Clinical Chemistry

portance of the complexity and pattern of neuronal connections was emphasized by Cajal long ago, but since the determination of the number of connections of an individual neuron is very difficult, Dr. Sholl's stimulating idea is that "the connective field of the neurons may be defined and measured in statistical terms." The background of the author led him to adopt a statistical approach to the problem. By this means some explanation can be offered for the plasticity of response shown in physiological and psychological experiments. The exposition is extremely lucid, but some arguments against the thesis may have been underestimated. For example, it is true that localization of some functions such as "memory" cannot be pinpointed and regional specialization is sometimes difficult to show. However, the problem could be dealt with in terms of regional hierarchies, in the sense that some areas play a more important role in controlling a specific function. Memory, for instance, is impaired by temporal lobe destruction but is not modified by extirpation of area 4, and it is difficult to accept "memory" as a "general attribute of all cortical tissue." "Cortical instability" cannot be considered axiomatic. There is some feeling in the literature that it could be attributed to artefact if experimental conditions were changed, and particularly if the electrodes to stimulate the cortex were reapplied. Another questionable point is the concept of the cortex as the highest part of the central nervous system; the importance of "subcortical" neuronal fields in the highest mental processes should be considered. However, these are questions occasioned by the excellent intellectual level of the book which will probably stimulate many constructive controversies. In the last chapter mathematical theories of cortical organization are discussed and a main thesis is expressed: models used to study the cortex "should be based on the concept of probability and discussed in a statistical language." Complicated problems are explained clearly but with depth, which makes reading of the book very enjoyable. Six pages of bibliography are offered and alphabetical indices of subjects and authors complete the book.