Response of the Telencephalic Neurons of the Budgerigar Melopsittacus undulatus to Species-Specific Warble Song Elements

Abstract

The response of neurons of the budgerigar (Melopsittacus undulatus) was obtained in Field L, which is a laminated auditory structure of the caudal neostriatum in the telencephalon. Warble song of this species is comprised of a number of sounds (elements). The influence of sequence and silent intervals between elements on neuronal response was investigated. First, neurons in Field L were examined to know if neuronal response to isolated elements differed from that to the same elements in warble song, a sequence of elements. Sixty-two percent of the neurons exhibited increases of spike activity in response to elements in isolation compared with that to elements in warble song. These neurons thus exhibited temporally suppressed response. We then examined neuronal activity using the stimulation with paired elements, separated by various silent intervals (delta t msec). The spike activity in response to a specified element decreased as the interval was shortened. The responses of most neurons were strongly suppressed at the delta t of 80 msec, which is often seen in element intervals of warble song. In some neurons in Field L the response was suppressed, although they did not respond to the preceding sound. We hypothesize that temporally suppressed neurons may play a role in vocal discrimination.