Altered Motor and Motor Perceptual Cognitive Imagery Task-Related Activation in Diabetic Peripheral Neuropathy: Insights From Functional MRI.

OBJECTIVE: To compare central nervous system (CNS) activation in patients with and without diabetic peripheral neuropathy (DPN) during motor and motor imagery tasks and to correlate activation with functional performance. RESEARCH DESIGN AND METHODS: Twenty-six participants (13 with DPN, 13 without DPN) underwent functional MRI during three tasks: ankle dorsi plantar flexion (motor task [MT]) and motor imagery tasks of walking on a smooth surface (SMIT) and rough surface (RMIT). Functional assessment included gait analysis, ankle muscle strength, and ankle range of motion. RESULTS: The tasks activated the sensorimotor, motor preparation, visual processing, and decision-making regions. Activation was significantly lower in patients with DPN than in those without DPN during MT and SMIT but not RMIT. Poor functional performance in patients with DPN was associated with greater activation in motor preparation regions. CONCLUSIONS: In patients with DPN, CNS responses appear muted compared with patients without DPN, but they remain capable of enhancing CNS activation when tasks are more challenging or when functional deficits are substantial.

Brain plasticity following MI-BCI training combined with tDCS in a randomized trial in chronic subcortical stroke subjects: a preliminary study.

Brain-computer interface-assisted motor imagery (MI-BCI) or transcranial direct current stimulation (tDCS) has been used in stroke rehabilitation, though their combinatory effect is unknown. We investigated brain plasticity following a combined MI-BCI and tDCS intervention in chronic subcortical stroke patients with unilateral upper limb disability. Nineteen patients were randomized into tDCS and sham-tDCS groups. Diffusion and perfusion MRI, and transcranial magnetic stimulation were used to study structural connectivity, cerebral blood flow (CBF), and corticospinal excitability, respectively, before and 4 weeks after the 2-week intervention. After quality control, thirteen subjects were included in the CBF analysis. Eleven healthy controls underwent 2 sessions of MRI for reproducibility study. Whereas motor performance showed comparable improvement, long-lasting neuroplasticity can only be detected in the tDCS group, where white matter integrity in the ipsilesional corticospinal tract and bilateral corpus callosum was increased but sensorimotor CBF was decreased, particularly in the ipsilesional side. CBF change in the bilateral parietal cortices also correlated with motor function improvement, consistent with the increased white matter integrity in the corpus callosum connecting these regions, suggesting an involvement of interhemispheric interaction. The preliminary results indicate that tDCS may facilitate neuroplasticity and suggest the potential for refining rehabilitation strategies for stroke patients.