Corpus callosum and cerebral laterality in a modular brain model

Abstract

This paper elaborates the function of corpus callosum in the brain model that contains encoding and modulating axons: the former encode data as presynaptic axonal 'on-off' patterns, and the latter help the former convert data into long-term memory through the development of long-term potentiation and depression. It is hypothesized that callosal axons transfer data codes as interhemispheric memory. Bisection of corpus callosum cuts off interhemispheric data transfer and results in strange-hand syndrome, decreased attention and difficulties in acquiring new interdependent bimanual skills. While uniting two hemispheres for a unitary consciousness, corpus callosum contributes to two similar sets of integrated abstract memory, one in each hemisphere. Therefore, it takes bilateral cerebral lesions to manifest a failure of converting short-term memory into long-term memory. The asymmetric callosal data transfer may correlate with cerebral laterality where a cerebral function, such as language, is conducted mainly in one hemisphere for the benefit of less interhemispheric data-traffic. Complete lateralization of a cerebral function is the rare occasion when the specialized neuron groups (modules) for that function all reside in one hemisphere. It is possible that many cerebral functions including language are incompletely lateralized, and corpus callosum links the non-lateralized modules with the lateralized ones. The more the cerebral lateralization, the fewer the non-lateralized modules to be linked, and the smaller the corpus callosum.