Attention and Interhemispheric Communication: Implications for Language Dominance.

Dominance of the left hemisphere for language processing is a prominent feature of brain organisation. Whereas structural models clarify the functional asymmetry due to direct access to local language circuits, dynamic models propose functional states of intrahemispheric activation and interhemispheric inhibition that are coupled with attentional processes. Real word settings often require modulations of lateralised neural processing and further express individual heterogeneity.

The interactive functional biases of manual, language and attention systems.

Hemispheric lateralisation is a fundamental principle of functional brain organisation. We studied two core cognitive functions-language and visuospatial attention-that typically lateralise in opposite cerebral hemispheres. In this work, we tested both left- and right-handed participants on lexical decision-making as well as on symmetry detection by means of a visual half-field paradigm with various target-distractor combinations simultaneously presented to opposite visual fields.

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.

Stability and flexibility in cognitive control: Interindividual dynamics and task context processing.

Adaptive behaviour requires cognitive control for shielding current goals from distractors (stability) but at the same time for switching between alternative goals (flexibility). In this behavioural study, we examine the stability-flexibility balance in left- and right-handers during two types of decision-making, instructed (sensory cued) and voluntary (own choice), by means of distractor inhibition and hand/task switching. The data revealed that both groups showed opposite tendencies for instructed decision-making.

Individual Differences and Hemispheric Asymmetries for Language and Spatial Attention.

Language and spatial processing are cognitive functions that are asymmetrically distributed across both cerebral hemispheres. In the present study, we compare left- and right-handers on word comprehension using a divided visual field paradigm and spatial attention using a landmark task. We investigate hemispheric asymmetries by assessing the participants' behavioral metrics; response accuracy, reaction time and their laterality index.

Motor Timing and Covariation with Time Perception: Investigating the Role of Handedness.

Time is a fundamental dimension of our behavior and enables us to guide our actions and to experience time such as predicting collisions or listening to music. In this study, we investigate the regulation and covariation of motor timing and time perception functions in left- and right-handers who are characterized by distinct brain processing mechanisms for cognitive-motor control. To this purpose, we use a combination of tasks that assess the timed responses during movements and the perception of time intervals.

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.

Hemispheric asymmetries and the control of motor sequences.

Sequencing of finger positions reflects a prototype of skilled behaviour. In order to perform sequencing, cognitive control supports the requirements and postural transitions. In this electroencephalography (EEG) study, we evaluate the effects of hand dominance and assess the neural correlates of unimanual and bimanual sequencing in left- and right-handers.

Cognitive control of response inhibition and switching: hemispheric lateralization and hand preference.

Changing environmental constraints often make already prepared responses unnecessary or inappropriate. Under such circumstances, cognitive control enables to suppress the response or switch to alternative behavior. Here, we examine the neural dynamics of both functions in left- and right-handers who performed two variants of a paradigm that required either inhibition of the response or switching the response between hands.

Developmental changes in motor control: insights from bimanual coordination.

Manual dexterity is known to gradually progress with developmental age. In this study, we evaluate the performance of unimanual and bimanual actions under perturbed and unperturbed conditions in children between 4 and 10 years of age. Behavior was assessed by means of trajectory measurements and degree of bimanual coupling.

Bimanual control processes and the role of handedness.

Objective: Bimanual movements are a fundamental motor skill. Whereas substantial research is available from right-handers, much less is known from left-handers. Accordingly, in the present electroencephalography (EEG) study we evaluated bimanual behavior in left- versus right-handers.

Subliminal priming and effects of hand dominance.

In the masked priming paradigm, motor responses to targets are influenced by previously presented subliminal primes, and are guided by facilitatory and inhibitory mechanisms that depend on prime-target compatibility/duration. In this study, we evaluate subliminal-driven priming in right- and left-handers during unimanual as well as bimanual tasks. The data from the unimanual tasks confirmed that prime-target compatibility affects performance as a function of prime-target duration.

Handedness and the excitability of cortical inhibitory circuits.

Inhibitory processes play a significant role in the control of goal-directed actions. To increase insights into these mechanisms as a function of handedness, we measured the transient inhibition of volitional motor activity induced by single pulse transcranial magnetic stimulation during bimanual isometric contractions with symmetrical and asymmetrical force demands. Here, we assess the cortical silent period (cSP), which associates with intrahemispheric inhibition, and the ipsilateral silent period (iSP), which provides an estimation of interhemispheric inhibition.

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.

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.

Coupling between perception and action timing during sensorimotor synchronization.

Time is an important parameter in behaviour, especially when synchronization with external events is required. To evaluate the nature of the association between perception and action timing, this study introduced pitch accented tones during performance of a sensorimotor tapping task. Furthermore, regularity of the pacing cues was modified by small (subliminal) or large (conscious) timing perturbations.

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.

The role of hand dominance and sensorimotor congruence in voluntary movement.

The present study evaluated the neural changes due to effector use (unimanual left, unimanual right, and bimanual) and visuomotor conflict induced by mirror-reversed vision during drawing behavior. EEG phase synchronization, expressing interregional communication, showed that visuomotor incongruence perturbed information processing in both hemispheres. Furthermore, it was observed that the left hemisphere became temporally dominant when movements were executed with visuomotor conflict, independent of the performing hand(s).

Effects of task complexity and sensory conflict on goal-directed movement.

Interactions between brain regions are necessary for compound activities to take place. Accordingly, evaluating hemispheric information processing during skilled behaviour provides valuable knowledge about brain regulation. To this end, the present study assessed the neural changes in response to task complexity and visuomotor discrepancy during motor (drawing) actions.

Bimanual information processing and the impact of conflict during mirror drawing.

Successful motor behavior depends on optimal information processing and planning. In the present study, the neural response of the motor system to conflict of visuomotor discrepancy (mirror-reversed vision) and complexity (task difficulty and hand laterality) was evaluated during the performance of bimanual actions. EEG coherence, expressing interregional communication, showed that conflict of visuomotor incongruence resulted in activation changes in both hemispheres, whereas conflict of complexity evoked adjustments primarily in the left hemisphere.

Interactions between new and pre-existing dynamics in bimanual movement control.

Motor skills are commonly acquired through practice. This process not only involves acquisition of the particular task demands but also requires overcoming pre-existing modes. In the present study, interactions between new and intrinsic dynamics were evaluated.