Posts Tagged ‘plasticity of the brain’

One of the most distinctive physical features of the human brain is the fact that the cortex is divided into two hemispheres. The main connection between the two halves is a thick bundle of fibers called the corpus callosum. This is no quiet lane, it’s a major freeway constituting around 200 million neural tracts.

In an increasingly rare procedure, the callosum is sliced as a radical treatment for epilepsy. People who receive this treatment are referred to colloquially as split-brain patients and lab tests reveal profound effects on their mental functioning. In many ways, it’s as if the surgery leaves their mind divided in two.

A new report presents the case of an elderly gentleman, referred to as H.W., who aged 88 presented at a clinic complaining of recent intermittent problems controlling his left hand and some mild memory difficulties. Preliminary tests found him to be high functioning. But when the researchers – a team led by Natalie Brescian – scanned H.W.’s brain, they made a surprising discovery. He had no corpus callosum. The main channel between his two brain hemispheres was completely missing.

The medical name for H.W.’s rare condition is agenesis of the corpus callosum, meaning that he was born with this structure missing. Despite of this he’d led a normal, independent life – first in the military and later as a flower delivery man. Until recently, he appeared to have suffered no significant psychological or neurological effects of his unusual brain. The problems with his left hand, H.W. said, were new.

Brescian and her colleagues conducted comprehensive neuropsych tests on H.W. and on most he excelled or performed normally. He did display memory problems and also some difficulties with fine motor control, especially when using both hands at once, and drawing. These issues, especially of motor control, are likely related to his congenital [from birth] condition, but they may also result from age-related neurological changes. The main message, though, is H.W.’s remarkable high-functioning, and his apparently unaffected life.

How can such a profound brain abnormality have so little functional consequence? The corpus callosum is not the only connection between the hemispheres, but it is by far the most important. “This case study underscores the plasticity of the developing brain,” the researchers said. Their theory is that the “congenital absence of the corpus callosum stimulates early cerebral organization and the development of new or stronger stronger connections compensating for the losses.

Nature must surely play a part in repairing damages considering there are great many accidents owing to circumstances of the very planet we live in. Earliest cosmic impact that wrenched the earth a fiery ball from the Sun gives it a slight tilt. Seasons owe to it. Even here some parts are away from the Sun to be called inhospitable.

Take the case of the tundra biome It is called cold desert where the harshness of desert and coldness of Arctic region are upon any life form that must survive there. How do they still? (To be Continued)

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