Unsuspected Connections and Disconnections

Until recently it was believed that the entire corpus callosum must be sev-
ered to provide relief from severe epileptic seizures. However this is not
necessarily the case — the corpus callosum only needs to be severed enough
to provide relief, without losing all neural integration. Based on this new
form of surgery, Dr H G Gordon, a neurobiologist at the California Institute
of Technology, also found that a connection at the back of the brain alone
is enough to integrate both human minds. According to him, ‘the cerebral
hemispheres totally integrate if but a small fraction of the corpus callosum
remains intact.’
On the other hand, tumors or blood clots pressing on only part of an
intact corpus callosum can cause full-blown Jekyll/Hyde reactions (similar
to split-brain patients). Gordon and his co-workers J E Bogen and Roger
Sperry believe that tumors and clots cause waves of inhibition to spread to
all parts of the corpus callosum. The shocked nerve fibers simply do not
carry impulses from one side of the brain to the other. Furthermore, it has
also been found that even in a healthy corpus callosum only certain types
of information can be carried. Complicated higher level information cannot
pass through from one brain to the other.
Split-brains can be initiated both physically and chemically. It may also
be initiated psychologically through thought processes and communica-
tions between the left and right brain selves — resulting in one side being
dominant. Logically, this could mean that a normal person with a dominant
left brain may exhibit behavior similar to a split brain person with a partially
damaged right brain.