Unit responses of the torus semicircularis of frogs to acoustic stimuli of different duration

Abstract

The action of tonal stimuli of a characteristic frequency but of varied duration on 76 neurons of the mesencephalic auditory center (the torus semicircularis) of the frogRana temporaria was investigated. Responses to short stimuli (10 msec) of five groups of neurons differentiated by their responses to a long (300 msec) stimulus, were studied. Responses of some neurons were strengthened on shortening of the stimulus, while others responded only to tones of longer than the critical duration; this critical duration is independent of stimulus intensity over a wide range. The possible synaptic mechanisms lying at the basis of the observed effects are discussed.