Location of Inhibitory Respiratory Center in Cerebral Cortex of the Dog

Abstract

There is considerable discrepancy in the literature concerning the location of the inhibitory respiratory center in the cerebral cortex of the dog. Spencer 1 originally located it in the allocortex, medial to the sulcus rhinalis. Bucy and Case 2 located it just below the anterior extremity of the coronal sulcus and Smith 3 farther posteriorly in the gyrus compositus anterior. Because of this uncertainty we have repeated these experiments using the technic of Bailey and Sweet 4 which, by exenteration of the orbit, permits access to the entire orbital region of the frontal lobe without the necessity of retracting the brain. Under these circumstances, using either ether or nembutal for light anesthesia, the inhibitory respiratory region is found to be a very small area situated in the gyrus compositus anterior just lateral to the posterior extremity of the gyrus proreus. It is definitely lateral to the sulcus rhinalis and sulcus supraorbitalis.

We have never obtained slowing or arrest of respiration by stimulation medial to the sulcus rhinalis. There is considerable variation in the pattern of gyri and sulci in this region of the dog's cortex. The accompanying diagram (Fig. 1) shows the location of the inhibitory respiratory center in 6 dogs. It lies always in the gyrus compositus anterior just posterior to the area indicated by Smith. This seems to be the area 4 c of Klempin. 5 We have never obtained inhibition from any other area of the lateral, orbital or medial surface of the frontal lobe.