Hyder, Fulbright, Shulman and Rothman, ‘Glutamatergic function in the resting awake human brain is supported by uniformly high oxidative energy’.
108 108 R. M. Birn, J. B. Diamond, M. A. Smith and P. A. Bandettini, ‘Separating respiratory-variation-related fluctuations from neuronal-activity-related fluctuations in fMRI’, Neuroimage, 31, no. 4 (2006), pp. 1536–48; R. G. Wise, K. Ide, M. J. Poulin and I. Tracey, ‘Resting fluctuations in arterial carbon dioxide induce significant low frequency variations in BOLD signal’, Neuroimage, 21, no. 4 (2004), pp. 1652–64.
109 109 G. K. Aguirre, E. Zarahn and M. D’Esposito, ‘The inferential impact of global signal covariates in functional neuroimaging analyses’, Neuroimage, 8, no. 3 (1998), pp. 302–6; P. M. Macey, K. E. Macey, R. Kumar and R. M. Harper, ‘A method for removal of global effects from fMRI time series’, Neuroimage, 22, no. 1 (2004), pp. 360–6.
110 110 K. Murphy, R. M. Birn, D. A. Handwerker, T. B. Jones and P. A. Bandettini, ‘The impact of global signal regression on resting state correlations: are anti-correlated networks introduced?’ Neuroimage, 44, no. 3 (2009), pp. 893–905;M. D. Fox, D. Zhang, A. Z. Snyder and M. E. Raichle, ‘The global signal and observed anticorrelated resting state brain networks’, Journal of Neurophysiology, 101, no. 6 (2009), pp. 3270–83.
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2 The Cortex and the Mind in the Work of Sherrington and His Protégés
2.1 Charles Sherrington: The Continuing Cartesian Impact
Sherrington’s work left the role of the mind and its relation to the cortex problematic
As we have seen, it was the brilliant research of Sherrington that finally revealed the true nature of the spinal cord as a reflex centre and the role of the cortex in the generation of reflexes. He also clarified the beautiful specificity of the localization of function within the motor and somatosensory cortex. However, although the notion of a ‘spinal soul’ no longer figured in neurophysiology, the question of whether a ‘cortical soul’ existed remained moot. Or, to put it more perspicuously, the question of the relationship between the mind and the cortex remained deeply puzzling. Sherrington considered this question, tackling it in his usual methodical manner by first considering it in a historical setting through the work of Jean Fernel and the beginnings of the conception of physiology and neurophysiology. Later, he took up the problem at length in Man on his Nature, his Gifford Lectures of 1937/8.1
Sherrington’s dualism
Sherrington studied Fernel carefully, and read extensively in the works of philosophers, from Aristotle onwards. But, as we shall see, his grasp of philosophical problems and his understanding of the differences between scientific problems and philosophical ones were infirm. Despite acquaintance with Aristotle’s De Anima, he failed to see the depth and fruitfulness of the Aristotelian conception of the psuche¯ and its bearing on the essentially conceptual questions that plagued him. He noted Aristotle’s ‘complete assurance that the body and its thinking are just one existence’, and that ‘the “oneness” of the living body and its mind together seems to underlie the whole [Aristotelian] description as a datum for it all’.2 Nevertheless, Sherrington did not probe the Aristotelian philosophical doctrine properly. Instead, he moved towards a dualist conception of the relation between mind and body, unsurprisingly encountering the same insoluble problems as Descartes had in the seventeenth century. Using the term ‘energy’ to signify matter as well as energy, Sherrington held that ‘evolution has dealt with … us as compounded of “energy” and “psyche”, and has treated in us each of those two components along with the other. The two components are respectively, on our analysis, an energy-system and a mental system conjoined into one bivalent individual’ (MN 250). ‘Energy’, or matter, and mind are, he thought, ‘phenomena of two categories’ (MN 251).
Sherrington’s conception of mind
‘Energy’, in his view, is perceptible, spatio-temporally locatable, subject to the laws of physics and chemistry. Mind, by contrast, is ‘invisible’, ‘intangible’, without ‘sensual [sensory] confirmation’ (MN 256). Sometimes Sherrington states that mind is ‘unextended’;3 at others he states that since mind has a location, it is inconceivable to him that it should lack a magnitude or be without extension. ‘Accepting finite mind as having a “where” and that “where” within the brain, we find that the energy-system with which we correlate the mind has of course extension and parts … Different “wheres” in the brain correlate with different mental actions … We have to accept that finite mind is in extended space’ ( MN 249f.). On the other hand, he remarks, more sapiently than he evidently realized, that the mind is not ‘a thing’ (MN 256). He conceived of mind as the agent of thought, the source of desire, zest, truth, love, knowledge, values – of all, as he put it, ‘that counts in life’ (MN 256). It is, he wrote, ‘the conscious “I”’.4 But this is misconceived. The mind is no more located in the head or brain than is the ability to walk or talk. It is neither extended, nor an unextended point, any more than the ability to score a goal is either extended or an unextended point. The mind is not ‘the conscious “I”’, since there is no such thing as ‘an I’, any more than there is such a thing as ‘a you’ or ‘a he’ (see below, §14.4). I am not my mind – I have a mind, not as I have a car, or even as I have a head or a brain, but rather as I have eyesight or the ability to think.
Sherrington’s conception of the relation between mind and body
How we should conceive of the conceptual relationships between mind, body (and brain) and person is a deep philosophical problem – the character of whose solution we have intimated, and shall discuss below (see, e.g., §4.8). Sherrington was exceedingly unclear about the issue, not fully realizing that this is not an empirical problem at all, but a purely conceptual one. Sometimes he seems to accept the mistaken idea that the mind has a body,5 even though, to be sure, it is not minds that ‘have bodies’, it is human beings.6 At other times he seems to go so far as to claim that the body (or at any rate parts of the body) has (or have) a mind – a part of the body that is sensitive has ‘mind only lent it, in the form of sensation by proxy’ (MN 187). But this is confused. What would a body do with a mind? People, human beings, have minds as, indeed, they have bodies. ‘So much of the body as feels, has its sensations done for it’ by the brain, Sherrington argued, and so too, ‘the body’s thinking seems to be done for it, namely in the brain’ (MN 187), presumably by the mind. Here too he was confused, since the brain does not ‘do’ sensations – there is no such thing as ‘doing’ sensations. But we have sensations in various