Sensory modalities and receptive fields in the abdominal nervous system of the hermit crab, Pagurus granosimanus (Stimpson).

Abstract

ABSTRACT The way in which adaptation to a particular environment takes place within the central nervous system of vertebrates has been the subject of research for over a hundred years. The development of specific reflexes from generalized action patterns, the precedence of changes in motor systems over changes in sensory systems, and the metamorphosis of sensory relay nuclei and centres of primary integration into areas subserving more complex functions (Herrick, 1948) are some of the ways in which adaptation is reported to have occurred. Furthermore, Bishop (1961) has suggested that the emphasis upon functional criteria alone as a key to the function of a specific nervous system neglects those features of the system which owe their presence to its evolution from a nervous system adapted to perform other tasks. During their evolution, the newer centres of integration which have developed as a result of new requirements have not abolished the older centres, which may retain many of their old properties. It is clearly of interest to determine whether nervous systems of groups other than vertebrates exhibit the same regularities in their adaptation, and if possible to examine the alterations in response to different selective forces at the single-unit level.