Along the whole auditory pathway, an acoustic signal is expressedby a spatiotemporal pattern of the binary neural activity. The authorpoints out several general features of neural auditory preprocessing. Onthe first level of the auditory system, the amplitude changes ofnarrowband stimuli are encoded by an instantaneous firing rate in afrequency channel consisting of 30-40 fibres. On the next level, owingto the summation of the inputs received from neighboring frequencychannels and to the effect of delayed lateral inhibition, the dynamicrange of single units increases considerably. In phasic neurons,enhancement of the amplitude changes due to short-term adaptationeffects is observed. The role of delayed inhibition is also considered.Finally, in many tonic neurons of the auditory pathway, long-termadaptation leads to the adjustment of the threshold level to the meanlevel of the received synaptic input. This effect may play the leadingrole in the process of small amplitude change enhancement forlong-duration stimuli
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