<P> The corpus callosum is a structure in the brain along the longitudinal fissure that facilitates much of the communication between the two hemispheres and its main function is in allowing for communication between the brain's right and left hemispheres . This structure is composed of white matter: millions of axons that have their dendrites and terminal buttons projecting in both the right and left hemisphere . However, there is evidence that the corpus callosum may also have some inhibitory functions . Post-mortem research on human and monkey brains show that the corpus callosum is functionally organized . It proves that the right hemisphere is superior for detecting faces . This organization results in modality - specific regions of the corpus callosum that are responsible for the transfer of different types of information . Research has revealed that the anterior midbody transfers motor information, the posterior midbody transfers somatosensory information, the isthmus transfers auditory information and the splenium transfers visual information . Although much of the interhemispheric transfer occurs at the corpus callosum, there are trace amounts of transfer via subcortical pathways . </P> <P> Studies of the effects on the visual pathway on split - brained patients has revealed that there is a redundancy gain (the ability of target detection to benefit from multiple copies of the target) in simple reaction time . In a simple response to visual stimuli, split - brained patients experience a faster reaction time to bilateral stimuli than predicted by model . A model proposed by Iacoboni et al. suggests split - brained patients experience asynchronous activity that causes a stronger signal, and thus a decreased reaction time . Iacoboni also suggests there exists dual attention in split - brained patients, which is implying that each cerebral hemisphere has its own attentional system . An alternative approach taken by Reuter - Lorenz et al. suggests that enhanced redundancy gain in the split brain is primarily due to a slowing of responses to unilateral stimuli, rather than a speeding of responses to bilateral ones . It is important to note that the simple reaction time in split - brained patients, even with enhanced redundancy gain, is slower than the reaction time of normal adults . </P> <P> Following a stroke or other injury to the brain, functional deficiencies are common . The deficits are expected to be in areas related to the part of the brain that has been damaged; if a stroke has occurred in the motor cortex, deficits may include paralysis, abnormal posture, or abnormal movement synergies . Significant recovery occurs during the first several weeks after the injury . However, recovery is generally thought not to continue past 6 months . If a specific region of the brain is injured or destroyed, its functions can sometimes be transferred and taken over by a neighboring region . There is little functional plasticity observed in partial and complete callosotomies; however, much more plasticity can be seen in infant patients receiving a hemispherectomy, which suggests that the opposite hemisphere can adapt some functions typically performed by its opposite pair . In a study done by Anderson, it proved a correlation between the severity of the injury, the age of the individual and their cognitive performance . It was evident that there was more neuroplasticity in older children, even if their injury was extremely severe, than infants who suffered moderate brain injury . In some incidents of any moderate to severe brain injury, it mostly causes developmental impairments and in some of the most severe injuries it can cause a profound impact on their development that can lead to long - term cognitive effects . In the aging brain, it is extremely uncommon for neuroplasticity to occur; "olfactory bulb and hippocampus are two regions of the mammalian brain in which mutations preventing adult neurogenesis were never beneficial, or simply never occurred" (Anderson, 2005). </P> <P> Corpus callosotomy is a surgical procedure that sections the corpus callosum, resulting in either the partial or complete disconnection between the two hemispheres . It is typically used as a last resort measure in treatment of intractable epilepsy . The modern procedure typically involves only the anterior third of the corpus callosum; however, if the epileptic seizures continue, the following third is lesioned prior to the remaining third if the seizures persist . This results in a complete callosotomy in which most of the information transfer between hemispheres is lost . </P>

Individuals who have received a split brain operation (commisurectomy)