DESCRIPTION: The ability to organize motor acts as sequential events in time is an essential component of human behavior. The relevance of understanding motor sequencing can be readily appreciated if one considers a world in which we had to relearn simple skills such as buttoning a shirt or tying your shoes every morning. Organizing motor actions is also a necessary processing for patients relearning movements during neuro- rehabilitation. Using functional brain mapping by positron emission tomography, previous experiments from our laboratory have been structured to dissociate brain systems that are involved in sequencing under different attentional and contextual settings. To date, our focus has been to distinguish those systems involved in motor learning from those related to secondary factors that can modulate learning, but are not necessarily required for motor learning. The goal of this continued research is to identify the functional substrates of sequence learning at the level of motor output systems and alternatively, how sequences can be represented perceptually. We will use PET to map brain areas in normal subjects that show learning related changes as they learn to make sequential movements. The specific aims are organized to clarify three critical issues. Specific Aim #1. Define neural systems that represent sequences as a series of motor responses compared to a sequence of visual stimuli learned in perceptual systems. Specific Aim #2. Establish if different types of movement modify localization of sequence knowledge. Are sequences of isolated finger movement, temporal patterns of one limb, gestures, direction movements through space, or isometrics represented in the same or different motor areas? Specific Aim #3: Identify systems that are involved in discrete versus continues sequence learning. Are complex movements constructed from sequence of discreet movements or alternative, as single actions?