[Neurophysiological mechanisms of auditory adaptation. II. Poststimulus effects]

The problem of interaction of spike neuronal activity evoked by successive sounds in single elements of auditory system is considered. The forward masking situation, when pairs of signals are presented independently, as well as the condition of long sequences of signals with different on-of ratios are analyzed. The strong increase of a diversity of single units ability to reproduce fast sequences really observed from the lowest to the higher nuclei of an auditory pathway. Complex units, reacting only on "new" signals, appear from midbrain region of auditory pathway. However such elements are found out usually not in a direct lemniscal auditory way, but in surrounding nuclei. While poststimulus adaptation to specified type of signals usually causes the considerable increase in threshold of detection, differential sensitivity to small changes can remain quite high. This aspect of auditory sensation remains poorly investigated both in physiological and in psychophysical experiments.