Humans are limited in their ability to perform multiple cognitive-motor tasks in parallel. In eight participants, we examined whether transcranial direct current stimulation (tDCS) to dorsal premotor cortex (PMD) coul...Humans are limited in their ability to perform multiple cognitive-motor tasks in parallel. In eight participants, we examined whether transcranial direct current stimulation (tDCS) to dorsal premotor cortex (PMD) could attenuate a delay of reaction time (RT) while the participants responded to two visual stimuli presented in temporally close succession. We provided anodal, cathodal, or sham tDCS while the participants performed a task requiring two choice responses or a control task requiring two fixed responses. When the interval between the two stimuli was shorter, the RTs were delayed in both tasks, but anodal tDCS shortened them only in the former task, probably by promoting the response selection function of PMD. Non-invasive neuro-modulation to the brain can boost human ability to multi-task.展开更多
Vibratory stimulation but also motor imagery and action observation can induce corticomotor modulation, as a bottom-up stimulus and top-down stimuli, respectively. However, it remains unknown whether the combination o...Vibratory stimulation but also motor imagery and action observation can induce corticomotor modulation, as a bottom-up stimulus and top-down stimuli, respectively. However, it remains unknown whether the combination of motor imagery, action observation, and vibratory stimulation can effectively increase corticomotor excitability. This study aimed to investigate the effect of motor imagery and/or action observation, in the presence or absence of vibratory stimulation, on the corticomotor excitability of healthy young adults. Vibratory stimulation was provided to the palm of the right hand. Action observation consisted in viewing a movie of someone else’s finger flexion and extension movements. The imagery condition required the participants to imagine they were moving their fingers while viewing the movie and attempting to move their fingers in accordance with the movie. Eleven right-handed healthy young adults were asked to perform six conditions randomly: 1) vibratory stimulation, imagery, and action observation, 2) vibratory stimulation and action observation, 3) vibratory stimulation and viewing of a blank screen, 4) imagery and action observation, 5) action observation, and 6) viewing of a blank screen. Single-pulse transcranial magnetic stimulation was conducted to assess corticomotor excitability and the peak-to-peak amplitude of the motor evoked potentials. The results showed that vibratory stimulation increases corticospinal excitability. The findings further revealed that performing motor imagery while viewing finger movement is more effective at inducing an augmentation of corticomotor excitability compared to action observation alone. Thus, the combination of motor imagery, action observation, and vibratory stimulation can effectively augment corticomotor excitability.展开更多
Once people have a well-trained motor skill, their performance becomes stabilized and achieving substantial improvement is difficult. Recently, we have shown that even a plateaued hand motor skill can be upgraded with...Once people have a well-trained motor skill, their performance becomes stabilized and achieving substantial improvement is difficult. Recently, we have shown that even a plateaued hand motor skill can be upgraded with short-period electrical stimulation to the hand prior to the task. Here, we identify the neuronal substrates underlying the improvement of the plateaued skill by examining the enhanced functional connectivity in the sensory-motor regions that are associated with motor learning. We measured brain activity using functional magnetic resonance imaging and performed psychophysiological interaction analysis. We recruited seven right-handed very-well trained participants, whose motor performance of continuously rotating two balls with their right hands became stabilized at higher performance levels. We prepared two experiments, in each of which they repeated an experimental run 16 times. In each run, they performed this cyclic rotation as many times as possible in 16 s. In the thenar-stimulation experiment, we applied 60-s stimulation to the thenar muscle before each of the 5th - 12th runs, and the others were preceded by ineffective sham stimulation. In the control experiment, the sham was always provided. Thenar stimulation enabled the participants to perform the movements at higher cycles. In association with this performance improvement, we found enhanced activity couplings between the primary motor cortex and the sensorimotor territory of the putamen and between the cerebellum and the primary sensorimotor cortices, without any quantitative activity increase. Neither behavioral change nor these increased activity couplings were observed in the control.Thus, in contrast to the stable neuronal states in the cortico-subcortical motor circuits when the well-learned task is repeated at the later stages of motor skill learning, plastic changes in the motor circuits seem to be required when the plateaued skill is upgraded, and the stimulation may entail a state of readiness for the plastic change that allows subsequent performance improvement.展开更多
Transparent visualization is used in many fields because it can visualize not only the frontal object but also other important objects behind it.Although in many situations,it would be very important for the 3D struct...Transparent visualization is used in many fields because it can visualize not only the frontal object but also other important objects behind it.Although in many situations,it would be very important for the 3D structures of the visualized transparent images to be perceived as they are simulated,little is known quantitatively as to how such transparent 3D structures are perceived.To address this question,in the present study,we conducted a psychophysical experiment in which the observers reported the perceived depth magnitude of a transparent object in medical images,presented with a multiview 3D display.For the visualization,we employed a stochastic point-based rendering(SPBR)method,which was developed recently as a technique for efficient transparentrendering.Perceived depth of the transparent object was smaller than the simulated depth.We found,however,that such depth underestimation can be alleviated to some extent by(1)applying luminance gradient inherent in the SPBR method,(2)employing high opacities,and(3)introducing binocular disparity and motion parallax produced by a multi-view 3D display.展开更多
文摘Humans are limited in their ability to perform multiple cognitive-motor tasks in parallel. In eight participants, we examined whether transcranial direct current stimulation (tDCS) to dorsal premotor cortex (PMD) could attenuate a delay of reaction time (RT) while the participants responded to two visual stimuli presented in temporally close succession. We provided anodal, cathodal, or sham tDCS while the participants performed a task requiring two choice responses or a control task requiring two fixed responses. When the interval between the two stimuli was shorter, the RTs were delayed in both tasks, but anodal tDCS shortened them only in the former task, probably by promoting the response selection function of PMD. Non-invasive neuro-modulation to the brain can boost human ability to multi-task.
文摘Vibratory stimulation but also motor imagery and action observation can induce corticomotor modulation, as a bottom-up stimulus and top-down stimuli, respectively. However, it remains unknown whether the combination of motor imagery, action observation, and vibratory stimulation can effectively increase corticomotor excitability. This study aimed to investigate the effect of motor imagery and/or action observation, in the presence or absence of vibratory stimulation, on the corticomotor excitability of healthy young adults. Vibratory stimulation was provided to the palm of the right hand. Action observation consisted in viewing a movie of someone else’s finger flexion and extension movements. The imagery condition required the participants to imagine they were moving their fingers while viewing the movie and attempting to move their fingers in accordance with the movie. Eleven right-handed healthy young adults were asked to perform six conditions randomly: 1) vibratory stimulation, imagery, and action observation, 2) vibratory stimulation and action observation, 3) vibratory stimulation and viewing of a blank screen, 4) imagery and action observation, 5) action observation, and 6) viewing of a blank screen. Single-pulse transcranial magnetic stimulation was conducted to assess corticomotor excitability and the peak-to-peak amplitude of the motor evoked potentials. The results showed that vibratory stimulation increases corticospinal excitability. The findings further revealed that performing motor imagery while viewing finger movement is more effective at inducing an augmentation of corticomotor excitability compared to action observation alone. Thus, the combination of motor imagery, action observation, and vibratory stimulation can effectively augment corticomotor excitability.
文摘Once people have a well-trained motor skill, their performance becomes stabilized and achieving substantial improvement is difficult. Recently, we have shown that even a plateaued hand motor skill can be upgraded with short-period electrical stimulation to the hand prior to the task. Here, we identify the neuronal substrates underlying the improvement of the plateaued skill by examining the enhanced functional connectivity in the sensory-motor regions that are associated with motor learning. We measured brain activity using functional magnetic resonance imaging and performed psychophysiological interaction analysis. We recruited seven right-handed very-well trained participants, whose motor performance of continuously rotating two balls with their right hands became stabilized at higher performance levels. We prepared two experiments, in each of which they repeated an experimental run 16 times. In each run, they performed this cyclic rotation as many times as possible in 16 s. In the thenar-stimulation experiment, we applied 60-s stimulation to the thenar muscle before each of the 5th - 12th runs, and the others were preceded by ineffective sham stimulation. In the control experiment, the sham was always provided. Thenar stimulation enabled the participants to perform the movements at higher cycles. In association with this performance improvement, we found enhanced activity couplings between the primary motor cortex and the sensorimotor territory of the putamen and between the cerebellum and the primary sensorimotor cortices, without any quantitative activity increase. Neither behavioral change nor these increased activity couplings were observed in the control.Thus, in contrast to the stable neuronal states in the cortico-subcortical motor circuits when the well-learned task is repeated at the later stages of motor skill learning, plastic changes in the motor circuits seem to be required when the plateaued skill is upgraded, and the stimulation may entail a state of readiness for the plastic change that allows subsequent performance improvement.
基金JSPS KAKENHI Grant Number 16H02826MEXT-Supported Program for the Strategic Research Foundation at Private Universities(2013–2017)。
文摘Transparent visualization is used in many fields because it can visualize not only the frontal object but also other important objects behind it.Although in many situations,it would be very important for the 3D structures of the visualized transparent images to be perceived as they are simulated,little is known quantitatively as to how such transparent 3D structures are perceived.To address this question,in the present study,we conducted a psychophysical experiment in which the observers reported the perceived depth magnitude of a transparent object in medical images,presented with a multiview 3D display.For the visualization,we employed a stochastic point-based rendering(SPBR)method,which was developed recently as a technique for efficient transparentrendering.Perceived depth of the transparent object was smaller than the simulated depth.We found,however,that such depth underestimation can be alleviated to some extent by(1)applying luminance gradient inherent in the SPBR method,(2)employing high opacities,and(3)introducing binocular disparity and motion parallax produced by a multi-view 3D display.
