Body–Space Interactions: Same Spatial Encoding but Different Influence of Valence for Reaching and Defensive Purposes

Abstract

The space around our body, the so-called “peripersonal space,” is where interactions with nearby objects may occur. “Defensive space” and “Reaching space” respectively refer to two opposite poles of interaction between our body and the external environment: protecting the body and performing a goal-directed action. Here, we hypothesized that mechanisms underlying these two action spaces are differentially modulated by the valence of visual stimuli, as stimuli with negative valence are more likely to activate protective actions whereas stimuli with positive valence may activate approaching actions. To test whether such distinction in cognitive/evaluative processing exists between Reaching and Defensive spaces, we measured behavioral responses as well as neural activations over sensorimotor cortex using EEG while participants performed several tasks designed to tap into mechanisms underlying either Defensive (e.g., respond to touch) or Reaching space (e.g., estimate whether object is within reaching distance). During each task, pictures of objects with either positive or negative valence were presented at different distances from the participants' body. We found that Defensive space was smaller for positively compared with negatively valenced visual stimuli. Furthermore, sensorimotor cortex activation (reflected in modulation of beta power) during tactile processing was enhanced when coupled with negatively rather than positively valenced visual stimuli regarding Defensive space. On the contrary, both the EEG and behavioral measures capturing the mechanisms underlying Reaching space did not reveal any modulation by valence. Thus, although valence encoding had differential effects on Reaching and Defensive spaces, the distance of the visual stimulus modulated behavioral measures as well as activity over sensorimotor cortex (reflected in modulations of mu power) in a similar way for both types of spaces. Our results are compatible with the idea that Reaching and Defensive spaces involve the same distance-dependent neural representations of sensory input, whereas task goals and stimulus valence (i.e., contextual information) are implemented at a later processing stage and exert an influence on motor output rather than sensory/space encoding.

Mirror visual feedback during unilateral finger movements is related to the desynchronization of cortical electroencephalographic somatomotor alpha rhythms

“…Nonetheless, our findings are in line with other MVF studies showing a hemispheric asymmetry in the motor alpha ERD/ERS distribution in the control condition (i.e., without the mirror) only during the preparation of the movement rather than the movement execution (Bartur et al, 2015 ; Li et al, 2018 ). Another explanation of this spread centro‐parietal alpha ERD might be given by a tactile sensation of the finger on the surface of the table (Spaccasassi et al, 2021 ). However, previous studies showing a central alpha suppression in response to tactile sensation used high‐frequency vibrotactile stimuli (Kim et al, 2020 ; Shen et al, 2017 ; Van Ede et al, 2011 ).…”

Egocentric value maps of the near-body environment

“…Peripersonal responses are often said to be related to separate classes of movements. Specifically, a distinction is frequently made between defensive avoidance movements, and grabbing or appetitive movements (17,(85)(86)(87). This distinction is based on the type of movements associated with the brain areas where peripersonal neurons are found: VIP and F4, for instance, are more linked to defensive movements, while MIP, AIP, F5 and 7B are more related to reaching and grasping (86).…”

“…It remains debated why these action classes are represented in different cortical areas, and how they relate to peripersonal responses (52,56,85,87,90). Our model offers a perspective that clarifies the issue: the separation between classes of actions and their…”

“…It remains debated why these action classes are represented in different cortical areas, and how they relate to peripersonal responses (52, 56, 85, 87, 90). Our model offers a perspective that clarifies the issue: the separation between classes of actions and their subserving functional networks can be understood by considering the effect of the sign of the reward r t , which is equivalent to stimulus valence.…”

Tools and peripersonal space: an enactive account of bodily space

“…3 This fact is clearly not lost on experimental PPS researchers. Bassolino et al (2010, p.804) note: "an important property of PPS is the possibility of being modified as a function of experience", while Spaccasassi et al (2021Spaccasassi et al ( , p.2150 claim: "objects located inside PPS are represented in terms of potential actions… PPS is not solely a metrical representation of the space around us but includes a more complex (operational) representation". Ferri et al (2015, p.469) contrast a 'metric' with a 'functional' understanding of PPS as follows:…”