We investigated the role of somatosensory feedback during bimanual coordination by testing a bilaterally deafferented patient, a unilaterally deafferented patient, and three control participants on a repetitive bimanual circle-drawing task. Circles were drawn symmetrically or asymmetrically at varying speeds with full, partial, or no vision of the hands. Strong temporal coupling was observed be...

In order to study the role of the corpus callosum in two-handed coordination we tested callosotomy subjects while they attempted to initiate simultaneous discrete movements with both hands. We observed four split-brain patients, including one pre- and post-operatively, as well as normal and epileptic control subjects. Split-brain patients made button presses that were less synchronous than eith...

Sonographic guidance has long been employed for biopsy with sector scanners by utilizing attachable offset guides,’-5 by dedicated linear array system^,^,^ or by “free hand.”’ All of these techniques are bimanual, in contrast to a diagnostic scan or biopsy alone. The dedicated systems provide a slot that causes the needle to be directed into the center of the scanning plane. When the procedure ...

Coordinated bimanual oscillatory movements often involve one of two intrinsically stable phasing relationships characterized as in-phase (symmetrical) or antiphase (asymmetrical). The in-phase mode is typically more stable than antiphase, and if movement frequency is increasing during antiphase movements, a spontaneous transition to the in-phase pattern occurs. There is converging neurophysiolo...

The effects of dual-task constraints on bimanual coordination and walking in three age groups: young (4-6 years old), middle (7-9 years old), and older groups (10-13 years old) were examined. Children were asked to first walk along a path (baseline condition) and then to walk along the same path while carrying a box steady and level (dual-task condition). The young group showed less bimanual co...

We studied multi-joint coordination during tasks of transporting real and imaginary objects with two arms. One of the arms was unexpectedly arrested in one-third of trials performed. In the absence of perturbation, multi-joint synergies stabilizing the distance between the arms early and late in the movement were seen in both conditions and even were stronger in the imaginary object condition. ...

Optimal feedback control postulates that feedback responses depend on the task relevance of any perturbations. We test this prediction in a bimanual task, conceptually similar to balancing a laden tray, in which each hand could be perturbed up or down. Single-limb mechanical perturbations produced long-latency reflex responses ("rapid motor responses") in the contralateral limb of appropriate d...

How do humans and other animals accomplish coordinated movements? How are novel combinations of limb joints rapidly assembled into new behavioral units that move together in in-phase or anti-phase movement patterns during complex movement tasks? A neural central pattern generator (CPG) model simulates data from human bimanual coordination tasks. As in the data, anti-phase oscillations at low fr...

Effect-based models of motor control assign a crucial role to anticipated perceptual feedback in action planning. Two experiments were conducted to test the validity of this proposal for discrete bimanual key press responses. The results revealed that the normally observed performance advantage for the preparation of two responses with homologous rather than non-homologous fingers becomes inver...

Anticipatory postural adjustments (APA) during bimanual actions can be observed when participants hold an object in one hand and then lift it with the other hand. The postural force used to hold the object is reduced in anticipation of unloading, indicating an accurate prediction of the change in load. We examined patients with unilateral or bilateral cerebellar damage as well as two individual...