Giuseppina Porciello

rTMS-induced virtual lesion of the posterior parietal cortex (PPC) alters the control of reflexive shifts of social attention triggered by pointing hands

In highly social groups like human and non-human primates, gaze and pointing cues are fundamentally important for directing the attention of conspecifics. Although neuroimaging studies indicate that shifts of attention triggered by observation of social cues activate the onlookers׳ fronto-parietal cortices, information on whether these regions play a causative role in orienting and re-orienting of social attention is lacking. To advance our understanding of this, we used event-related repetitive dual pulse transcranial magnetic stimulation to interfere with neural activity in the right frontal eye field (rFEF) and posterior parietal cortex (rPPC). This procedure allowed us to explore how inhibiting rFEF and rPPC influences shifts of attention triggered by the observation of body-related (gaze and hand) and non body-related (arrow) directional distractors. Participants were asked to perform a leftward or rightward pointing movement according to the color change of a central imperative signal while ignoring a distractor, which was either a gaze, a pointing hand or an arrow. Stimulation of rPPC in a region supposedly linked to attentional re-orienting and to planning and execution of upper limb movements increased the reflexive tendency to follow distracting pointing hands but not oriented gaze or arrows. These findings suggest that inhibition of cortical structures that control attentional shifts triggered by social stimuli brings forth an increase of the cost of attentional re-orienting. Moreover, our results provide the first causative evidence that reflexive social attention in humans may be coded according to body-part-centered frames of reference.

Self-identification with another person's face: the time relevant role of multimodal brain areas in the enfacement illusion

The illusory subjective experience of looking at ones own face while in fact looking at another persons face can surprisingly be induced by simple synchronized visuotactile stimulation of the two faces. A recent study (Apps MA, Tajadura-Jiménez A, Sereno M, Blanke O, Tsakiris M. Cereb Cortex. First published August 20, 2013; doi:10.1093/cercor/bht199) investigated for the first time the role of visual unimodal and temporoparietal multimodal brain areas in the enfacement illusion and suggested a model in which multisensory mechanisms are crucial to construct and update self-face representation.

Fortunes and misfortunes of political leaders reflected in the eyes of their electors

Gaze-following is a pivotal social behaviour that, although largely automatic, is permeable to high-order variables like political affiliation. A few years ago we reported that the gaze of Italian right-wing voters was selectively captured by the gaze of their leader Silvio Berlusconi. This effect was particularly evident in voters who saw themselves as similar to Berlusconi. Two years later, we were able to run the present follow-up study because Berlusconi’s popularity had drastically dropped due to sex and political scandals, and he resigned from office. In a representative subsample of our original group, we investigated whether perceived similarity and gaze-following reflected Berlusconi’s loss in popularity. We were also able to test the same hypothesis in an independent group of right-wing voters when their leader, Renata Polverini, resigned as Governor of ‘Regione Lazio’ due to political scandals. Our results show that the leaders’ fall in popularity paralleled the reduction of their gaze’s attracting power, as well as the decrease in similarity perceived by their voters. The less similar right-wing voters felt to their leader, the less they followed his/her gaze. Thus, the present experimental findings suggest that gaze-following can be modulated by complex situational and dispositional factors such as leader’s popularity and voter–leader perceived similarity.

The ‘Enfacement’ illusion: A window on the plasticity of the self

Understanding how self-representation is built, maintained and updated across the lifespan is a fundamental challenge for cognitive psychology and neuroscience. Studies demonstrate that the detection of body-related multisensory congruency builds bodily and facial self-representations that are crucial to developing self-recognition. Studies showing that the bodily self is more malleable than previously believed were mainly concerned with full-bodies and non-facial body parts. Crucially, however, intriguing recent evidence indicates that simple experimental manipulations could even affect self-face representation that has long been considered a stable construct impervious to change. In this review, we discuss how Interpersonal Multisensory Stimulation (IMS) paradigms can be used to temporarily induce Enfacement, i.e., the subjective illusion of looking at oneself in the mirror when in fact looking at another persons face. We show that Enfacement is a subtle but robust phenomenon occurring in a variety of experimental conditions and assessed by multiple explicit and implicit measures. We critically discuss recent findings on i) the role of sensory extero/proprio-ceptive (visual, tactile, and motor) and interoceptive (cardiac) signals in self-face plasticity, ii) the importance of multisensory integration mechanisms for the bodily self, and iii) the neural network related to IMS-driven changes in self-other face processing, within the predictive coding theoretical framework.

Not That Heart-Stopping After All: Visuo-Cardiac Synchrony Does Not Boost Self-Face Attribution

Recent experimental evidence and theoretical models suggest that an integration of exteroceptive and interoceptive signals underlies several key aspects of the bodily self. While it has been shown that self-attribution of both the hand and the full-body are altered by conflicting extero-exteroceptive (e.g. visuo-tactile) and extero-interoceptive (e.g. visuo-cardiac) information, no study has thus far investigated whether self-attribution of the face might be altered by visuo-cardiac stimulation similarly to visuo-tactile stimulation. In three independent groups of participants we presented ambiguous (i.e. morphed with a strangers face) self-faces flashing synchronously or asynchronously with the participants’ heartbeat. We then measured the subjective percentages of self-face attribution of morphed stimuli. To control for a potential effect of visuo-cardiac synchrony on familiarity, a task assessing the attribution of a familiar face was introduced. Moreover, different durations of visuo-cardiac flashing and different degrees of asynchronicity were used. Based on previous studies showing that synchronous visuo-cardiac stimulation generally increases self-attribution of the full-body and the hand, and that synchronous visuo-tactile stimulation increases self-face attribution, we predicted higher self-face attribution during the synchronous visuo-cardiac flashing of the morphed stimuli. In contrast to this hypothesis, the results showed no difference between synchronous and asynchronous stimulation on self-face attribution in any of the three studies. We thus conclude that visuo-cardiac synchrony does not boost self-attribution of the face as it does that of hand and full-body.

“Atypical touch perception in MTS may derive from an abnormally plastic self-representation”

Abstract Mirror Touch Synesthetes (MTSs) feel touch while they observe others being touched. According to the authors, two complementary theoretical frameworks, the Threshold Theory and the Self-Other Theory, explain Mirror Touch Synesthesia (MTS). Based on the behavioral evidence that in MTSs the mere observation of touch is sufficient to elicit self-other merging (i.e., self-representation changes), a condition that in non-MTSs just elicits self-other sharing (i.e., mirroring activity without self-other blurring), and on the rTPJ anatomical alterations in MTS, we argue that MTS may derive from an abnormally plastic self-representation and atypical multisensory integrative mechanisms.

The Gastric Network: How the stomach and the brain work together at rest

Low-frequency electrical waves in the stomach seem to be synchronised with the activity of a newly discovered resting-state network in the human brain.