Analysis of circulation of neuronal activity in the waking cortex.

It is well known that the rhythmic activity of the cerebral cortex is closely associated with a highly organized circulation of neuronal impulses through the networks in which the activity develops. The present study has attempted to determine by quantitative methods, the consistency of this circulation and of its association with the cortical waves, over relatively long periods. Cortical gross waves and neuronal activity have been recorded by means of arrays of extracellular microelectrodes, in freely moving cats as well as in cats immobilized with flaxedil. Autocorrelations have been performed on trains of rhythmic waves and on associated clusters of action potentials; cross-correlations and multiple correlations have been performed between waves and action potentials and between action potentials generated by different groups of neurons. It has been found that the rhythmicity of the waves, the rhythmicity of the associated clusters of action potentials, the time and phase relations between them, and the circulation of neuronal activity through the networks, remain highly consistent over periods as long as two hours.