Bilateral auditory processing studied by selective cold-deactivation of cricket hearing organs

We studied bilateral processing in the auditory ON neurons of crickets using reversible cold-deactivation of the hearing organs by means of Peltier elements. Intracellular recordings of the neurons activity in response to acoustic stimuli were obtained, while either the ipsilateral or the contralateral hearing organ was cold-deactivated. Afferent activity was abolished at a temperature of about 10{degrees}C. In ON1 contralateral inhibition has no effect on the latency and amplitude of the phasic onset activity, it enhances the decline of the onset activity and decreases the subsequent tonic spiking response to acoustic stimuli. As a consequence the phasic onset activity becomes more salient and reciprocal inhibition may support the detection of sound pulses. Contralateral inhibition had a significant impact on the tonic ON1 response, in line with its presumed function to enhance the bilateral auditory contrast. In ON2, experiments confirmed a bilateral excitatory input, with the ipsilateral input dominating the response, and no inhibitory coupling between the ON2 neurons.