It has been our clinical observation for several years that music therapy techniques, which were initially designed to address socioemotional needs, elicited motor responses in neurologically impaired clients not readily accessible to other forms of therapy. Over the past 8 years we have conducted a series of experiments to better understand the role of music therapy in motor rehabilitation. Our research is concentrated on auditory rhythm as a sensory stimulus to facilitate gait and arm movement patterns in patients with a variety of movement disorders. Our studies have focused primarily on mechanisms in rhythm perception and rhythm production in order to be able to assess the effect of auditory rhythm on the organization and guidance of movement. We believe that among all musical elements utilized in music therapy and motor rehabilitation, rhythm has the most promising cognitive and physiological attributes and can influence motor control substantially. For example, auditory rhythm may be a useful stimulus because of the speed and high resolution in time and synchronization processing in the auditory system and also the existence of auditory-motor arousal circuitry at the reticulo-spinal level. Conceptually our work has been based on an oscillator-entrainment model in which the perception of rhythmic stimuli in the auditory system entrains movement frequency and stability in neural motor networks. In order to evaluate the effect of rhythm on motor facilitation, we first studied the effect of rhythmic cuing on stride and muscle activation patterns through use of electromyography (EMG) in the gait of normal individuals (Thaut, Mclntosh, Rice, & Prassas, 1992a). © 1999 Springer Publishing Company We found improvement in stride parameters, especially symmetry, and EMG patterns, particularly the amplitude variability in muscle contractions across the stride cycle. Similar results were seen when we applied rhythmic cues to individual patients with stroke, cerebellar, and transverse myelitis (Thaut, Mclntosh, Prassas, & Rice, 1992b). Based on these encouraging observations we began to study rhythmic auditory stimulation (RAS) as a potential therapeutic measure in neurologic rehabilitation. Since then, we have conducted 3 studies on persons with stroke, 3 on persons with Parkinson's Disease (PD), 1 study on persons with traumatic brain injury (TBI), and 1 on persons with Huntington's Disease (HD). Studies with PD patients and cerebral palsy children are currently under way. RAS IN MOBILITY AND ARM TRAINING FOR POST CVA PATIENTS We first explored the immediate effect of rhythm on gait ability in stroke patients. In a rehabilitation study with 10 hemispheric stroke patients who were post-CVAfrom 4 weeks to 24 months, we matched the beat frequency of musical 'on'-beats to the step rate of the patients (Thaut, Mclntosh, Rice, & Prassas, 1993). Five of the subjects had either thrombotic or hemorrhagic lesions affecting the right cerebral hemisphere, and five had lesions affecting the left cerebral hemisphere, typically in a middle cerebral artery distribution. Patients walked for six meters at free speed to determine their baseline walking ability. During the second walk RAS was matched to their baseline step rate (cadence) to determine if immediate entrainment effects would occur without interference from practice. The same trial was repeated three times with each trial spaced a week apart. Results from this study showed that most patients were clearly able to synchronize their step times to the rhythm. In the course of synchronizing their gait movements to the rhythm, stride time symmetry, as well as stride length symmetry improved significantly, as did weight bearing time on the paretic side (p