Neuro-behavioral ontogeny. A synthesis of ethological and neurophysiological concepts.

The hypothesis of the critical period of socialization as originally presented by Scott and Marston sl was reviewed and extended by Scott ?s in describing the behavioral development of non-precocial mammals, in other words, those born relatively immature. In this way, the term critical period originally used in embryology was applied to ethology, the objective study of animal behavior 9z. For purposes of this review the mouse, dog and cat are considered as examples of the non-precocial group and correlations in other parameters of neurological development common to all these animals will be used to extend the critical period hypothesis. Other critical periods, dependent on neuro-endocrine and environmental factors are seen during later life, notably in the onset of sexual and maternal activities. These activities are themselves greatly influenced by the developmental processes underlying the establishment of primary social relationships during the critical period of socialization. In much of the research on behavior undertaken by earlier American psychologists, theoretical conclusions were drawn from empirical observations restricted to one species observed in a synthetic laboratory environment. Indeed plasticity and adaptibility of behavioral development were considered undesirable variables and animals not conforming to the rigid theoretical model were often discarded. At about the same time, in Europe, the students of animal behavior were, in contrast, developing a discipline for studying adaptive behavior within the natural environment, as shown for example, by the increased focus of research within the field of behavioral development, resulting from the earlier work of Loren# 1 on imprinting. With a fundamental knowledge of the processes underlying behavioral development we may