Spectro-temporal receptive fields in auditory cortex

Christian Machens, Mike Wehr, Carlos Brody, and Tony Zador

Cold Spring Harbor

How do cortical neurons represent the acoustic environment? To address this question, we use in vivo whole cell methods in rat auditory cortex and record subthreshold membrane potentials of single neurons in response to complex acoustic stimuli, including animal vocalizations and music.

In a first step, we estimated the linear component---the spectro-temporal receptive field (STRF)---of the transformation from the sound (as represented by its time-varying spectrogram) to the neuron's membrane potential. We find that the STRF has a rich dynamical structure, including excitatory regions positioned in general accord with the prediction of the simple tuning curve. While the STRF successfully predicts the responses to some of the natural stimuli, it surprisingly fails completely to predict the responses to others. Hence, much of the neuron's response, although deterministically related to the stimulus, cannot be predicted by the linear component.

In a second step, we now investigate to what extent the STRF can be amended by including the time-varying dynamics of different adaptation mechanisms.