December 2011 Archives

In an article printed in the American Academy of Neurology, researchers found that people who have lost a substantial amount of cells in the hippocampus area of the brain are more likely to develop dementia.

They performed a study with 64 Alzheimer's patients, 44 people with mild cognitive impairment, and 34 people with no thinking or memory problems. MRI scans were performed at the beginning of the study and then performed half a year later. During that time 23 people with mild cognitive problems had developed Alzheimer's, along with three of the healthy patients. Researchers measured the whole volume of the brain and the hippocampus area. At the beginning and end of the study they calculated the rank of shrinking in the brain over that time. For the people who did not have dementia at the beginning of the study, those with smaller hippocampal volumes, and higher rates of shrinkage were two to four times as likely to develop dementia as those with larger volumes and a slower rate of atrophy. These findings demonstrate that people with mild cognitive impairment have already experienced atrophy within the hippocampus. In people who already have Alzheimer's disease, the loss of nerve cells is spread throughout the brain.

Alzheimer's disease affects millions of people worldwide with no cure at hand. By 2050 it is projected that this disease will affect 1 in 85 people worldwide.

Here is a short video which discusses the effects of the disease:
http://video.about.com/alzheimers/Alzheimer-s-Disease.htm

How different would our perception of the world be if we could hear colors and taste words? That is the case for people who experience the neural condition, synesthesia. Understanding synesthesia will make it easier to understand how the brain is organized. Synesthesia is condition in which one sense is simultaneously perceived as if by one or more additional senses. Another form of synesthesia joins different objects such as letters and shapes with a sensory perception such as smell, color, or flavor.

Synesthesia was first documented in 1812 but the perceptions of this condition was widely misunderstood. Scientists believe that it is caused from "cross-wiring" in the brain. One theory is that neurons and synapses that are supposed to be confined within one sensory system cross to another sensory system. Some scientists believe that at birth, infants have cross wiring, but it is than refined later in development. Researchers are still discovering which part of the brain is connected with this condition. Some believe that the limbic system is primarily responsible for synesthesia experiences. Others believe that the cerebral cortex is responsible. Also, this condition is seen to be inheritable which indicates a genetic component. Some believe that synesthesia survived evolutionary effects because it benefited some with the addition of a creative thinking process.

A tool to help scientists take a closer look at brain connections is DTI (diffusion tensor imaging). Not only are they able to visualize connections between brain sensory regions, but it can help explain why syesthesia exists and why it is undirectional. For example, why is it that numbers evoke colors but typically colors don't evoke numbers. Different studies could help test the idea that all humans possess synesthesia but in most cases it's suppressed.

Is it beneficial to have synesthesia? Recent research has shown that this condition is seven times more prevalent in artists, poets, and novelists than the rest of the population. Some scientists have hypothesized that people who have the condition are better at linking unrelated problems. One person who had synesthesia was able to memorize 22,514 digits of pi. Others are able to distinguish colors which seem similar, and others have a heightened sense of touch. Even though many advances have been made in understanding this condition, there is still a vast amount which is still misunderstood. The mechanism for which it occurs is still being studied. Scientists are also trying to understand if animals experience synesthesia as well. The exact role of genetics is still being researched, but one of the most interesting questions that remains is, why don't we all possess this trait?