SITES OF ORIGIN OF ELECTRIC POTENTIALS IN STRIATE CORTEX

Publisher Website
Google Scholar
Abstract
The locations of the sources of certain potential components of the responses to optic nerve stimulation in the optic cortex of cats and rabbits have been detd. The technic involves a null-point method in which fractions of the total cortical response led from a potentiometer subtending the cortex from surface to white matter are balanced against the responses of fractions of the cortex, led from electrodes subtending only a part of the cortical thickness. A series of at least 6 spikes of 1.5 m. sec. duration can be differentiated in the response, the 1st assignable to optic radiation, the remainder to cell bodies of cortical neurones. These spikes originate at successively higher levels of cortex, following the 1st 3 arising at about the 4th layer. A longer lasting positive wave underlies the spike series, thought to represent the more prolonged responses of basal dendrites of these same cells. An early negative wave, following the positive immediately, signalizes the responses of the apical dendrites of pyramidal cells, and a later negative wave arises from the 5th and 6th layers. The action of dilute strychnine is chiefly on the responses of apical dendrites; in the normal condition conduction over these structures is minimal following optic nerve stimuli. Strychnine in higher concn. gives similar negative paroxysmal spikes without stimulation, and without a positive spike and wave response preceding it, althouth such responses may be masked by the high negativity. To the extent that apical dendrites conduct antidromically following volley stimuli to the optic nerve or radiation, such volley responses probably have paroxysmal properties.

This publication has 17 references indexed in Scilit: