Auditory Response Properties of the Anuran Thalamus: Nonlinear Facilitation

Abstract

Auditory evoked responses were first recorded in the anuran diencephalon by Mudry and her colleagues (Mudry, 1978; Mudry, Constantine-Paton, and Capranica, 1977). These investigators showed, in several anuran species, that evoked responses from the dorsal thalamus exhibited a property that they termed “nonlinear facilitation”. That is, thalamic evoked potentials responded preferentially to two-tone stimuli containing acoustic energy that simultaneously excited both of the peripheral auditory papillae. The magnitudes of responses to these two-tone stimuli were larger than that predicted by the linear summation of response magnitudes to each tone presented separately. Such an effect was not observed in the torus semicircularis of the midbrain. In this auditory center, evoked response magnitudes to two-tone stimuli are equal to the summed responses to each tone presented alone.