Information processing in human parieto-frontal circuits during goal-directed bimanual movements.

It is known that, in macaques, movements guided by somatosensory information engage anterior parietal and posterior precentral regions. Movements performed with both visual and somatosensory feedback additionally activate posterior parietal and anterior precentral areas. It remains unclear whether the human parieto-frontal circuits exhibit a similar functional organization.

Neural basis of aging: the penetration of cognition into action control.

Although functional imaging studies have frequently examined age-related changes in neural recruitment during cognitive tasks, much less is known about such changes during motor performance. In the present study, we used functional magnetic resonance imaging to investigate age-related changes in cyclical hand and/or foot movements across different degrees of complexity. Right-handed volunteers (11 young, 10 old) were scanned while performing isolated flexion-extension movements of the right wrist and foot as well as their coordination, according to the "easy" isodirectional and "difficult" nonisodirectional mode.

The role of anterior cingulate cortex and precuneus in the coordination of motor behaviour.

Behavioral studies in humans have shown that bimanual coordination imposes specific demands on the central nervous system that exceed unimanual task control. In the present study we used functional magnetic resonance imaging to investigate the neural correlate of this additional coordination effort, i.e.

Spatial interference during bimanual coordination: differential brain networks associated with control of movement amplitude and direction.

Bimanual interference emerges when spatial features, such as movement direction or amplitude, differ between limbs, as indicated by a mutual bias of limb trajectories. Although first insights into the neural basis of directional interference have been revealed recently, little is known about the neural network associated with amplitude interference. We investigated whether amplitude versus directional interference activates differential networks.

Ipsilateral coordination deficits and central processing requirements associated with coordination as a function of aging.

Young and elderly participants performed concurrent ipsilateral hand-foot movements either isodirectionally or nonisodirectionally. We determined performance by measuring the maximal cycling frequency at which the coordination pattern could be performed successfully (CF(max)). We also determined attentional costs by means of a dual-task paradigm.

Parieto-premotor areas mediate directional interference during bimanual movements.

In bimanual movements, interference emerges when limbs are moved simultaneously along incompatible directions. The neural substrate and mechanisms underlying this phenomenon are largely unknown. We used functional magnetic resonance imaging to compare brain activation during directional incompatible versus compatible bimanual movements.

Internal vs external generation of movements: differential neural pathways involved in bimanual coordination performed in the presence or absence of augmented visual feedback.

It is commonly agreed that a functional dissociation with respect to the internal vs external control of movements exists for several brain regions. This has, however, only been tested in relation to the timing and preparation of motor responses, but not to ongoing movement control. Using functional magnetic resonance imaging (fMRI), the present study addressed the neuroanatomical substrate of the internal-external control hypothesis by comparing regional brain activation for cyclical bimanual movements performed in the presence or absence of augmented visual feedback.