OBJECTIVES/GOALS: A stroke can impair neural communication between sensory and motor pathways thus compromising walking function. Paired associative stimulation (PAS) is a useful assay of sensorimotor integration (SMI) with limited use post-stroke. The objective of this study will be to determine lower extremity PAS effectiveness and reliability post-stroke. METHODS/STUDY POPULATION: This study will use a pre-post, cross-sectional design. Ten healthy controls and 10 individuals with chronic stroke (>6 months) will be recruited. PAS protocols will be individualized to account for between-subject variability in sensorimotor signaling by first measuring cortical sensory signaling using electroencephalography. Post-stroke participants will then receive PAS targeting the paretic tibialis anterior muscle; healthy controls will receive PAS targeting the non-dominant TA. Changes in cortically derived muscle responses will be characterized by absolute motor-evoked potential amplitude (MEPAmp) change, elicited by transcranial magnetic stimulation, over two sessions separated by >24 hours. Clinical measures of sensorimotor function and walking ability will also be performed. RESULTS/ANTICIPATED RESULTS: By individualizing PAS protocols, we expect to see significant increases in MEPAmp pre to post PAS, determined using paired t-tests. We also anticipate reliable PAS-induced increases in MEPAmp, which will be assessed using two reliability statistics: intraclass correlation coefficient and coefficients of variation of method error. Lastly, the increases in MEPAmp will be correlated with measures of sensorimotor function and walking ability, anticipating that greater increases in MEPAmp will be related to better walking ability and sensorimotor functioning. Correlations will be assessed via a Pearson’s correlation. A preset alpha = 0.05 will be used to determine significant findings. DISCUSSION/SIGNIFICANCE: The importance of this study is that establishing individualized PAS protocols could potentially provide a reliable and clinically relevant measure of SMI. Understanding post-stroke lower extremity SMI is necessary for furthering targeted and personalized interventions to combat walking deficits.