- Studies of the cerebral cortex of man have long since established the proprietary status of the left hemisphere in regard to verbal performance. Instances of language dominance in the right hemisphere are rare even among left-handed people who display left-eye dominance (Penfield and Rasmussen ). This has been strikingly illustrated in recent years by the behaviour of patients who have undergone therapeutic transections of the inter-cerebral commissures1 (Sperry et al. ). These patients can identify palpably but not visually those otherwise familiar objects presented to the left hand. The tentative explanation of their deficit is that the tactile cues delivered to the left hand are ultimately transmitted to sensory centres in the right hemisphere wherein mechanisms associated with speech are either deficient or absent.
- In a summoning article on 'split-brain' man, Roland Puccetti has proposed that studies of commissurotomised patients offer evidence of multiple personal identity (Puccetti ). His argument rests upon the putative discovery that such patients are, individually, in possession of two functionally distinct minds. Larry Dewitt has now challenged this by denying that there is 'a self in the minor hemisphere' (Dewitt [19751).
- I believe that Puccetti has exaggerated the implications of 'split-brain' studies to the issue of personal identity and that Dewitt's attempted rebuttal shares many of the confusions introduced by Puccetti's analysis.
- Before this loose talk about hemispheres, minds, selves, and culture becomes habitual we are advised to economise in the use of the human nervous system for metaphorical purposes.
- The lateralisation of speech mechanisms has been a secure fact in neurology for more than a century. Disturbances of language and perception come in great variety with no two very alike. Some are expressive, some receptive, some mixed. Some are irreversible, others remediable.
- The consequence of treating these diseases as evidence of new persons will be to render the concept of person inarticulate and that of pathology virtuous.
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