The Cockroach DCMD Neurone: II. Dynamics of Response Habituation and Convergence of Spectral Inputs

Abstract

1. The projections and response properties of a bilateral pair of large visual interneurones in the cockroach Periplaneta are described. The cells are shown to be analogous to the DCMD neurones of locust (Rowell, 1971a). 2. The organization of the afferent input to the cockroach DCMD was explored by examining the response to different types of visual stimuli. The afferent input is organized into an array of parallel channels. Response habitutation occurs within each channel independently of habituation in other channels. 3. The dynamics of habituation and recovery from habituation were examined. A simple model based on these data is proposed that can predict the DCMD response to repetitive stimuli having a wide range of interstimulus intervals. The relation of this model to models of synaptic depression is discussed. 4. Both u.v.-sensitive and green-sensitive photoreceptors in the eye provide input to the DCMD, but this cell remains unable to detect colour.