Effects of adaptation on spectrotemporal receptive fields in primary auditory cortex

Spectrotemporal receptive fields of nonlinear neurons in primary auditory cortex are stimulus dependent or context dependent. Here we show that a variant of stimulus-specific adaptation also contributes to this context dependence. Responses to sound stimulus frequencies close to the neuron's best frequency adapt with an average time constant of approximately 7 s. In contrast, responses away from the best frequency do not adapt, but in fact slightly increase over our 30-s observation window. Such stimulus-specific adaptation could function in enhancing stimulus discrimination and in maximizing neural information transmission by reducing redundancy. It also needs to be taken into account when comparing spectrotemporal receptive fields measured under adapted and nonadapted conditions.