2002 Archive‎ > ‎

Vol. 3, No. 3 - 22 January 2002

This week's issue of COMET focuses on recent research in the neurosciences



(1) "The Secret Life of the Brain"

Source:  PBS

URL:  http://www.pbs.org/wnet/brain/

"The Secret Life of the Brain"...reveals the fascinating processes involved in brain development across a lifetime. The five-part series, which will premiere nationally on PBS [tonight, January 22, at 9 p.m. on most stations], informs viewers of exciting new information in the brain sciences, introduces the foremost researchers in the field, and utilizes dynamic visual imagery and compelling human stories to help a general audience understand otherwise difficult scientific concepts.

(2) "Wired for Mathematics: A Conversation with Brian Butterworth" by Marcia D'Arcangelo

Source:   Educational Leadership - November 2001

URL:  http://www.ascd.org/readingroom/edlead/0111/darcangelo.html

...Brian Butterworth [Professor of Cognitive Neuropsychology, Institute of Cognitive Neuroscience, University College-London] describes the brain's innate ability to process numbers and explains why some students, nevertheless, have trouble understanding mathematics.

Marcia D'Arcangelo (MD): One of the most fascinating ideas in your book What Counts: How Every Brain Is Hardwired for Math (Free Press, 1999) is that we are born with a sense of numbers. What exactly is this number sense?

Brian Butterworth (BB): The number sense is having a sense of the manyness, or numerosity, of a collection of things. We believe that babies are born with a kind of start-up kit for learning about numbers that is coded in the genome. Even in the first week of life, babies are sensitive to changes in the number of things that they're looking at, and at six months they can do very simple addition and subtraction. Then, with this start-up kit, they build all the cultural tools--the number words, the counting practices, and the arithmetical procedures and facts that they learn from parents and from school...

MD: Perhaps many people are better at math than they think they are. But if our brains are hardwired for math, why do so many students have such difficulty with it?

BB: Not being good at mathematics can have two main causes. The first is genetic. A minority of people may be born with a condition that makes it difficult for them to learn mathematics; that is, they are born with dyscalculia or are born with dyslexia, which also can have a consequence for mathematics learning. A far more likely cause is that they were taught badly. That means taught in a way that left them failing to understand what they were doing. Thus, everything else that they learned that was based upon what they didn't understand was going to be very fragile. So, they avoided mathematics.

MD: You mentioned dyslexia. Do we use the same parts of the brain that we use for learning to read to learn mathematics?

BB:  The parts of the brain that process words are different from the parts of the brain that process numbers. We store words in two areas, Wernicke's area in the left temporal lobe, at least in most right-handers; and Broca's area, in the left frontal lobe. Numbers are stored in the parietal lobe--not that far away, but far enough to be a separate system. No part of the brain is specialized at birth for reading because reading is a very recent skill for which the brain adapts the language areas. The brain, however, does seem to have evolved special circuits for numbers. There's an important difference between those two types of learning. Mathematics is built on a specific innate basis, and reading is not. It's quite important for teachers to remember that when children are learning mathematics, they are using distinctly different brain areas than they use when learning to read.

MD: What is dyscalculia?

BB: Dyscalculia is a condition a child is born with that affects the ability to acquire the usual arithmetical skills. Dyscalculic students may show difficulty understanding even simple number concepts and, as a consequence, will have problems learning the standard number facts and procedures. Even when dyscalculic students can produce the correct answer or the correct method, they may do so mechanically and without confidence because they lack an intuitive grasp of numbers that the rest of us possess. Dyscalculia is rather like a dyslexia for numbers--but unlike dyslexia, little is currently known about its prevalence, causes, or treatment...

MD: How is dyscalculia diagnosed? Are there tests for it?

BB: Generally, discrepancies between mathematics learning and other cognitive functions, such as reading or I.Q., are taken as diagnostic. We are currently looking at qualitative differences between dyscalculics and other children. By March 2002, we plan to have a fully standardized test battery for this...

MD: Traditionally, schools have emphasized drill and practice for learning mathematics, assuming that understanding would come as a natural result of learning facts and skills. Is this a good practice?

BB: We don't know whether fluency with number facts actually leads to a better understanding of the number system, but we do know that good understanding makes you much better with number facts. Try to make sure that students understand what they're doing before you start drilling with number facts. Going over the same thing again and again gets information from short-term memory into long-term memory, but you have to rehearse reflectively. Recent studies of musicians suggest that what's really important in becoming a truly excellent musician is reflective practice. This means playing a Bach cantata over and over again, but not just in a rote way. The musician must rehearse in a reflective way, thinking about how the parts of that piece are connected together and what those parts and what the whole means...

MD: Educators are eager to learn about neuroscience in hopes that it will lead to improved ways to help students learn. What do you think will come of educators' interest in neuroscientific developments?

BB:  Education and neuroscience are just starting out on a great adventure. The more we talk to each other, the more we will begin to understand the kinds of problems that we're each interested in and seek common solutions. Perhaps most of the interest will be in the area of special education needs--teaching mathematics to dyscalculics, to dyslexics, and to others who have inherited disorders that make it hard for them to learn. In the future, we might be able to move to more general theories of how the brain learns abstract concepts. And then, I think the great adventure will really have taken off.

(3) "Old Memories Must Make Way for New: Study" by Alison McCook

Source:  Reuters Health - 1 January 2002 (Neuron 2001;32: 911-926)

URL:  http://dailynews.yahoo.com/h/nm/20020101/hl/memories_1.html

Forming new memories as an adult may rely on the brain's ability to clear away those that are no longer needed, study results suggest.

Researchers say they hope the findings will help explain what happens inside the brains of people who develop Alzheimer's disease. Presenilin-1 (PS1) is a gene found in both mice and humans. Mutations in PS1 are found in most people with early-onset Alzheimer's disease.

PS1 encodes for a protein inside brain cells that make up the regions associated with learning and memory. One of these regions, the hippocampus, is the site where most new brain cells are generated in adult brains. But this portion of the brain has only a limited number of neurons, so once a memory becomes long-term, a copy moves from the hippocampus to the outermost layer of brain tissue, the cortex...

When Tsien and his colleagues tested the memories of mice with and without PS1, much to their surprise, they found that mice without PS1--who therefore experienced less neurogenesis--were better able to recall something they had learned before spending 2 weeks in the more stimulating environment.

These findings led Tsien to conclude that forming new neurons in the hippocampus helps free up space for new memories by clearing away information that had already been copied to the cortex. Although mice with less neurogenesis temporarily appeared to remember more, Tsien believed it was simply easier for them to recall a memory that was stored in both the hippocampus and the cortex. But over time, he suspected they would develop memory problems due to lack of space within the hippocampus...

"If it is overloaded, the system may crash, it can no longer process new information, and it loses the function to convert the new (memories) into long-term memory," he explained.

"It's quite possible, because in the early stage of Alzheimer's disease, people begin to show problems forming new long-term memory, and that is a sign of a breakdown in the hippocampus system," he added.

(4) "Repeat After Me: Memory Takes Practice" by Valerie Strauss

Source: The Washington Post - 7 August 2001

URL: http://www.washingtonpost.com/ac2/wp-dyn?pagename=article&node=&contentId=A40685-2001Aug6

...Researchers--who are just now learning about the complex brain processes that create and store short-term, episodic and long-term retention--say memory can indeed be improved. But the keys to achieving it are simpler than you might think: lots of practice and better organization...

"Improving memory for specific things we know can be achieved either through use of specific pneumonic devices, associations, imagery and the like," said Daniel L. Schacter, Harvard University Psychology Department chairman and an author of books on memory...

And new research is showing that memories can be diminished by stress, nicotine and even small amounts of alcohol, as well as physical trauma. Young soccer players who take a lot of head shots report some mild memory problems, Spilich said...

"We function so well as human beings because in fact we forget things at a very efficient rate," said neuroscientist James L. Olds, director of George Mason University's Krasnow Institute for Advanced Study, which is dedicated to the study of human cognition. "If we flawlessly remember everything about every aspect of every day, we would have tremendous difficulty given the fact that our brains are limited. . . . Forgetting is as important biologically as memory"...

(5) "Gesturing While Talking Shown To Help Memory"

Source: Reuters - 15 November 2001

URL: http://www.drbobmartin.com/2001k_11_15news04.html

...The value of gesturing to convey meaning to the listener has been shown in previous research, but it also may help the conveyor of the information, Susan Goldin-Meadow and colleagues report in the journal Psychological Science...

"Producing gestures can actually lighten a speaker's burden," the researchers write. They suggest that by tapping into a part of the brain dealing with visual and spatial subjects, gesturing while talking may make demands on additional memory stores and allow the speaker to remember more.

"Whatever the mechanism," the authors note, "our findings suggest that gesturing can help to free up cognitive resources that can then be used elsewhere. Traditional injunctions against gesturing while speaking may, in the end, be ill-advised."

(6) "The Brain's Halves Cooperate To Help Us Remember Events, Giving "Lefty Family" Members Better Episodic Memory"

Source:  American Psychological Association - 21 October 2001

URL:  http://www.apa.org/releases/leftymemory.html

Does coming from a family full of "lefties" tend to make a person better at remembering events? The data from two recent experiments answer in the affirmative. What's more, psychologists may finally be able to explain why kids don't remember events until they are about four years old. This recent research is reported in the October issue of Neuropsychology...

Stephen D. Christman, Ph.D., and Ruth E. Propper, Ph.D., of the University of Toledo in Ohio, studied memory as a function of family handedness. Interestingly, people don't have to be personally left-handed to share a unique trait: There is evidence that the two brain hemispheres of even right-handers with left-handed relatives share functions more equally, interact more and are connected by a larger corpus callosum (the bundle of mediating fibers) than the hemispheres of people with right-handed relatives. Although it is not well understood, there is a hereditary component to handedness.

Christman and Propper studied two types of memory--episodic (the recall and recognition of events) and non-episodic (factual memory and implicit memory, the latter of which concerns things people "just know"). Strength or weakness in either, says Christman, "may not have much effect in educational settings, as we can recall things we have learned by 'remembering' them (episodic memory) or by 'knowing' them (implicit memory). The main difference is that people who 'remember' can also recall details about the time and place at which they first learned this fact"...

Christman and Propper conclude that because our brains' two halves work together to help us remember events, people whose brains' halves work together more actively (people with left-handedness in their families) remember events better than they remember facts. As a result, the authors say that memory studies should factor in the familial and probably personal handedness of participants (having a weak versus strong hand preference may also matter). Further research may help explain why episodic memory benefits from the two halves working together, whereas factual/implicit memory is better processed in one half alone.

The researchers stress that memory performance has nothing to do with so-called "brain dominance." "While the notion of people being right-brained or left-brained is common in the popular press," says Christman, "it has received very little support in the scientific literature. Both hemispheres of all people are going to be involved in virtually all tasks."

Finally, the findings shed light on why children have no episodic memories until about age 4. The onset of episodic memory roughly coincides with the corpus callosum's maturation and myelinization, the growth of fatty protective sheaths around nerve fibers. In light of the findings, it would mean that a functional corpus callosum is critical in the formation of event memories and therefore explain why its maturation in early childhood is at least partly responsible for the emergence of episodic memory...

(7) "Imaging Studies Illuminate Competition Between Brain Systems"

Source:  EurekAlert (American Association for the Advancement of Science); Contact: Susan McGreevey (smcgreevey@partners.org)

URL:  http://www.eurekalert.org/pub_releases/2001-11/mgh-isi112601.php

What areas of the brain are activated during the process of learning and how does the pattern of activation change as learning proceeds? Brain imaging studies conducted by researchers at Massachusetts General Hospital (MGH) in collaboration with scientists at Rutgers University-Newark, are revealing that brain systems known to be involved in learning seem to compete with each other, with the type of learning involved determining which system is dominant.

In a study appearing in the Nov. 29 issue of Nature, the researchers describe how increased activity in one brain system is associated with decreased activity in another system during learning of a simple skill. The findings, which suggest how the brain mediates between the need to store and access a wide range of information and the need for virtually automatic responses in key situations, may eventually lead to new strategies for dealing with learning disorders or for diagnosing Alzheimer's disease, Parkinson's disease and other brain disorders.

Previous studies have identified several brain structures that are key to learning and memory and have suggested associations with particular learning tasks. The medial temporal lobe of the brain, which includes a structure called the hippocampus, has been associated with what is called declarative learning, the learning of facts and events. An area called the basal ganglia, deep within the brain, has been associated with nondeclarative learning, learning based on experience that may not involve conscious memory. In the current study, conducted at the Martinos Center for Biomedical Imaging located at the MGH, healthy volunteers were given a simple learning task while undergoing functional MRI scans, which reveal the level of activity in various areas of the brain...

Gluck and Catherine Myers, PhD, [coauthors], have developed [a]... theory: that the hippocampus is involved in all learning and is responsible for determining how new information is encoded by other brain regions. Gluck explains, "The current results provide the first functional neuroimaging data to support our theory. As our models predicted, the hippocampus was activated in the earliest stages of learning, when we expect new encodings to be established, but not in later learning when the encodings are used by other brain structures, such as the basal ganglia." Gluck and Myers' theory is detailed in their recent book Gateway to Memory: An Introduction to Neural Network Modeling of the Hippocampus and Learning...

(8) "Einstein's Brain 'Markedly Different' From Norm" by Joene Hendry

Source: Reuters - 13 November 2001

URL:  http://www.drbobmartin.com/2001k_11_13news07.html

...To investigate whether the brain of a genius might show special features, Dr. Dahlia W. Zaidel of the University of California, Los Angeles, examined two slides made from the physicist's brain shortly after his death in 1955 at age 76. The slides contained samples of Einstein's hippocampus, a part of the brain responsible for memory and word associations.

Zaidel compared Einstein's brain with tissue from 10 individuals of ordinary intelligence who ranged in age from 22 to 84 at the time of death.

The neurons on the left side of the Nobel Prize winner's hippocampus were consistently larger than those on the right. Zaidel said these findings were "markedly different" from those seen in the brains of individuals with normal intelligence...

The larger neurons in the left hippocampus, she noted, imply that Einstein's left brain may have had stronger nerve cell connections between the hippocampus and another part of the brain called the neocortex than his right. The neocortex is "where detailed, logical, analytical and innovative thinking takes place," Zaidel noted...

(9) "UCLA Team Maps How Genes Affect Brain Structure, Intelligence; Dramatic Images Shed Light on Brain Diseases, Personality Differences"

Source:  Reuters - 5 November 2001 ("Genetic Influences on Brain Structure" now available at below web site)

URL:  http://www.loni.ucla.edu/~thompson/MEDIA/NN/genetics_article_NN.pdf

UCLA brain mapping researchers have created the first images to show how an individual’s genes influence their brain structure and intelligence.

The findings, published in the Nov. 5 issue of the journal Nature Neuroscience, offer exciting new insight about how parents pass on personality traits and cognitive abilities, and how brain diseases run in families.

The team found that the amount of gray matter in the frontal parts of the brain is determined by the genetic make-up of an individual’s parents, and strongly correlates with that individual’s cognitive ability, as measured by intelligence test scores.

More importantly, these are the first images to uncover how normal genetic differences influence brain structure and intelligence. Brain regions controlling language and reading skills were virtually identical in identical twins, who share exactly the same genes, while siblings showed only 60 percent of the normal brain differences...

Recent research has shown that many cognitive skills are surprisingly heritable, with strong genetic influences on verbal and spatial abilities, reaction times, and even some personality qualities, including emotional reactions to stress. These genetic relationships persist even after statistical adjustments are made for shared family environments, which tend to make members of the same family more similar. Until this study, little was known about how much individual genotype accounts for the wide variations among individual brains, as well as individuals cognitive ability. The UCLA researchers are also applying this new genetic brain mapping approach to relatives of schizophrenic patients, and individuals at genetic risk for Alzheimer’s disease, to screen them for early brain changes, and help understand familial risk for inherited brain disorders where specific risk genes are unknown.

(10) "At the Frontier Of Science: Social Cognitive Neuroscience Merges Three Distinct Disciplines in Hopes if Deciphering the Process Behind Social Behavior" by Beth Azar

Source:  Monitor on Psychology - January 2002

URL:  http://www.apa.org/monitor/frontier.html

Last year researchers launched the Decade of Behavior as a natural follow-up to the Decade of the Brain. Now, a new generation of researchers are looking toward the next decade as the marriage of the two. They're self-proclaimed members of one of the fastest-growing research areas in psychology: social cognitive neuroscience.

This group of pioneers includes social psychologists, neuroscientists, cognitive psychologists, anthropologists, neurologists and sociologists who are collaborating in the hopes of understanding social behavior from the perspective of the brain. They're using brain-imaging techniques and studies of people with brain injuries to decipher how neural pathways control attitudes, stereotypes, emotions and other socially motivated phenomena.

And they're getting a lot of attention for their efforts...

The basic premise behind social cognitive neuroscience is to infuse social psychology with brain science methodology in the hopes of deciphering how the brain controls such cognitive processes as memory and attention, which then influence social behaviors such as stereotyping, emotions, attitudes and self-control...

What makes this research cutting-edge is the availability of brain-imaging technology--functional magnetic resonance imaging (fMRI) in particular--that allows psychologists to look at brain function...

"With the new methodologies the intersection [between social behavior and brain mechanisms] has become much more accessible," says Carolyn Morf, PhD, chief of the Personality and Social Cognition Program at the National Institute of Mental Health, and coordinator of NIH's new effort in the area of social neuroscience. "There are huge gaps in our knowledge that can be filled now."

In particular, researchers can begin to piece together the neural pathways and mechanisms responsible for social phenomena. Several areas within social psychology are ripe for this approach, having been studied enough that researchers can make some educated guesses about where to begin brain studies, says UCLA's Matt Lieberman, PhD, who, along with Stanford postdoc Kevin Ochsner, PhD, coined the term social cognitive neuroscience. For example, teams have begun looking at stereotyping, attitudes, self-control and interpreting emotions, with some intriguing results...

The power of these types of studies "comes from working at the intersection of the triad of neuroscience, cognition and social psychology," says NSF's Breckler. "By working from the perspective that our brains evolved in a social context, we can begin to understand the origin of social behavior and social phenomena"...

Social cognitive neuroscience "is big science and it's at the leading edge," says Breckler. "That may frighten some who might worry that it will take us down the road of biological reductionism. On the other hand, there's no doubt that huge amounts of social behavior, perception and cognition are supported by the central nervous system. And now the tools are available that makes that a really exciting prospect."

 



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