Associative Visuomotor Learning Using Transcranial Magnetic Stimulation Induces Stimulus-Response Interference.

Classical conditioning states that the systematic co-occurrence of a neutral stimulus with an unconditioned stimulus can cause the neutral stimulus to, over time, evoke the same response as the unconditioned stimulus. On a neural level, Hebbian learning suggests that this type of learning occurs through changes in synaptic plasticity when two neurons are simultaneously active, resulting in increased connectivity between them. Inspired by associative learning theories, we here investigated whether the mere co-activation of visual stimuli and stimulation of the primary motor cortex using TMS would result in stimulus-response associations that can impact future behavior. During a learning phase, we repeatedly paired the presentation of a specific color (but not other colors) with a TMS pulse over the motor cortex. Next, participants performed a two-alternative forced-choice task where they had to categorize simple shapes and we studied whether the shapes' task-irrelevant color (and its potentially associated involuntary motor activity) affected the required motor response. Participants showed more errors on incongruent trials for stimuli that were previously paired with high intensity TMS pulses, but only when tested on the same day. Using a drift diffusion model for conflict tasks, we further demonstrate that this interference occurred early, and gradually increased as a function of associated TMS intensity. Taken together, our findings show that the human brain can learn stimulus-response associations using externally induced motor cortex stimulation. Although we were inspired by the Hebbian learning literature, future studies should investigate whether Hebbian or other learning processes were also what brought about this effect.

The social roots of self development: from a bodily to an intellectual interpersonal dialogue.

In this paper, we propose that interpersonal bodily interactions represent a fertile ground in which the bodily and psychological self is developed, gradually allowing for forms of more abstract and disembodied interactions. We start by focusing on how early infant-caregiver bodily interactions play a crucial role in shaping the boundaries of the self but also in learning to predict others' behavior. We then explore the social function of the sense of touch in the entire life span, highlighting its role in promoting physical and psychological well-being by supporting positive interpersonal exchanges. We go on by introducing the concept of implicit theory of mind, as the early ability to interpret others' intentions, possibly grounded in infant-caregiver bodily exchanges (embodied practices). In the following part, we consider so-called higher level forms of social interaction: intellectual exchanges among individuals. In this regard, we defend the view that, beside the apparent private dimension of "thinking abstractly", using abstract concepts is intrinsically a social process, as it entails the re-enactment of the internalized dialogue through which we acquired the concepts in the first place. Finally, we describe how the hypothesis of "dialectical attunement" may explain the development of abstract thinking: to effectively transform the world according to their survival needs, individuals co-construct structured concepts of it; by doing so, humans fundamentally transform not merely the world they are being in, but their being in the world.

Anatomical bases of fast parietal grasp control in humans: A diffusion-MRI tractography study.

The dorso-posterior parietal cortex (DPPC) is a major node of the grasp/manipulation control network. It is assumed to act as an optimal forward estimator that continuously integrates efferent outflows and afferent inflows to modulate the ongoing motor command. In agreement with this view, a recent per-operative study, in humans, identified functional sites within DPPC that: (i) instantly disrupt hand movements when electrically stimulated; (ii) receive short-latency somatosensory afferences from intrinsic hand muscles. Based on these results, it was speculated that DPPC is part of a rapid grasp control loop that receives direct inputs from the hand-territory of the primary somatosensory cortex (S1) and sends direct projections to the hand-territory of the primary motor cortex (M1). However, evidence supporting this hypothesis is weak and partial. To date, projections from DPPC to M1 grasp zone have been identified in monkeys and have been postulated to exist in humans based on clinical and transcranial magnetic studies. This work uses diffusion-MRI tractography in two samples of right- (n = 50) and left-handed (n = 25) subjects randomly selected from the Human Connectome Project. It aims to determine whether direct connections exist between DPPC and the hand control sectors of the primary sensorimotor regions. The parietal region of interest, related to hand control (hereafter designated DPPChand), was defined permissively as the 95% confidence area of the parietal sites that were found to disrupt hand movements in the previously evoked per-operative study. In both hemispheres, irrespective of handedness, we found dense ipsilateral connections between a restricted part of DPPChand and focal sectors within the pre and postcentral gyrus. These sectors, corresponding to the hand territories of M1 and S1, targeted the same parietal zone (spatial overlap > 92%). As a sensitivity control, we searched for potential connections between the angular gyrus (AG) and the pre and postcentral regions. No robust pathways were found. Streamline densities identified using AG as the starting seed represented less than 5 % of the streamline densities identified from DPPChand. Together, these results support the existence of a direct sensory-parietal-motor loop suited for fast manual control and more generally, for any task requiring rapid integration of distal sensorimotor signals.

Cerebellar lesions at a young age predict poorer long-term functional recovery.

Early studies on long-term functional recovery after motor and premotor lesions showed better outcomes in younger monkeys than in older monkeys. This finding led to the widespread belief that brain injuries cause less impairment in children than adults. However, this view has limitations and a large body of evidence now indicates that cerebral damages can be more harmful when inflicted at young age, during critical periods of neural development. To date, this issue has been mainly investigated in the context of focal and diffuse cortical lesions. Much less is known about the potential influence of early cerebellar damages. Several studies exist in survivor of posterior fossa tumours. However, in these studies, critical confounders were not always considered and contradictory conclusions were provided. We studied the impact or early cerebellar damage on long-term functional recovery in three groups of 15 posterior fossa survivors, comparable with respect to their tumour characteristics (type, size and location) but operated at different ages: young (≤7 years), middle (>7 and ≤13 years) and older (>13 years). Daily (health-related quality of life scale, performance status scale), motor (International Cooperative Ataxia Rating Scale, Pegboard Purdue Test) and cognitive (full-scale intelligence quotient) functioning were assessed. A general linear model controlling for age at surgery, radiotherapy, preservation of deep cerebellar nuclei, tumour volume and delay between surgery and assessment was used to investigate significant variations in outcome measures. Early age at surgery, lesion of deep cerebellar nuclei and postoperative radiotherapy had a significant, independent negative influence on long-term recovery. Tumour volume and delay between surgery and assessment had no statistically detectable impact. The negative influence of early age at surgery was significant in all domains: daily functioning (health-related quality of life scale, performance status scale), motor functioning (International Cooperative Ataxia Rating Scale, Pegboard Purdue Test) and cognitive functioning (full-scale intelligence quotient). These results support the existence of an early critical period of development during which the cerebellar 'learning machine' is of critical importance. Although the extent to which the early deficits here observed can be reversed needs now to be established, our data plead for the implementation of prompt and intense rehabilitation interventions in children operated before 7 years of age.

Support from a TMS/MEP study for a direct link between positive/negative stimuli and approach/avoidance tendencies.

Previous behavioral studies using stimulus-response compatibility tasks have shown that people are faster to carry out instructed approach/avoidance responses to positive/negative stimuli. This result has been taken as evidence that positive/negative stimulus valence directly activates a tendency to approach/avoid, which in turn, facilitates execution of instructed approach/avoidance behavior. In these studies, however, it cannot be excluded that the results reflect a purely semantic link between stimulus valence and instructed responses. According to this alternative interpretation, positive/negative stimuli do not elicit an approach/avoidance tendency, but instead they interact with the positive/negative valence of the instructed responses, and in this way, produce the observed compatibility effect. To circumvent this possible disadvantage of compatibility tasks, we used a novel method for the measurement of early action tendencies: TMS induced MEPs. In two experiments, participants were first trained to abduct the index finger to approach and the thumb to avoid. Then, they observed a series of positive and negative stimuli. Each stimulus was followed by a TMS pulse (at 400 ms post-stimulus onset) and MEPs were measured continuously on the muscles of both fingers. These observation trials were randomly intermixed with response trials, in which neutral stimuli were presented and participants were instructed to approach/avoid the stimuli. In Experiment 1, participants received clear visual feedback on the outcome of their response in the response trials. In Experiment 2, we omitted this feedback to test whether it was necessary for the effect to occur. The results indicated higher MEPs for the approach/avoidance finger after positive/negative stimuli in Experiment 1 but not in Experiment 2. Analyses on the data aggregated over both experiments suggest that the visual feedback was necessary for stimulus valence to elicit action tendencies. Taken together, the results are in line with the results of behavioral studies with compatibility tasks, suggesting that stimulus valence directly elicits specific action tendencies already at 400 ms but they indicate that clear visual feedback is necessary for this effect to occur.

Measuring spontaneous mentalizing with a ball detection task: putting the attention-check hypothesis by Phillips and colleagues (2015) to the test.

Theory of Mind (ToM) or mentalizing refers to the ability to attribute mental states (such as desires, beliefs or intentions) to oneself or others. ToM has been argued to operate in an explicit and an implicit or a spontaneous way. In their influential paper, Kovács et al. (Science 330:1830-1834, 2010) introduced an adapted false belief task-a ball detection task-for the measurement of spontaneous ToM. Since then, several studies have successfully used versions of this paradigm to investigate spontaneous ToM. This paradigm has, however, been criticized by Phillips et al. (Psychol Sci 26(9):1353-1367, 2015), who argue that the effects are fully explained by timing artifacts in the paradigm, namely differences in timing of the attention check. The main objective of the current study is to test this attention-check hypothesis. An additional aim was to relate the findings to autism spectrum disorder (ASD) symptomatology in our neurotypical sample, as ASD has been linked to deficits in spontaneous mentalizing. We applied an adjusted version of the paradigm in which the timings for all conditions are equalized, ruling out any potential timing confounds. We found significant main effects of own and agent beliefs on reaction times. Additionally, we found a significant 'ToM-effect': When participants believe the ball is absent, they detect the ball faster if the agent believes the ball would be present rather than absent, which refers to the original effect in the paper of Kovács et al. (2010), taken as evidence for spontaneous ToM and which was contested by Phillips et al. (2015). Our findings cannot be explained by the attention-check hypothesis. Effects could not be associated with ASD symptoms in our neurotypical sample, warranting further investigation on the link between spontaneous mentalizing and ASD.

Defining the neural correlates of spontaneous theory of mind (ToM): An fMRI multi-study investigation.

There is a major debate in the theory of mind (ToM) field, concerning whether spontaneous and explicit ToM are based on the same or two distinct cognitive systems. While extensive research on the neural correlates of explicit ToM has demonstrated involvement of the temporo-parietal junction (TPJ) and the medial prefrontal cortex (mPFC), few studies investigated spontaneous ToM, leaving some open questions. Here, we implemented a multi-study approach by pooling data from three fMRI studies to obtain a larger sample to increase power and sensitivity to better define the neurocognitive mechanisms underlying spontaneous ToM. Participants watched videos in which an agent acquires a true or false belief about the location of a ball. Thus, the belief of the agent and that of the participant could either match or differ. Importantly, participants were never asked to consider the belief of the agent and were only instructed to press a button when they detected the presence of the ball after an occluder fell at the end of each video. By analysing the blood-oxygen level dependent signal during the belief formation phase for false versus true beliefs, we found a cluster of activation in the right, and to a lesser extent, left posterior parietal cortex spanning the TPJ, but no mPFC activation. Region of interest (ROI) analysis on bilateral TPJ and mPFC confirmed these results and added evidence to the asymmetry in laterality of the TPJ in spontaneous ToM. Interestingly, the whole brain analysis, supported by an overlap with brain maps, revealed maximum activation in areas involved in visuospatial working memory and attention switching functions, such as the supramarginal gyrus, the middle temporal gyrus, and the inferior frontal gyrus. By contrast, evidence for the presence of brain-behaviour correlations was mixed and there was no evidence for functional connectivity between the TPJ and mPFC. Taken together, these findings help clarifying the brain system supporting spontaneous ToM.

Reward anticipation changes corticospinal excitability during task preparation depending on response requirements and time pressure.

The preparation of an action is accompanied by transient corticospinal (CS) excitability changes. Motivation can modulate these changes. Specifically, when a cue indicates that a reward can be obtained, CS excitability initially increases, followed by a pronounced decrease. This dynamic could reflect processes related to reward expectancy, processes related to action preparation, or a combination of both. Here we set up two experiments to dissociate these accounts. A rewarded choice reaction time task was used in which individuals were cued at the beginning of each trial whether or not a response would be required at target onset and whether or not a reward could be obtained. We used single-pulse transcranial magnetic stimulation (spTMS) over the left primary motor cortex (M1) early (shortly after cue onset) or late (shortly before target onset) preceding target onset to examine CS excitability during motivated action preparation. Electromyography (EMG) was obtained from the right first dorsal interosseous (FDI) muscle. In the first experiment, we used a lenient response deadline, whereas a strict response time-out procedure was employed in the second experiment. Reward modulated CS excitability differentially only in the second experiment: CS excitability was highest during reward anticipation for the early stimulation epoch and was reduced for the late stimulation epoch when individuals were required to prepare a response, while CS excitability remained unchanged during non-reward anticipation. Our findings suggest that the reward effect on CS excitability is dependent on the actual implementation of effort to attain reward (i.e., the preparation of an actual action), as well as on temporal requirements (i.e., time pressure) invoked by the task.

The role of stimulus-driven versus goal-directed processes in fight and flight tendencies measured with motor evoked potentials induced by Transcranial Magnetic Stimulation.

This study examines two contrasting explanations for early tendencies to fight and flee. According to a stimulus-driven explanation, goal-incompatible stimuli that are easy/difficult to control lead to the tendency to fight/flee. According to a goal-directed explanation, on the other hand, the tendency to fight/flee occurs when the expected utility of fighting/fleeing is the highest. Participants did a computer task in which they were confronted with goal-incompatible stimuli that were (a) easy to control and fighting had the highest expected utility, (b) easy to control and fleeing had the highest expected utility, and (c) difficult to control and fleeing and fighting had zero expected utility. After participants were trained to use one hand to fight and another hand to flee, they either had to choose a response or merely observe the stimuli. During the observation trials, single-pulse Transcranial Magnetic Stimulation (TMS) was applied to the primary motor cortex 450 ms post-stimulus onset and motor-evoked potentials (MEPs) were measured from the hand muscles. Results showed that participants chose to fight/flee when the expected utility of fighting/fleeing was the highest, and that they responded late when the expected utility of both responses was low. They also showed larger MEPs for the right/left hand when the expected utility of fighting/fleeing was the highest. This result can be interpreted as support for the goal-directed account, but only if it is assumed that we were unable to override the presumed natural mapping between hand (right/left) and response (fight/flight).

Spontaneous Theory of Mind is reduced for nonhuman-like agents as compared to human-like agents.

Theory of Mind research has shown that we spontaneously take into account other's beliefs. In the current study, we investigate, with a spontaneous Theory of Mind (ToM) task, if this belief representation also applies to nonhuman-like agents. In a series of three experiments, we show here that we do not spontaneously take into account beliefs of nonhuman-like others, or at least we do it to a lesser extent than for human and human-like agents. Further, the experience we have with the other agent, in our case a dog, does not modulate spontaneous ToM: the same pattern of results was obtained when dog owners and no owners were compared. However, when more attention was attracted to the dog behavior, participants' behavior was influenced by the beliefs of the dog. In sum, spontaneous belief representation seems to be primarily restricted to human and human-like agents, but can be facilitated when more attention is drawn to a nonhuman-like agent.

Anticipating actions and corticospinal excitability: A preregistered motor TMS experiment.

Past research on action observation and imitation suggests that observing a movement activates a corresponding motor representation in the observer. However, recent research suggests that individuals may not only reflexively simulate the observed behavior but also simulate and engage in anticipated action without another person actually engaging in it. For example, it has been demonstrated that observing a triggering event (i.e., nose wrinkling) that potentially leads to the anticipation of an action (i.e., nose scratching) increases the likelihood that the observer will perform that action. In the present research, we applied motor Transcranial Magnetic Stimulation (TMS) to investigate such anticipated social action effects at the neurophysiological level within a trial-by-trial measure. While a pilot study suggests that observing nose wrinkling elicits stronger motor evoked potentials (MEPs) in participants' biceps muscles than observing control events, this effect could not be fully replicated in a preregistered study. Although a post hoc meta-analysis across both studies supports the general hypothesis, these results need to be taken cautiously. Implications of the results reported in the manuscript are discussed.

Brain activity for spontaneous and explicit mentalizing in adults with autism spectrum disorder: An fMRI study.

The socio-communicative difficulties of individuals with autism spectrum disorder (ASD) are hypothesized to be caused by a specific deficit in the ability to represent one's own and others' mental states, referred to as Theory of Mind or mentalizing. However, many individuals with ASD show successful performance on explicit measures of mentalizing, and for this reason, the deficit is thought to be better captured by measures of spontaneous mentalizing. While there is initial behavioral support for this hypothesis, spontaneous mentalizing in ASD has not yet been studied at the neural level. Recent findings indicate involvement of the right temporoparietal junction (rTPJ) in both explicit and spontaneous mentalizing (Bardi et al., 2016). In the current study, we investigated brain activation during explicit and spontaneous mentalizing in adults with ASD by means of fMRI. Based on our hypothesis of a core mentalizing deficit in ASD, decreased rTPJ activity was expected for both forms of mentalizing. A group of 24 adults with ASD and 21 neurotypical controls carried out a spontaneous and an explicit version of the same mentalizing task. They watched videos in which both they themselves and another agent formed a belief about the location of an object (belief formation phase). Only in the explicit task version participants were instructed to report the agent's belief on some trials. At the behavioral level, no group differences were revealed in either of the task versions. A planned region-of-interest analysis of the rTPJ showed that this region was more active for false- than for true-belief formation, independent of task version, especially when the agent's belief had a positive content (when the agent was expecting the object). This effect of belief was absent in adults with ASD. A whole-brain analysis revealed reduced activation in the anterior middle temporal pole in ASD for false - versus true-belief trials, independent of task version. Our findings suggest neural differences between adults with ASD and neurotypical controls both during spontaneous and explicit mentalizing, and indicate the rTPJ to be crucially involved in ASD. Moreover, the possible role of the anterior middle temporal pole in disturbed mentalizing in ASD deserves further attention. The finding that these neural differences do not necessarily lead to differential performance warrants further research.

Automatic imitation: A meta-analysis.

Automatic imitation is the finding that movement execution is facilitated by compatible and impeded by incompatible observed movements. In the past 15 years, automatic imitation has been studied to understand the relation between perception and action in social interaction. Although research on this topic started in cognitive science, interest quickly spread to related disciplines such as social psychology, clinical psychology, and neuroscience. However, important theoretical questions have remained unanswered. Therefore, in the present meta-analysis, we evaluated seven key questions on automatic imitation. The results, based on 161 studies containing 226 experiments, revealed an overall effect size of gz = 0.95, 95% CI [0.88, 1.02]. Moderator analyses identified automatic imitation as a flexible, largely automatic process that is driven by movement and effector compatibility, but is also influenced by spatial compatibility. Automatic imitation was found to be stronger for forced choice tasks than for simple response tasks, for human agents than for nonhuman agents, and for goalless actions than for goal-directed actions. However, it was not modulated by more subtle factors such as animacy beliefs, motion profiles, or visual perspective. Finally, there was no evidence for a relation between automatic imitation and either empathy or autism. Among other things, these findings point toward actor-imitator similarity as a crucial modulator of automatic imitation and challenge the view that imitative tendencies are an indicator of social functioning. The current meta-analysis has important theoretical implications and sheds light on longstanding controversies in the literature on automatic imitation and related domains. (PsycINFO Database Record

Repetitive TMS of the temporo-parietal junction disrupts participant's expectations in a spontaneous Theory of Mind task.

A recent debate about Theory of Mind (ToM) concerns whether spontaneous and explicit mentalizing are based on the same mechanisms. However, only a few neuroimaging studies have investigated the neural bases of spontaneous ToM, with inconsistent results. The present study had two goals: first, to investigate whether the right Temporo-Parietal Junction (rTPJ) is crucially involved in spontaneous ToM and second, to gain insight into the role of the rTPJ in ToM. For the first time, we applied rTMS to the rTPJ while participants were engaged in a spontaneous false belief task. Participants watched videos of a scene including an agent who acquires a true or false belief about the location of an object. At the end of the movie, participants reacted to the presence of the object. Results show that, during stimulation of the control site, RTs were affected by both the participant's expectations and the belief of the agent. Stimulation of the rTPJ significantly modulated task performance, supporting the idea that spontaneous ToM, as well as explicit ToM, relies on TPJ activity. However, we did not observe a disruption of the representation of the agent's belief. Rather, the stimulation interfered with participant's predictions, supporting the idea that rTPJ is crucially involved in self-other distinction.

Mimicry and automatic imitation are not correlated.

It is widely known that individuals have a tendency to imitate each other. However, different psychological disciplines assess imitation in different manners. While social psychologists assess mimicry by means of action observation, cognitive psychologists assess automatic imitation with reaction time based measures on a trial-by-trial basis. Although these methods differ in crucial methodological aspects, both phenomena are assumed to rely on similar underlying mechanisms. This raises the fundamental question whether mimicry and automatic imitation are actually correlated. In the present research we assessed both phenomena and did not find a meaningful correlation. Moreover, personality traits such as empathy, autism traits, and traits related to self- versus other-focus did not correlate with mimicry or automatic imitation either. Theoretical implications are discussed.

Transcranial direct current stimulation (tDCS) reveals a dissociation between SNARC and MARC effects: Implication for the polarity correspondence account.

The concept of stimulus response compatibility (SRC) refers to the existence of a privileged association between a specific stimulus feature and a specific response feature. Two examples of SRC are the Spatial Numerical Association of Response Codes (SNARC) and the Markedness Association of Response Codes (MARC) effects. According to the polarity correspondence principle, these two SRC effects occur because of a match between the most salient dimensions of stimulus and response. Specifically, the SNARC effect would be caused by a match between right-sided responses and large numbers, while a match between right-sided responses and even numbers would give rise to the MARC effect. The aim of the present study was to test the validity of the polarity correspondence principle in explaining these two SRC effects. To this end, we applied transcranial direct current stimulation (tDCS) over left and right posterior parietal cortex (PPC), which is thought to be the neural basis of salience processing, during a parity judgement task. Results showed that cathodal tDCS over the PPC significantly reduced the MARC effect but did not affect the SNARC effect, suggesting a dissociation between the two effects. That is, the MARC would rely on a salience processing mechanism, whereas the SNARC would not. Despite this interpretation is in need of further experimental confirmations (i.e., testing different tasks or using different tDCS montages), our results suggest that the polarity correspondence principle can be a plausible explanation only for the MARC effect but not for the SNARC effect.

Brain activation for spontaneous and explicit false belief tasks overlaps: new fMRI evidence on belief processing and violation of expectation.

There is extensive discussion on whether spontaneous and explicit forms of ToM are based on the same cognitive/neural mechanisms or rather reflect qualitatively different processes. For the first time, we analyzed the BOLD signal for false belief processing by directly comparing spontaneous and explicit ToM task versions. In both versions, participants watched videos of a scene including an agent who acquires a true or false belief about the location of an object (belief formation phase). At the end of the movies (outcome phase), participants had to react to the presence of the object. During the belief formation phase, greater activity was found for false vs true belief trials in the right posterior parietal cortex. The ROI analysis of the right temporo-parietal junction (TPJ), confirmed this observation. Moreover, the anterior medial prefrontal cortex (aMPFC) was active during the outcome phase, being sensitive to violation of both the participant's and agent's expectations about the location of the object. Activity in the TPJ and aMPFC was not modulated by the spontaneous/explicit task. Overall, these data show that neural mechanisms for spontaneous and explicit ToM overlap. Interestingly, a dissociation between TPJ and aMPFC for belief tracking and outcome evaluation, respectively, was also found.

Transcranial direct current stimulation (tDCS) of the inferior frontal cortex affects the "social scaling" of extrapersonal space depending on perspective-taking ability.

When we have to judge the distance between another person and an object (social condition), we judge this distance as being smaller compared to judging the distance between two objects (nonsocial condition). It has been suggested that this compression is mediated by the attribution of a motor potential to the reference frame (other person vs. object). In order to explore the neural basis of this effect, we investigated whether the modulation of activity in the inferior frontal cortex (IFC) of the left hemisphere (recruited during visuospatial processes with a social component) changes the way we categorize space in a social compared with a nonsocial condition. We applied transcranial direct current stimulation to the left IFC, with different polarities (anodal, cathodal, and sham) while subjects performed an extrapersonal space categorization task. Interestingly, anodal stimulation of IFC induced an higher compression of space in the social compared to nonsocial condition. By contrast, cathodal stimulation induced the opposite effect. Furthermore, we found that this effect is modulated by interindividual differences in cognitive perspective taking. Our data support the idea that IFC is recruited during the social categorization of space.

TPJ-M1 interaction in the control of shared representations: New insights from tDCS and TMS combined.

There is extensive evidence that perceived and internally planned actions have a common representational basis: action observation can induce an automatic tendency to imitate others. If perceived and executed action, however, are based on shared representations, the question arises how we can distinguish self-related and other-related representations. It has been suggested that the control of shared representations involves a neural network centered on the temporo-parietal junction (TPJ). However, the specific role of the TPJ in controlling shared representations is still not clear. In a conflict situation where participants have to execute action A while observing action B, the TPJ might either facilitate the relevant action A or inhibit the irrelevant action B (mirror response). In the present study, we used transcranial Direct Current Stimulation (tDCS) to condition neural activity in the right temporo-parietal junction (TPJ). We then analyzed the corticospinal output as indexed by motor-evoked potentials (MEPs) induced by single-pulse TMS (spTMS) of the left primary motor cortex (M1) during action observation in the context of a conflict task. Results showed that tDCS-mediated increased control did not entail the attenuation of the task-irrelevant response activation: the effect of motor mirroring was not suppressed or reduced. Rather, facilitating TPJ activity via anodal tDCS selectively enhanced the instructed motor plan (self-related representation). This outcome supports the idea that TPJ plays a critical role in detecting the mismatch between self-related and other-related representations and is at work to enhance task-relevant representations.