Responses of cat primary auditory cortex neurons to moving stimuli with dynamically changing interaural delays.

The spike responses of individual neurons in the primary auditory cortex were studied in anesthetized cats during exposure to stationary and moving stimuli with static or dynamically changing interaural delays (deltaT). Static stimuli were tones and clicks. Dynamic stimuli were created using series of synphase and antiphase clicks with interaural delays which changed over time. Sensitivity to changes in deltaT was predominantly present in neurons with low characteristic frequencies (less than 2.8 kHz). Changes in deltaT in moving stimuli induced responses in neurons sensitive to changes in deltaT in the stationary stimulus. The effect of movement could be a relationship between the level of spike activity and the direction and rate of change of deltaT or it could be a displacement of the tuning curve for the response to deltaT (the deltaT function) in the direction opposite to that of the direction of the change in deltaT. The magnitude of the effects of movement depended on the position of the period for changes in deltaT relative to the deltaT function. The greatest effects were seen with changes in deltaT on the sloping part of the deltaT function.