Neurosurgery A professional group for neurosurgeons practicing stereotactic surgery, a technique for inserting delicate instruments in precise areas of the nervous system. The group compiles statistics, maintains a biographical archives, and plans to establish a museum.
Founded in 1968, the group is affiliated with the AMERICAN ASSOCIATION OF NEUROLOGICAL SURGEONS and the congress of neurological surgeons.
The group publishes the bimonthly Stereotactic and Functional Neurosurgery and holds a biennial scientific meeting and a semiannual congress.
American Spinal Injury Association A professional organization for health care professionals who have been trained in the care of spinal paralytic patients. They are either actively engaged in the field and acknowledged to be competent or have made a significant contribution to the advancement of the basic sciences or one of the clinical fields of practice as they are applicable to the treatment of the spine.
The purposes of the association are to develop knowledge and investigation of the causes, cure, and prevention of spinal injury and related trauma; to pursue excellence in patient care; to promote and exchange ideas; to standardize medical terminology in spinal cord injury; to coordinate basic research; to develop teaching material; and to provide specialized training. Founded in 1973, the association publishes a semiannual bulletin and other publications.
amino acids The fundamental building blocks of protein, this term refers to any of a number of organic compounds containing an amine and a car-boxyl group. The body uses amino acids as the basic substance from which to construct not only proteins but neurotransmitters as well.
Individual amino acid molecules are linked together by chemical bonds (called peptide bonds) to form short chains of peptides called polypep-tides. In turn, hundreds of these polypeptides are linked together to form a protein molecule. one protein differs from another in the way their amino acids are arranged.
A total of 20 different amino acids make up all the proteins found in the human body; 12 can be made within the body (known as nonessential amino acids). The other eight (called the essential amino acids) must be obtained from the diet and cannot be produced by the body. In addition, there are about 200 other amino acids not found in proteins but which play an important part in chemical reactions within cells.
Animal sources usually provide a wider range of amino acids than do plant sources, so people on a vegetarian diet must be especially careful that their selection of food includes all of the essential amino acids.
Because the amino acids are responsible for producing neurotransmitters, some researchers believe that boosting the brain's supply of certain amino acids should also increase the production of neuro-transmitters, affecting both mood and cognition. Two amino acids have been singled out for particular study: tryptophan and tyrosine.
Some studies have suggested that tryptophan may ease depression and boost effectiveness of antidepressants. In addition, several controlled trials have suggested that tyrosine appears to improve alertness and cognitive performance in the face of stress.
on the other hand, increasing the pool of amino acids does not necessarily mean more neurotrans-mitters will be made.
amnesia Loss of the ability to memorize or recall stored information. In most cases of amnesia, the patient has problems storing information in long-term memory and recalling this information.
There are many theories that explain the underlying mechanism of amnesia and many different causes, including brain damage from injury or disease. Anterograde amnesia is the loss of memory for events following trauma; retrograde amnesia is a loss of memory for events preceding the trauma. Some patients experience both types of amnesia.
Amnesia following an injury (such as a concussion) in areas of the brain concerned with memory function is known as traumatic amnesia. Degenerative disorders such as Alzheimer's disease or other types of dementia may also cause amnesia, as can infections such as encephalitis or a thiamine deficiency in alcoholics. Amnesia could also be caused by a brain tumor, a stroke or a subarachnoid hemorrhage, or certain types of mental illness for which there is no apparent physical damage.
This type of uncommon amnesia refers to an abrupt loss of memory for a few seconds to a few hours without loss of consciousness or other impairment. During the amnesia period, the patient cannot store new experiences and suffers a permanent memory gap for the period of time during the amnesic episode. There may also be loss of memory encompassing many years prior to the amnesia attack; this retrograde amnesia gradually disappears, although it leaves a permanent gap in memory that does not usually extend backward more than an hour before onset of the attack. These attacks, which may occur more than once, are believed to be caused by a temporary reduction in blood supply in certain brain areas. Sometimes, they act as a warning sign of an impending stroke.
The attacks, which usually strike healthy, middle-aged patients, may be set off by many things, including sudden temperature changes, stress, overeating, or sexual intercourse. While several toxic substances have been associated with transient global amnesia, it is believed that the attacks are usually caused by a transient cerebral ischemia to regions of the brain involved in memory.
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