Distribution in time and space of prepyriform electrical activity

Abstract

IN A PREVIOUS STUDY (9) evidence was found that a large proportion of the spontaneous electrical activity recorded from the basal forebrain of the anesthetized cat was generated bilaterally by the prepyriform cortex, not by the subcortical structures in which the recording electrodes were located. This finding raised the question of how the oscillating potentials of the brain are transmitted, i.e., to what extent the spread of EEG activity is due (i) to continuous spread of membrane depolarization along axonal or dendritic fibers; (ii) to the formation of intracellular?extracellular current loops such as occur on a shorter time scale in peripheral nerve, with instantaneous field distribution of the current through the brain; and (iii) to successive activation of contiguous cells. To approach this question a study was made of the nature of the various wave forms generated by the prepyriform cortex and of their rates, directions, and distances of spread in and around the cortex.