Social cognition abilities in patients with primary and secondary chronic pain.

Previous evidence suggested that chronic pain is characterized by cognitive deficits, particularly in the social cognition domain. Recently, a new chronic pain classification has been proposed distinguishing chronic primary pain (CPP), in which pain is the primary cause of patients' disease, and chronic secondary pain (CSP), in which pain is secondary to an underlying illness. The present study aimed at investigating social cognition profiles in the two disorders. We included 38 CPP, 43 CSP patients, and 41 healthy controls (HC). Social cognition was assessed with the Ekman-60 faces test (Ekman-60F) and the Story-Based Empathy Task (SET), whereas global cognitive functioning was measured with the Montreal Cognitive Assessment (MoCA). Pain and mood symptoms, coping strategies, and alexithymia were also evaluated. Correlations among clinical pain-related measures, cognitive performance, and psychopathological features were investigated. Results suggested that CSP patients were impaired compared to CPP and HC in social cognition abilities, while CPP and HC performance was not statistically different. Pain intensity and illness duration did not correlate with cognitive performance or psychopathological measures. These findings confirmed the presence of social cognition deficits in chronic pain patients, suggesting for the first time that such impairment mainly affects CSP patients, but not CPP. We also highlighted the importance of measuring global cognitive functioning when targeting chronic pain disorders. Future research should further investigate the cognitive and psychopathological profile of CPP and CSP patients to clarify whether present findings can be generalized as disorder characteristics.

Top-down reconfiguration of SMA cortical connectivity during action preparation.

The Bereitschaftspotential (BP), a scalp potential recorded in humans during action preparation, is characterized by a slow amplitude increase over fronto-central regions as action execution approaches. We recorded TMS evoked-potentials (TEP) stimulating the supplementary motor area (SMA) at different time-points during a Go/No-Go task to assess whether and how cortical excitability and connectivity of this region change as the BP increases. When approaching BP peak, left SMA reactivity resulted greater. Concurrently, its effective connectivity increased with the left occipital areas, while it decreased with the right inferior frontal gyrus, indicating a fast reconfiguration of cortical networks during the preparation of the forthcoming action. Functional connectivity patterns supported these findings, suggesting a critical role of frequency-specific inter-areal interactions in implementing top-down mechanisms in the sensorimotor system prior to action. These findings reveal that BP time-course reflects quantitative and qualitative changes in SMA communication patterns that shape mechanisms involved in motor readiness.

The role of the right posterior parietal cortex in prism adaptation and its aftereffects.

Adaptation to optical prisms (Prismatic Adaptation, PA) displacing the visual scene laterally, on one side of visual space, is both a procedure for investigating visuo-motor plasticity and a powerful tool for the rehabilitation of Unilateral Spatial Neglect (USN). Two processes are involved in PA: i) recalibration (the reduction of the error of manual pointings toward the direction of the prism-induced displacement of the visual scene); ii) the successive realignment after prisms' removal, indexed by the Aftereffects (AEs, in egocentric straight-ahead pointing tasks, the deviation in a direction opposite to the visual displacement previously induced by prisms). This study investigated the role of the posterior parietal cortex (PPC) of the right hemisphere in PA and AEs, by means of low frequency repetitive Transcranial Magnetic Stimulation (rTMS). Proprioceptive and Visuo-proprioceptive egocentric straight-ahead pointing tasks were used to assess the presence and magnitude of AEs. The primary right visual cortex (V1) was also stimulated, to assess the selectivity of the PPC effects on the two processes of PA (recalibration and realignment) in comparison with a cortical region involved in visual processing. Results showed a slower adaptation to prisms when rTMS was delivered before PA, regardless of target site (right PPC or V1). AEs were reduced only by PPC rTMS applied before or after PA, as compared to a sham stimulation. These findings suggest a functional and neural dissociation between realignment and recalibration. Indeed, PA interference was induced by rTMS to both the PPC and V1, indicating that recalibration is supported by a parieto-occipital network. Conversely, AEs were disrupted only by rTMS delivered to the PPC, thus unveiling a relevant role of this region in the development and maintenance of the realignment.

The Role of the Left and Right Anterior Temporal Poles in People Naming and Recognition.

People's identity recognition and the neural correlates underlying this process are still a matter of debate. While neuropsychological reports on single cases show a crucial role of the left anterior temporal lobe (ATL) in proper naming, and of the right ATL in people's identification, reviews are less consistent. Moreover, it is still controversial whether familiarity and personal semantics access rely on amodal processes or follow modality-dependent paths. To disentangle these issues, we tested, in a parallel-group design, neurologically unimpaired subjects in two famous people recognition tasks after anodal tDCS over the left or right ATL or after a placebo stimulation condition. In the famous people recognition task, subjects were presented with visual (face recognition) or auditory (voice recognition) stimuli and subjects had to judge whether stimuli belonged to a famous or non-famous person (familiarity test); then, if the stimulus was recognized as famous, participants had to provide personal semantic information about the character; finally, to investigate proper naming, subjects were asked to name the famous person. While right ATL anodal tDCS increased accuracy in famous faces (but not voices) judgment and personal semantics retrieval, left ATL stimulation increased proper naming for both visual and auditory stimuli. Our data support a key role of the right ATL in famous people recognition and access to personal semantics from visual inputs, while the left ATL seems crucial for proper naming, which seems to occur at a later stage, when presentation modality no longer affects the process.

The role of ventromedial prefrontal cortex and temporo-parietal junction in third-party punishment behavior.

Third parties punish, sacrificing personal interests, offenders who violate either fairness or cooperation norms. This behavior is defined altruistic punishment and the degree of punishment typically increases with the severity of the norm violation. An opposite and apparently paradoxical behavior, namely anti-social punishment, is the tendency to spend own money to punish cooperative or fair behaviors. Previous fMRI studies correlated punishment behavior with increased activation of brain areas belonging to the reward system (e.g. the ventromedial prefrontal cortex, VMPFC), the mentalizing (e.g. the temporoparietal junction, TPJ) and central-executive networks. In the present study, we aimed at investigating the causal role of VMPFC and TPJ in punishment behaviors through the application of anodal transcranial direct current stimulation (tDCS). Sixty healthy participants were randomly assigned to three tDCS conditions: (1) anodal tDCS over VMPFC, (2) anodal tDCS over right TPJ (rTPJ), (3) sham stimulation. At the end of the stimulation, participants played a third-party punishment game, consisting in viewing a series of fair or unfair monetary allocations between unknown proposers and recipients. Participants were asked whether and how much they would punish the proposers using their own monetary endowment. To test membership effects, proposers and recipients could be either Italian or Chinese. Anodal tDCS over VMPFC increased altruistic punishment behavior whereas anodal tDCS over rTPJ increased anti-social punishment choices compared with sham condition, while membership did not influence participant's choices. Our results support the idea that the two types of punishment behaviors rely upon different brain regions, suggesting that reward and mentalizing systems underlie, respectively, altruistic and anti-social punishment behaviors.

Can Monetary Reward Modulate Social Attention?

Selective visual attention is a primary cognitive function, which allows the selection of the most relevant stimuli in the environment by prioritizing their processing. Several studies showed that this process can be influenced by both social signals, such as gaze direction (i.e., the Gaze Cueing Effect, GCE) and by the motivational valence of gratifying stimuli, such as monetary rewards. The aim of this study was to explore whether GCE could be modulated by a monetary reward. To this end, we created an experiment in which participants performed a gaze cuing task before and after an implicit learning task aiming to induce an association between gaze direction and monetary reward (experimental condition), or after a perceptual task (control condition). Statistical analyses were conducted following both a frequentist and a Bayesian approach. Results supported previous findings showing the presence of the GCE, i.e., faster responses in congruent trials when the target appeared in the gazed-at location. Interestingly, our results did not reveal significant differences among the conditions. Therefore, contrary to what was reported by previous attentional orienting studies with non-social stimuli, monetary reward does not seem to be able to modulate (or interfere with) the orienting of attention mediated by gaze direction as measured by the GCE. Taken together our results suggest that social signals such as gaze direction have a greater impact than monetary reward in orienting selective attention.

Cortical dynamics underpinning the self-other distinction of touch: A TMS-EEG study.

Touch supports processes crucial to human social behaviour, adding a bodily dimension to the perception and understanding of others' feelings. Mirror cortical activity was proposed to underpin the interpersonal sharing of touch, allowing an automatic and unconscious simulation of others' somatic states. However, recent evidence questioned the existence of a tactile shared representation in the primary somatosensory cortex (S1), and the neural correlates of self-other distinction in the somatosensory system remains unknown. We address these issues by exploring S1 reactivity, and the associated neural network oscillations and connectivity, to self and others' touch. Transcranial Magnetic Stimulation combined with Electroencephalography (TMS-EEG) recordings were performed during tactile perception and observation, looking for differences in cortical activation and connectivity between felt and seen touch. The sight of a touch directed to a human body part, but not to an object, triggered an early activation of S1 as a felt touch did, which, in both conditions, propagated to fronto-parietal regions. Critically, touch perception and observation shared an effective connectivity network generated in the beta band, which is typically associated to unconscious tactile processing. Conversely, alpha band connectivity, a marker of conscious tactile processing, was detected only for real tactile stimulation. Alpha connectivity within a fronto-parietal pathway seems to underpin the ability to distinguish self and others' somatosensory states, controlling and distinguishing shared tactile representations in S1.

Stimulating Self-Regulation: A Review of Non-invasive Brain Stimulation Studies of Goal-Directed Behavior.

Self-regulation enables individuals to guide their thoughts, feelings, and behaviors in a purposeful manner. Self-regulation is thus crucial for goal-directed behavior and contributes to many consequential outcomes in life including physical health, psychological well-being, ethical decision making, and strong interpersonal relationships. Neuroscientific research has revealed that the prefrontal cortex plays a central role in self-regulation, specifically by exerting top-down control over subcortical regions involved in reward (e.g., striatum) and emotion (e.g., amygdala). To orient readers, we first offer a methodological overview of tDCS and then review experiments using non-invasive brain stimulation techniques (especially transcranial direct current stimulation) to target prefrontal brain regions implicated in self-regulation. We focus on brain stimulation studies of self-regulatory behavior across three broad domains of response: persistence, delay behavior, and impulse control. We suggest that stimulating the prefrontal cortex promotes successful self-regulation by altering the balance in activity between the prefrontal cortex and subcortical regions involved in emotion and reward processing.

Fair play doesn't matter: MEP modulation as a neurophysiological signature of status quo bias in economic interactions.

Transcranial magnetic stimulation (TMS) studies show that watching others' movements enhances motor evoked potential (MEPs) amplitude of the muscles involved in the observed action (motor facilitation, MF). MF has been attributed to a mirror neuron system mediated mechanism, causing an excitability increment of primary motor cortex. It is still unclear whether the meaning an action assumes when performed in an interpersonal exchange context could affect MF. This study aims at exploring this issue by measuring MF induced by the observation of the same action coupled with opposite reward values (gain vs loss) in an economic game. Moreover, the interaction frame was manipulated by showing the same actions within different economic games, the Dictator Game (DG) and the Theft Game (TG). Both games involved two players: a Dictator/Thief and a receiver. Experimental participants played the game always as receivers whereas the Dictator/Thief roles were played by our confederates. In each game Dictator/Thief's choices were expressed by showing a grasping action of one of two cylinders, previously associated with fair/unfair choices. In the DG the dictator decides whether to share (gain condition) or not (no-gain condition) a sum of money with the receiver, while in TGs the thief decides whether to steal (loss condition) or not to steal (no-loss condition) it from the participants. While the experimental subjects watched the videos showing these movements, a single TMS pulse was delivered to their motor hand area and a MEP was recorded from the right FDI muscle. Results show that, in the DG, MF was enhanced by the status quo modification, i.e. MEP amplitude increased when the dictator decided to change the receivers' status quo and share his/her money, and this was true when the status quo was more salient. The same was true for the TG, where the reverse happened: MF was higher for trials in which the thief decided to steal the participants' money, thus changing the status quo, in the block in which the status quo maintenance occurred more often. Data support the hypothesis that the economic meaning of the observed actions differently modulates MEP amplitude, pointing at an influence on MF exerted by a peculiar interaction between economic outcomes and variation of the subjects' initial status quo.