Thresholds of Ischaemia in Brain Cortex
The effects of ischaemia on the central nervous system have been the subject of much experimental and clinical investigation. Occlusion of the middle cerebral artery in baboons simulates the production of an acute clinical stroke (Harvey and Rasmussen,1951, Symon, 1961, Symon et al, 1974, Symon et al, 1972, Yagamuchi et al, 1971) and produces an ischaemic lesion whose extent is restricted to known regions of the cerebral hemisphere and which therefore interferes only selectively with the neural pathways. We have shown (Symon et al, 1974) that the density of ischaemia produced by occlusion of the middle cerebral artery is graded over the surface of the hemisphere, and, for example, that areas of the sensori-motor strip, show varying levels of residual blood flow. Since the thalamic nuclei are not significantly affected by occlusion of the middle cerebral artery (Kaplan and Ford, 1966, Lazorthes and Campan, 1964) the electrical activity of the sensorimotor strip assessed as the somatosensory evoked response may be measured in relation to regional changes in tissue blood flow.
KeywordsMiddle Cerebral Artery Middle Cerebral Artery Occlusion Brain Cortex Local Blood Flow Tissue Blood Flow
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