Functions of the centre section (trunk) of the corpus callosum in man

The case is reported of a patient in whom the middle sagittal third of the corpus callosum had been removed for the treatment of an underlying angioma. The special advantages of the case are that the patient is a young, relatively healthy person of normal IQ. The angioma had not interfered with interhemispheric transmission and the patient was described as neurologically normal before operation. After operation left-side neglect and extensive somatic disconnection were seen. A change in the balance between the hemispheres for handedness and ear superiority in dichotic listening was observed. The patient developed an aphasia after operation characterized by a simplification of language, the inavailability of complex ideas and emotional communication. He showed a disorder of memory--'autopragmatic amnesia'--in whice. The patient showed disorders of visuo-spatial transfer. These symptoms are thought to typify a syndrome of the centre trunk region of the corpus callosum, to follow as a direct function of the operation performed upon the callosum, and to illustrate the function of this region of the brain.