Responses of neurons of the parietal association cortex of the cat to acoustic stimulation before and after suppression of the auditory cortex in the cat

The aim of this work was to study the influence of auditory cortex suppression in cat on response patterns of the parietal associative cortex neurons responding to different frequency tones. Suppression was performed by two methods: bilateral isolation and application of 6% nembutal solution on the cortex surface. Frequency-thresholds curves were plotted for all neurons studied. Prior to suppression the majority (84%) of studied neurons had one or two characteristic frequencies. After suppression the percentage of such cells fell to 63% of all responding neurons. Frequency range to which neurons could respond was altered as well. Normally almost all neurons tested could respond to a wide spectrum of presented frequencies. After suppression 69% of neurons did not respond to tones above 8-10 kHz. This may indicate that mainly information about high frequency tones is transmitted via the auditory cortex. The possibility that associative thalamic nuclei are the main source of acoustic information for parietal associative cortex neurons is discussed.