RESUMO
Reactions of 141 cat caudate nucleus neurons to auditory signals--tone (500 and 2000 Hz) and clicks with different frequency (0.2 and 0.8/s) and intensity (75, 80, 95 dB) were recorded extracellularly. Neuronal reactions were highly variable as to the character of responses (phasis, tonic), their structure (one or two phases of activation), latent periods (from 7.5 to 300 ms), discharge frequency in burst responses (from 90 to 800 imp/s). Analysis of the averaged poststimulus histograms and plots of the dynamic reaction modifications showed that in most units (74%) the responses became considerably better expressed in case of a decreased stimulus frequency: the response regularity and the number of spikes in each response rose. The neuronal reactions also increased and acquired more distinct time structure with an increase in the stimulus intensity, 17% of recorded units showed qualitative differences in the character of neuronal reactions to clicks and tones: phasic activation arosed to clicks and tonic change of pulse activity occurred to tones. Peculiarities of the caudate nucleus neuronal reactions to auditory stimuli with different parameters are discussed.
