Split-Brain Research Biological Foundations of Behavior

Running head: Split-Brain Research

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Split brain research is a field that has continued to bring insight to the functioning of the brain and in particular on the link between its partitions, their organization and consciousness. The two, hemispheres of the brain are connected to each other through a mass of neurons that are called the corpus callosum. Epilepsy is a disorder involving the nervous system. It occurs when neural transmissions of a great intensity are passed to and fro between the two lobes of the brain. This interferes with regular neural transmissions. When diagnosed early, it is possible to control epilepsy using prescribed conventional medication. In some cases the medicine fails to work and surgery is the only option. The first attempt to such a procedure was done by Roger W. Sperry, Joseph E. Bogen, P.J. Vogel and Michael S. Gazzaniga, who severed the neural connection between the two hemispheres of the brain. This stopped the flow of neural impulses between the two hemispheres and cured the patient. The recipients of these surgeries are referred to as split brain patients.

After the procedure the neural scientists observed that the patients retained their overall intellectual abilities and unique personalities. This was unexpected because the operation had severed the connections between the two lobes of the brain. It was expected that this would affect the intelligence and personality of the patients since the sensory cortex in the right lobe of the brain receives neural impulses from the left side of the body

Researchers conducted further studies on the phenomenon by placing familiar objects like keys in the left hands of the patients. When blindfolded, the split brain patients could not identify the object that was in their hands but could apply it to its correct use. If a key was placed on the left hand they could not identify it as a key but if asked to open a door with it they would successfully open it. Normally due to the coordination between the right hemisphere that receives the neural impulses from the left side of the body and the centers of speech which are located in the right hemisphere, it would be easy to identify what was in the left hand by simply touching it. However this was different in spilt brain patients. From this study it was evident that there is no exchange of visual neural impulses between the two hemispheres of the brain.

By dividing the field of vision to right and left visual fields scientists flashed images to the right visual field and observed that the patients could select the image from a variety hidden behind the screen. However when the object was flashed to the left visual field the patient could not select the correct object .From these observations it was deduced that this was likely to happen because the right visual field transmits information to the left hemisphere that then communicates to the right hemisphere. The left hemisphere mainly controls speech and since the connection is severed between the two lobes of the brain the patient cannot identify the correct image. If the object was flashed to the left visual field the neural impulses are transmitted to the right hemisphere that is able to recognize the object by touch.

By repeating similar experiments to test for touch, olfactory and sound transmissions it became apparent that neural transmissions between the two lobes was completely obliterated. The patients could not synthesize information from the two lobes and come up with a complete picture. Each of the two brain hemispheres controlled the upper muscles of both hands but the muscles controlling the lower hand were controlled by the other hemisphere.

From these studies, it was evident that the two hemispheres were distinctly specialized and though they worked better when linked, could still operate as a functional whole with two different entities to people suffering from drug resistant epilepsy.

References

Jeffrey S. Nevid, (2007), Nevid Essentials of Psychology (2nd ed.), Boston, Houghton Mifflin College Division.