- Email: [email protected]
The mystery of the mind
Neuroscirncr. 1976.Vol. I, pp. 227-232. Pergamon Press. Printed m Great Britain
BOOK TheMystery
of the Mind, W.
PENFIELD, With
Princeton
University
REVIEWS
discussions by Dr. W. FEINDEL, Prof. C. HENDEL and Sir C. SVMONDS Press, New Jersey (1975). 156 pp., f4.60.
CANNOT but warm to the gentle spirit of this short book, in which one of the world’s great neuroscientist& now retired, looks back on the sum of his researches and draws an eminently humane and humble conclusion. “The challenge that comes to every neurophysiologist is to explain in terms of brain mechanisms all that men have come to consider the work of the mind, if he can. without philosophical or religious bias. If he does not sucteed the time should come, as it has to me, to consider other possible explanations”. (p. 73). “For my own part, after years of striving to explain the mind on the basis of brain-action alone, I have come to the conclusion that it is simpler (and far easier to be logical) if one adopts the hypothesis that our being does consist of two fundamental elements” (p. 80). The final message of the book, then, is that “the scientist, too, can legitimately believe in the existence of the spirit” (p. 85). Given a sufficiently careful definition, the last statement is one that many neuroscientists, including the present reviewer, would wholeheartedly endorse. What is less clear, and is indeed strongly questioned in Sir Charles Symonds’ “reflections” at the end, is whether Penfield’s famous series of observations on epileptic automatisms and related abnormalities of brain function offer adequate support for either his technical conclusions or the metaphysical case he rests on them. Briefly, the argument is that because even large removals of the cerebral cortex can be carried out without abolishing consciousness, whereas interference with the function of even small areas of the higher brain-stem can abolish consciousness completely, therefore “the indispensublr substratum of consciousness lies outside the cerebral cortex. probably in the diencephalon” (p. 18). When this hypothetical ‘mind’s mechanism’ is put out of action by epilepsy or by electrical stimulation of the upper brain-stem, goaldirected behaviour can continue but becomes ‘mindless’, and no experience of the episode can be recalled. In sleep or unconsciousness the diencephalic mechanism “may switch off the mind and switch it on by supplying and by taking away the energy that might come to the mind from the brain” (p. 79). The issues raised by this argument are of two kinds that must be kept distinct. The first are scientific. If we grant that both upper brain-stem and cerebral cortex are integrated in normal conscious experience, which, if either, is rssential for consciousnrss? To what extent can we remain conscious when one or the other is out of action? How do we judge someone to be unconscious’? By lack of retrospective recall? By the absence of all capacity to revise ONE
227
at the time’! The 1965 symposium on Brain and Conscious Experirncr (ed. ECCLES J. C.), Springer, Berlin, contains some extensive discussions of these technical matters. It can be argued on information engineering principles that revision of goal-priorities is not at all outside the scope of a mechanistic system; and that in the brain. the ‘meta-organizing system’ concerned with this might with advantage be distinct from (though normally integrated with) the organizing system of the cerebral cortex. What is so far known of the functions of the upper brain-stem would fit well enough with its playing a ‘meta-organizing’ role in this sense. The issue awaits further evidence, but appears in any case to have no fundamental bearing on Penfield’s metaphysical arguments, which would seem to stand (or fall) wherever in the brain his hypothetical ‘mind’s mechanism’ were located. The second group of issues are philosophical. Granted that our conscious experience is effectively correlated with our brain activity, why must the coupling be enqrtic’? Why could it not be like the even more intimate correlation between the solving of an equation in a computer, say, and the electronic workings of its transistors? There is a real sense in which the equation determinrs the behaviour of the computer, however complete our electronic explanation may be. There is surely a corresponding sense in which we can say that our mental activity determines our own behaviour even if there were no regions of our brains exposed to “action of mind” in the sense of a flow of “a second form of energy” (p. 79). It may be true (p. 77) that “there is no place in the cerebral cortex where electrical stimulation will cause a patient to believe or to decide”: but even in a computer there are few places where similarly crude electrical stimulation would have a sensible outcome. In short, as Penfield himself acknowledges, the evidence he advances for his metaphysical thesis is mostly negative, and far from conclusive. One might add that from the standpoint of the Christian religion, to which he refers sympathetically (p. 115).to speak of mind as a “separate element” seems no more and no less acceptable than to speak of it as a distinct ‘aspect’ of our unitary human nature. With its II5 pages divided into 21 Chapters and two postscripts. this book will make easy bedtime reading. Introduced by personal forewords from Dr William Feindel and Professor Charles Hendel, it offers a rewarding glimpse into the mind and work of a distinguished pioneer of brain research and a lovable human being. priorities
D. M. MACKAY
BOOK TheMystery
of the Mind, W.
PENFIELD, With
Princeton
University
REVIEWS
discussions by Dr. W. FEINDEL, Prof. C. HENDEL and Sir C. SVMONDS Press, New Jersey (1975). 156 pp., f4.60.
CANNOT but warm to the gentle spirit of this short book, in which one of the world’s great neuroscientist& now retired, looks back on the sum of his researches and draws an eminently humane and humble conclusion. “The challenge that comes to every neurophysiologist is to explain in terms of brain mechanisms all that men have come to consider the work of the mind, if he can. without philosophical or religious bias. If he does not sucteed the time should come, as it has to me, to consider other possible explanations”. (p. 73). “For my own part, after years of striving to explain the mind on the basis of brain-action alone, I have come to the conclusion that it is simpler (and far easier to be logical) if one adopts the hypothesis that our being does consist of two fundamental elements” (p. 80). The final message of the book, then, is that “the scientist, too, can legitimately believe in the existence of the spirit” (p. 85). Given a sufficiently careful definition, the last statement is one that many neuroscientists, including the present reviewer, would wholeheartedly endorse. What is less clear, and is indeed strongly questioned in Sir Charles Symonds’ “reflections” at the end, is whether Penfield’s famous series of observations on epileptic automatisms and related abnormalities of brain function offer adequate support for either his technical conclusions or the metaphysical case he rests on them. Briefly, the argument is that because even large removals of the cerebral cortex can be carried out without abolishing consciousness, whereas interference with the function of even small areas of the higher brain-stem can abolish consciousness completely, therefore “the indispensublr substratum of consciousness lies outside the cerebral cortex. probably in the diencephalon” (p. 18). When this hypothetical ‘mind’s mechanism’ is put out of action by epilepsy or by electrical stimulation of the upper brain-stem, goaldirected behaviour can continue but becomes ‘mindless’, and no experience of the episode can be recalled. In sleep or unconsciousness the diencephalic mechanism “may switch off the mind and switch it on by supplying and by taking away the energy that might come to the mind from the brain” (p. 79). The issues raised by this argument are of two kinds that must be kept distinct. The first are scientific. If we grant that both upper brain-stem and cerebral cortex are integrated in normal conscious experience, which, if either, is rssential for consciousnrss? To what extent can we remain conscious when one or the other is out of action? How do we judge someone to be unconscious’? By lack of retrospective recall? By the absence of all capacity to revise ONE
227
at the time’! The 1965 symposium on Brain and Conscious Experirncr (ed. ECCLES J. C.), Springer, Berlin, contains some extensive discussions of these technical matters. It can be argued on information engineering principles that revision of goal-priorities is not at all outside the scope of a mechanistic system; and that in the brain. the ‘meta-organizing system’ concerned with this might with advantage be distinct from (though normally integrated with) the organizing system of the cerebral cortex. What is so far known of the functions of the upper brain-stem would fit well enough with its playing a ‘meta-organizing’ role in this sense. The issue awaits further evidence, but appears in any case to have no fundamental bearing on Penfield’s metaphysical arguments, which would seem to stand (or fall) wherever in the brain his hypothetical ‘mind’s mechanism’ were located. The second group of issues are philosophical. Granted that our conscious experience is effectively correlated with our brain activity, why must the coupling be enqrtic’? Why could it not be like the even more intimate correlation between the solving of an equation in a computer, say, and the electronic workings of its transistors? There is a real sense in which the equation determinrs the behaviour of the computer, however complete our electronic explanation may be. There is surely a corresponding sense in which we can say that our mental activity determines our own behaviour even if there were no regions of our brains exposed to “action of mind” in the sense of a flow of “a second form of energy” (p. 79). It may be true (p. 77) that “there is no place in the cerebral cortex where electrical stimulation will cause a patient to believe or to decide”: but even in a computer there are few places where similarly crude electrical stimulation would have a sensible outcome. In short, as Penfield himself acknowledges, the evidence he advances for his metaphysical thesis is mostly negative, and far from conclusive. One might add that from the standpoint of the Christian religion, to which he refers sympathetically (p. 115).to speak of mind as a “separate element” seems no more and no less acceptable than to speak of it as a distinct ‘aspect’ of our unitary human nature. With its II5 pages divided into 21 Chapters and two postscripts. this book will make easy bedtime reading. Introduced by personal forewords from Dr William Feindel and Professor Charles Hendel, it offers a rewarding glimpse into the mind and work of a distinguished pioneer of brain research and a lovable human being. priorities
D. M. MACKAY