Facilitation of Learning and Rehabilitation in Rats by Inducing Response-like Movement (Special Editorials : Five Selected Articles in ABE)

We investigated the effects of forced response-like movements on serial reversal learning of a sensorimotor task in normal and hemiplegic (unilateral cortical lesion in the forepaw sensorimotor area) rats. The rats were trained to respond to an air-puff stimulus applied to one forepaw; the response involved releasing either the stimulated or non-stimulated forepaw from a lever. During the training, an error trial was followed by a correction trial wherein a lever on the correct-response side (n=4 in each group) or the incorrect-response side (n=4 in each group) was automatically elevated at 220 ms after the air-puff stimulation, mimicking the ratsʼ lever-release movement. No lever activation was applied to the rats in the control condition (n=4 in each group). We found that learning speed was generally facilitated by the lever activation procedure on the incorrectresponse side, but not on the correct-response side. As an exception, however, lever activation on the correctresponse side facilitated learning in the contralesional (paralyzed side) forepaw of the hemiplegic group. Reaction time was not affected by the lever activation procedure, although it was longer for the contralesional forepaw compared to the ipsilesional forepaw in the hemiplegic group and both forepaws in the normal group. We conclude that the sensory inputs induced by the same forced response-like movement facilitate learning or rehabilitation differently in normal and hemiplegic rats. The results and the animal model in this study are useful for the development of more efficient motion-assisting devices for rehabilitation.