[NEUROPHYSIOLOGIC APPROACHES TO THE STUDY OF FUNCTIONAL ROLE OF THE AUDITORY CRITICAL BANDS]

Neurophysiologic data on participation of the critical band mechanism in sound localization and recognition are presented. Single unit activity was recorded extracellularly-in the central nucleus of inferior colliculus of the house mouse females. First, we studied sensitivity of neurons to acoustic signals simulating spectral localization cues (notch noise with different bandwidths). Comparison of neuron responses depending on notch bandwidths revealed that 1/3 octave notch bandwidths was optimal for the analysis of the localization-significant spectral information. This notch bandwidths corresponded to the critical bandwidths of the auditory midbrain neurons evaluated earlier by the simultaneous masking paradigm. Second, we studied selectivity of neuronal responses to the mouse pups' wriggling call, a set of its models and frequency components. The data obtained showed that models of wriggling call frequency components, located as in natural call, in three non-overlapping critical bands produced stronger neuronal responses than other models. We assume that our finding proves the universal role of the critical bands mechanism in processing different parameters of acoustic stimuli. Key words: inferior colliculus, auditory critical bands, sound source localization, analysis of bioacoustic signals.