Akihiro Matsuura

[Purpose] This study investigated whether inhibition of unilateral vestibular function by transcranial direct current stimulation (tDCS) facilitates center-of-gravity (CoG) displacement. [Participants and Methods] Ten healthy individuals participated in this study. During a CoG displacement task, the subjects received 3 minutes cathodal tDCS applied to the right mastoid (tDCS condition) or first 30 seconds sham stimulation. The center of pressure (CoP), the weight load ratio, and the EMG of the lower leg were compared between pre- and post-stimulation. [Results] CoP and weight load ratio were significantly shifted to the right by the tDCS. [Conclusion] Vestibular tDCS might be a possible clinical intervention for the correction of displaced standing posture.

Lack of attention to obstacles on the floor or walking path may cause trip and fall accidents. The preparatory activity in the motor cortex to the perturbation associated with obstacle avoidance movements with cognitive task is still unclear. The purpose of this study was to investigate the motor cortical activity involved in the preparation and execution of concurrent obstacle avoidance movement and cognitive task. Twenty young adults were required to step over obstacles that were projected on the floor while performing a cognitive task. The electroencephalogram was recorded, and the movement-related cortical potentials (MRCP) aligned by foot dorsiflexion were evaluated. There was no significant difference in the number of contacts between the toe and the obstacle between the obstacle avoidance task and obstacle avoidance with cognitive task; however, the distance between the toe and the obstacle just before obstacle avoidance movement was significantly extended in the latter task. The amplitude and the onset of MRCP during the dual task were decreased and delayed, respectively, compared with the simple obstacle avoidance movement task. These results suggest that the young participants changed their clearance strategy to stepping over the obstacle during the concurrent motor and cognitive dual task to reduce motor cortical activity.

Background and purpose: This double‐blind, randomized, placebo‐controlled study investigated the beneficial effects of repetitive transcranial magnetic stimulation (rTMS) to patients with motor paresis in acute subcortical stroke on functional recovery and electrophysiological measures.Methods: Twenty patients with acute stroke were randomized into real rTMS (n = 10) or sham (n = 10) groups. Patients received five daily sessions of rTMS with 1200 pulses at 1 Hz for 20 min or sham stimulation over the contralesional motor cortex. Movement‐related cortical potential MRCP, consisting of the Bereitschaftpotential, negative slope (NS′) and motor potential (MP), was recorded during self‐paced wrist extension of the affected limb associated with assessment of the Fugl−Meyer assessment (FMA) of the upper extremity, the pegboard test and the grip strength before and after the rTMS session.Results: Real rTMS improved the FMA and pegboard test scores compared to the sham group in the affected hand. This improvement was associated with increases in the MP and NS′ over the front‐central sites in the ipsilesional hemisphere, whereas the sham group did not show significant changes in MRCP components by rTMS.Conclusions: Our findings suggest that low‐frequency rTMS to the contralesional motor cortex facilitates functional recovery of paretic limbs in acute stroke patients through enhancing the the neuronal activity of ipsilesional motor and pre‐motor areas.