The contribution of glial cells to spontaneous and evoked potentials.

The mechanism by which brain cells generate alpha and other rhythms remains obscure, and the possible participation of glial cells in the process continues to be debated. We will present data obtained from freely moving rats in which flashes produced by a light emitting diode implanted under the skin of the scalp evoke retinal and cortical responses recorded through electrodes implanted behind the eye and over visual cortex. In the retina, which is a brain-like structure isolated in the periphery during embryology, the b-wave evoked response is thought to be produced by the Müller glial cells as they maintain potassium ion homeostasis in the extracellular space during the synaptic events initiated by rod and cone activation. We will report on the results of a search in this retinal analogue of the brain for spontaneous activity in the EEG spectrum.