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Spinal cord injury can cause cognitive impairments even when no cerebral lesion is appreciable. As patients are forced to explore the environment in a non‐canonical position (i.e., seated on a wheelchair), a modified relation with space can explain motor‐related cognitive differences compared to non‐injured individuals. Peripersonal space is encoded in motor terms, that is, in relation to the representation of action abilities and is strictly related to the affordance of reachability. In turn, affordances, the action possibilities suggested by relevant properties of the environment, are related to the perceiver's peripersonal space and motor abilities. One might suppose that these motor‐related cognitive abilities are compromised when an individual loses the ability to move. We shed light on this issue in 10 patients with paraplegia and 20 matched controls. All have been administered an affordances‐related reachability judgement task adapted from Costantini, Ambrosini, Tieri, Sinigaglia, and Committeri (2010, Experimental Brain Research, 207, 95) and neuropsychological tests. Our findings demonstrate that patients and controls show the same level of accuracy in estimating the location of their peripersonal space boundaries, but only controls show the typical overestimation of reaching range. Secondly, patients show a higher variability in their judgements than controls. Importantly, this finding is related to the patients' ability to perform everyday tasks. Finally, patients are not faster in making their judgements on reachability in peripersonal space, while controls are. Our results suggest that not moving freely or as usual in the environment impact decoding of action‐related properties even when the upper limbs are not compromised. [ABSTRACT FROM AUTHOR]

We live in a dynamic environment, constantly confronted with approaching objects that we may either avoid or be forced to address. A multisensory and sensorimotor interface, the peripersonal space (PPS), mediates every physical interaction between our body and the environment. Behavioral investigations show high variability in the extension of PPS across individuals, but there is a lack of evidence on the neural underpinnings of these large individual differences. Here, we used approaching auditory stimuli and fMRI to capture the individual boundary of PPS and examine its neural underpinnings. Precisely, we tested the hypothesis that intertrial variability (ITV) in brain regions coding PPS predicts individual differences of its boundary at the behavioral level. Selectively in the premotor cortex, we found that ITV, rather than trial-averaged amplitude, of BOLD responses to far rather than near dynamic stimuli predicts the individual extension of PPS. Our results provide the first empirical support for the relevance of ITV of brain responses for individual differences in human behavior. [ABSTRACT FROM AUTHOR]

The power of an object to afford a suitable act has been shown to depend on its reachability. Nevertheless, most of our perception and action occur in a social context. Little research has directly explored whether the possibility for other people to act upon an object may affect our processing of its affording features. To tackle this issue, we magnetically stimulated the left primary motor cortex and recorded motor-evoked potentials (MEPs) while participants were presented with a handled object (i.e. a mug) close either to them or to a virtual individual such as an avatar. We found highest MEPs both when the mug was near enough to be actually reachable for the participants and also when it was out of reach for them, provided that it was ready to the avatar’s hand. We propose that this effect is likely to be due to an interpersonal bodily space representation, which plays critical role in basic social interaction. [ABSTRACT FROM PUBLISHER]

Abstract: Previous evidence has shown that active tool-use remaps agents’ reaching space with far objects being perceived as reachable and graspable. To date, however, there is no evidence that tool-use observation might also be effective in reaching space remapping. The present six experiments show that not only performing but also observing tool actions may extend the representation of reaching space, useful for grasping objects. In addition, like active tool-use, tool-use observation also impacts on visual distance judgment. Interestingly, these effects only occurred when observers shared the same action potentialities with the agent, i.e., while passively holding a tool compatible with the goal and the spatial range of the observed action. The present findings demonstrate that observing someone else acting with a tool may actually shape the way we map the objects and the space around us, suggesting that such a mapping could provide us with a keystone for coordinating and integrating our actions with those of others. [Copyright &y& Elsevier]

The peripersonal space (PPS) is a multisensory and sensorimotor interface between our body and the environment. The location of PPS boundary is not fixed. Rather, it adapts to the environmental context and differs greatly across individuals. Recent studies have started to unveil the neural correlates of individual differences in PPS extension; however, this picture is not clear yet. Here, we used approaching auditory stimuli and magnetoencephalography to capture the individual boundary of PPS and examine its neural underpinnings. In particular, building upon previous studies from our own group, we investigated the possible contribution of an intrinsic feature of the brain, that is the "resting state" functional connectivity, to the individual differences in PPS extension and the frequency specificity of this contribution. Specifically, we focused on the activity synchronized to the premotor cortex, where multisensory neurons encoding PPS have been described. Results showed that the stronger the connectivity between left premotor cortex (lPM) and a set of fronto-parietal, sensorimotor regions in the right and left hemisphere, the wider the extension of the PPS. Strikingly, such a correlation was observed only in the beta-frequency band. Overall, our results suggest that the individual extension of the PPS is coded in spatially- and spectrally-specific resting state functional links. • Resting state functional connectivity contributes to individual differences in PPS extension. • Wider PPS is linked to stronger synchronization between lPM and bilateral sensorimotor cortices. • MEG synchronization patterns relevant to individual PPS are specifically observed in the beta-frequency band. • Our results support the notion of PPS extension as a "trait-like" feature of the individual. [ABSTRACT FROM AUTHOR]

In order to survive in a complex environment, inhabited by potentially threatening and noxious objects or living beings, we need to constantly monitor our surrounding space, especially in the vicinity of our body. Such a space has been commonly referred to as one's ‘peripersonal space’ (PPS). In this study we investigated whether emotion-inducing approaching sound sources impact the boundaries of PPS. Previous studies have indeed showed that the boundaries of PPS are not fixed but modulate according to properties of stimuli in the surrounding environment. In Experiment 1, participants performed a simple tactile detection task of targets presented to their right hand. Concurrently, they were presented with intensity-changing task-irrelevant artificial sound sources perceived as approaching toward their body. The physical properties of the sound elicited emotional responses of either neutral or negative valence. Results showed larger PPS when the approaching stimulus had negative as compared to neutral emotional valence. In Experiment 2, we used ecological sounds which content (i.e., psychological associations to the sound producing source), rather than physical properties, elicited emotional responses of negative, positive or neutral valence. In agreement with results from experiment 1, we found larger PPS when the approaching stimuli had negative emotional valence as compared to both neutral and positive ones. Results are discussed within the theoretical framework that conceives PPS as a safety zone around one’s body. [ABSTRACT FROM AUTHOR]

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]

Abstract: In this study we investigated whether objects and their name evoke the activation of the same motor programs. In the first experiment participants had to make speeded responses based on the category of an object. They had to signal whether an object, presented visually, either within or outside their reachable space, was natural or manufactured, by making reach-to-precision or reach-to-power grasp responses. We found a compatibility effect between the response required by task, and the grip evoked by the object, for reachable space only. Nevertheless, this finding holds for artefacts and not for natural objects. In the second experiment, participants had to make reach-to-precision or reach-to-power grasp responses when deciding whether an object, presented either within or outside their reachable space, was congruent with a previously displayed word. In this case we found a compatibility effect between the response required by task and the grip evoked by the object''s name, however this effect was not limited by participants’ reaching range. Our data suggest that objects and objects’ name likely correspond to different motor representations. That is, while the former seem to house both stable (i.e., shape and size) and temporary (i.e., orientation and distance with respect to the perceiver) action-relevant information, the latter seem to house only stable action-relevant information. [Copyright &y& Elsevier]