Meditation alters representations of peripersonal space: Evidence from auditory evoked potentials

Mindfulness Affects the Boundaries of Bodily Self-Representation: The Effect of Focused-Attention Meditation in Fading the Boundary of Peripersonal Space

Peripersonal space (PPS) is a dynamic multisensory representation of the space around the body, influenced by internal and external sensory information. The malleability of PPS boundaries, as evidenced by their expansion after tool use or modulation through social interactions, positions PPS as a crucial element in understanding the subjective experiences of self and otherness. Building on the existing literature highlighting both the cognitive and bodily effects of mindfulness meditation, this study proposes a novel approach by employing focused-attention meditation (FAM) and a multisensory audio-tactile task to assess PPS in both the extension and sharpness of its boundaries. The research hypothesis posits that FAM, which emphasizes heightened attention to bodily sensations and interoception, may reduce the extension of PPS and make its boundaries less sharp. We enrolled 26 non-meditators who underwent a repeated measure design in which they completed the PPS task before and after a 15-min FAM induction. We found a significant reduction in the sharpness of PPS boundaries but no significant reduction in PPS extension. These results provide novel insights into the immediate effects of FAM on PPS, potentially shedding light on the modulation of self-other representations in both cognitive and bodily domains. Indeed, our findings could have implications for understanding the intricate relationship between mindfulness practices and the subjective experience of self within spatial contexts.

Bliss in and Out of the Body: The (Extra)Corporeal Space Is Impervious to Social Pleasant Touch

Slow, gentle stimulation of hairy skin is generally accompanied by hedonic sensations. This phenomenon, also known as (positive) affective touch, is likely to be the basis of affiliative interactions with conspecifics by promoting inter-individual bindings. Previous studies on healthy humans have demonstrated that affective touch can remarkably impact behavior. For instance, by administering the Rubber Hand Illusion (RHI) paradigm, the embodiment of a fake hand enhances after a slow, affective touch compared to a fast, neutral touch. However, results coming from this area are not univocal. In addition, there are no clues in the existing literature on the relationship between affective touch and the space around our body. To overcome these lacks, we carried out two separate experiments where participants underwent a RHI paradigm (Experiment 1) and a Visuo-Tactile Interaction task (Experiment 2), designed to tap into body representation and peripersonal space processing, respectively. In both experiments, an affective touch (CT-optimal, 3 cm/s) and neutral touch (CT-suboptimal, 18 cm/s) were delivered by the experimenter on the dorsal side of participants’ hand through a “skin to skin” contact. In Experiment 1, we did not find any modulation of body representation—not at behavioral nor at a physiological level—by affective touch. In Experiment 2, no visuo-tactile spatial modulation emerged depending upon the pleasantness of the touch received. These null findings are interpreted in the light of the current scientific context where the real nature of affective touch is often misguided, and they offer the possibility to pave the way for understanding the real effects of affective touch on body/space representation.

Psychedelic drugs and perception: a narrative review of the first era of research

Psychedelic drugs are well-known for transiently altering perception, and in particular, for their visual effects. Although scientific interest into the substances' effects on perception increased during the first era of psychedelic research during the early to mid-20th century, there is currently no source where these findings have been synthesized. In addressing this gap, the current narrative review found that psychedelics were examined for their influences across all levels of the visual system (e.g., retinal, cortical, subcortical, simple visual processing, complex imagery, hallucinations). Psychedelics were also shown to affect auditory discrimination/generalization, neural correlates of auditory processing, and led to auditory hallucinations in subsets of participants. Several studies demonstrated that psychedelics can distort representations of body schema and time perception. Concerns regarding methodological standards of this era are a limitation to the findings and are discussed. Collectively, this review preserves and increases the accessibility of the work done by pioneering psychedelic/perception researchers, synthesizes findings, and critically analyzes areas of discrepancy to inform future studies.