The effects of applied polarization on evoked electro-cortical waves in the cat

1. 1. Observations on the responsiveness, wave-form, pattern of pyramidal relayed activity, and thalamic threshold stimulus intensity were made during polarization of the cortex giving rise to recruiting and augmenting waves. 2. 2. Augmenting waves were more sensitive to alteration by polarization than were recruiting waves. 3. 3. The latency of the peaks was unchanged by polarization with the exception of the augmenting negativity during surface positive polarization. In this case, the initial responses in the train had a decreased latency which disappeared with the growth of augmenting positivity in the later responses. 4. 4. The net effect of surface positive polarization was an increase in the amount of negativity recorded in each response. Surface negative polarization produced the opposite effect. These changes were explainable on the basis of increases and decreases respectively in the negative component common to both responses. The qualitatively similar reaction to polarization in both phenomena was considered evidence for the idea that the negative components represent similar forms of activity. 5. 5. Polarization produced no change in thalamic stimulus threshold, or the pattern of relayed pyramidal activity. 6. 6. The results were discussed in detail. It was concluded that the effects of polarization were best explained on the basis of alterations produced in the resting membrane potentials of graded-response structures located in the superficial layers of the cortex.