Neurobiology of the Hippocampus

Dr Miller has acquired a deserved reputation for writing lucid and thorough neuropsychological reviews, and the present book is no exception. Starting from the premise that the role of psychological assessment in neurological diagnosis is becoming "severely limited" as radiological techniques advance, Dr Miller reviews studies of recovery from neuropsychological deficits and psychological attempts to facilitate that recovery. The book covers three main issues. In the first section Dr Miller outlines eight assumptions held by many professionals regarding the nature of recovery from brain lesions; for example, that there is a consistent and regular recovery curve, and that younger subjects show less behavioural disruption from comparable lesions than older patients. Arguing that these assumptions "give the impression of being passed down rather more as folklore instead of being systematically organised principles," Dr Miller reviews the evidence regarding their validity, finding that they can be accepted only with considerable qualification. In particular, we know pitifully little about how the various factors influencing recovery interact with each other. In the central chapter of the book, Dr Miller discusses the various theories purporting to explain recovery from neuropsychological impairments. He divides these into artifact theories, and theories of anatomical reorganisation and of functional adaptation. Artifact theories suggest that injury or disease results not only in the primary brain lesion, but in the suppression or inhibition of the functioning of other parts of the brain: loss of this inhibition produces" recovery". Anatomical reorganisation implies a change in the brain regions subserving a particular function, whereas functional adaptation implies that the patient develops a new means to obtain a particular goal. Dr Miller finds that there is evidence that all three processes can play a role in recovery, but that we still have little knowledge of which particular processes operate in which circumstances and to what degree. In the final portion of the book, Dr Miller reviews psychological attempts to improve function either by restituting lost capacities or by ameliorating the effects of such loss. He discusses dysphasic and amnesic disorders in some detail, and other dysfunctions more sketchily. He finds that many studies claiming gains from psychological intervention are poorly designed and controlled, and that, in general, evidence regarding efficacy is disappointingly meagre. Nevertheless, there are sufficient pointers to suggest that further, better designed, studies are well worth pursuing; and, as Miller rightly points out, even relatively small gains can be of great significance to the patient. In the course of his review, Dr Miller encompasses a large literature, and the book is a valuable source of references. The tone is generally sceptical and somewhat pessimistic, but this is a welcome antidote to the larger claims sometimes made in psychological and pharmacological studies of neurological rehabilitation. The present reviewer particularly enjoyed Dr Miller's lucid discussion of the assumptions which underlie our views about recovery, but felt that, on occasion, he dwelt a little too lengthily upon the animal literature and failed to explore why clinicians hold the views that they do. For example, clinicians firmly believe that rapidly developing lesions have more dramatic effects upon psychological function than slowly progressive ones. The author reviewed the animal literature regarding the effects of one-stage versus serial lesions, and found the evidence in support of the clinicians' view to be somewhat equivocal. It is possible that the clinicians' impression is an artifact of the different types of lesion which develop rapidly or slowly, or that the animal experiments are an inappropriate analogy. Although mentioning the latter possibility, Dr Miller did not really discuss what he felt might underlie this apparent discrepancy. I hope that this book will be widely read. It will encourage neurologists and psychiatrists to think more carefully about the recovery of psychological function, clinical psychologists and speech therapists to look more sceptically at the rather inadequate literature on rehabilitation, and cognitive psychologists to focus their attention upon a problem which is clinically important as well as theoretically challenging. MICHAEL D KOPELMAN