Serial pattern learning during skilled walking.

Rats possess a rich repertoire of sequentially organized, natural behaviors. It is possible that these natural behaviors may reflect implicit learning or relatively fixed movement patterns. The present study was conducted to determine whether factors known to influence implicit learning produce similar effects on the acquisition of skilled walking. Three groups of rats were trained to cross a horizontal ladder with rungs spaced according to three different levels of complexity. All training and testing were performed under dark conditions to assess the influence of non-visual modalities on skilled walking. Although all groups' performance improved throughout training, pattern complexity influenced the rate of improvement. In addition, performance during a probe session provided further evidence that each group encoded the rung spacing pattern experienced during training to create an internal representation. These observations demonstrate that the engram established during repetitive training represents either the temporal or spatial characteristics of rung spacing. These findings indicate that implicit learning contributes to the acquisition of natural sequential behaviors. Furthermore, serial pattern learning of rung spacing provides a novel task to determine sensory and motor contributions to the consolidation of skilled movement.