Potential phenomena in thalamus and cortex.

1. The cortical response to stimulation of an afferent path consists of two parts, a specific response indicating projection of the afferent and a response of the alpha mechanism. The former of these under the influence of strychnine can be identified with the cortical spikes of paroxysmal activity. 2. The response of the geniculate and other simply arranged nuclei are monophasic spikes. The diphasic spikes of the cortex and elsewhere are inferred to be assignable to two different groups of cells related by synaptic passage. 3. The unit cell potential may be interpreted as the resultant of unequal depolarization during activity of the two ends of the cell dendritic and axonal. If this is so, polarization by external currents should modify or even reverse the potentials and this proves to be the case. The phenomena are comparable to the effects of polarization on nerve axons. 4. Three types of potential fields can be visualized of which different cell structures of the brain may be considered as variants. Plots of the potentials of these fields indicate what relation of potential form to structure may be expected to obtain. 5. The character of the relation between thalamus and cortex appears to be different for the specific response apparatus which is not spontaneously active expect in paroxysmal states and the regulatory apparatus which is normally spontaneously active but suppressed in paroxysm. It is not necessary to infer reverberating closed circuits to account for the activity in either system.