Fig. 3.

Specific inhibitory neuron type mediates auditory adaptation. (a) Top: The effect of SOM and PV inactivation on stimulus-specific adaptation to frequent tones was tested using an oddball stimulus, with two tones at 10–90 ratio, light every 5th tone. Bottom: The mean firing rate (FR) during repeated tones adapted with successive presentations of the standard tone. (b) SOMs provide stimulus-specific inhibition, as the effect of SOM suppression increased with repeated standard tones. PVs provided constant inhibition regardless of adaptation. a, b adapted from ref. ³⁴. (c) Passive exposure to a tone stimulus lead to a decrease in excitatory and an increase in inhibitory activity over 5 days. Left: calcium activity was imaged using two-photon microscopy in populations of identified inhibitory and excitatory neurons before and after subjecting the mouse to prolonged exposure to tones. Neuronal activity was measured as spike counts inferred from the imaged fluorescence signal. Right: change index of the mean activity in response to the tone to which the mouse was exposed, averaged over populations of excitatory (red) or inhibitory (blue) neurons, over days since prolonged tone exposure onset. Mean excitatory activity decreased with exposure, whereas mean inhibitory activity increased. (d) Among the inhibitory neurons, the activity of SOMs increased following passive tone exposure, whereas the activity of PVs decreased. Mean z-scored time course of Calcium activity of SOMs or PVs in response to a tone at day 1 (black traces) and day 5 (blue traces). c, d adapted from ref. ³⁷