Acute and Chronic Effects of Unilateral Cerebral Infarction on the EEG and Behavior of the Rat

Abstract

Abstract• Anoxic ischemia with resultant unilateral cerebral infarction was produced in the rat by unilateral ligation of the external and common carotid arteries and exposure of the animal to nitrogen. EEG and behavior were studied for one month after the anoxic insult. Infarcted animals showed prominent circling, contralateral flexion postures, and absent visual and tactile placing. At the end of one month the only persistent clinical abnormality was absent contralateral tactile placing. Acutely the EEG showed loss of normal background activity and high voltage slow waves over the infarcted hemisphere. EEG improvement paralleled clinical improvement. At the end of one month only minor asymmetries were observed in the EEG but sleep spindles remained absent on the infarcted side.

Pyramidal tract responses (PTR) during hypoxia and hypotension.

“…In previous experiments 7 with spontaneously breathing animals, hypoxia was complicated by apnea requiring frequent resuscitations. This was eliminated in the present PYRAMIDAL TRACT RESPONSES/Su/ter et al study by mechanically ventilating curarized animals.…”

“…During hypoxia EEG activity is lost rapidly within 10 to 60 seconds. 2 ' 7 In the visual system hypoxia first produces loss of synaptic activity in the occipital cortex and only later is synaptic activity impaired in the lateral geniculate body. 8 Hossmann and Sato 1 have shown that pyramidal tract responses (PTRs) persist during anoxia in the absence of spontaneous EEG activity.…”