Spinal cord injury (SCI) causes significant sensorimotor deficits that negatively impact autonomy and quality-of-life. In a previous study, we determined that optogenetic spinal stimulation significantly enhanced forelimb recovery, axonal growth, and angiogenesis compared to sham controls. However, we have yet to determine the synaptic changes associated with optogenetic stimulation after SCI. The current project addresses this important detail by quantifying the synaptic changes that occur with and without optogenetic spinal stimulation in rats with cervical SCI.To investigate this, rats received a moderate hemicontusion of the 4th cervical segment (C4) and a spinal injection of an optogenetic viral vector (AAV2-hSyn-ChR2-YFP) to express light-sensitive proteins in the ipsilateral sixth segment (C6). Four weeks later, rats received a second surgery to receive a blue uLED implanted over ipsilateral C6 for optogenetic or sham stimulation. Rats were trained and scored regularly on a variety of forelimb behavioral tasks throughout the course of the study, while the rats in the stimulated group received stimulation 1x/week for 6 weeks beginning on the 6th week post-injury. After perfusion, the cervical spinal cord was sectioned and underwent immunohistochemistry (IHC) staining to examine synaptic density around motoneurons caudal to the lesion site where stimulation or sham stimulation occurred. Synaptic quantification has been completed using FIJI software. Our initial results reveal increased synaptic density around the motoneurons of rats that received optogenetic spinal stimulation, suggesting an increase in synaptic plasticity and connectivity. This indicates that stimulation not only enhances axonal growth but also supports the formation of new connections with downstream neurons partially disconnected by the injury. This study provides insight into the circuitry-related changes involved in SCI recovery. Identifying specific mechanisms of how optogenetic stimulation improves recovery can guide the development of more effective stimulation paradigms and treatment strategies in order to optimize functional recovery for people with spinal cord injury

Down syndrome (DS), a chromosomal condition that affects 1 in 700 babies in the United States, is associated with intellectual disability and delays in motor development. Early intervention can support motor and social development and participation in children with DS. While both Partial Body Weight Support (PBWS) systems and enriched play environments have been shown to enhance development and participation in children with DS, few studies have looked at these interventions in combination. The purpose of this study was to explore the benefits of a PBWS harness system within an enriched play environment on the mobility and social exploration of infants with DS. Our team hypothesized that PWBS would lead to a greater percentage of time engaged in both mobility and social behaviors during play. We conducted a multi-site clinical trial with 15 pre-walking infants with DS. The infants and their caregivers participated in 30-minute play sessions within an enriched 9’x9’ indoor play area with standardized toys 3 times a week for 6 weeks. Children used a PBWS harness for 3 of the 6 weeks, with harness/no harness order randomized for each participant. All play sessions were recorded and a subset of 6 participants’ data were analyzed using an adapted version of the CASPER-III coding scheme. Results showed that on average, infants showed a 5.28% increase in motor activity when using the PBWS harness compared to a 4.11% increase in motor activity when not using the harness. Additionally, when using the harness, infants on average showed an 8.99% increase in social activity whereas they showed a 0.07% decrease in social activity without the harness. These results show promise in facilitating greater access to mobility and exploration opportunities for children with DS using low-tech interventions such as PWBS in enriched play environments.