From the List Universe -- Top 10 Bizarre Mental [/neurological] Disorders

The theory explains how the brain compensates for damage from injuries such as stroke

Carnegie Mellon University neuroscientist Marcel Just and Stanford postdoctoral fellow Sashank Varma have put forward a new computational theory of brain function that provides answers to one of the central questions of modern science: How does the human brain organize itself to give rise to complex cognitive tasks such as reading, problem solving and spatial reasoning? Just and Varma's theory, called 4CAPS, is described in the fall issue of the journal Cognitive, Affective, and Behavioral Neuroscience.

More than a decade of research involving functional Magnetic Resonance Imaging brain scans in hundreds of laboratories has yielded a tremendous amount of information about what parts of the brain are activated when a person performs various tasks. Some researchers have been tempted to conclude that a simple one-to-one relationship exists between high-level mental tasks and brain areas. For example, some believe that a specific brain area is responsible for a specific cognitive task, such as identifying a face.

Just and Varma, however, propose that the evidence reveals a more complex picture in which thinking is a network function - a collaboration of several brain areas that is constantly adapting itself, based on the task at hand and the brain's own resources and biological limitations. The collaborating parts of the brain, according to Just, are like members of a sports team whose players substitute in and out of the action. 4CAPS (an acronym for Capacity Constrained Concurrent Cortical Activation-based Production System), proposes a decentralized process by which members of the cortical team volunteer themselves when their strengths are called for, but also permits less efficient but capable members to step forward when the primary player is injured or disabled, as might occur as a result of a stroke. Just and Varma have constructed a number of computational models to demonstrate this process, such as a model that understands English sentences.

A unique characteristic of the theory is that it can accurately predict the change in brain activation that results from some types of brain damage or disease. For example, if a stroke damages the part of the brain known as Broca's area - which is located in the left prefrontal cortex and is involved in language processing - the corresponding site on the right side of the brain often becomes activated during language processing, even within hours after a stroke. According to 4CAPS, the same dynamic allocation mechanism that allows brain areas to volunteer themselves on a moment-by-moment basis would also come into play if Broca's area were damaged, and would allow any excess computational load to spill over to the right hemisphere mirror site on a more permanent basis. Another example occurs with Alzheimer's disease, where the damage to some brain areas causes additional "helper" areas to be recruited to perform a task, additional areas that are not typically used by control subjects who do not have the disease.

"Many brain-imaging studies have shown as the nature of the task changes, so does the set of activating brain areas," said Just, the D.O. Hebb Professor of Psychology. "It is as though substitutions of team players are being made dynamically in response to changes in the game."

"We credit this dynamic mechanism with the fluidity or adaptability of human intelligence, and with much of the plasticity that occurs with learning or with recovery from brain damage," Just said.

4CAPS provides a framework for scientists and medical researchers to better understand nascent topics in neuroscience, such as how brain areas communicate and collaborate with one another during the thought process and how this can go awry. For example, Just and his colleagues have proposed an influential theory of autism, called the underconnectivity theory, that attributes the disorder to poor connectivity and hence communication between frontal areas of the brain and more posterior areas. The individual areas still have their specializations, according to the theory, but they cannot communicate as well with each other, and may develop a tendency to operate more independently of each. The theory also provides an account of what limits our ability to do multitasking.

"The thousands of facts that scientists have learned from brain imaging studies cry out for some sort of organization, some way to impose coherence, and ultimately to understand the brain system that is producing the results," Just said. "The theory provides a new conceptual framework for understanding how the fluidity of thought arises from the dynamics of brain activity.

"As neurological issues arise in education, aging and development, and as a basis for a knowledge-based economy, it will become increasingly important that human brain function be understood by students, parents and educators, patients and doctors, trainees and managers, citizens and policy-makers."

Carnegie Mellon Press Release
15 November 2007

The correlation between car and driver

Imagine a leisurely drive on a Sunday morning. As you make your way down the scenic country road, a car comes speeding behind you. The driver remains as close to you as possible. But you’re not surprised seeing as the driver is at the wheel of an electric blue Honda Civic. Is that prejudicial?

“Not really,” answers Amélie Auger. The undergrad psychology student studied, along with her classmate Marie-Hélène Lemyre, the influence one’s perception of their vehicle has on their aggressiveness at the wheel following a stressful situation on the road. They discovered that people who perceive their cars as big or performing take on riskier behavior at the wheel. They get angry faster and feel personally targeted by the behavior of other drivers.

“We wanted to demonstrate that what we believe to be a stereotype, for instance, that Mustang drivers are more aggressive, is sometimes founded,” explains Auger. The results are a part of a broader study conducted within the framework of a course given by Professor Jacques Bergeron. Students had to choose a theme linked to dissatisfaction at the wheel. Bergeron finds the results obtained by Auger and Lemyre to be “very interesting” despite being preliminary and partial.

The students surveyed 380 men and women between 18 and 78-years-old with the help of two questionnaires. The first questionnaire measured the reaction of people facing stressful situations at the wheel. The second questionnaire addressed perception of the vehicle. Is it perceived as high-performance or luxurious? Is the driver embarrassed by his or her vehicle? What importance is attributed to the vehicle?

These results bring up many more questions according to Bergeron who is faced with the paradox of the chicken or the egg. “Is it our personality that dictates our car choice or vice versa?” he asks. Auger intends to answer these types of questions within the framework of her master’s degree.


University of Montreal News Digest
17 September 2007

Scientists are finding new evidence that a good night's rest plays a crucial role in cementing memories formed during the day.

One new study has identified a brain region involved, along with the hippocampus, in creating memories of the day's activities during sleep. Another study suggests melatonin, a hormone involved in regulating our day-night cycle, or "circadian rhythm," acts to suppress the formation of new memories as bedtime nears, perhaps in an effort to give memories made earlier in the day a chance to be prepared for long-term storage.

Both studies are detailed in the Nov. 16 issue of the journal Science.