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The goal of the present neuroanatomical study in macaque monkeys was twofold: (1) to clarify whether the hand representation of the primary motor cortex (M1) has a transcallosal projection to M1 of the opposite hemisphere; (2) to compare the topography and density of transcallosal connections for the hand representations of M1 and the supplementary motor(More)
We studied the effect of support stability on postural responses to the vibration of Achilles tendons and of neck dorsal muscles in healthy humans. For this purpose we compared postural responses on a rigid floor and on 6 cm high rocking supports (see-saws) of different curvatures (different radii: 30, 60 and 120 cm). The subject stood with eyes closed, the(More)
We attempted to elicit automatic stepping in healthy humans using appropriate afferent stimulation. It was found that continuous leg muscle vibration produced rhythmic locomotor-like stepping movements of the suspended leg, persisting up to the end of stimulation and sometimes outlasting it by a few cycles. Air-stepping elicited by vibration did not differ(More)
A chronic single-unit study of motor cortical activity was undertaken in two monkeys trained to perform a bimanually coordinated task. The hypothesis was tested that the supplementary motor area plays a specific role in coordinating the two hands for common goal-oriented actions. With this objective, a special search was made for neurons that might exhibit(More)
Does the state of postural instability require a high hierarchical level of posture control? Electromyographic (EMG) activity of leg muscles was recorded during transcranial magnetic stimulation (TMS) of the motor cortex and electrical stimulation of the tibial nerve (H-reflex) in healthy subjects standing on a rigid floor and on a rocking platform. In the(More)
The aim of the study was to elucidate the underlying principles of bimanual coordination and to establish quantitative coordination criteria. Healthy human subjects were instructed to open a loaded drawer with the left hand and to grasp, lift and reinsert with the right hand a small peg in the drawer recess. This bimanual goal-oriented task was executed(More)
Transcranial magnetic brain stimulation (TMS) was used to assess the influence of the corticospinal system on motor output during forearm unloading in humans. Unloading was obtained either "passively" by the experimenter, or "actively" with the subjects' own contralateral arm. Anticipatory postural adjustments consisted of changes in the activity of a(More)
Here, we compared motor evoked potentials (MEP) in response to transcranial magnetic stimulation of the motor cortex and the H-reflex during voluntary and vibration-induced air-stepping movements in humans. Both the MEPs (in mm biceps femoris, rectus femoris and tibialis anterior) and H-reflex (in m soleus) were significantly smaller during(More)
The aim of the present investigation was to assess a bimanual goal-oriented movement sequence with particular emphasis on its temporal structure. The three monkeys (Macaca fascicularis) used in this study chose the left arm as the leading and more postural arm to reach out and pull back a spring-loaded drawer containing a food morsel. The right arm followed(More)
Playing string instruments implies motor skills including asymmetrical interlimb coordination. How special is musical skill as compared to other bimanually coordinated, non-musical skillful performances? We succeeded for the first time to measure quantitatively bimanual coordination in violinists playing repeatedly a simple tone sequence. A motion analysis(More)