Day/night difference in extradural cortical stimulation for motor relearning in a subacute stroke rat model

Abstract

Purpose: The aim of this study was to assess the proper timing of extradural cortical stimulation (ECS) on the motor relearning in a rat model of subacute photothrombotic stroke. Methods: Photothrombotic infarction was induced on the dominant sensorimotor cortex in male Sprague-Dawley rats after training in a single-pellet reaching task (SPRT). Rats were randomly divided into three groups after stroke: ECS during the inactive period (Day-ECS group), ECS during the active period (Night-ECS group) and no ECS (Non -stimulated group). Six sham -operated rats were assigned to the control group. The Day-and Night-ECS group received continuous ECS for 12 hours during the day or night for 2 weeks from day 4 after the stroke. Behavioral assessment with SPRT was performed daily. Results: SPRT showed a significantly faster and greater improvement in the Day and Night-ECS groups than in the Non stimulated group. In the Day- and Night-ECS groups, the success rate of SPRT differed significantly from Non -stimulated group on day 11 and day 8, respectively. In addition, the Night-ECS group showed a significantly higher SPRT success rate than the Day-ECS group from days 10 to 13. Conclusion: ECS during the active period might be more effective for motor relearning in the subacute stroke rat model.