The relationship between neuron activity and cortical steady potentials

Abstract

Simultaneous recordings of single neuron activity and of the EEG, recorded with nonpolarizable electrodes and a DC amplifier, were obtained from the posterior lateral gyrus in cat encéphale isolé preparations. The cortex was usually negative relative to the reference electrode in one of the frontal sinuses, voltages near −1.2 mV and −3.1 mV being the most frequently encountered values. The neurons observed tended to fire during surface positive waves and to cease firing during surface negative waves, both during evoked potentials produced by light flashes and during spontaneous activity after section of the optic nerves. This correlation was less marked in the cells recorded from when the cortical steady potential level was around −3.1 mV than in those studied when the steady potential was around −1.2 mV. The amplitude of the negative components of the evoked potential was usually smaller when the steady potential was near −3.1 mV. A few neruons studied whent he steady potential level was much more negative showed a reverse relationship, firing mostly during surface negative waves.