PROJECT SUMMARY This proposal describes the first randomized controlled trial of a new therapy for improving hand function in children with hemiplegic cerebral palsy. It is estimated that a third of the almost 800,000 Americans with cerebral palsy have hemiplegia, which results in disuse of the weaker hand in everyday life from childhood on with very few effective treatments. Recent research has shown that interventions that facilitate repetitive goal-oriented motion of the paretic limb, such as constraint-induced movement therapy and bimanual intensive therapy, may facilitate cortical change and improved hand function in hemiparetic CP. However, these emerging therapies require some residual movement and therefore are not applicable to those who do not have sufficient hand movement for functional task practice. The proposed pilot study investigates an innovative neuromuscular electrical stimulation therapy that incorporates several rehabilitation techniques shown to improve recovery. Contralaterally Controlled Functional Electrical Stimulation (CCFES) activates paretic muscles to open and close the affected hand in direct proportion to the degree of opening and closing of the unimpaired contralateral hand, as detected by a sensor glove. Aim 1 of the study is to collect pilot data estimating the effect of CCFES on upper extremity motor outcomes. We begin exploring our theory that Hebbian synaptic change plays a role in CCFES's mechanisms of action by exploring (in Aim 2) the possibility that paretic hand proprioception acuity can be a moderator and (in Aim 3) the number of motor repetitions can be a mediator of motor learning in CCFES. Twenty children with upper extremity hemiplegic cerebral palsy (age 6-12) will be randomized to CCFES + video game therapy or video game therapy without stimulation for six weeks and will be followed for 3 months. The six-week treatment consists of daily video game therapy at home and functional task practice sessions in the lab twice a week for the first 3 weeks and once per week for the final 3 weeks. Outcome measures will include assessments of upper extremity motor impairment and activity limitation using clinical assessments, along with instrumented assessments of finger tracking ability, finger flexor tone, maximum volitional hand extension ability, proprioception acuity, and the number of paretic hand motor repetitions. The clinical measures will help power larger future clinical trials, while the instrumented assessments directly examine motor dysfunctions targeted by CCFES and will begin to reveal neural circuits and behaviors that can influence CCFES-mediated motor learning in hemiplegic CP.