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The presentation of simple auditory stimuli can significantly impact visual processing and even induce visual illusions, such as the auditory-induced double flash illusion (DFI). These cross-modal processes have been shown to be driven by occipital oscillatory activity within the alpha band. Whether this phenomenon is network specific or can be generalized to other sensory interactions remains unknown. The aim of the current study was to test whether cross-modal interactions between somatosensory-to-visual areas leading to the same (but tactile-induced) DFI share similar properties with the auditory DFI. We hypothesized that if the effects are mediated by the oscillatory properties of early visual areas per se, then the two versions of the illusion should be subtended by the same neurophysiological mechanism (i.e., the speed of the alpha frequency). Alternatively, if the oscillatory activity in visual areas predicting this phenomenon is dependent on the specific neural network involved, then it should reflect network-specific oscillatory properties. In line with the latter, results recorded in humans (both sexes) show a network-specific oscillatory profile linking the auditory DFI to occipital alpha oscillations, replicating previous findings, and tactile DFI to occipital beta oscillations, a rhythm typical of somatosensory processes. These frequency-specific effects are observed for visual (but not auditory or somatosensory) areas and account for auditory-visual connectivity in the alpha band and somatosensory-visual connectivity in the beta band. We conclude that task-dependent visual oscillations reflect network-specific oscillatory properties favoring optimal directional neural communication timing for sensory binding. [ABSTRACT FROM AUTHOR]

How deep is the linkage between action and perception? Much is known about how object perception impacts on action performance, much less about how action performance affects object perception. Does action performance affect perceptual judgment on object features such as shape and orientation? Answering these questions was the aim of the present study. Participants were asked to reach and grasp a handled mug without any visual feedback before judging whether a visually presented mug was handled or not. Performing repeatedly a grasping action resulted in a perceptual categorization aftereffect as measured by a slowdown in the judgment on a handled mug. We suggest that what people are doing may impact on their perceptual judgments on the surrounding things. [ABSTRACT FROM AUTHOR]

Our coherent perception of external events is enabled by the integration of inputs from different senses occurring within a range of temporal offsets known as the temporal binding window (TBW), which varies from person to person. A relatively wide TBW may increase the likelihood that stimuli originating from different environmental events are erroneously integrated and abnormally large TBW has been found in psychiatric disorders characterized by unusual perceptual experiences. Despite strong evidence of inter-individual differences in TBW, both within clinical and nonclinical populations, the neurobiological underpinnings of this variability remain unclear. We adopted an integrated strategy linking TBW to temporal dynamics in functional magnetic resonance imaging (fMRI)-resting-state activity and cortical excitation/inhibition (E/I) balance. E/I balance was indexed by glutamate/Gamma-AminoButyric Acid (GABA) concentrations and common variation in glutamate and GABA genes in a healthy sample. Stronger resting-state long-range temporal correlations, indicated by larger power law exponent (PLE), in the auditory cortex, robustly predicted narrower audio-tactile TBW, which was in turn associated with lower cognitive-perceptual schizotypy. Furthermore, PLE was highest and TBW narrowest for individuals with intermediate levels of E/I balance, with shifts towards either extreme resulting in reduced multisensory temporal precision and increased schizotypy, effectively forming a neural "tuning curve" for multisensory experience and schizophrenia risk. Our findings shed light on the neurobiological underpinnings of multisensory integration and its potentially clinically relevant inter-individual variability. [ABSTRACT FROM AUTHOR]

Background: As social animals we share the space with other people. It is known that perceived extension of the peripersonal space (the reaching space) is affected by the implicit representation of our own and other's action potentialities. Our issue concerns whether the co-presence of a body in the scene influences our extrapersonal space (beyond reaching distance) categorization. Methodology/Principal Findings: We investigated, through 3D virtual scenes of a realistic environment, whether egocentric spatial categorization can be influenced by the presence of another human body (Exp. 1) and whether the effect is due to her action potentialities or simply to her human-like morphology (Exp. 2). Subjects were asked to judge the location ("Near" or "Far") of a target object located at different distances from their egocentric perspective. In Exp. 1, the judgment was given either in presence of a virtual avatar (Self-with-Other), or a non-corporeal object (Self-with-Object) or nothing (Self). In Exp. 2, the Self condition was replaced by a Self-with-Dummy condition, in which an inanimate body (a wooden dummy) was present. Mean Judgment Transition Thresholds (JTTs) were calculated for each subject in each experimental condition. Self-with-Other condition induced a significant extension of the space judged as “Near” as compared to both the Self-with-Object condition and the Self condition. Such extension was observed also in Exp. 2 in the Self-with-Dummy condition. Results suggest that the presence of others impacts on our perception of extrapersonal space. This effect holds also when the other is a human-like wooden dummy, suggesting that structural and morphological shapes resembling human bodies are sufficient conditions for the effect to occur. Conclusions: The observed extension of the portion of space judged as near could represent a wider portion of “accessible” space, thus an advantage in the struggle to survive in presence of other potential competing individuals. [ABSTRACT FROM AUTHOR]

The present study asks when infants are able to selectively anticipate the goals of observed actions, and how this ability relates to infants’ own abilities to produce those specific actions. Using eye-tracking technology to measure on-line anticipation, 6-, 8- and 10-month-old infants and a control group of adults were tested while observing an adult reach with a whole hand grasp, a precision grasp or a closed fist towards one of two different sized objects. The same infants were also given a comparable action production task. All infants showed proactive gaze to the whole hand grasps, with increased degrees of proactivity in the older groups. Gaze proactivity to the precision grasps, however, was present from 8 months of age. Moreover, the infants’ ability in performing precision grasping strongly predicted their ability in using the actor’s hand shape cues to differentially anticipate the goal of the observed action, even when age was partialled out. The results are discussed in terms of the specificity of action anticipation, and the fine-grained relationship between action production and action perception. [ABSTRACT FROM AUTHOR]

In social life actions are tightly linked with emotions. The integration of affective- and action-related information has to be considered as a fundamental component of appropriate social understanding. The present functional magnetic resonance imaging study aimed at investigating whether an emotion (Happiness, Anger or Neutral) dynamically expressed by an observed agent modulates brain activity underlying the perception of his grasping action. As control stimuli, participants observed the same agent either only expressing an emotion or only performing a grasping action. Our results showed that the observation of an action embedded in an emotional context (agent's facial expression), compared with the observation of the same action embedded in a neutral context, elicits higher neural response at the level of motor frontal cortices, temporal and occipital cortices, bilaterally. Particularly, the dynamic facial expression of anger modulates the re-enactment of a motor representation of the observed action. This is supported by the evidence that observing actions embedded in the context of anger, but not happiness, compared with a neutral context, elicits stronger activity in the bilateral pre-central gyrus and inferior frontal gyrus, besides the pre-supplementary motor area, a region playing a central role in motor control. Angry faces not only seem to modulate the simulation of actions, but may also trigger motor reaction. These findings suggest that emotions exert a modulatory role on action observation in different cortical areas involved in action processing. [ABSTRACT FROM AUTHOR]

Body-awareness relies on the representation of both interoceptive and exteroceptive percepts coming from one's body. However, the exact relationship and possible interaction of interoceptive and exteroceptive systems for body-awareness remain unknown. We sought to understand for the first time, to our knowledge, the interaction between interoceptive and exteroceptive awareness of the body. First, we measured interoceptive awareness with an established heartbeat monitoring task. We, then, used a multi-sensory-induced manipulation of body-ownership (e.g. Rubber Hand Illusion (RHI)) and we quantified the extent to which participants experienced ownership over a foreign body-part using behavioural, physiological and introspective measures. The results suggest that interoceptive sensitivity predicts the malleability of body representations, that is, people with low interoceptive sensitivity experienced a stronger illusion of ownership in the RHI. Importantly, this effect was not simply owing to a poor proprioceptive representation or differences in autonomic states of one's body prior to the multi-sensory stimulation, suggesting that interoceptive awareness modulates the online integration of multi-sensory body-percepts. [ABSTRACT FROM AUTHOR]

Abstract: Although vision is the primary sensory modality that humans and other primates use to identify objects in the environment, we can recognize crucial object features (e.g., shape, size) using the somatic modality. Previous studies have shown that the occipito-temporal areas dedicated to the visual processing of object forms, faces and bodies also show category-selective responses when the preferred stimuli are haptically explored out of view. Visual processing of human bodies engages specific areas in lateral (extrastriate body area, EBA) and medial (fusiform body area, FBA) occipito-temporal cortex. This study aimed at exploring the relative involvement of EBA and FBA in the haptic exploration of body parts. During fMRI scanning, participants were asked to haptically explore either real-size fake body parts or objects. We found a selective activation of right and left EBA, but not of right FBA, while participants haptically explored body parts as compared to real objects. This suggests that EBA may integrate visual body representations with somatosensory information regarding body parts and form a multimodal representation of the body. Furthermore, both left and right EBA showed a comparable level of body selectivity during haptic perception and visual imagery. However, right but not left EBA was more activated during haptic exploration than visual imagery of body parts, ruling out that the response to haptic body exploration was entirely due to the use of visual imagery. Overall, the results point to the existence of different multimodal body representations in the occipito-temporal cortex which are activated during perception and imagery of human body parts. [Copyright &y& Elsevier]

Abstract: Previous studies have shown a motor recruitment during the observation of graspable objects. This recruitment has been considered crucial in encoding the observed objects in terms of one or more potential motor acts. However, an agent can actually act upon an object only when the latter is close enough to be reached. Thus, the question we deal with in this paper is whether the motor system is always activated whenever a graspable object comes into view or whether it requires the object to be located within the reachable space of the perceiver. The left primary motor cortex was magnetically stimulated and motor evoked potentials (MEPs) were recorded while participants observed graspable and non graspable objects located within or outside their own reachable space. We found higher MEPs during the observation of graspable objects falling within the reachable space compared to the observation of either a non graspable object or a graspable object falling outside the reachable space. Our results shed new light on the functional role of the motor system in encoding visually presented objects. Indeed, they clearly indicate that its recruitment is spatially constrained, as it depends on whether the object falls within the actual reaching space of the onlooker. [Copyright &y& Elsevier]

Abstract: The mental representation of one’s own body does not necessarily correspond to the physical body. For instance, a dissociation between perceived and actual reach-ability has been shown, that is, individuals perceive that they can reach objects that are out of grasp. We presented participants with 3D pictures of objects located at four different distances, namely near-reaching space, actual-reaching space, perceived-reaching space and non-reaching space. Immediately after they were presented with function, manipulation, observation or pointing verbs and were required to judge if the verb was compatible with the object. Participants were faster with function and manipulation verbs than with observation and pointing verbs. Strikingly, with both function and manipulation verbs participants were faster when objects were presented in actual than the perceived reaching space. These findings suggest that our knowledge of the world is implicitly built online through behaviour, and is not necessarily reflected in explicit estimates or conscious representations. [Copyright &y& Elsevier]