DESCRIPTION (provided by applicant): Walking ability is an important predictor of health and survival in aging populations. This proposal will provide a scientific basis for designing walking rehabilitation regimens that take maximum advantage of 3 distinct forms of motor learning: instructive, adaptive and reinforcement learning. We will determine how these 3 motor learning mechanisms interact in people with and without neurological damage, and how they can be augmented with non-invasive brain stimulation. Our overarching goal is to understand how different learning circuits communicate, synergize, or interfere with each other. In Aim 1 we will determine the advantages of instructive, adaptive, and reinforcement learning of a new walking pattern. We will study each learning mechanism in isolation and in combinations, analyzing the (a) acquisition rates of new walking patterns, (b) immediate and long-term retention of patterns, and (c) transfer of new patterns to natural, over ground walking. We hypothesize that careful scheduling of instructive, adaptive, and reinforcement training is essential to optimize learning and avoid interference between mechanisms. In Aim 2 we will determine the advantages of learning multiple features of walking simultaneously. We will use dual adaptation (e.g. visuomotor adaptation and split-belt adaptation) to simultaneously train two features of the walking pattern in healthy adults and chronic stroke patients. In Aim 3, we will develop specific schedules of training, combining learning mechanisms and non-invasive brain stimulation to mitigate the walking deficits of stroke patients. We will study staged use of learning mechanisms with and without non-invasive brain stimulation in a 4-week training paradigm (with 1 and 3 month tests of retention). We hypothesize that cerebral stroke patients will benefit from specific combinations of the 3 learning mechanisms, and from non-invasive brain stimulation. In sum, this comprehensive study will provide fundamental information about how instructive, adaptive, and reinforcement motor learning mechanisms interact in training regimens for rehabilitation.