Correlation of the macrogram and the microgram of the penicillin focus in turtle (Testudo) cerebral cortex. Localization of the capillary microelectrode tip with Pontamine Sky Blue 6BX.

Localization of the tip of the recording microelectrode with Pontamine Sky Blue 6BX introduced into the tissue iontophoretically was used to study the relationship of the morphological type of the neurone to a given type of elecrographic activity during the epileptic focal discharge. Paroxysmal depolarization shifts (PDSs) and short bursts of spikes in the negative phase of the focal discharge were found to be related to cells of the pyramidal type. Conversely, ovoid cells were active only in quiescent intervals and were inhibited throughout the whole duration of the focal discharge.