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Skilled interactions with new environments require flexible changes to the transformation from somatosensory signals to motor outputs. Transcortical reflex gains are known to be modulated according to task and environmental dynamics, but the mechanism of this modulation remains unclear. We examined reflex organization in the sensorimotor cortex. Subjects(More)
The purpose of this study was to characterize the neuromuscular control during shortening (SHO) and lengthening (LEN) contractions by investigating the input-output (I/O) property in the corticospinal tract. To this end, the relation between various stimulus intensities applied via transcranial magnetic stimulation and the size of motor evoked potentials(More)
It is known that somatosensory reflex during voluntary arm movement is modulated anticipatorily according to given tasks or environments. However, when and how reflex amplitude is set remains controversial. Is the reflex modulation completed preparatorily before movement execution or does it vary with the movement? Is the reflex amplitude coded in a(More)
We investigated how a gradual isometric force-increment and -decrement task modulates the behavior of a soleus stretch reflex. Six healthy subjects performed isometric plantar-flexion torque exertion tasks in which they adjusted the torque level to a target changing triangularly (3 s/cycle; the amplitude is 15% of maximal voluntary isometric contraction(More)
Although speech articulation relies heavily on the sensorimotor processing, little is known about its brain control mechanisms. Here, we investigate, using transcranial magnetic stimulation, whether the motor cortex contributes to the generation of quick sensorimotor responses involved in speech motor coordination. By applying a jaw-lowering perturbation,(More)
Abstract. The purpose of this study was to investigate the cortical activities during two types of Go/NoGo task with different movement instructions (Push-Go and Release-Go) using transcranial magnetic stimulation (TMS) and event-related potential (ERP) recordings. In the Push-Go condition, ten subjects were instructed either to push a button with their(More)
The experimental design included three conditions in which the sounds produced by tapping with one's hand on a surface were spatially manipulated. Zero Distance (0D): the tapping sound originated at the tapping location; Double Distance (2D): the sound originated at double the distance to the tapping location; and Quadruple Distance (4D): the sound(More)
The aim of this study was to test whether anticipation of upcoming head blow stimuli, which elicit reflex responses in the neck muscle, makes the reflex responses greater or not. In nine healthy subjects the reflex responses were elicited in the sternocleidomastoid (SCM) muscle in the eyes-open (EO) and eyes-closed (EC) conditions, which corresponded to the(More)
Human brain uses visual motion inputs not only for generating subjective sensation of motion but also for directly guiding involuntary actions. For instance, during arm reaching, a large-field visual motion is quickly and involuntarily transformed into a manual response in the direction of visual motion (manual following response, MFR). Previous attempts to(More)
We investigated the difference between brain activities in speeded and precisely timed responses to identical visual stimulus using fMRI. Stimulus used was a row of seven light-emitting diodes (LEDs) lightened up one after another with constant speed within a trial but with various speeds between trials. Subjects were asked to execute finger-thumb tapping(More)