Functions of the Centre Section (Trunk) of the Corpus Callosum in Man

Abstract

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.

Somesthetic Disconnection Syndromes in Patients with Callosal Lesions

“…Finger touch localization was defective in the contralateral conditions in case 2 in our study, and similar cases have been reported previously [1, 2, 9, 11, 13, 15, 16, 17, 18]. Since these cases can localize the point being touched with the ipsilateral hand, they could be considered as having problems not in finger recognition itself but in the interhemispheric transfer of the information of touch localization.…”

“…In the gross touch localization task [9], the blindfolded subject was touched on the shoulder, elbow or hand of one arm, and he/she was required to indicate, using the other hand, the point at which he/she had been touched. All cases performed well (case 1, 7/7, case 2, 10/10, and case 3, 20/20).…”

“…Stereognosis, recognition of a solid object by active touch, might also require the transformation of compound somatosensory information into spatial images. Dimond et al [9], Degos et al [10], Habib et al [12]and the authors investigated pure stereognosis using controlled materials such as wooden blocks and geometrical forms, and the results suggest that such pure stereognosis might also be transferred via the corpus callosum. Cases with callosal lesions who exhibit transfer deficits of hand posture [10, 12, 13]and/or stereognosis [9, 10, 12], including cases 1 and 2 in our study, most commonly have lesions in the posterior truncus of the corpus callosum, suggesting that this callosal part might be important for the interhemispheric transfer of hand posture and stereognosis.…”

“…Since these cases can localize the point being touched with the ipsilateral hand, they could be considered as having problems not in finger recognition itself but in the interhemispheric transfer of the information of touch localization. All of these cases with transfer deficit of finger touch localization had lesions in the truncus; 3 cases reported by Bentin et al [17]had lesions in the anterior truncus, posterior to the foramen of Monro, and the case reported by Dimond et al [9]had a lesion in the middle third of the corpus callosum. Three of the 5 cases reported by Geffen et al [18], who showed cross-localization deficits in the finger localization tasks, had lesions in the caudal portions of the anterior truncus, and the remaining two had lesions in the posterior truncus.…”

Disconnection Syndrome and Verbal, Spatial and Tactile Amnesia following a Tumor of the Splenium of the Corpus Callosum

“…In surgical lesions of the corpus callosum in order to reach subcallosal tumors the splenium has always been spared. Nevertheless, a persistent anterograde memory deficit was reported both in Dimond et al's (1977) patient, and in one of the three patients studied by J eeves et al (1979) and in three of the six patients reported by Bentin et al (1984).…”