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 adaptationof neurons in the primary and anterior fields of the awake housemice auditory cortex to sound sequences of four 100-ms tonal signals,with a frequency of tones corresponding to the neuronal characteristicfrequency, and also with the inter-tone interval constant for onesequence and varying from 0 to 2000 ms in different sequences. Theanalysis of the data obtained showed the adaptation effect in theresponses of all studied primary auditory cortex neurons, whichwas observed as the absence or significant decrease in activityevoked by the components of a series of tones following the 1st,at inter-stimulus intervals of 0–500 ms. A quantitative assessmentof the adaptation effects as a function of inter-stimulus intervalswithin the tonal sequence, performed over a whole population ofstudied neurons, showed that the individual time scales of adaptationof neurons varied significantly, which may be crucial for the formationof optimal time windows for the processing of grouping and separationof sound events, which are important both for perception of animal vocalizationsand human speech.