EFFECT OF LATERAL GENICULATE LESIONS ON PHASIC ELECTRICAL ACTIVITY OF CORTEX DURING DESYNCHRONIZED SLEEP IN CAT

By the method of bilateral coagulation in the lateral geniculate nucleus and adjacent areas of the optic radiations, the present study was designed to investigate whether the phasic electrical activity recorded from the cortex during desynchronized sleep traveled exclusively via a discrete ponto-geniculo-cortical fiber tract. Despite extensive damage of the subcortical areas of the visual system in all 5 cats operated on, cortical phasic activity was not abolished after coagulation. Rather, while the frequency of cortical waves remained the same as it had been prior to coagulation, the average amplitude and duration of each single wave was greater. The results indicate that the pathway transmitting the phasic activity is not discretely localized in the area of the LGN and optic radiations but is more diffuse at the thalamic level. The enhancement of sharp-wave amplitude is attributed to release of posterolateral cortical elements from tonic regulation by the lateral geniculate nucleus. © 1969.