Science News, November 16, 2002 Vol 162, p. 307. Thoughtful lessons: training may enhance learning in elderly In work reported in JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, healthy people between the ages of 65 and 94 were randoomly assigned to one of three training groups in the three domains of though (memory, problem solving, concentration) or to a control group that received no training. Those in thought training received about 10 hours of training over a five to six week period, with a refresher course 11 months later. Those involved in training improved their thought techniques with results lasting at least two years. 26% of those in memory training showed substantial improvement” in the targeted skills, while 74% did so in reasoning and 87% did in visual concentration. Those in the group receiving no training demonstrated either no improvement or a decline in thinking skills over the same period of time. The results show promise for helping the elderly maintain the ability to perform daily tasks later in life.
Science News, November 2, 2002 Vol 162, p. 285. Brain trait fosters stress disorder The hippocampus, unusually small in humans who experience post-traumatic stress disorder, may in fact possess an undersized hippocampus before developing PTSD.
In work reported out of Harvard Medical School in the NATURE NEUROSCIENCE, the long held theory that hormonal response to trauma shrinks the hippocampus may in fact be incorrect. A naturally small hippocampus may actually predispose an individual to formation of intense and highly emotional response to stimuli associated with traumatic events. Other research does indicate that there is indeed trauma-induced atrophy of the hippocampus. So hippocampal size may predispose one to as well as be effected by trauma.
Science News, November 2, 2002 Vol 162, p. 275. Neural Shape-Up: Brain anticipates object perception It appears that when humans see objects, the frontal lobe of the brain make actually take precedence over the primary visual cortex in identification of that object and hence, understanding of it. It appears that the brain actually assembles the features perceived into perceptions of shapes and objects, by anticipating structure based on past experiences, and “fills in the blanks.” Although preliminary in nature, the research reported in PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES may indicate that the primary visual cortex sorts basic visual elements until the lateral occipital complex recognizes the object and thus inhibits neural activity in the visual cortex. This runs contrary to earlier belief that feedback always enhances neural activity in another brain region.
Nature, Vol. 419, 17 October 2002, p 683-684. Neurotrophin channels excitement, by Yves-Alain Barde. Although sodium ion channels open in response to the change of voltage across the membrane in which they reside, there is an additional growth factor secreted by neurons that triggers the quick opening of a specific sodium channel. It is ion channels, proteins, that regulate the transfer of ions. These proteins aid in the physiological processes for brain communication and action, transferring information. These ions are sodium in vertebrates, entering neurons through channels in a cell membrane that open as a result of trans-membrane voltage changes.
Work by A. Konnerth, K. Kafitz, and R. Blum from the Institut fur Physiologie, Ludwig-Maximilians-Universitat Munchen now “…indicate that a brain protein secreted by neurons is involved in opening one particular sodium channel, known to occur in sensory neurons of the peripheral nervous system” (BDNF: a growth factor, neurotrophin). Until now, only neurotransmitters were known to have this rapid effect on potentiation of neurons. The speed of action is milliseconds, important when they bind to receptors that are ion channels which open briefly.
BDNF is comprised of amino acids; neither of the two known receptors to which it binds is an ion channel. One receptor is an enzyme (tyrosine kinase), which mediates some typical biological activities. Such work may erase a distinction between the physiological properties of neurotrophins and neurotransmitters.
Nature Reviews Neuroscience, Volume 3, October 2002, p.803-811. Activity Dependent Regulation of Dendritic Growth and Patterning, by Rachel O. L. Wong and Anirvan Ghosh. This article examines the causes of dendritic development, central to neuronal communication and activity. Although growth and patterning are not fully understood, calcium plays a major role. Changes in intracellular calcium in affected pathways influence the differentiation of neurons and axon path-finding. Recent findings prove that dendritic development is regulated by both activity dependent and independent cues. The latter may indeed dominate during embryonic periods, and the former may dominate after the birth of mammals.
Science News, October 12, 2002, Vol. 162, p.237. Stressing out Research done in the Netherlands and reported in the October DIABETES publication indicates that some of the more than 200 people in a long term health study showed a particular gene variant that caused less sensitivity to the effects of cortisol, a stress hormone. Those with the gene variant were less prone to high concentrations of insulin, glucose and cholesterol in their blood. There was also less of a tendency to develop atherosclerosis. This may reduce risks of heart disease and diabetes.
The gene variant was two times as common in volunteers past age 66 – perhaps an indication that the gene variant affects longevity. The belief is that this discovery will help doctors determine which patients might require aggressive treatment for maladies related to diabetes, heart disease, and other age-related illness.
Science News, October 12, 2002, Vol. 162,p.227. Attention Loss In work done by F. Xavier Castellanos of NYU and reported in the JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, October 9, , it was found that ADHD children had brain volumes roughly 3% less than those of unafflicted children. Although brain development was parallel in both groups, the proportion of the disparity remained the same. White matter, the portion of the brain that indicates established neural connections, was also smaller in volume in non-medicated ADHD children than normal brains.
Data revealed that several brain areas were smaller in youngsters with the most severe forms of ADHD, including inattention, hyperactivity and impulsiveness, than in children with milder symptoms. The areas involved are located in the frontal and temporal lobs, in the caudate nucleus in the mid-brain region, and the cerebellum. Much earlier research found the frontal lobe to be primarily implicated. The implication of the cerebellum, usually associated with coordinated motion and balance, may indicate that the additional role of the cerebellum in coordinating thoughts and emotions.
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Science News, October 19, 2002 Vol 162, p. 251-252. Spreading Consciousness: Awareness goes global in the brain. By Bruce Bower. Dan Lloyd of Trinity College in Hartford, Connecticut has begun a controversial analyses of brain data from people performing visual tasks. The neural response extraneous to the tasks is eliminated, leaving dramatic highlights of activity surges. This gives a brain-based sense of time, creating a sort of awareness of consciousness. Although Lloyd, as well as neuroscientists, doubt there is a center of consciousness in a human brain, but Lloyd says that the sense of time is created through a “…melding of awareness of what one has just perceived, what one currently perceives, and what one expects to perceive in the coming moments.”
Nature, Vol. 419, 17 October 2002, p 683-684. Neurotrophin channels excitement, by Yves-Alain Barde. Although sodium ion channels open in response to the change of voltage across the membrane in which they reside, there is an additional growth factor secreted by neurons that triggers the quick opening of a specific sodium channel. It is ion channels, proteins, that regulate the transfer of ions. These proteins aid in the physiological processes for brain communication and action, transferring information. These ions are sodium in vertebrates, entering neurons through channels in a cell membrane that open as a result of trans-membrane voltage changes.
Science News, October 12, 2002, Vol. 162, p.237. Stressing out Research done in the Netherlands and reported in the October DIABETES publication indicates that some of the more than 200 people in a long term health study showed a particular gene variant that caused less sensitivity to the effects of cortisol, a stress hormone. Those with the gene variant were less prone to high concentrations of insulin, glucose and cholesterol in their blood. There was also less of a tendency to develop atherosclerosis. This may reduce risks of heart disease and diabetes.
Science News, October 19, 2002 Vol 162, p. 251-252. Spreading Consciousness: Awareness goes global in the brain. By Bruce Bower. Dan Lloyd of Trinity College in Hartford, Connecticut has begun a controversial analyses of brain data from people performing visual tasks. The neural response extraneous to the tasks is eliminated, leaving dramatic highlights of activity surges. This gives a brain-based sense of time, creating a sort of awareness of consciousness. Although Lloyd, as well as neuroscientists, doubt there is a center of consciousness in a human brain, but Lloyd says that the sense of time is created through a “…melding of awareness of what one has just perceived, what one currently perceives, and what one expects to perceive in the coming moments.”
A statistical analysis of sets of MRI data supports this theory, according to the August 15 JOURNAL OF COGNITIVE NEUROSCIENCE. Lloyd claims that there is a “…global brain state that is in constant flux, creating conscious experiences.” In the snapshots of blood flow taken during the fMRIs, the activated parts of the brain of control volunteers is extracted from the pictures taken from experimental volunteers performing assigned tasks. The average data arising from repeated samples of comparisons and then subtracting responses from control conditions leave islands of brain activity for the experimental brain function goal. This grows from theories concerning consciousness proposed over half a century ago by Philosopher E. Husserl. The theory held that conscious perceptions are always in flux as a result of being a blending of past perceptions, current experience, and anticipation of what is to come.
Nature Reviews Neuroscience, Volume 3, October 2002, p.765. To branch or not to branch, by Heather Wood. In studies of the nervous system using Drosophila and reported in SCIENCE magazine, the amount of branching in neuronal dendrites may depend on genetic tendencies. A gene nicknamed “ham” (a mutated gene) causes all neurons to adopt the characteristics of those which allow densely branched dendrites. The more complex the branching of dendrites, the more imput a neuron will receive.
Those with the Ham gene alternatively expressed have suppressed dendritic branching. Much research needs to be done to discover if human dendritic branching is affected by similar genetic predispositions.
Nature Reviews Neuroscience, Volume 3, October 2002, p.767-779. Developmental
Dyslexia: Genetic Dissection of a Complex Cognitive Trait, by Simon E. Fisher and John C. DeFries.The impairment of reading ability known as dyslexia results from a neurobiological syndrome that is inheritable. This research isolates the genetic risk factors, and implicates genes that influence dyslexia and other language traits. Dyslexia is an impairment in the “…representation and manipulation of phonemes.” Because of the varied symptoms of the disorder, there is a possibility that more than one process that are in deficit: the processing of phonemes, and the timely naming of visual stimuli (such as digits, letters, objects, etc.).
This article gives a good picture of the current state of research in developmental dyslexia. It examines the background of the study of dyslexia, and the theories as to causes of the impairment. It also deals with the dilemma resulting from lack of understanding of the true “mechanisms that underlie dyslexia,” and therefore state that there is no reason yet to believe that a single gene will be the sole risk factor. In fact, there is suspicion that there may be related subtypes of the disorder (spelling, reading, speech, etc.) and selective deficits that can take phonological or orthographic pathways. Also a dilemma is that there is no apparent and clear correspondence between a person’s genetic makeup (such as those with inherited high-risk genotypes) and that same person’s cognitive abilities.
Science News, October 5, 2002, p.213. Making Mice Mellow: Rodents yield clues to improved anxiety drugs. New drugs are being tested for treatment of anxiety disorders that fight anxiety, zeroing in on medications that deviate from the traditional approach of treatment by working on receptors for GABA and serotonin. Mice are bred to lack the gene for protein kinase Cepsilon in order to bring on calmness and curiosity in stressful situations. The lack of this protein improves the sensitivity of GABA receptor sites on neurons, increasing the effects of GABA at the synapse. GABA is an inhibitor, and its depletion is linked to anxiety disorders. These new drugs appear to reduce signs of fearfulness and the increase the willingness for exploration – while avoiding the addictive nature and drowsy behavior associated with previous treatments for anxiety. This work comes out of University of North Carolina, Chapel Hill. Its co-author is Clyde W. Hodge.
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