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Transferring a unimanual motor skill to the untrained hand, a phenomenon known as cross-limb transfer, was shown to deteriorate as a function of age. While transcranial direct current stimulation (tDCS) ipsilateral to the trained hand facilitated cross-limb transfer in older adults, little is known about the contribution of the contralateral hemisphere to cross-limb transfer. In the present study, we investigated whether tDCS facilitates cross-limb transfer in older adults when applied over the motor cortex (M1) contralateral to the trained hand. Furthermore, the study aimed at investigating short-term recovery of tDCS-associated cross-limb transfer. In a randomized, doubleblinded, sham-controlled setting, 30 older adults (67.0 4.6 years, 15 female) performed a short grooved-pegboard training using their left hand, while anodal (a-tDCS) or sham-tDCS (s-tDCS) was applied over right M1 for 20 min. Left (LHtrained) - and right-hand (RHuntrained) performance was tested before and after training and in three recovery measures 15, 30 and 45 min after training. LHtrained performance improved during both a-tDCS and s-tDCS and improvements persisted during recovery measures for at least 45 min. RHuntrained performance improved only following a-tDCS but not after s-tDCS and outlasted the stimulation period for at least 45 min. Together, these data indicate that tDCS over the M1 contralateral to the trained limb is capable of enhancing cross-limb transfer in older adults, thus showing that cross-limb transfer is mediated not only by increased bi-hemispheric activation.

To address the research question of cortical processing of light touch, this dissertation is following two lines of investigation. The first line of research investigated the working mechanisms of light touch more closely and whether its effects are due to the additional sensory information form the fingertip or its suprapostural properties. Additionally, the timely properties of light touch were investigated, looking at the effects of intermittent light touch. The other line of research investigated the cortical processing of light touch for balance control. The effects of disrupting the Posterior Parietal Cortex on light touch and balance control was the main focus in these studies, investigating static, as well as dynamic situations., Um die Forschungsfrage der kortikalen Verarbeitung von leichten Berührungen zu beantworten, folgt diese Dissertation zwei Untersuchungssträngen. Der erste Forschungsstrang untersuchte die Wirkmechanismen leichter Berührung genauer und ob ihre Auswirkungen auf die zusätzlichen sensorischen Informationen der Fingerspitze oder auf ihre supraposturalen Eigenschaften zurückzuführen sind. Zusätzlich wurden die zeitlichen Eigenschaften der leichten Berührung untersucht und die Auswirkungen der intermittierenden leichten Berührung. Der andere Forschungsstrang untersuchte die kortikale Verarbeitung von leichter Berührung zur Gleichgewichtskontrolle. Die Auswirkungen einer Störung des Posterior Parietalen Kortex auf die Verarbeitung leichter Berührung und die Gleichgewichtskontrolle standen im Mittelpunkt dieser Studien, in denen sowohl statische als auch dynamische Situationen untersucht wurden.

To address the research question of cortical processing of light touch, this dissertation is following two lines of investigation. The first line of research investigated the working mechanisms of light touch more closely and whether its effects are due to the additional sensory information form the fingertip or its suprapostural properties. Additionally, the timely properties of light touch were investigated, looking at the effects of intermittent light touch. The other line of research investigated the cortical processing of light touch for balance control. The effects of disrupting the Posterior Parietal Cortex on light touch and balance control was the main focus in these studies, investigating static, as well as dynamic situations., Um die Forschungsfrage der kortikalen Verarbeitung von leichten Berührungen zu beantworten, folgt diese Dissertation zwei Untersuchungssträngen. Der erste Forschungsstrang untersuchte die Wirkmechanismen leichter Berührung genauer und ob ihre Auswirkungen auf die zusätzlichen sensorischen Informationen der Fingerspitze oder auf ihre supraposturalen Eigenschaften zurückzuführen sind. Zusätzlich wurden die zeitlichen Eigenschaften der leichten Berührung untersucht und die Auswirkungen der intermittierenden leichten Berührung. Der andere Forschungsstrang untersuchte die kortikale Verarbeitung von leichter Berührung zur Gleichgewichtskontrolle. Die Auswirkungen einer Störung des Posterior Parietalen Kortex auf die Verarbeitung leichter Berührung und die Gleichgewichtskontrolle standen im Mittelpunkt dieser Studien, in denen sowohl statische als auch dynamische Situationen untersucht wurden.

Low-intensity transcranial electrical stimulation (tES), including alternating or direct current stimulation, applies weak electrical stimulation to modulate the activity of brain circuits. Integration of tES with concurrent functional MRI (fMRI) allows for the mapping of neural activity during neuromodulation, supporting causal studies of both brain function and tES effects. Methodological aspects of tES-fMRI studies underpin the results, and reporting them in appropriate detail is required for reproducibility and interpretability. Despite the growing number of published reports, there are no consensus-based checklists for disclosing methodological details of concurrent tES-fMRI studies. The objective of this work was to develop a consensus-based checklist of reporting standards for concurrent tES-fMRI studies to support methodological rigor, transparency and reproducibility (ContES checklist). A two-phase Delphi consensus process was conducted by a steering committee (SC) of 13 members and 49 expert panelists through the International Network of the tES-fMRI Consortium. The process began with a circulation of a preliminary checklist of essential items and additional recommendations, developed by the SC on the basis of a systematic review of 57 concurrent tES-fMRI studies. Contributors were then invited to suggest revisions or additions to the initial checklist. After the revision phase, contributors rated the importance of the 17 essential items and 42 additional recommendations in the final checklist. The state of methodological transparency within the 57 reviewed concurrent tES-fMRI studies was then assessed by using the checklist. Experts refined the checklist through the revision and rating phases, leading to a checklist with three categories of essential items and additional recommendations: (i) technological factors, (ii) safety and noise tests and (iii) methodological factors. The level of reporting of checklist items varied among the 57 concurrent tES-f

The ability to maintain balance is based on various processes of motor control in complex neural networks of subcortical and cortical brain structures. However, knowledge on brain processing during the execution of whole-body balance tasks is still limited. In the present study, we investigated brain activity during slacklining, a task with a high demand on balance capabilities, which is frequently used as supplementary training in various sports disciplines as well as for lower extremity prevention and rehabilitation purposes in clinical settings. We assessed hemodynamic response alterations in sensorimotor brain areas using functional near-infrared spectroscopy (fNIRS) during standing (ST) and walking (WA) on a slackline in 16 advanced slackliners. We expected to observe task-related differences between both conditions as well as associations between cortical activity and slacklining experience. While our results revealed hemodynamic response alterations in sensorimotor brain regions such as primary motor cortex (M1), premotor cortex (PMC), and supplementary motor cortex (SMA) during both conditions, we did not observe differential effects between ST and WA nor associations between cortical activity and slacklining experience. In summary, these findings provide novel insights into brain processing during a whole-body balance task and its relation to balance expertise. As maintaining balance is considered an important prerequisite in daily life and crucial in the context of prevention and rehabilitation, future studies should extend these findings by quantifying brain processing during task execution on a whole-brain level.

Despite a rise in the use of “learning by doing” pedagogical methods in praxis, little is known as to how the brain benefits from these methods. Learning by doing strategies that utilize complementary information (“enrichment”) such as gestures have been shown to optimize learning outcomes in several domains including foreign language (L2) training. Here we tested the hypothesis that behavioral benefits of gesture-based enrichment are critically supported by integrity of the biological motion visual cortices (bmSTS). Prior functional neuroimaging work has implicated the visual motion cortices in L2 translation following sensorimotor-enriched training; the current study is the first to investigate the causal relevance of these structures in learning by doing contexts. Using neuronavigated transcranial magnetic stimulation and a gesture-enriched L2 vocabulary learning paradigm, we found that the bmSTS causally contributed to behavioral benefits of gesture-enriched learning. Visual motion cortex integrity benefitted both short- and long-term learning outcomes, as well as the learning of concrete and abstract words. These results adjudicate between opposing predictions of two neuroscientific learning theories: While reactivation-based theories predict no functional role of specialized sensory cortices in vocabulary learning outcomes, the current study supports the predictive coding theory view that these cortices precipitate sensorimotor-based learning benefits.:I. Abkürzungsverzeichnis II. Abbildungsverzeichnis III. Einleitung 1. Fremdsprachenlernen 1.1 Sensorische Modalitätsvergleiche 1.2 Sensomotorisches Lernen 2. Lerntheorien 2.1 Theorie des prädiktiven Kodierens 2.2 Theorie des prädiktiven Kodierens für multisensorisches Lernen 3. Sulcus temporalis superior für biologische Bewegung 4. Transkranielle Magnetstimulation 4.1 Passagere Funktionsinhibition mittels transkranieller Magnetstimulation IV. Ableitung der Rationale V. Publikationsmanuskript VI. Zusammenfassung

Background Low intensity transcranial electrical stimulation (tES), including alternating or direct current stimulation (tACS or tDCS), applies weak electrical stimulation to modulate the activity of brain circuits. Integration of tES with concurrent functional magnetic resonance imaging (fMRI) allows for the mapping of neural activity during neuromodulation, supporting causal studies of both brain function and tES effects. Methodological aspects of tES-fMRI studies underpin the results, and reporting them in appropriate detail is required for reproducibility and interpretability. Despite the growing number of published reports, there are no consensus-based checklists for disclosing methodological details of concurrent tES-fMRI studies. Objective To develop a consensus-based checklist of reporting standards for concurrent tES-fMRI studies to support methodological rigor, transparency, and reproducibility (ContES Checklist). Methods A two-phase Delphi consensus process was conducted by a steering committee (SC) of 13 members and 49 expert panelists (EP) through the International Network of the tES-fMRI (INTF) Consortium. The process began with a circulation of a preliminary checklist of essential items and additional recommendations, developed by the SC based on a systematic review of 57 concurrent tES-fMRI studies. Contributors were then invited to suggest revisions or additions to the initial checklist. After the revision phase, contributors rated the importance of the 17 essential items and 42 additional recommendations in the final checklist. The state of methodological transparency within the 57 reviewed concurrent tES-fMRI studies was then assessed using the checklist. Results Experts refined the checklist through the revision and rating phases, leading to a checklist with three categories of essential items and additional recommendations: (1) technological factors, (2) safety and noise tests, and (3) methodological factors. The level of reporting of checklist