Gesa Hartwigsen - Academia.edu (original) (raw)

Papers by Gesa Hartwigsen

NeuroImage, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

arXiv: Neurons and Cognition, 2019

Despite a rise in the use of "learning by doing" pedagogical methods in praxis, little ... more Despite a rise in the use of "learning by doing" pedagogical methods in praxis, little is known as to how these methods improve learning outcomes. Here we show that visual association cortex causally contributes to performance benefits of a learning by doing method. This finding derives from transcranial magnetic stimulation (TMS) and a gesture-enriched foreign language (L2) vocabulary learning paradigm performed by 22 young adults. Inhibitory TMS of visual motion cortex reduced learning outcomes for abstract and concrete gesture-enriched words in comparison to sham stimulation. There were no TMS effects on words learned with pictures. These results adjudicate between opposing predictions of two neuroscientific learning theories: While reactivation-based theories predict no functional role of visual motion cortex in vocabulary learning outcomes, the current study supports the predictive coding theory view that specialized sensory cortices precipitate sensorimotor-based lea...

Brain Stimulation, 2020

Background: The COVID-19 pandemic has broadly disrupted biomedical treatment and research includi... more Background: The COVID-19 pandemic has broadly disrupted biomedical treatment and research including non-invasive brain stimulation (NIBS). Moreover, the rapid onset of societal disruption and evolving regulatory restrictions may not have allowed for systematic planning of how clinical and research work may continue throughout the pandemic or be restarted as restrictions are abated. The urgency to provide and develop NIBS as an intervention for diverse neurological and mental health indications, and as a catalyst of fundamental brain research, is not dampened by the parallel efforts to address the most life-threatening aspects of COVID-19; rather in many cases the need for NIBS is heightened including the potential to mitigate mental health consequences related to COVID-19. Objective: To facilitate the re-establishment of access to NIBS clinical services and research operations during the current COVID-19 pandemic and possible future outbreaks, we develop and discuss a framework for balancing the importance of NIBS operations with safety considerations, while addressing the needs of all stakeholders. We focus on Transcranial Magnetic Stimulation (TMS) and low intensity transcranial Electrical Stimulation (tES)-including transcranial Direct Current Stimulation (tDCS) and transcranial Alternating Current Stimulation (tACS). Methods: The present consensus paper provides guidelines and good practices for managing and reopening NIBS clinics and laboratories through the immediate and ongoing stages of COVID-19. The document reflects the analysis of experts with domain-relevant expertise spanning NIBS technology, clinical services, and basic and clinical research e with an international perspective. We outline regulatory aspects, human resources, NIBS optimization, as well as accommodations for specific demographics. Results: A model based on three phases (early COVID-19 impact, current practices, and future preparation) with an 11-step checklist (spanning removing or streamlining in-person protocols, incorporating telemedicine, and addressing COVID-19-associated adverse events) is proposed. Recommendations on implementing social distancing and sterilization of NIBS related equipment, specific considerations of COVID-19 positive populations including mental health comorbidities, as well as considerations regarding regulatory and human resource in the era of COVID-19 are outlined. We discuss COVID-19 considerations specifically for clinical (sub-)populations including pediatric, stroke, addiction, and the elderly. Numerous case-examples across the world are described. Conclusion: There is an evident, and in cases urgent, need to maintain NIBS operations through the COVID-19 pandemic, including anticipating future pandemic waves and addressing effects of COVID-19 on brain and mind. The proposed robust and structured strategy aims to address the current and anticipated future challenges while maintaining scientific rigor and managing risk.

ABSTRACTDespite the widespread use of transcranial magnetic stimulation (TMS), the precise cortic... more ABSTRACTDespite the widespread use of transcranial magnetic stimulation (TMS), the precise cortical location underlying the physiological and behavioral stimulation effects are still only coarsely known. So far, mapping strategies rely on center of gravity approaches and therefore localize the stimulated cortical site only approximately and indirectly. Focusing on the motor cortex, we present a novel method to reliably determine the effectively stimulated cortical site at the individual subject level. The approach combines measurements of motor evoked potentials (MEPs) at different coil positions and orientations with numerical modeling of induced electric fields. We identify sharply bounded cortical areas around the gyral crowns and rims of the motor hand area as the origin of MEPs and show that the tangential component and the magnitude of the electric field is most relevant for the observed effect. To validate our approach, we determined motor thresholds for coil positions and or...

Cortex, 2019

Sentence comprehension requires the rapid analysis of semantic and syntactic information. These p... more Sentence comprehension requires the rapid analysis of semantic and syntactic information. These processes are supported by a left hemispheric dominant frontotemporal network, including left posterior inferior frontal gyrus (pIFG) and posterior superior temporal gyrus/sulcus (pSTG/STS). Previous electroencephalography (EEG) studies have associated semantic expectancy within a sentence with a modulation of the N400 and syntactic gender violations with increases in the LAN and P600. Here, we combined focal perturbations of neural activity by means of short bursts of transcranial magnetic stimulation (TMS) with simultaneous EEG recordings to probe the functional relevance of pIFG and pSTG/STS for sentence comprehension. We applied 10 Hz TMS bursts of three pulses at verb onset during auditory presentation of short sentences. Verb-based semantic expectancy and article-based syntactic gender requirement were manipulated for the sentence final noun. We did not find any TMS effect at the noun. However, TMS had a short-lasting impact at the mid-sentence verb that differed for the two stimulation sites. Specifically, TMS over pIFG elicited a frontal positivity in the first 200 ms post verb onset whereas TMS over pSTG/STS was limited to a parietal negativity at 200-400 ms post verb onset. This indicates that during verb processing in sentential context, frontal brain areas play an earlier role than temporal areas in predicting the upcoming noun. The short-living perturbation effects at the mid-sentence verb suggest a high degree of online compensation within the language system since the sentence final noun processing was unaffected.

PLOS ONE, 2017

Semantic cognition, i.e. processing of meaning is based on semantic representations and their con... more Semantic cognition, i.e. processing of meaning is based on semantic representations and their controlled retrieval. Semantic control has been shown to be implemented in a network that consists of left inferior frontal (IFG), and anterior and posterior middle temporal gyri (a/ pMTG). We aimed to disrupt semantic control processes with continuous theta burst stimulation (cTBS) over left IFG and pMTG and to study whether behavioral effects are moderated by induced alterations in resting-state functional connectivity. To this end, we applied real cTBS over left IFG and left pMTG as well as sham stimulation on 20 healthy participants in a within-subject design. Stimulation was followed by resting-state functional magnetic resonance imaging and a semantic priming paradigm. Resting-state functional connectivity of regions of interest in left IFG, pMTG and aMTG revealed highly interconnected left-lateralized fronto-temporal networks representing the semantic system. We did not find any significant direct modulation of either task performance or resting-state functional connectivity by effective cTBS. However, after sham cTBS, functional connectivity between IFG and pMTG correlated with task performance under high semantic control demands in the semantic priming paradigm. These findings provide evidence for the functional relevance of interactions between IFG and pMTG for semantic control processes. This interaction was functionally less relevant after cTBS over aIFG which might be interpretable in terms of an indirect disruptive effect of cTBS.

NeuroImage, Jan 7, 2017

Storage and reordering of incoming information are two core processes required for successful sen... more Storage and reordering of incoming information are two core processes required for successful sentence comprehension. Storage is necessary whenever the verb and its arguments (i.e., subject and object) are separated over a long distance, while reordering is necessary whenever the argument order is atypical (e.g., object-first order in German, where subject-first order is typical). Previous neuroimaging work has associated storage with the left planum temporale (PT), and reordering with the left posterior inferior frontal gyrus (pIFG). Here, we tested the causal role of the PT and pIFG in storage and reordering using repetitive transcranial magnetic stimulation (rTMS). We applied either effective rTMS over PT or pIFG, or sham rTMS, while subjects listened to sentences that independently varied storage demands (short vs. long argument-verb distance) and reordering demands (subject- vs. object-first argument order). We found that rTMS over pIFG, but not PT, selectively affected reorder...

Klinische Neurophysiologie, 2010

Clinical Neurophysiology, 2016

Brain stimulation, Jan 7, 2015

The rapid adaptation of actions to changes in the environment is crucial for survival. We previou... more The rapid adaptation of actions to changes in the environment is crucial for survival. We previously demonstrated a joint contribution of left dorsal premotor cortex (PMd) and left supramarginal gyrus (SMG) to action reprogramming. However, we did not probe the contribution of PMd to the speed and accuracy of action reprogramming and how the functional relevance of PMd changes in the presence of a dysfunctional SMG. This study further dissociated the unique contribution of left PMd and SMG to action reprogramming. Specifically, we tested whether the critical contribution of PMd during action reprogramming depends on the functional integrity of SMG. Adopting a condition-and-perturb repetitive transcranial magnetic stimulation (rTMS) approach, we first transiently conditioned left SMG with 1 Hz offline rTMS and then perturbed PMd activity with online rTMS whilst human subjects performed a spatially-precued reaction time task. Relative to sham rTMS, effective online perturbation of lef...

Cerebral cortex (New York, N.Y. : 1991), Jun 7, 2015

Left posterior inferior frontal gyrus (pIFG) and supramarginal gyrus (SMG) are key regions for ph... more Left posterior inferior frontal gyrus (pIFG) and supramarginal gyrus (SMG) are key regions for phonological decisions, whereas angular gyrus (ANG) and anterior IFG (aIFG) are associated with semantics. However, it is less clear whether the functional contribution of one area changes in the presence of a dysfunctional area within the network. Using repetitive transcranial magnetic stimulation (rTMS), we first tested whether perturbing one area would disrupt behavior. Second, we applied a condition-and-perturb approach, combining parietal offline rTMS with frontal online rTMS to investigate how the functional contribution of a frontal region changes in the presence of a dysfunctional parietal region. We found that rTMS over SMG or pIFG delayed phonological decisions, but this was not enhanced by combining supramarginal rTMS with pIFG rTMS. In contrast, semantic decisions were only impaired when angular rTMS was combined with aIFG rTMS. We infer that offline rTMS caused a dysfunction o...

Brain and language, Jan 15, 2014

With the advent of non-invasive brain stimulation (NIBS), a new decade in the study of language h... more With the advent of non-invasive brain stimulation (NIBS), a new decade in the study of language has started. NIBS allows for testing the functional relevance of language-related brain activation and enables the researcher to investigate how neural activation changes in response to focal perturbations. This review focuses on the application of NIBS in the healthy brain. First, some basic mechanisms will be introduced and the prerequisites for carrying out NIBS studies of language are addressed. The next section outlines how NIBS can be used to characterize the contribution of the stimulated area to a task. In this context, novel approaches such as multifocal transcranial magnetic stimulation and the condition-and-perturb approach are discussed. The third part addresses the combination of NIBS and neuroimaging in the study of plasticity. These approaches are particularly suited to investigate short-term reorganization in the healthy brain and may inform models of language recovery in ...

The neural mechanisms that support aphasia recovery are not yet fully understood. It has been arg... more The neural mechanisms that support aphasia recovery are not yet fully understood. It has been argued that the functional reorganization of language networks after left-hemisphere stroke may engage perilesional left brain areas as well as homologous right-hemisphere regions. In this chapter, we summarize how noninvasive brain stimulation can be used to elucidate mechanisms of plasticity in language networks and enhance language recovery after stroke. We first outline some basic principles of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). We then present evidence from studies in healthy volunteers for a causal role of the right hemisphere in different language functions. Finally, we review recent studies that used TMS or tDCS to promote language recovery after stroke. Most of these studies applied noninvasive brain stimulation over contralateral right-hemisphere areas to suppress maladaptive plasticity. However, some studies also suggest that right-hemisphere regions may beneficially contribute to recovery in some patients. More recently, some investigators have targeted perilesional brain regions to promote neurorehabilitation. In sum, these studies indicate that language recovery after stroke may integrate left-as well as right-hemisphere brain regions to a different degree over the time course of recovery. Although the results of these preliminary studies provide some evidence that noninvasive brain stimulation may promote aphasia recovery, the reported effect sizes are not striking. Future studies on larger patient collectives are needed to explore whether noninvasive brain stimulation can enhance language functions at a level that is clinically relevant.

The Journal of Neuroscience, 2012

The ability to discard a prepared action plan in favor of an alternative action is critical when ... more The ability to discard a prepared action plan in favor of an alternative action is critical when facing sudden environmental changes. We tested whether the functional contribution of left supramarginal gyrus (SMG) during action reprogramming depends on the functional integrity of left dorsal premotor cortex (PMd). Adopting a dual-site repetitive transcranial magnetic stimulation (rTMS) strategy, we first transiently disrupted PMd with “off-line” 1 Hz rTMS and then applied focal “on-line” rTMS to SMG while human subjects performed a spatially precued reaction time (RT) task. Effective on-line rTMS of SMG but not sham rTMS of SMG increased errors when subjects had to reprogram their action in response to an invalid precue regardless of the type of preceding off-line rTMS. This suggests that left SMG primarily contributes to the on-line updating of actions by suppressing invalidly prepared responses. On-line rTMS of SMG additionally increased RTs for correct responses in invalidly prec...

Proceedings of the National Academy of Sciences, 2010

Recent functional imaging studies demonstrated that both the left and right supramarginal gyri (S... more Recent functional imaging studies demonstrated that both the left and right supramarginal gyri (SMG) are activated when healthy right-handed subjects make phonological word decisions. However, lesion studies typically report difficulties with phonological processing after left rather than right hemisphere damage. Here, we used a unique dual-site transcranial magnetic stimulation (TMS) approach to test whether the SMG in the right hemisphere contributes to modality-independent (i.e., auditory and visual) phonological decisions. To test task-specificity, we compared the effect of real or sham TMS during phonological, semantic, and perceptual decisions. To test laterality and anatomical specificity, we compared the effect of TMS over the left, right, or bilateral SMG and angular gyri. The accuracy and reaction times of phonological decisions were selectively disrupted relative to semantic and perceptual decisions when real TMS was applied over the left, right, or bilateral SMG. These e...

Proceedings of the National Academy of Sciences, 2013

Significance The role of the right hemisphere in aphasia recovery is unclear. We demonstrate that... more Significance The role of the right hemisphere in aphasia recovery is unclear. We demonstrate that a virtual lesion of left inferior frontal gyrus (IFG) decreased activity in the targeted area and increased activity in the contralateral homologous area during pseudoword repetition. This was associated with a stronger facilitatory drive from the right IFG to the left IFG. Importantly, responses became faster with increased influence of the right IFG on the left IFG. Our results shed new light on the dynamic regulation of interhemispheric interactions in the human brain. Particularly, these findings are of potential importance for understanding language recovery after left-hemispheric stroke, indicating that homologous right hemisphere areas actively contribute to language function after a left hemisphere lesion.

Journal of Cognitive Neuroscience, 2013

Previous studies have demonstrated that the repetition of pseudowords engages a network of premot... more Previous studies have demonstrated that the repetition of pseudowords engages a network of premotor areas for articulatory planning and articulation. However, it remains unclear how these premotor areas interact and drive one another during speech production. We used fMRI with dynamic causal modeling to investigate effective connectivity between premotor areas during overt repetition of words and pseudowords presented in both the auditory and visual modalities. Regions involved in phonological aspects of language production were identified as those where regional increases in the BOLD signal were common to repetition in both modalities. We thus obtained three seed regions: the bilateral pre-SMA, left dorsal premotor cortex (PMd), and left ventral premotor cortex that were used to test 63 different models of effective connectivity in the premotor network for pseudoword relative to word repetition. The optimal model was identified with Bayesian model selection and reflected a network ...