Interregional synchrony of visuomotor tracking: perturbation effects and individual differences

The present study evaluated the neural and behavioural correlates associated with a visuomotor tracking task during which a sensory perturbation was introduced that created a directional bias between moving hand and cursor position. The results revealed that trajectory error increased as a result of the perturbation in conjunction with a dynamic neural reorganization of cluster patterns that reflected distinct processing. In particular, a negatively activated cluster, characterizing the degraded information processing due to the perturbation, involved both hemispheres as well as midline area. Conversely, a positively activated cluster, indicative of compensatory processing was strongly confined to the left (dominant) hemisphere. In addition, a brain-behavioural association of good vs. poor performing participants enabled to localize a neural circuit within the left hemisphere and midline area that linked with successful performance. Overall, these data reinforce the functional significance of interregional synchrony in defining response output and behavioural success

Manual dexterity: functional lateralisation patterns and motor efficiency

Manual tasks are an important goal-directed ability. In this EEG work, we studied how handedness affects the hemispheric lateralisation patterns during performance of visually-driven movements with either hand. The neural correlates were assessed by means of EEG coherence whereas behavioural output was measured by motor error. The EEG data indicated that left- and right-handers showed distinct recruitment patterns. These involved local interactions between brain regions as well as more widespread associations between brain systems. Despite these differences, brain-behaviour correlations highlighted that motor efficiency depended on left-sided brain regions across groups. These results suggest that skilled hand motor control relies on different neural patterns as a function of handedness whereas behavioural efficiency is linked with the left hemisphere. In conclusion, the present findings add to our understanding about principles of lateralised organisation as a function of handedness

Space, time and number : common coding mechanisms and interactions between domains

Space, time and number are key dimensions that underlie how we perceive, identify and act within the environment. They are interconnected in our behaviour and brain. In this study, we examined interdependencies between these dimensions. To this end, left- and right-handed participants performed an object collision task that required space–time processing and arithmetic tests that involved number processing. Handedness of the participants influenced collision detection with left-handers being more accurate than right-handers, which is in line with the premise that hand preference guides individual differences as a result of sensorimotor experiences and distinct interhemispheric integration patterns. The data further showed that successful collision detection was a predictor for arithmetic achievement, at least in right-handers. These findings suggest that handedness plays a mediating role in binding information processing across domains, likely due to selective connectivity properties within the sensorimotor system that is guided by hemispheric lateralisation patterns.Peer reviewe

Prediction of collision events: an EEG coherence analysis

Objective: A common daily-life task is the interaction with moving objects for which prediction of collision events is required. To evaluate the sources of information used in this process, this EEG study required participants to judge whether two moving objects would collide with one another or not. In addition, the effect of a distractor object is evaluated. Methods: The measurements included the behavioural decision time and accuracy, eye movement fixation times, and the neural dynamics which was determined by means of EEG coherence, expressing functional connectivity between brain areas. Results: Collision judgment involved widespread information processing across both hemispheres. When a distractor object was present, task-related activity was increased whereas distractor activity induced modulation of local sensory processing. Also relevant were the parietial regions communicating with bilateral occipital and midline areas and a left-sided sensorimotor circuit. Conclusions: Besides visual cues, cognitive and strategic strategies are used to establish a decision of events in time. When distracting information is introduced into the collision judgment process, it is managed at different processing levels and supported by distinct neural correlates

Motor awareness and dissociable levels of action representation

The present study evaluated the performance of a tracking task during which no, a small (subliminal: 20°) or a large (conscious: 60°) rotational perturbation was implemented. The instantaneous as well as carry-over effects of the perturbations were assessed. The subjective reports revealed that the subjects did not discriminate between the 0° and 20° perturbation conditions, despite increased trajectory error and directional trajectory changes in the latter than former condition, which suggests augmented error processing and task monitoring. Conversely, the 60° perturbation condition was characterized by subjective awareness in association with objective performance changes. Furthermore, a carry-over effect for the 60° but not for the 20° perturbation was observed when the distortion was removed midway into the trajectory. Together, the data underline distinct functioning of motor control and motor awareness with implications across time scales

Control of manipulative forces during unimanual and bimanual tasks in patients with Huntington's disease

The aim of the study was to investigate gripload force regulation in Huntington's disease (HD) patients as compared to control subjects during the performance of a manipulative task that required rhythmical unimanual or bimanual isodirectional/non-isodirectional actions in the sagittal plane. Results showed that the profile of grip-load ratio force was characterized by maxima and minima that were attained at upward and downward hand positions, respectively. Minimum force ratio was higher in patients than in controls, which points to an elevated baseline that may be related to the inherent bradykinesia observed in HD. Maximum force ratio was also increased in patients, but this effect depended on the performance condition, with largest amplifications occurring during non-isodirectional movements. The latter rescaling may be associated with the complexity of the coordination mode and its asymmetrical load characteristics. In addition, the temporal delay between the grip and load force peaks was augmented in patients versus controls, indicating a disturbed coupled activation of both forces. Furthermore, the interval was largest during nonisodirectional movements followed by isodirectional and unimanual movements, which denotes that the grip-load force coupling deteriorated as a function of coordinative complexity. Together, these data indicate a deficit in the grip-load force constraint due to HD and illustrate the degrading effect of striatal dysfunction on (bi)manual manipulative functio