We investigated the influence of motor imagery at 50% of maximal voluntary contraction on maximal ankle plantar flexion torque. Thirty-six healthy volunteers were included in this study. The participants were divided randomly into two groups: a motor imagery group and a control group. Maximal ankle plantar flexion torque was measured before and after intervention using a Biodex System 3 dynamometer. The participants were positioned and secured in the adjustable chair of the dynamometer, with the hip and knee joints in the flexion position and the ankle joint in the neutral position. In the motor imagery group, the participants imagined isometric contraction of the ankle plantar flexor muscle at 50% of maximal voluntary contraction for 1 min. In the control group, the participants maintained a resting state for 1 min without performing motor imagery. Maximal torque was normalized by body mass, and the relative value was obtained by dividing maximal ankle plantar flexion torque after intervention with that before intervention. The relative value of maximal ankle plantar flexion torque/body mass was significantly higher in the motor imagery group than in the control group. These results indicate that motor imagery at 50% of maximal voluntary contraction has a facilitative effect on maximal ankle plantar flexion torque.

We investigated the effect of different pressure stimulation intensities on the abductor pollicis brevis muscle on the excitability of spinal cord anterior horn cells. The subjects were 25 healthy right-handed adults. Pressure stimulation was applied vertically on the skin surface of the abductor pollicis brevis muscle for 30 seconds. The median nerve was electrically stimulated before and after the pressure stimulus was applied, and the F wave was recorded from the abductor pollicis brevis muscle. Two pressure stimulation intensities were applied: the pain threshold intensity and 50% of the pain threshold intensity. The analysis of the F-wave persistence and F/M amplitude ratio. No significant change was observed in the appearance F-wave persistence (before: 47.3±16.7%, after: 48.1±15.9%) and F/M amplitude ratio (before: 1.13±0.49%, after: 1.11±0.51%) after pressure stimulation at the pain threshold intensity compared with those before pressure stimulation. After pressure stimulation at 50% of the pain threshold intensity, the appearance F-wave persistence (before: 50.8±18.5%, after: 41.6±17.1%) and F/M amplitude ratio (before: 1.21±0.61%, after: 1.02±0.48%) decreased compared with those before pressure stimulation (p<0.05). This study suggests that the excitability of the anterior horn cells of the spinal cord was unchanged after compression stimulation at pain threshold intensity and decreased after compression stimulation at 50% of pain threshold intensity.

Neurodevelopmental disorders are diagnosed based on a narrative set of specific clinical symptoms, so simple markers that reflect the underlying neurobiological mechanisms would be useful for follow-up. In the present study, we focused on (1) pupil diameter alteration in the face recognition task (Thatcher illusion) in ASD, (2) decreased spontaneous blink frequency in ADHD, and (3) increased non-REM atonia in the sleep EEG in ASD to investigate their relationship to the underlying pathophysiology. The results suggest functional alterations of (1) locus coeruleus-noradrenaline system, (2) brainstem dopamine system, and (3) dorsal raphe nucleus-serotonin system, respectively. All of these parameters were measured under little (or no) cognitive load and were thought to reflect a given innate and implicit condition. Because of these inadequacies, they take a variety of compensatory strategies.