In dog and monkey permanent occlusion of the middle cerebral artery (abbreviated to m.c.a. herein) ordinarily produces a lateralized neurological deficit, the degree of impairment varying from one animal to the next.4,9,10 Rosomoff10 reported that of 15 dogs in which the artery was occluded under normothermic conditions, 8 developed severe deficit, 6 lesser but significant involvement, and one none at all. Temporary occlusion can also produce neurological symptoms. In the monkey 50 minutes is required to yield an impairment equivalent to that produced by permanent occlusion.4 Changes in the brain's electrical activity during and for short intervals after an experimental occlusion are also variable.5,6 Pertinent to this study is the fact that occlusion does not invariably provoke electrical changes.6 Both the electrocorticogram (ECG) and steady potential (SP) have been studied.6 The latter refers to relatively sustained departures from the resting potential recorded between a