Influence of acetylcholine on shifts in spatial synchronization of cortical potentials of the rabbit, elicited by reversible interruption of the associations of the mammillary bodies.

A decrease in 25 out of 53 calculated coefficients of linear correlation of the potentials between pickups from the visual and motor areas of the cortex, far removed from one another, was observed during anode polarization (20-30 microA, 24 min) of the mammillary nuclei, the column of the fornix, and the mammillothalamic tract, using monopolar 24-channel pickup of the potentials of the cerebral cortex in six rabbits. Application of a 1-2% solution of acetylcholine to the visual area of the cortex leads to an increase in spatial synchronization (13 out of 53 coefficients of correlation) for 5 minutes and between the 10th and 15th minutes from the start of the application. With the combined effect of the polarization of these formations and of the acetylcholine applied to the cortex, reciprocal compensation of the changes in spatial synchronization which wer elicited by each of the influences separately was observed. The hypothesis is advanced of the existence of a nonspecific cholinergic synchronizing system which is active when the mammillothalamocortical connections are preserved.