The corpus callosum is a structure containing around 250 million nerve fibres, which connect the right and left hemispheres of the cerebral cortex. Their function is to facilitate communication and cooperation between the two hemispheres. This function is most readily observed in patients who have undergone surgical disconnection of the corpus callosum, (know as a split brain procedure), which is sometimes done in extreme cases of epilepsy to prevent the seizure signal from passing from one hemisphere to the other.
In a normally functioning individual, one hemisphere becomes dominant, - this developmental process, known as laterallisation is usually completed by around the sixth year of age and in most people it is the left hemisphere of the brain, which becomes dominant. however, in individuals who have undergone surgical disconnection of the corpus callosum, this left hemisphere dominance, which has masked the individuality of the right hemisphere is stripped away with interesting consequences.
Each hemisphere is still able to learn after the split brain operation but one hemisphere has no idea about what the other hemisphere has experienced or learned because their route of communication, the corpus callosum, is no longer functional.
Split brain operations have also managed to throw some light on the different desires of the two hemispheres. In one patient, the right hemisphere stated that he wanted to be an automobile racer while his left hemisphere wanted to be a draftsman.
These hidden differences are allowed to demonstrate themselves after a split brain operation because the two hemispheres are closer to existing independently. One hemisphere may not be able to suppress or influence differing opinions, emotions, or desires of the other because most of the communication between the two can no longer occur. As a result, conflicting hemispheric desires or opinions can cause split brain patients to exhibit some strange behaviors. One patient found his left hand struggling against his right hand when trying to pull up his pants in the morning. While the right hand tried to pull them up, the left was trying to pull them down. On another occasion, he was angry with his wife and attacked her with his left hand while simultaneously trying to protect her with his right!
What is agenesis of the corpus callosum?
Agenesis of the corpus callosum is a disorder where the structure either only partially develops, or fails to develop altogether.The effects of the disorder range from subtle or mild to severe, depending on associated brain abnormalities. Intelligence may be normal with mild compromise of skills requiring matching of visual patterns. But children with the most severe brain malformations may have intellectual retardation, seizures, hydrocephalus, and spasticity. ACC does not cause death in the majority of children. learning difficulties do not worsen. Although many children with the disorder have average intelligence and lead normal lives, neuropsychological testing reveals subtle differences in higher cortical function compared to individuals of the same age and education without ACC.
Can ACC be treated?
We believe that the developmental problems, which are caused by ACC can be addressed in in a logical manner and that children with this disorder can make developmental progress when treated with a programme of neuro-cognitive therapy.