Time Scale of Adaptation at the Tonal Sequence Processing in the Awake Mice Auditory Cortex Neurons

The study was first carried out on stimulus-specific adaptation of neurons in the primary and anterior fields of the awake house mice auditory cortex to sound sequences of four 100-ms tonal signals, with a frequency of tones corresponding to the neuronal characteristic frequency, and also with the inter-tone interval constant for one sequence and varying from 0 to 2000 ms in different sequences. The analysis of the data obtained showed the adaptation effect in the responses of all studied primary auditory cortex neurons, which was observed as the absence or significant decrease in activity evoked by the components of a series of tones following the 1st, at inter-stimulus intervals of 0-500 ms. A quantitative assessment of the adaptation effects as a function of inter-stimulus intervals within the tonal sequence, performed over a whole population of studied neurons, showed that the individual time scales of adaptation of neurons varied significantly, which may be crucial for the formation of optimal time windows for the processing of grouping and separation of sound events, which are important both for perception of animal vocalizations and human speech.