Background: Prism adaptation (PA) is a behavioral training paradigm shown to induce immediate changes in visuospatial and motor function. PA may modulate the input and output stages of processing spatial cognitive information. However, the cortical plasticity mechanisms related to the behavioral effects of PA are poorly understood. Non-invasive sensorimotor electrical stimulation (Stim) may upregulate corticomotor excitability and is commonly used as a therapeutic adjunct during motor training. Objective: To evaluate the effects of combining PA with Stim on corticomotor excitability and visuo-spatial-motor behavior. Methods: We used a repeated-measures design to evaluate the effects of 1 session of PA with and without Stim in 15 young able-bodied individuals (18-35 years). Corticomotor output, intracortical inhibition, and facilitation were evaluated before and after PA with motor-evoked potentials (MEPs) elicited from single and paired-pulse transcranial magnetic stimulation (TMS) delivered to M1 hotspots of bilateral upper and left lower limbs. Results: Behaviorally, both PA+Stim and PA+Sham showed significant sensorimotor aftereffects (visuo-spatial and proprioceptive pointing). Neurophysiologically, suprathreshold MEP amplitude increased in the left first dorsal interossei, left tibialis anterior, and left soleus following the PA+Stim condition compared to the PA+Sham condition. Additionally, following PA+Stim, Short Interval Intra-Cortical Inhibition (SICI) increased in the left tibialis anterior and left soleus. Conclusion: Although both PA+Stim and PA+Sham had similar behavioral aftereffects, only PA+Stim increased cortical excitability in M1 representations of the left upper and lower limb (toward the direction of the PA aftereffect), suggesting that PA+Stim may elicit greater neurophysiological changes than PA alone. Keywords: visuomotor adaptation; sensorimotor adaptation; non-invasive brain stimulation; young adults; neuroplasticity; electrical stimulation.

The authors have declared no competing interest.

NCT06053320

This study was funded by: NIH NINDS T32NS096050; NIH NINDS 1F31NS131020 and NIH NINDS L30NS139361

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Ethics committee/IRB of Emory University Atlanta, GA gave ethical approval for this work. IRB ID: STUDY00005012

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