The effects of motor imagery training and conventional therapy on the functioning of stroke survivors: A resting-state fMRI study

Objective To measure the efficacy of combining motor imagery training (MIT) with conventional therapy in improving stroke patients′ upper-extremity function. And to seek a cortical reorganization mechanism associated with the improvement using resting-state functional magnetic resonance imaging (rs-fMRI). Methods Ten stroke survivors were selected as an experimental group. They were given motor imagery training for four weeks (30 minutes a day, 5 days a week) and conventional rehabilitation therapy (40 minutes a day, 5 days a week). Another 10 healthy counterparts were the control group. Before and after the four weeks of treatment, both groups were assessed using the upper extremity Fugl-Meyer assessment (FMA-UE) and the modified Barthel index (MBI). Moreover, rs-fMRI was conducted to assess functional connectivity between cortical regions and the ipsilesional primary motor cortex (M1) before and after the intervention. The laterality index (LI) of the primary motor or sensory cortex was also calculated. Results After the intervention, the average FMA-UE and MBI scores of the experimental group had increased significantly. After MIT and conventional therapy there was increased functional connectivity between the ipsilesional and contralesional M1 areas, and between the ipsilesional M1 and contralesional primary sensory cortex (S1) and frontal lobe, the functional connection between the ipsilesional M1 and the ipsilesional paracentral lobule and the anterior cingutate was also increased. More specifically, the LI relating M1 and S1 decreased after the intervention, tending toward the normal level. LIMI decreased significantly. Conclusion The 4-week regimen of motor imagery training and conventional therapy resulted in functional improvement in the upper limbs and greater ability in the activities of daily living. The observed improvements may be due to cortical reorganization, including better functional connectivity between the bilateral M1 areas and increased connectivity between the ipsilesional M1 area and some non-motor areas. There is some recovery of symmetry in the bilateral primary motor cortex. Key words: Resting-state functional magnetic resonance imaging; Functional magnetic resonance imaging; Motor imagery training; Stroke; Cortical reorganization