RECOVERY OF FUNCTIONS AFTER NEONATAL OR ADULT HEMISPHERECTOMY IN CATS .3. COMPLEX FUNCTIONS - OPEN-FIELD EXPLORATION, SOCIAL INTERACTIONS, MAZE AND HOLEBOARD PERFORMANCES

Complex behavioral patterns were studied in cats with removal of the entire left cerebral hemisphere either as neonates (n=10) or adults (n=11), and in intact control cats (n=24). Adult-lesioned cats showed decreased upon field activity in locomotion, rearing and sniffing. Lesioned kittens showed similar deficits at 100 days of age, but by 150 days of age they resembled normal littermates in all 3 measures. In the presence of another cat, adult-hemispherectomized cats violated species-typical body-buffer space, approaching and attacking other cats. By comparison, normal cats never attacked and seldom approached in the open field. Neonatal-lesioned adults showed only occasional approach and a tendency to site or stiff-walk in the presence of other cats; attacks were rare. Adult-lesioned cats responded poorly to reversal training for preferred arm of a T-maze, whereas neonatal-lesioned adults were significantly more trainable. Similarly, adult-lesioned cats exhibited a search deficit in a baited holeboard, while neonatal-lesioned adults searched normally. Overall, these results demonstrate that in this animal model, enhanced recovery following early vs adult lesions can also be found in relatively complex, spontaneous behavioral responses not previously studied in this regard.