Early development of synchronized walking on the rotorod in rats. Effects of training and handling.

There is considerable improvement of motor coordination on the rotorod during the first 3 weeks of development in rats. The purpose of the present study was to determine some factors implicated in this improvement. From days 15-22 of age, rats were: (1) extensively trained on the rotorod; (2) minimally trained on the rotorod; (3) handled daily but not trained on the rotorod; and (4) neither handled nor trained. All animals were tested on the rotorod on day 23, with separate groups of the naive rats also being tested on days, 19, 20, 21 or 22. Latencies before falling and the percentage of time spent walking in time to the movement of the rotating rod were recorded. There was a close correspondence between these two scores during ontogeny. The percentage of time spent walking was similar among extensively trained, minimally trained, and handled rats and significantly higher than that measured in rats tested only on 1 day. These results indicate that the emergence of this postural sensorimotor skill is more dependent on the maturation of sensorimotor brain region than on previous training on the apparatus.