primary foci of the study. When the relationships between such other factors and the research measures of interest are not well understood themselves, the...

Tomasz Zabiega

Neurology is the practice of medicine that concentrates on the human brain and nervous system. From higher cognitive disorders (such as Alzheimer dementia) to diseases of nerve and muscle (neuropathies and myopathies), neurologists serve as nervous system specialists at every level. With compassion and dedication, neurologists take care of patients presenting with a wide variety of complaints headaches, numbness, weakness, tremors, seizures, speech difficulty, and changes in consciousness. Although they deal with some of the most distressing and debilitating diseases in medicine, neurologists tend to have an upbeat, calm, and casual attitude. They typically combine a sophisticated level of intellectual curiosity with down-to-earth friendliness and optimism.

Simulations

Effects of specifically the human corpus callosum remains unachieved, but, for the present purposes, it is sufficient to note that the constraints normally imposed on neural network simulations in light of neuron physiology produce a range of effects that include (i) complete hemispheric independence of information processing, (ii) symmetrical or identical processing in both hemispheres, and (iii) asymmetrical or complementary hemispheric activity. These are the three main possibilities that must be examined in relation to the known functional asymmetries of the human brain. Despite the fact that almost every animal nervous system has approximately bilateral symmetry and the problem of bilateral coordination is perhaps the first behavioral issue that must be solved by every mobile organism, there is a surprising lack of simulations specifically on the bilaterality issue. (The exceptions are the bilateral aspects of stereoscopic vision, sound localization and bipedal locomotion, but...

What Brains Do

The anatomy and major lobes of the human brain are shown in figure 4.1. The two halves are called the right and left cerebral hemispheres. The hemispheres are covered with the cerebral cortex, a thin, gray, moist matter richly equipped with the tiny neurons that carry vital information. A diagram of the network of cortical neurons is shown in figure 4.2. The human brain has more than 100 billion (that is, 100,000,000,000) neurons, each capable of receiving messages from and passing on messages to sometimes thousands of other neurons through its many branched-end fibers. Even a simple cognitive act, such as viewing a solitary colored square, involves billions of neurons. The brain is alive with electrochemical messages, which dart through millions of intricate connections choosing some pathways while rejecting others. Through the most elaborate system known to man, percepts are combined with other impressions, encoded for future use, and stored in neural network archives. In a typical...

Genetic Fictions

The word DNA discovered how to rearrange chemicals so as to capture little eddies in the stream of entropy and make them live. . . . The word eventually blossomed and became sufficiently ingenious to build a porridgy contraption called a human brain that could discover and be aware of the word itself.1

The Case of HM

Scientists learned a lot about the neuroanatomy of memory and amnesia more than half a century ago from the case of a young man in Connecticut (now famous in the medical literature as HM) who underwent brain surgery for relief from epileptic seizures. Taking desperate measures to stop the seizures, a Yale surgeon removed large portions of both medial temporal lobes, including the hippocampus, the amygdala, and the entorhinal and perirhinal cortices. The surgery controlled HM's epilepsy, but it left him with profound amnesia.

Pharmacology

The laboratory test most commonly used to measure the effects of warfarin is the one-stage PT test. The PT is sensitive to reduced activity of factors II, VII, and X but is insensitive to reduced activity of factor IX. Confusion about the appropriate therapeutic range has occurred because the different tissue thromboplastins used for measuring the PT vary considerably in sensitivity to the vitamin K-dependent clotting factors and in response to warfarin.86,87 Rabbit brain thromboplastin, which has been widely used in North America, is less sensitive than is standardized human brain thromboplastin, which has been widely used in the United Kingdom and other parts of Europe. A PT ratio of 1.5 to 2.0 using rabbit brain thromboplastin is equivalent to the current therapeutic range (i.e., INR 2.0 to 3.0).86,87 Conversely, a two- to three-fold increase in the PT using standardized human brain thromboplastin is equivalent to a 1.25- to 1.5fold increase in the PT using a rabbit brain...

Individualized Atlas

And cytoarchitectural boundaries can be used to measure neuroanatomy differences in individual subjects or groups (see Figures 5.5-5.10). Three-dimensional mapping of very local differences in structure (d) is possible only with a high-dimensional warping technique (Christensen et al., 1996 Da-vatzikos et al., 1996 Thompson and Toga, 1996). (See Color Plate 1.) and cytoarchitectural boundaries can be used to measure neuroanatomy differences in individual subjects or groups (see Figures 5.5-5.10). Three-dimensional mapping of very local differences in structure (d) is possible only with a high-dimensional warping technique (Christensen et al., 1996 Da-vatzikos et al., 1996 Thompson and Toga, 1996). (See Color Plate 1.)