[Comparative study of interneuronal relations in neighboring microareas of the cerebral cortex in untrained wakeful...

Multineuronal activity was studied in unrestrained cats with bundles of 7 electrodes (50 mcm dia of the tips) chronically implanted in the auditory and motor cortex. Impulses of the highest and lowest amplitude were isolated from each neurogram by an amplitude discriminator. By means of AI-128 analyser interval cross-histograms were built for spike series, isolated from two simultaneous records. Functional connections between neurones located under different electrodes at a distance of up to 500 mcm were defined by statistical dependence of spike series. A higher level of interneuronal interaction was revealed in the motor cortex. In both cortical zones, excitatory connections dominated for neurones which generated high amplitude spikes. For neurones with low amplitude spikes, connections of the inhibitory type were typical in the auditory cortex, and inhibitory and inhibitory-excitatory connections were typical for neurones in the motor cortex. The excitatory type of dependence in the auditory cortex was manifested on histograms during the first 6 ms after the triggering spike, in the motor cortex-by 4 to 6 ms more frequently; the inhibitory type was manifested in both zones only during the first 2 ms.