STIMULUS INDUCED AND SPONTANEOUS RHYTHMIC FIRING OF SINGLE UNITS IN CAT PRIMARY AUDITORY-CORTEX

Recordings were made under ketamine anesthesia from 385 neurons in primary auditory cortex in adult cat and from 265 neurons in 10-55 day old kittens. The temporal Modulation Transfer Function for the response to repetitive click stimuli peaked at 8 Hz. After a click a suppression period of 130-155 ms in duration, depending on click-rate, was observed. This suppression period limited the response to high click rates and thereby determined the `resonance' in the click response. The suppression duration in kittens decreased in exponential fashion toward the adult value with a time constant of about 1 month. After the one second duration click-trains an oscillatory rebound with a mean period of 113 ms was observed in about 60% of the recordings in the adult cat. Spontaneous activity showed in about 30% of the neurons an oscillatory auto-correlogram with an average period of 126 ms in the adult cats and 170 ms in kittens.