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There is some evidence that disordered self-processing in autism spectrum disorders is linked to the social impairments characteristic of the condition. To investigate whether bodily self-consciousness is altered in autism spectrum disorders as a result of multisensory processing differences, we tested responses to the full body illusion and measured peripersonal space in 22 adults with autism spectrum disorders and 29 neurotypical adults. In the full body illusion set-up, participants wore a head-mounted display showing a view of their 'virtual body' being stroked synchronously or asynchronously with respect to felt stroking on their back. After stroking, we measured the drift in perceived self-location and self-identification with the virtual body. To assess the peripersonal space boundary we employed an audiotactile reaction time task. The results showed that participants with autism spectrum disorders are markedly less susceptible to the full body illusion, not demonstrating the illusory self-identification and self-location drift. Strength of self-identification was negatively correlated with severity of autistic traits and contributed positively to empathy scores. The results also demonstrated a significantly smaller peripersonal space, with a sharper (steeper) boundary, in autism spectrum disorders participants. These results suggest that bodily self-consciousness is altered in participants with autism spectrum disorders due to differences in multisensory integration, and this may be linked to deficits in social functioning.

Efficient inhibitory control in the context of prepotent actions is vital. However, such action inhibition may be profoundly influenced by affective states. Interestingly, research indicates that action control can be either impaired or improved by emotional stimuli. Thus, a great deal of confusion surrounds our knowledge of the complex dynamics subtending emotions and action control. Here, we aimed to investigate whether negative stimuli, even when non-consciously presented and task-irrelevant, can affect action control relative to neutral stimuli. Additionally, we tested whether individual differences in intracortical excitability may predict action control capabilities. To address these issues, we asked participants to complete a modified version of the Stop Signal Task (SST) in which fearful or neutral stimuli were subliminally presented before the go signals as primes. Moreover, we assessed participants' resting-state corticospinal excitability, short intracortical inhibition (SICI), and intracortical facilitation (ICF). Results demonstrated better action control capabilities when fearful stimuli were subliminally presented and interindividual SICI predicted stronger action inhibition capabilities. Taken together, these results shed new light on the intricate dynamics between action, consciousness, and motor control, suggesting that intracortical measures can be used as potential biomarkers of reduced motor inhibition in research and clinical settings. [ABSTRACT FROM AUTHOR]

Joint action (JA) is a continuous process of motor co‐regulation based on the integration of contextual (top‐down) and kinematic (bottom‐up) cues from partners. The fine equilibrium between excitation and inhibition in sensorimotor circuits is, thus, central to such a dynamic process of action selection and execution. In a bimanual task adapted to become a unimanual JA task, the participant held a bottle (JA), while a confederate had to reach and unscrew either that bottle or another stabilized by a mechanical clamp (No_JA). Prior knowledge was manipulated in each trial such that the participant knew (K) or not (No_K) the target bottle in advance. Online transcranial magnetic stimulation (TMS) was administered at action‐relevant landmarks to explore corticospinal excitability (CSE) and inhibition (cortical silent period [cSP]). CSE was modulated early on before the action started if prior information was available. In contrast, cSP modulation emerged later during the reaching action, regardless of prior information. These two indexes could thus reflect the concurrent elaboration of contextual priors (top‐down) and the online sampling of partner's kinematic cues (bottom‐up). Furthermore, participants selected either one of two possible behavioural strategies, preferring early or late force exertion on the bottle. One translates into a reduced risk of motor coordination failure and the other into reduced metabolic expenditure. Each strategy was characterised by a specific excitatory/inhibitory profile. In conclusion, the study of excitatory/inhibitory balance paves the way for the neurophysiological determination of individual differences in the combination of top‐down and bottom‐up processing during JA coordination. [ABSTRACT FROM AUTHOR]

Communicative gaze (e.g., mutual or averted) has been shown to affect attentional orienting. However, no study to date has clearly separated the neural basis of the pure social component that modulates attentional orienting in response to communicative gaze from other processes that might be a combination of attentional and social effects. We used TMS to isolate the purely social effects of communicative gaze on attentional orienting. Participants completed a gaze-cueing task with a humanoid robot who engaged either in mutual or in averted gaze before shifting its gaze. Before the task, participants received either sham stimulation (baseline), stimulation of right TPJ (rTPJ), or dorsomedial prefrontal cortex (dmPFC). Results showed, as expected, that communicative gaze affected attentional orienting in baseline condition. This effect was not evident for rTPJ stimulation. Interestingly, stimulation to rTPJ also canceled out attentional orienting altogether. On the other hand, dmPFC stimulation eliminated the socially driven difference in attention orienting between the two gaze conditions while maintaining the basic general attentional orienting effect. Thus, our results allowed for separation of the pure social effect of communicative gaze on attentional orienting from other processes that are a combination of social and generic attentional components. [ABSTRACT FROM AUTHOR]

The functional connection between ventral premotor cortex (PMv) and primary motor cortex (M1) is critical for the organization of goal‐directed actions. Repeated activation of this connection by means of cortico‐cortical paired associative stimulation (cc‐PAS), a transcranial magnetic stimulation (TMS) protocol, may induce Hebbian‐like plasticity. However, the physiological modifications produced by Hebbian‐like plasticity in the PMv‐M1 network are poorly understood. To fill this gap, we investigated the effects of cc‐PAS on PMv‐M1 circuits. We hypothesized that specific interactions would occur with I2‐wave interneurons as measured by the short intracortical facilitation protocol (SICF). We used different paired‐pulse TMS protocols to examine the effects of PMv‐M1 cc‐PAS on SICF, on GABAergic circuits as measured by short (SICI) and long (LICI) intracortical inhibition protocols, and varied the current direction in M1 to target different M1 neuronal populations. Finally, we examined the effects of cc‐PAS on PMv‐M1 connectivity using a dual coil approach. We found that PMv‐M1 cc‐PAS induces both a long‐term potentiation (LTP)‐ or long‐term depression (LTD)‐like after‐effect in M1 neuronal activity that is strongly associated with a bidirectional‐specific change in I2‐wave activity (SICF = 2.5 ms ISI). Moreover, cc‐PAS induces a specific modulation of the LICI circuit and separately modulates PMv‐M1 connectivity. We suggest that plasticity within the PMv‐M1 circuit is mediated by a selective mechanism exerted by PMv on M1 by targeting I2‐wave interneurons. These results provide new mechanistic insights into how PMv modulates M1 activity that are relevant for the design of brain stimulation protocols in health and disease. Key points: The I2‐wave is specifically modulated by the induction of ventral premotor cortex – primary motor cortex (PMv‐M1) plasticity.After PMv‐M1 cortico‐cortical paired associative stimulation (cc‐PAS), corticospinal excitability correlates negatively with I2‐wave amplitude.Different cc‐PAS coil orientations can lead to a long‐term potentiation‐ or long‐term depression‐like after‐effect in M1. [ABSTRACT FROM AUTHOR]

Emotions are able to impact our ability to control our behaviors. However, it is not clear whether emotions play a detrimental or an advantageous effect on action control and whether the valence of the emotional stimuli differently affects such motor abilities. One way to measure reactive inhibitory control is the stop-signal task (SST), which estimates the ability to cancel outright a response to the presentation of a stop signal by means of the stop signal reaction times (SSRT). Impaired as well as facilitated action control has been found when faced with emotional stimuli such as stop signals in SSTs and mixed results were observed for positive versus negative stimuli. Here, we aimed to investigate these unresolved issues more deeply. Action control capabilities were tested in 60 participants by means of a SST, in which the stop signals were represented by a fearful and a happy body posture together with their neutral counterpart. Results showed that both positive and negative body postures enhanced the ability to suppress an ongoing action compared to neutral body postures. These results demonstrate that emotional valence-independent emotional stimuli facilitate action control and suggest that emotional stimuli may trigger increased sensory representation and/or attentional processing that may have promote stop-signal processing and hence improved inhibitory performance. [ABSTRACT FROM AUTHOR]

Since the dawn of cognitive neuroscience, emotions have been recognized to impact on several executive processes, such as action inhibition. However, the complex interplay between emotional stimuli and action control is not yet fully understood. One way to measure inhibitory control is the stop-signal task (SST), which estimates the ability to cancel outright an action to the presentation of a stop signal by means of the stop- signal reaction times (SSRTs). Impaired as well as facilitated action control has been found when faced with intrinsic emotional stimuli as stop signals in SSTs. Here, we aimed at investigating more deeply the power of negative stimuli to influence our action control, testing the hypothesis that a previously neutral stimulus [i.e., the image of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)], which has been conditioned through vicarious fear learning, has the same impact on reactive action inhibition performance as an intrinsically negative stimulus (i.e., a fearful face or body). Action control capabilities were tested in 90 participants by means of a SST, in which the stop signals were represented by different negative stimuli. Results showed that the SARS-CoV-2 image enhanced the ability to suppress an ongoing action similarly to observing fearful facial expressions or fearful body postures. Interestingly, we found that this effect was predicted by impulsivity traits: for example, the less self-control the participants had, the less they showed emotional facilitation for inhibitory performance. These results demonstrated that vicarious fear learning has a critical impact on cognitive abilities, making a neutral image as threatening as phylogenetically innate negative stimuli and able to impact on our behavioral control. [ABSTRACT FROM AUTHOR]

Modulation of cortical beta rhythm (15–30 Hz) is present during preparation for and execution of voluntary movements as well as during somatosensory stimulation. A rebound in beta synchronization is observed after the end of voluntary movements as well as after somatosensory stimulation and is believed to describe the return to baseline of sensorimotor networks. However, the contribution of efferent and afferent signals to the beta rebound remains poorly understood. Here, we applied electrical median nerve stimulation (MNS) to the right side followed by transcranial magnetic stimulation (TMS) on the left primary motor cortex after either 15 or 25 ms. Because the afferent volley reaches the somatosensory cortex after about 20 ms, TMS on the motor cortex was either anticipating or following the cortical arrival of the peripheral stimulus. We show modulations in different beta sub-bands and in both hemispheres, following a pattern of greater resynchronization when motor signals are paired with a peripheral one. The beta rebound in the left hemisphere (stimulated) is modulated in its lower frequency range when TMS precedes the cortical arrival of the afferent volley. In the right hemisphere (unstimulated), instead, the increase is limited to higher beta frequencies when TMS is delivered after the arrival of the afferent signal. In general, we demonstrate that the temporal integration of afferent and efferent signals plays a key role in the genesis of the beta rebound and that these signals may be carried in parallel by different beta sub-bands. [ABSTRACT FROM AUTHOR]