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•Transcutaneous Vagus Nerve Stimulation (tVNS) may boost GABAergic neurotransmission.•We assessed tVNS effects on intracortical inhibition and visuomotor learning.•tVNS enhanced GABAa- but not GABAb-mediated cortical inhibition.•tVNS boosted motor learning during a visuomotor task.•tVNS effects varied by sex and motor cortex laterality. Transcutaneous Vagus Nerve stimulation (tVNS) has been proposed as a treatment for refining GABAergic transmission. While the effects of tVNS on behavioral performance in inhibitory control tasks have been already demonstrated, neurophysiological studies investigating its effects on GABA-mediated inhibition in the motor cortex provided contrasting findings. Concurrently, the influence of participants’ sex and state conditions remains unexplored. Here we applied single- and paired-pulse TMS to the right or left primary motor cortex in two groups of participants. We measured corticospinal excitability (CSE), short and long intracortical inhibition (SICI and LICI), cortical silent period (cSP) and intracortical facilitation (ICF) indexes. These measures were taken, in a within-subject design, at a baseline session before tVNS and after delivering active or sham tVNS in the Cymba conchae of the left ear. To exploit state-dependent effects and assess the role of tVNS in motor learning, tVNS was applied during the execution of a computerized visuomotor task. In the left TMS group, we observed that the visuomotor performance improved across task blocks during active tVNS only, regardless of participant’s sex. Interestingly, in both groups, we found a specific increase of SICI, a proxy of GABAa activity, after active versus sham-tVNS and baseline evaluations, which was specifically limited to female participants. No effects on CSE, ICF or GABAb-mediated intracortical inhibition indexes were observed. The results show specific effects of tVNS on motor learning and GABAa-mediated motor inhibition, providing supportive evidence for the application of tVNS as a coadjuvant treatment for disorders with altered inhibition mechanisms.

Using a combination of behavioral measures and transcranial magnetic stimulation (TMS), this study finds that elite basketball players are better at predicting whether a free basketball throw will land in the basket or out and that they also have higher TMS-evoked motor potentials for when the ball misses its mark. We combined psychophysical and transcranial magnetic stimulation studies to investigate the dynamics of action anticipation and its underlying neural correlates in professional basketball players. Athletes predicted the success of free shots at a basket earlier and more accurately than did individuals with comparable visual experience (coaches or sports journalists) and novices. Moreover, performance between athletes and the other groups differed before the ball was seen to leave the model's hands, suggesting that athletes predicted the basket shot's fate by reading the body kinematics. Both visuo-motor and visual experts showed a selective increase of motor-evoked potentials during observation of basket shots. However, only athletes showed a time-specific motor activation during observation of erroneous basket throws. Results suggest that achieving excellence in sports may be related to the fine-tuning of specific anticipatory 'resonance' mechanisms that endow elite athletes' brains with the ability to predict others' actions ahead of their realization.

•IGF-tuned cerebellar tACS enhances visuomotor precision.•tACS reduces cortical silent period, indexing GABAB-mediated disinhibition.•Theta power increases post-tACS, suggesting cross-frequency modulation. The cerebellum plays a key role in motor control, yet its oscillatory dynamics remain poorly understood due to anatomical and methodological constraints. Transcranial alternating current stimulation (tACS) has emerged as a promising tool to modulate cerebellar activity, particularly when tailored to individual neural oscillations. This study examined the effects of EEG-guided gamma-frequency cerebellar tACS—matched to each participant’s individual gamma frequency (IGF)—on motor performance and neurophysiological markers in healthy adults. Forty-four male and female participants completed a visuomotor task while undergoing either real or sham tACS across two sessions. Critically, EEG activity was recorded before and immediately after the stimulation while participants performed the visuomotor task to assess electrophysiological changes in power spectrum density. Measures of corticospinal excitability and inhibition were collected via transcranial magnetic stimulation (TMS) protocols following each stimulation session. tACS at IGF enhanced motor precision during challenging task conditions and reduced corticospinal inhibition, without affecting corticospinal excitability. EEG analyses revealed IGF-dependent increases in theta-band power post-stimulation in motor regions, suggesting cross-frequency interactions. These findings highlight the potential of personalized cerebellar tACS to enhance motor performance and modulate inhibitory cortical dynamics, supporting its use as a precision neuromodulation tool in both research and clinical settings.

Several neurophysiologic and neuroimaging studies suggested that motor and perceptual systems are tightly linked along a continuum rather than providing segregated mechanisms supporting different functions. Using correlational approaches, these studies demonstrated that action observation activates not only visual but also motor brain regions. On the other hand, brain stimulation and brain lesion evidence allows tackling the critical question of whether our action representations are necessary to perceive and understand others' actions. In particular, recent neuropsychological studies have shown that patients with temporal, parietal, and frontal lesions exhibit a number of possible deficits in the visual perception and the understanding of others' actions. The specific anatomical substrates of such neuropsychological deficits however, are still a matter of debate. Here we review the existing literature on this issue and perform an anatomic likelihood estimation meta-analysis of studies using lesion-symptom mapping methods on the causal relation between brain lesions and non-linguistic action perception and understanding deficits. The meta-analysis encompassed data from 361 patients tested in 11 studies and identified regions in the inferior frontal cortex, the inferior parietal cortex and the middle/superior temporal cortex, whose damage is consistently associated with poor performance in action perception and understanding tasks across studies. Interestingly, these areas correspond to the three nodes of the action observation network that are strongly activated in response to visual action perception in neuroimaging research and that have been targeted in previous brain stimulation studies. Thus, brain lesion mapping research provides converging causal evidence that premotor, parietal and temporal regions play a crucial role in action recognition and understanding.

·Contextual and kinematic information is continuously integrated during action observation.·Motor resonance is modulated by contextual expectations independently from the reliability of kinematic information.·Subclinical autistic traits are correlated with the contextual effects on motor resonance. Contextual information may shape motor resonance and support intention understanding during observation of incomplete, ambiguous actions. It is unclear, however, whether this effect is contingent upon kinematics ambiguity or contextual information is continuously integrated with kinematics to predict the overarching action intention. Moreover, a differentiation between the motor mapping of the intention suggested by context or kinematics has not been clearly demonstrated. In a first action execution phase, 29 participants were asked to perform reaching-to-grasp movements towards big or small food objects with the intention to eat or to move; electromyography from the First Dorsal Interosseous (FDI) and Abductor Digiti Minimi (ADM) was recorded. Depending on object size, the intentions to eat or to move were differently implemented by a whole-hand or a precision grip kinematics, thus qualifying an action-muscle dissociation. Then, in a following action prediction task, the same participants were asked to observe an actor performing the same actions and to predict his/her intention while motor resonance was assessed for the same muscles. Of note, videos were interrupted at early or late action phases, and actions were embedded in contexts pointing toward an eating or a moving intention, congruently or incongruently with kinematics. We found greater involvement of the FDI or ADM in the execution of precision or whole-hand grips, respectively. Crucially, this pattern of activation was mirrored during observation of the same actions in congruent contexts, but it was cancelled out or reversed in the incongruent ones, either when videos were interrupted at either early or long phases of action deployment. Our results extend previous evidence by showing that contextual information shapes motor resonance not only under conditions of perceptual uncertainty but also when more informative kinematics is available.

•Judgments of body emotions are slowed down by irrelevant variation of body sex.•This interference may arise due to bottom-up or top-down visual processing.•Forward ccPAS stimulation from V1 to EBA eliminates the interference.•Interference depends on attention capture of shared stimulus features. We effortlessly categorise other people along socially relevant categories such as sex, age, and emotion. A core question in social vision relates to whether we perceive these categories independently or in relation to each other. Here, we investigated categorisation of sex and emotion from the body, finding that participants generally fail to fully ignore task-irrelevant variations of sex while judging body emotional expressions. In contrast, sex categorisation was unaffected by variations in emotional expression. This asymmetric interaction between sex and emotion may arise because of bottom-up visual processing, due to partially shared visual features used for both judgments, or because of top-down, categorical associations between sex and emotion categories. To disentangle these possibilities, we used cortico-cortical paired associative stimulation (ccPAS) to modulate the connectivity between primary visual cortex and the extrastriate body area. We posited that boosting forward connectivity between these regions would increase efficiency of feature-based processing, while boosting feedback connectivity would enhance the separability of semantic categories related to sex and emotion. We found that boosting forward connectivity eliminated the interference of sex on emotion judgments, while that interference remained unaffected with modulation of feedback connectivity. These findings suggest that interactions between sex and emotion in body perception emerge during the perceptual analysis of the stimuli, and add to our understanding of person perception and social categorization.

•Motor and visuospatial functions are predictors of social skills in IDD children.•Deviation from typical development of cortical thickness might impair cognition.•Fronto-parietal areas impact social skills via attention and visuospatial abilities.•Early visuospatial rehabilitation may improve social skills in IDD. Different theoretical perspectives emphasize the significance of sensorimotor and visuospatial functions in shaping social perception, including theory of mind (ToM) and affect recognition (AR) abilities. This study aimed to investigate where in the brain cortical thickness (CT) predicts social perception, and which cognitive functions mediate such relationship. To these aims, we used a hierarchical analytical plan: Step 1 identified brain areas’ CT that correlate with cognitive measures; Step 2 used stepwise regression to predict social perception outcomes (ToM and AR) from brain areas’ CT; Step 3 assessed whether cognitive measures mediate the link between CT and social perception outcomes. The results showed that the CT of the left inferior frontal gyrus (IFG; pars triangularis) predicted both ToM and AR, while the CT of the right superior parietal gyrus (SPL) and of the right anterior occipital sulcus (AOcs) predicted only AR. Mediation models unveiled that visuo-constructive abilities and visual attention mediated the relationship between CT in these areas and social perception outcomes. These findings align with the role of the IFG in mentalizing abilities and underscore the involvement of SPL in visuospatial functions, including mental object rotation and spatial perspective-taking, which are essential for advanced social skills; the role of the AOcs in face processing was also highlighted. Importantly, the findings suggest that fronto-parietal areas are indirectly involved in social perception thorough their involvement in visuo-constructive abilities and visual attention.

Unmyelinated C-Tactile (CT) fibres are activated by caress-like touch, eliciting a pleasant feeling that decreases for static and faster stroking. Previous studies documented this effect also for vicarious touch, hypothesising simulation mechanisms driving the perception and appreciation of observed interpersonal touch. Notably, less is known about appreciation of vicarious execution of touch, that is as referred to the one giving gentle touch. To address this issue, 53 healthy participants were asked to view and rate a series of videoclips displaying an individual being touched by another on hairy (i.e., hand dorsum) or glabrous (i.e., palm) skin sites, with touch being delivered at CT-optimal (5 cm/s) or non-CT optimal velocities (0 cm/s or 30 cm/s). Following the observation of each clip, participants were asked to rate self-referred desirability and model-referred pleasantness of vicarious touch for both executer (toucher-referred) and receiver (touchee-referred). Consistent with the CT fibres properties, for both self-referred desirability and model-referred pleasantness judgements of vicarious touch execution and reception, participants provided higher ratings for vicarious touch delivered at CT-optimal than other velocities, and when observed CT-optimal touch was delivered to the hand-dorsum compared to the palm. However, higher ratings were attributed to vicarious reception compared to execution of CT-optimal touch. Notably, individual differences in interoceptive trusting and attitude to interpersonal touch were positively correlated with, respectively, toucher- and touchee-related overall appraisal ratings of touch. These findings suggest that the appreciation of both toucher- and touchee-referred vicarious touch is specifically attuned to CT-optimal touch, even though they might rely on different neurocognitive mechanisms to understand affective information conveyed by interpersonal tactile interactions.

Despite the fact that ageing causes dramatic changes in bodily appearance, little is known about how self-body recognition changes across life span. Here, we investigated whether older, compared to younger women, differed in the ability of recognising their own than other women’s body parts and whether this effect was associated to negative body image dispositions. Twenty-eight young (Mage: 25.93 years, SDage = 4.74) and 25 middle-aged (Mage: 54.36 years, SDage = 4.54) women completed an implicit task consisting of visual matching of self and others’ body parts and an explicit self–other body discrimination task. Stimuli comprised of images of body parts of the participant and of other age- and BMI-matched models, which were presented in the original size or modified to look rounder or thinner. Measures of adiposity (i.e. BMI), body image concerns and appearance-related worries for specific body parts and for the whole body were also collected. Whilst both groups showed a self-body advantage in the implicit, but not in the explicit task, the advantage was notably bigger for the younger group. However, the implicit self-advantage was higher in those middle-aged women that displayed more body image concerns and worries for specific body parts. Furthermore, the two groups were comparably less able in recognising their body parts when presented thinner as compared to rounder or in their actual size. Overall, these findings open the possibility that, as women age, their implicit self-recognition abilities may decline in association with more negative body image dispositions.

Congenital or acquired cerebellum alterations are associated with a complex pattern of motor, cognitive and social disorders. These disturbances may reflect the involvement of the cerebellum in generating and updating the internal models that sub-serve-the prediction of sensory events. Here, we tested whether the cerebellar involvement in using contextual expectations to interpret ambiguous sensory sceneries is specific for social actions or also extends to physical events. We applied anodic, cathodic and sham cerebellar transcranial Direct Current Stimulation (ctDCS) to modulate the performance of an adult sample in two tasks requiring the prediction of social actions or moving shapes. For both tasks, in an earlier implicit-learning phase (familiarization), we manipulated the probability of co-occurrence between a particular action/shape and contextual elements, which could provide either strongly or moderately informative expectations. The use of these expectations was then tested when participants had to predict the unfolding of temporally occluded videos, in situations of perceptual uncertainty (testing). Results showed that in the testing, but not in the familiarization phase, cathodic as compared to anodic and sham ctDCS hindered participants’ sensitivity in predicting actions embedded in strongly, but not moderately, informative contexts. Conversely, anodic as compared to sham ctDCS boosted the prediction of actions embedded in moderately, but not strongly, informative contexts. We observed no ctDCS effects for the shape prediction task, thus pointing to a specific involvement of the cerebellum in forming expectations related to social events. Our results encourage the exploration of rehabilitative effects of ctDCS in patients with social perception deficits.