[Reactions of neurons of the auditory cortex of unanesthetized cats to tones of a characteristic frequency].

Extra- and intracellular responses of primary auditory cortex (AI) neurons were studied in acute experiments on non-anaesthetized cats. It was found that auditory cortex neurons having similar best frequencies revealed various forms of responses to corresponding frequency tones. Neurons responded to the tone by on reactions constituted about 40% of nerve cells studied. 27% of neurons revealed responses of on-off and off types. 27% of cortical neurons responded by steady excitation or by inhibition of background activity. About 6% of neurons did not respond to the tone. During intracellular recordings about 85% of neurons studied responded to switching on and/or off of the tone by a spike-IPSP sequence. 96% of cortical neurons generated IPSP as a constant component of the response to tone. Tonic responses of auditory cortical neurons were the result of powerful and lasting depolarization of the postsynaptic membranes. The conclusion is made that interaction of excitatory and inhibitory processes is the most significant in any kind of responses of the auditory cortical neurons to tones.