Self-Grounded Vision: Hand Ownership Modulates Visual Location through Cortical β and γ Oscillations

Abstract

Vision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger ␣ suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher ␤/␥ power over frontotemporal regions. Higher ␥ connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on afterimage drifts is associated with ␤/␥ power and ␥ connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame.

Sensorimotor conflicts alter metacognitive and action monitoring

“…Together, our results extend the recent studies documenting the impact of the bodily self on low-level vision (Faivre et al, 2017; see Faivre, Salomon & Blanke, 2015 for review), and semantic processing of words (Canzoneri et al, 2016;Noel, Blanke, Serino & Salomon, 2017), by further showing that the . CC-BY-NC-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.…”

We Three: My Brain, My Homunculus, and Me

“…One distinct way that non-H parts of brain affect handwriting is that visual illusions of hand ownership alter connectivity between H and inferior parietal cortex (Faivre et al, 2017…”

Mapping the influence of social threat in the brain

“…Hand ownership is also a key factor in the extent to which the visual percept can be changed. Faivre et al (2017) used a combination of positive after images and a version of the RHI called the somatic rubber hand illusion. In this variation of the RHI, an illusion of self-touch is created by having a participant touch a fake hand with their right hand, while at the same time their left hand is being touched in synchrony by the experimenter (Ehrsson, Holmes, & Passingham, 2005).…”

“…In this variation of the RHI, an illusion of self-touch is created by having a participant touch a fake hand with their right hand, while at the same time their left hand is being touched in synchrony by the experimenter (Ehrsson, Holmes, & Passingham, 2005). In the experiment by Faivre et al (2017) they tested whether drifts in the afterimage of an illusory owned hand occur when the location of the real hand (and thus proprioceptive feedback) is kept constant. They found that the drift of the afterimage was dependent on experienced ownership over the fake hand (i.e.…”

“…away or towards the eyes, respectively; Carey & Allan, 1996). Both fading and size scaling of a hand in an afterimage occur irrespective of whether the movement is active or passive, suggesting that afferent proprioceptive information is sufficient to influence the percept (Bross, 2000;, and changes of the hand in the afterimage happen only when the viewed hand is perceived as one's own (Faivre et al, 2017).…”