EFFECTS OF BARBITURATES AND ETHER ON SPONTANEOUS ELECTRICAL ACTIVITY OF DOG BRAIN

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Abstract
The dominant spontaneous electrical activity of the cerebral hemispheres of normal dogs at a low level of excitation is about 25 per sec. A variable amt. of 12/sec. and 50/sec. activity is usually present, the former being more marked posteriorly and the latter more marked anteriorly. Excitement of the animal increases the 50/sec. activity in the anterior portion of the brain. During ether anesthesia the eeg. is dominated by 50/sec. activity, and during the induction of Na amytal anesthesia the 50, then 25, and finally 12/sec. activity disappears from the record. During ether anesthesia the amplitude of the brain waves was decreased more in the motor cortex than elsewhere, and during Na amytal narcosis the reverse was true. A striking characteristic of barbiturate narcosis was periods of decreased electrical activity followed by bursts of activity. This was manifested in light narcosis by the "barbiturate bursts," and in deep narcosis by bursts alternating with "blackouts." Electrical threshold studies suggested that Na amytal narcosis depressed the motor strip less than any other area of cortex. It is suggested that the action of ether and Na amytal may be selective and based on cell size.