Changes in receptive field of tectal neurons evoked by vestibular and acoustic stimulation in pigeons

Abstract

Responses to visual, acoustic, and vestibular stimuli were studied in neurons of the middle and deep layers of the tectum in the pigeon. Changes in the receptive field (RF) were assessed from comparison of unit responses to isolated movement of a shaped visual stimulus with responses to movement of a stimulus during simultaneous action of a vestibular or acoustic stimulus. Changes in RF of the neuron could be observed during the action of both a vestibular and an acoustic stimulus. These changes affected the identification of the predominant direction of movement of the stimulus, the position of the maximum in the response histogram, and the duration and number of spikes in the response. The direction of change in RF of the neuron was found not necessarily to coincide with the sign of the response to the same neuron to isolated presentation of a vestibular or acoustic stimulus. It is postulated on the basis of the results and data in the literature that the tectum transforms the flow of impulses arriving from the retina depending on the nature of the information received by it from other sensory systems.