Aminoacids and oscillatory electrocortical activity

The effects of the local application of glutamate, aspartate, glycine, GABA and dl-alanine were studied upon the intact and isolated cortices of barbiturate anesthetized cats and upon the intact cortex of similarly anesthetized terrapin turtles. Repetitive responses following the DCR's, and the strychnine spikes, were observed, and sometimes a long duration oscillatory regular activity appeared after the treatment with those aminoacids. The oscillations had a frequency similar to that of the waves in a sleep spindle. They also occurred in the isolated cortex. The negativity of the DCR's may show different susceptibility from that of the negative component of the strychnine spikes, to the depressant action of the aminoacids. The conclusion is that the oscillatory electrocortical activity occurs in the cortex out from some subcortical influence. As a possible mechanism, it is suggested the establishment of a circus-movement type of activity involving the neurons and their dendritic apical and basilar branches. The aminoacids could act by favoring the opening of the low-resistance junctions present between dendrites, thus facilitating its synchronized activity.