Effects of Injury to the Cerebral Cortex upon Sexually-Receptive Behavior in the Female Rat1

The expt. was designed to show the effects of partial and complete decortication upon each of the several discrete reactions that are coordinated in the pattern commonly termed "sexually receptive behavior." In the expt. 20 virgin $ rats raised in segregation were ovariectomized at 3 to 4 mos. of age. Estrus was induced by intramusc. injn. of 500 R.U. of estradiol benzoate followed 48 hrs. later by an intramusc. injn. of 0.5 mg. of progesterone. Six tests were conducted 16 to 18 hrs. after progesterone adm. Each of the exptl. animals was observed prior to cortical operations in mating tests with a sexually vigorous c? during 3 successive periods of induced estrus. Records taken included the 3 responses which have been found to be characteristic of the receptive ?, namely, the number of times the $ exhibited lordosis (concave arching of the back facilitating intromission), the number of hopping responses, and the number of ear wiggling responses. Part or all of the neocortex from one hemisphere of the $ rats was then removed. Following post-operative recovery estrus was induced by hormone adm. and a second series of 3 sex tests was administered to each animal. Seven of the ? rats were subjected to a 2d operation in which from 97 to 100% of the entire cortex was destroyed. Following recovery these animals were observed in 3 additional sex tests during induced estrus. Results showed that unilateral removal of 29 to 50% of the neocortex failed to cause any consistent changes in the exhibition of lordosis, ear-wiggling or hopping. Bilateral destruction of the remaining cortical tissue did not dissipate the female''s receptivity as indicated by continued ear-wiggling, lordosis and hopping. These responses tended, however, to become more variable, less well integrated into a total pattern, and to be elicited by biologically inappropriate stimuli.