AUTONOMIC AND SOMATIC REACTIONS INDUCED BY STIMULATION OF THE CINGULAR GYRUS IN DOGS

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Abstract
In Dial anaesthetized cf dogs the cingular gyrus, exposed by partial ablation of the opposite cerebral hemisphere, was stimulated faradically with bipolar electrodes using moderate current intensities or chemically by local application of minute pieces of blotting paper soaked with a 2.5% soln. of acetyl-[beta]-methylcholine. The effects on respiratory rate and depth, on arterial blood pressure, on intravesical pressure of urinary bladder and on somatic musculature were studied. For descriptive reasons a rostral, middle, and caudal cingular region were distinguished. Responses to chemical stimulation were essentially the same as those to electrical stimulation. Responses may be summarized as follows: A) Rostral region: decreased depth of respiratory movements; slight but definite blood pressure drop; no bladder response; complete inhibition of random somatic movements. B) Middle region: no appreciable respiratory changes; often no blood pressure response, unless after repeated stimulation, but, if present, definite drop; occasional increase of intravesical pressure; no effect on somatic musculature.'' C) Caudal region: usually increased respiratory rate; regular blood pressure drop of about 40 mm. Hg; strong (isometric) contractions of urinary bladder, often accompanied by a rise instead of a drop of blood pressure; no effect on somatic musculature. These expts. supported by the work of other investigators, suggest a somatic inhibitory and an autonomic function for the rostral region; the caudal region is mainly, if not exclusively, concerned with vegetative performances; the middle region is rather irregular in its responses and often does not respond at all. Acetyl-/3-methylcholine appears to be a useful cortical stimulant in the investigation of cortical functions.

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