Shortly after spinal cord transection at T8 in cats immobilized with Flaxedil the electrocorticogram continuously showed synchronized activity intermingled with runs of desynchronized activity. Similar changes were seen in the mesencephalic reticular formation, thalamic reticular formation and in the nucleus ventromedialis thalami. No significant changes were seen in the nucleus reticularis pontis oralis. Electrolysis at different levels of the reticular formation did not alter the synchronized electrical cortical activity induced by the spinal cord section at T8.