Beyond peripersonal boundaries: insights from crossmodal interactions.

We experience our self as a body located in space. However, how information about self-location is integrated into multisensory processes underlying the representation of the peripersonal space (PPS), is still unclear. Prior studies showed that the presence of visual information related to oneself modulates the multisensory processes underlying PPS. Here, we used the crossmodal congruency effect (CCE) to test whether this top-down modulation depends on the spatial location of the body-related visual information. Participants responded to tactile events on their bodies while trying to ignore a visual distractor presented on the mirror reflection of their body (Self) either in the peripersonal space (Near) or in the extrapersonal space (Far). We found larger CCE when visual events were presented on the mirror reflection in the peripersonal space, as compared to the extrapersonal space. These results suggest that top-down modulation of the multisensory bodily self is only possible within the PPS.

Guilt Feelings in Obsessive Compulsive Disorder: An Investigation between Diagnostic Groups.

Guilt plays a role in various forms of psychopathology. However, different types of guilt might be involved in different mental disorders. Obsessive-compulsive (OC) patients are prone to a type of guilt in which the violation of an internalized moral norm is necessary and sufficient, whereas data suggest that depression might be linked to more interpersonal types of guilt. However, the extent to which a specific guilt phenomenology is involved in each condition is yet to be determined. Here we assessed the association between different types of guilt and different diagnostic groups. Two clinical samples (33 OCD and 35 non-OCD) filled in the Moral Orientation Guilt Scale (MOGS) along with other OCD and depression measures. Regression was employed to test group differences in the MOGS subscales and to test the influence of MOGS subscales on OCD and depression levels. Results confirm that different types of guilt might be implicated in different psychopathological conditions. Specifically, moral norm violation guilt is more present in OC patients than in other disorders. Depression seems to be associated with different guilt feelings depending on the psychopathological condition, specifically in non-OC patients, with types of guilt involving a "victim", supporting the accounts viewing interpersonal guilt as involved in the emergence of depressive symptomatology and hyper-altruistic behavior as a vulnerability factor for depression.

Temporal binding window and sense of agency are related processes modifiable via occipital tACS.

The temporal binding window refers to the time frame within which temporal grouping of sensory information takes place. Sense of agency is the feeling of being in control of one's actions, and their associated outcomes. While previous research has shown that temporal cues and multisensory integration play a role in sense of agency, no studies have directly assessed whether individual differences in the temporal binding window and sense of agency are associated. In all three experiments, to assess sense of agency, participants pressed a button triggering, after a varying delay, the appearance of the circle, and reported their sense of agency over the effect. To assess the temporal binding window a simultaneity judgment task (Experiment 1) and a double-flash illusion task (Experiment 2 and 3) was also performed. As expected, the temporal binding window correlated with the sense of agency window. In Experiment 3, these processes were modulated by applying occipital tACS at either 14Hz or 8Hz. We found 14Hz tACS stimulation was associated with narrower temporal biding window and sense of agency window. Our results suggest the temporal binding window and the time window of sense of agency are related. They also point towards a possible underlying neural mechanism (alpha peak frequency) for this association.

Centriolar distal appendages activate the centrosome-PIDDosome-p53 signalling axis via ANKRD26.

Centrosome amplification results into genetic instability and predisposes cells to neoplastic transformation. Supernumerary centrosomes trigger p53 stabilization dependent on the PIDDosome (a multiprotein complex composed by PIDD1, RAIDD and Caspase-2), whose activation results in cleavage of p53's key inhibitor, MDM2. Here, we demonstrate that PIDD1 is recruited to mature centrosomes by the centriolar distal appendage protein ANKRD26. PIDDosome-dependent Caspase-2 activation requires not only PIDD1 centrosomal localization, but also its autoproteolysis. Following cytokinesis failure, supernumerary centrosomes form clusters, which appear to be necessary for PIDDosome activation. In addition, in the context of DNA damage, activation of the complex results from a p53-dependent elevation of PIDD1 levels independently of centrosome amplification. We propose that PIDDosome activation can in both cases be promoted by an ANKRD26-dependent local increase in PIDD1 concentration close to the centrosome. Collectively, these findings provide a paradigm for how centrosomes can contribute to cell fate determination by igniting a signalling cascade.

Euthymic bipolar disorder patients and EEG microstates: a neural signature of their abnormal self experience?

BACKGROUND: A growing number of neuroimaging studies have revealed spatial abnormalities of resting-state functional brain network activity in bipolar disorder (BD). Conversely, abnormalities of resting state temporal dynamics have been scarcely investigated so far. The aim of this study was to characterize the EEG microstates activity in BD patients with a history of manic predominant polarity. Patients were euthymic and pharmacologically stabilized. METHODS: Nineteen BD patients (mean age 34.4 ± 11.0, 7 female) and 19 healthy controls (HC; mean age 38.2 ± 9.9, 7 female) were recruited. The psychometric evaluation included the Hamilton Depression Scale (HAMD), the Young Mania Rating Scale (YMRS), the Dissociative Experience Scale (DES), and the State-Trait Anxiety Inventory (STAI).  Two runs of 2 minutes of EEG activity by a 128-channel system were acquired at rest and analyzed through microstate analysis. RESULTS: We found a reduced presence of microstate B in BD patients compared to HC, since BD patients have a tendency to transit from the microstate B to the microstates C and D significantly more than HC. Furthermore, microstate B features were correlated with DES, state STAI and trait STAI scores. CONCLUSION: The reduced presence of microstate B might be associated with episodic autobiographic memory deficit, exaggerated self-focusing and states of dissociations characteristic of BD. Strong correlations of microstate B metrics and dynamics with symptoms of dissociation and anxiety across the two groups supported this interpretation.

The impact of body posture on intrinsic brain activity: The role of beta power at rest.

Tying the hands behind the back has detrimental effects on sensorimotor perceptual tasks. Here we provide evidence that beta band oscillatory activity in a resting state condition might play a crucial role in such detrimental effects. EEG activity at rest was measured from thirty young participants (mean age = 24.03) in two different body posture conditions. In one condition participants were required to keep their hands freely resting on the table. In the other condition, participants' hands were tied behind their back. Increased beta power was observed in the left inferior frontal gyrus during the tied hands condition compared to the free hands condition. A control experiment ruled out alternative explanations for observed change in beta power, including muscle tension. Our findings provide new insights on how body postural manipulations impact on perceptual tasks and brain activity.

Individual Alpha Frequency Predicts Perceived Visuotactile Simultaneity.

Temporal encoding is a key feature in multisensory processing that leads to the integration versus segregation of perceived events over time. Whether or not two events presented at different offsets are perceived as simultaneous varies widely across the general population. Such tolerance to temporal delays is known as the temporal binding window (TBW). It has been recently suggested that individual oscillatory alpha frequency (IAF) peak may represent the electrophysiological correlate of TBW, with IAF also showing a wide variability in the general population (8-12 Hz). In our work, we directly tested this hypothesis by measuring each individual's TBW during a visuotactile simultaneity judgment task while concurrently recording their electrophysiological activity. We found that the individual's TBW significantly correlated with their left parietal IAF, such that faster IAF accounted for narrower TBW. Furthermore, we found that higher prestimulus alpha power measured over the same left parietal regions accounted for more veridical responses of non-simultaneity, which may be explained either by accuracy in perceptual simultaneity or, alternatively, in line with recent proposals by a shift in response bias from more conservative (high alpha power) to more liberal (low alpha power). We propose that the length of an alpha cycle constrains the temporal resolution within which perceptual processes take place.

Multisensory integration, body representation and hyperactivity of the immune system.

Multisensory stimuli are integrated over a delimited window of temporal asynchronies. This window is highly variable across individuals, but the origins of this variability are still not clear. We hypothesized that immune system functioning could partially account for this variability. In two experiments, we investigated the relationship between key aspects of multisensory integration in allergic participants and healthy controls. First, we tested the temporal constraint of multisensory integration, as measured by the temporal binding window. Second, we tested multisensory body representation, as indexed by the Rubber Hand Illusion (RHI). Results showed that allergic participants have a narrower temporal binding window and are less susceptible to the RHI than healthy controls. Overall, we provide evidence linking multisensory integration processes and the activity of the immune system. The present findings are discussed within the context of the effect of immune molecules on the brain mechanisms enabling multisensory integration and multisensory body representation.

Expected but omitted stimuli affect crossmodal interaction.

One of the most important ability of our brain is to integrate input from different sensory modalities to create a coherent representation of the environment. Does expectation affect such multisensory integration? In this paper, we tackled this issue by taking advantage from the crossmodal congruency effect (CCE). Participants made elevation judgments to visual target while ignoring tactile distractors. We manipulated the expectation of the tactile distractor by pairing the tactile stimulus to the index finger with a high-frequency tone and the tactile stimulus to the thumb with a low-frequency tone in 80% of the trials. In the remaining trials we delivered the tone and the visual target, but the tactile distractor was omitted (Study 1). Results fully replicated the basic crossmodal congruency effect. Strikingly, the CCE was observed, though at a lesser degree, also when the tactile distractor was not presented but merely expected. The contingencies between tones and tactile distractors were reversed in a follow-up study (Study 2), and the effect was further tested in two conceptual replications using different combinations of stimuli (Studies 5 and 6). Two control studies ruled out alternative explanations of the observed effect that would not involve a role for tactile distractors (Studies 3, 4). Two additional control studies unequivocally proved the dependency of the CCE on the spatial and temporal expectation of the distractors (Study 7, 8). An internal small-scale meta-analysis showed that the crossmodal congruency effect with predicted distractors is a robust medium size effect. Our findings reveal that multisensory integration, one of the most basic and ubiquitous mechanisms to encode external events, benefits from expectation of sensory input.

Temporal limits on rubber hand illusion reflect individuals' temporal resolution in multisensory perception.

Synchronous, but not asynchronous, multisensory stimulation has been successfully employed to manipulate the experience of body ownership, as in the case of the rubber hand illusion. Hence, it has been assumed that the rubber hand illusion is bound by the same temporal rules as in multisensory integration. However, empirical evidence of a direct link between the temporal limits on the rubber hand illusion and those on multisensory integration is still lacking. Here we provide the first comprehensive evidence that individual susceptibility to the rubber hand illusion depends upon the individual temporal resolution in multisensory perception, as indexed by the temporal binding window. In particular, in two studies we showed that the degree of temporal asynchrony necessary to prevent the induction of the rubber hand illusion depends upon the individuals' sensitivity to perceiving asynchrony during visuo-tactile stimulation. That is, the larger the temporal binding window, as inferred from a simultaneity judgment task, the higher the level of asynchrony tolerated in the rubber hand illusion. Our results suggest that current neurocognitive models of body ownership can be enriched with a temporal dimension. Moreover, our results suggest that the different aspects of body ownership operate over different time scales.

Altered multisensory temporal integration in obesity.

Eating is a multisensory behavior. The act of placing food in the mouth provides us with a variety of sensory information, including gustatory, olfactory, somatosensory, visual, and auditory. Evidence suggests altered eating behavior in obesity. Nonetheless, multisensory integration in obesity has been scantily investigated so far. Starting from this gap in the literature, we seek to provide the first comprehensive investigation of multisensory integration in obesity. Twenty male obese participants and twenty male healthy-weight participants took part in the study aimed at describing the multisensory temporal binding window (TBW). The TBW is defined as the range of stimulus onset asynchrony in which multiple sensory inputs have a high probability of being integrated. To investigate possible multisensory temporal processing deficits in obesity, we investigated performance in two multisensory audiovisual temporal tasks, namely simultaneity judgment and temporal order judgment. Results showed a wider TBW in obese participants as compared to healthy-weight controls. This holds true for both the simultaneity judgment and the temporal order judgment tasks. An explanatory hypothesis would regard the effect of metabolic alterations and low-grade inflammatory state, clinically observed in obesity, on the temporal organization of brain ongoing activity, which one of the neural mechanisms enabling multisensory integration.

Group membership and social status modulate joint actions.

The ability to form shared task representations is considered a keystone of social cognition. It remains, however, contentious if, and to what extent, social categorization impacts on shared representations. In the present study, we address the possibility of the modulation of action co-representation by social categorization, such as group membership and social status, as indexed by the social Simon effect. Italian participants were requested to perform a social Simon task, along with either an Italian (high-status in-group) or an Albanian (low-status out-group) participant. Results show that Italian participants co-represented the action of their partner when paired with a high-status in-group participant. Conversely, this effect was absent when they performed the task with a low-status out-group participant. Furthermore, the Albanian participants co-represented the action of their partner when paired with an Italian participant. These results suggest that group membership modulates action co-representation through the varying of the groups' relative status. The impact of this issue is boundless given the increasing multicultural nature of our society. Indeed, if multiculturalism fails, modern society does likewise.