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The effect of transcranial direct current stimulation (tDCS) on the precise nondominant hand movement was investigated by applying anodal stimulation over the right primary motor cortex. We recruited 14 healthy participants for this single-blind, sham-controlled crossover trial. A circle-drawing task was performed before, immediately after, and at 30 min after 20 min of 1 mA anodal or sham tDCS. Anodal tDCS, compared with sham stimulation, significantly improved the circle-drawing task compared with sham stimulation. The deviation area and path length of the task were significantly decreased after anodal tDCS application and were further enhanced at 30 min after stimulation. These results suggest that anodal tDCS over the primary motor cortex enhances the precise movement of the nondominant hand for 30 min in healthy participants.

BACKGROUND: Studies suggest that the observation of others' actions leads to enhanced motor skill learning. OBJECTIVE: We examined whether others' or self-action observation is effective for standing balance learning. In addition, we examined cortical activation during action observation using functional near-infrared spectroscopy. METHODS: Thirty-nine healthy young subjects were assigned randomly to the Control, Other-Observation (O-O), and Self-Observation (S-O) groups. The subjects learned to stand on a tilting platform while maintaining a horizontal position. The Control group alternated each trial with a rest period. The O-O and S-O groups were provided with information related to their performance during the rest period: the O-O group observed another person, while the S-O group observed their previous performance. Cortical activation was assessed by changes of hemoglobin oxygenation (oxyHb). RESULTS: A 2-way analysis of variance with repeated measures on balance performance revealed a significant difference in post-training (p < 0.05) and retention (p < 0.01) only in the S-O group. And an increase of oxyHb levels at post-training in the S-O group was observed in the supplementary motor area. CONCLUSION: Self-action observation improved standing balance and brain activity during training and at 24 h after training.

These results suggested that plantar perception exercises might efficiently stabilize standing postural balance in the old old as well as the very old.

Smooth social communication consists of both verbal and non-verbal information. However, when presented with incongruence between verbal information and nonverbal information, the relationship between an individual judging trustworthiness in those who present the verbal-nonverbal incongruence and the brain activities observed during judgment for trustworthiness are not clear. In the present study, we attempted to identify the impact of incongruencies between verbal information and facial expression on the value of trustworthiness and brain activity using event-related potentials (ERP). Combinations of verbal information [positive/negative] and facial expressions [smile/angry] expressions were presented randomly on a computer screen to 17 healthy volunteers. The value of trustworthiness of the presented facial expression was evaluated by the amount of donation offered by the observer to the person depicted on the computer screen. In addition, the time required to judge the value of trustworthiness was recorded for each trial. Using electroencephalography, ERP were obtained by averaging the wave patterns recorded while the participants judged the value of trustworthiness. The amount of donation offered was significantly lower when the verbal information and facial expression were incongruent, particularly for [negative × smile]. The amplitude of the early posterior negativity (EPN) at the temporal lobe showed no significant difference between all conditions. However, the amplitude of the late positive potential (LPP) at the parietal electrodes for the incongruent condition [negative × smile] was higher than that for the congruent condition [positive × smile]. These results suggest that the LPP amplitude observed from the parietal cortex is involved in the processing of incongruence between verbal information and facial expression.

PurposePain is a multidimensional experience with sensory-discriminative, cognitive-evaluative, and affective-motivational components. Emotional factors, such as unpleasantness or anxiety, are known to have influence on pain in humans. Repeated painful stimulation has been reported to reduce subjective pain intensity. Nevertheless, there is little evidence of the influence of such stimulation on the emotional factors of pain. The aim of this study was to evaluate the influence of repeated painful stimulation on the experience of unpleasantness and anxiety.Materials and methodsEight subjects (six females, two males) volunteered to participate in this study. Subjects received repeated painful stimulation for 3 consecutive days each instance lasting 6 seconds, 60 times per day, on the medial side of the forearm of the nondominant hand. We examined the following items to evaluate changes of responses to painful stimulation: pain thresholds, pain tolerance levels, pain intensities, unpleasantness, and anxiety. Furthermore, pain thresholds and pain tolerance levels were compared between different sites on the ipsilateral and contralateral forearms.ResultsNo immediate or chronological changes in pain thresholds or pain tolerance levels were observed. Pain intensities were reduced significantly over the 3-day experimental period (P<0.05). On the other hand, there was no great change in unpleasantness during the 3-day period. Anxiety was increased significantly after the painful stimulation compared with that without the painful stimulation and before day 1 of the stimulation (P<0.05).ConclusionThese results suggest that repeated painful stimulation may result in habituation to pain intensities but not habituation to emotional factors.

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