Abstract
A compound response was evoked in somatic area II by electrical stimula-tion to contralateral somatic II of the cerebral cortex of cat: surface positive deflection (P) prior to negative deflection (D) followed by a prolonged positive deflection (A). A spike sequence can also be recorded before and on the rising limb of component P.
Studies were made of excitability characteristics determined with the use of paired identical stimuli at various intervals and recurrence rates. The effects. of local cortical application of potassium cyanide and strychnine sulfate were evaluated. Intracortical recording was made with approximately 10μ pipette electrodes. Interaction studies were also made by means of various combinations, of paired stimuli at different intervals.
It is suggested from these experiments that component P represents the product of postsynaptic activity, being largely produced by the same cortical elements as the postsynaptic positive components of the primary response evoked. by contralateral and ipsilateral somatic afferent nerve stimulation. It is also suggested that component D is of similar origin as the dendritic response evoked by topical stimulation. Component A is considered to represent the activity of neurones different from those which occasion component P.
