SPEECH DISORDERS: Aphasia, Apraxia and Agnosia

Lord Brain's book comes aptly as a distinguished cele- bration for the centenary of Broca's historic pronounce- ment on the seat of articulate language.For he does not only retrace the steps of past investigators floundering in a mass of intriguing but obscure clinical discovery nor merely bring his great experience and critical judgment to bear on the facts as they present themselves today.These pious duties he certainly performs.But as well he takes us exploring with him in that attractive, perilous region where physiology,faute de mieux hypothetical, tries to link psychological fact with anatomical structure.So his book is lively, suggestive, and forward-looking, a worthy successor in the lineage of Jackson, Head, and Pick.Like Head he has sought inspiration in contem- porary neurophysiology; like Pick, in psychology.His own additions to these aids to constructive thought are some of the recent developments of quantitative linguistics and communication theory.'The task of the future,' he writes, 'is to use all the available modern methods of psychological testing, linguistics, phonetics and communi- cation theory, to correlate psychological with physiological functions.'Such foresight and faith in regard to trends not always familiar to the clinician might be unexpected did we not already know that Lord Brain's interests in language happily extend very far beyond its pathology.That for the present not even he can explain in very much detail the potential contribution of these new disciplines to an understanding of dysphasia emphasizes rather than detracts from the author's foresight.Faith is needed, too, when we turn to the particular concepts he uses in his interpretation of the physiological background to linguistic behaviour, expecially the notion of the schema.This notion, since its original introduction into neurology by Henry Head, has found wide applica- tion in psychology, especially by Bartlett and his followers.But in all its varied uses the central idea has been to allow reference to types of process-organization which more elementaristic terms, such as independent reflexes or dis- crete images or memory traces, fail to define.It has served at least to transform merely negative propositions about the physiological concomitants of perception, bodily skill, memory, and thinking into positive, if hypothetical, terms.So, for instance, to take but one example from the field of language, we find that any single word retains its communicational efficacy despite a manifestly enormous range of variety in the physical characteristics of different utterances of it.This must mean that the physiological process corresponding to hearing and understanding the word cannot be defined in terms of any fixed set of ele- ments, however numerous.The neural mechanisms involved must incorporate a set of criteria in accordance with which the word is identified as this one or that one, and the further processes appropriate to each initiated.