In executing purposeful actions, adults select sufficient and necessary limbs. But infants often move goal-irrelevant limbs, suggesting a developmental process of motor specialization. Two experiments with 9and 12-month-olds revealed gradual decreases in extraneous movements in non-acting limbs during unimanual actions. In Experiment 1, 9-month-olds produced more extraneous movements in the non...

The timing of repetitive movements was assessed in a callosotomy patient under unimanual and bimanual conditions. Similar to neurologically healthy individuals, the patient exhibited strong temporal coupling in the bimanual condition. Moreover, for both the left and right hands, within-hand temporal variability was reduced in the bimanual condition compared to the unimanual conditions. This bim...

In this paper we investigate the relationship between bimanual (two-handed) manipulation and the cognitive aspects of task integration, divided attention and epistemic action. We explore these relationships by means of an empirical study comparing a bimanual technique versus a unimanual (one-handed) technique for a curve matching task. The bimanual technique was designed on the principle of int...

Hand motor tasks are frequently used to assess impaired motor function in neurology and neurorehabilitation. Assessments can be varied by means of hand laterality, i.e. unimanual or bimanual performance, as well as by means of task complexity, i.e. different degrees ranging from simple to complex sequence tasks. The resulting functional activation in human primary motor cortex (M1) has been stu...

Performance of a unimanual hand motor task results in functional changes in both primary motor cortices (M1(ipsilateral) and M1(contralateral)). The neuronal mechanisms controlling the corticospinal output originated in M1(ipsilateral) and the resting hand during a unimanual task remain unclear. Here, we assessed functional changes within M1(ipsilateral) and in interhemispheric inhibition (IHI)...