[Responses of neurons of the auditory cortex in the cat to exposure to tones of different frequencies and electrical stimulation of the corresponding portions of the cochlea].

The characteristic frequencies for responses of the primary auditory cortical neurons (zone AI) whose receptive fields were located in different parts of cochlear basilar membrane were determined in nembutal-anesthetized cats. It is shown that the higher the characteristic frequency of the neuron, the nearer its receptive field to the base of the cochlea. The receptive fields of neurons with characteristic frequency above 4 kHz were located over the first 10 mm of the basilar membrane. Receptive fields of neurons with characteristic frequencies lower than 4 kHz occupied the rest of the basilar membrane. Electrical stimulation of the centre of the receptive field evoked neuronal responses which corresponded to reactions of the same unit produced by the tone of the characteristics frequency. The more the frequency of the tone differed from the characteristic one or the greater the distance between the centre of the receptive field and the point of stimulation, the lower is the probability of the response. The size of the receptive field of neurons with low characteristic frequencies was wider than that of high-frequency neurons. Using paired stimuli it is shown that excitation of cortical neurons was followed by inhibition. This inhibition was more prolonged and effective in responses to tones of characteristic frequency.