Neurophysiological approaches to studying the functional role of auditory critical bands

Neurophysiological data on the evaluation of neural correlates of the involvement of auditory critical bands in sound localization and recognition are presented. Single unit activity was recorded extracellularly in the central nucleus of the inferior colliculus in house mouse females. In the first part, the neuronal sensitivity to acoustic signals simulating spectral localization cues (notch noise with different bandwidths) was studied. Evaluation of neuronal response variability depending on notch bandwidths revealed that the 1/3 octave notch bandwidth was optimal for the analysis of the localization-significant spectral information. This notch bandwidth corresponded to the average critical bandwidth of the auditory midbrain neurons determined previously by the narrow-band masking method. In the second part, the selectivity of neuronal responses to a discomfort-signaling mouse pup wriggling call, its models and frequency components, was evaluated. The data obtained demonstrated that the wriggling call models with frequency components located, like in a natural call, in three non-overlapping critical bands evoked stronger neuronal responses than the other models. These findings support the suggestion of the universal role the critical-band mechanism plays in processing different parameters of acoustic stimuli.