This is a must for those wanting to add an up-to-date and readable book containing ‘mind’ or ‘brain’ in the title to their collection. Greenfield argues for consciousness to be more than mind, and proposes that we look to our emotional life for clues as to its emergence and continuity. In a nutshell, we are asked to believe that “the interaction between body and brain IS consciousness” and that whereas the mind needs the brain (alone?), consciousness requires the neuronal brain plus its modulatory interaction with the hormonal system(s) of the body as a whole. (i.e., the brain is necessary, but not sufficient to produce consciousness).

In a little more detail, although this volume provides the reader with an attempt to distinguish mind from consciousness, we are at the same time given a model continuum with ‘emotion’ at one end and ‘mind’ at the other; the goal of neuroscience (of whatever flavor its researcher) being to uncover the ‘Rosetta Stone’ of the physical brain Vs emotion/consciousness. Starting with the thesis that emotions are suppressed by logic and reason, we are taken on a tour of metaphysical models of mind-brain coexistence and a useful series of historical analogies of self-hood persistence are drawn from the literature. What an agent does (behaviorally) is rightly in my view distinguished from what it might think or understand (concerning its situation), but Greenfield pushes for the further dependence upon consciousness to underlay true understanding. What of consciousness itself, here as elsewhere in the book, there is little new.

The middle chapters concerning specific brain regions, their known behavioral correlates, and their modulation by the use of both clinical and street drugs are well written in a style accessible to the general reader, but perhaps cloud the formation of the ‘bigger picture’. However, such might be beyond the remit of this volume, requiring a different vocabulary and indeed a couple more chapters. The standard amine neurotransmitter stories are appropriately given, but I am left wondering whether we have really come thereby to know how (as opposed to that) “feelings influence thoughts” before turning to how “thoughts influence feelings”? (concluding Ch.6).

Discussing the ways in which thoughts and words might give rise to our emotional sensations is ‘difficult’ because we are unclear as to ‘the physical stimuli and triggers [which] impinge upon the senses’ – but this begs the question as if other behaviors such as sensorimotor transformations are already understood. Even if emotions are found to be “the most basic form of consciousness” as Greenfield contends, I’m not convinced that such a view helps me to know what consciousness IS (either for myself or another). Indeed, I’m rather afraid that this might result in the term disappearing following the phenomenon being explained away [c.f. the eliminative materialism of Churchland]. It is only in the latter two chapters that Greenfield comes clean, adding the effects of the (traditionally separated) endocrine system in progressing our understanding of consciousness (as opposed to merely describing the brain-mind). Keeping the two systems apart, Greenfield introduces peptides as “vying between the brain and the rest of the body”, affecting neuronal assemblies (as they do) and thus the extent, type and degree of consciousness experienced.

This is all intuitively plausible, but no clear mechanisms are offered here. I felt that the warrant for a further chapter had been given, and wanted to know Greenfield’s view as to how this might come together re the mind-brain correlates already ‘in-the-bag’ with regards neural plasticity in growth and development. I was expecting to go on to read, for example, how circulating hormones were involved in quite different time-courses of events (as the appendix discussed fast quantum theoretical proposition effects dismissively in contrast to the millisecond events occurring at the synapse) but there was no mention of the mush (significantly) longer min/hour/daylong effects of hormonal releases in contrast to synaptic (electrical and chemical) transmission. Furthermore, no mention was made of work [e.g., Alan Dixson (Cambridge) and Tom Insel (Emory)] currently attempting to determine the effects of hormonal regulation upon gene expression and its effects upon the developing nervous system (both postnatally and in utero). Such an inclusion would have provided for me a more rounded closure to this discussion of a complex ‘mindfield’ of mixed emotions, thoughts and conscious deliberations.

A. R. Dickinson, Dept. of Anatomy & Neurobiology, Washington University School of Medicine, St. Louis.

Categories: General, Philosophical