Deafferentation studies on motor activity in the chick. II. Activity pattern of wings

Abstract

Abstract A study of the effects of deafferentation of the brachial level of the spinal cord in chick embryos was undertaken to examine the influence of afferent input on activity patterns of the wings, during embryonic, hatching and posthatching periods. Neural crest precursors of dorsal root ganglia were destroyed by superficial cauterization at somite levels 17 to 21 in embryos of stages 13–14. Between nine and 17 days of incubation no significant differences were observed in the frequency of wing movements as part of either total or local activity patterns. The prehatching and hatching behavior patterns were typical except that none of the experimental embryos managed to tuck the head under the right wing (tucking phase). Wing lifting and lowering were absent between day 18 and hatching. In hatched chicks, wings were incable of making synchronous bilateral flapping movements. The results indicate that afferent input from the wings to the spinal cord is probably involved in the patterning of wing movements. In the absence of afferent input, the chick embryos show gross disturbances in the pattern of behavior involving the wings during hatching and after hatching.