Network activity underlying the illusory self‐attribution of a dummy arm

Abstract

Neuroimaging has demonstrated that the illusory self-attribution of body parts engages frontal and intraparietal brain areas, and recent evidence further suggests an involvement of visual body-selective regions in the occipitotemporal cortex. However, little is known about the principles of information exchange within this network. Here, using automated congruent versus incongruent visuotactile stimulation of distinct anatomical locations on the participant's right arm and a realistic dummy counterpart in an fMRI scanner, we induced an illusory self-attribution of the dummy arm. The illusion consistently activated a left-hemispheric network comprising ventral premotor cortex (PMv), intraparietal sulcus (IPS), and body-selective regions of the lateral occipitotemporal cortex (LOC). Importantly, during the illusion, the functional coupling of the PMv and the IPS with the LOC increased substantially, and dynamic causal modeling revealed a significant enhancement of connections from the LOC and the secondary somatosensory cortex to the IPS. These results comply with the idea that the brain's inference mechanisms rely on the hierarchical propagation of prediction error. During illusory self-attribution, unpredicted ambiguous sensory input about one's body configuration may result in the generation of such prediction errors in visual and somatosensory areas, which may be conveyed to parietal integrative areas.

Integration of Visual and Proprioceptive Limb Position Information in Human Posterior Parietal, Premotor, and Extrastriate Cortex

“…Our results thus suggest that the EBA is sensitive to visual and proprioceptive arm information and their congruence in the absence of action, visual or tactile motion, and motor imagery. That we found such effects only in the EBA contralateral to the right hand fits the results of previous studies (Astafiev et al, 2004;Ehrsson et al, 2004;Limanowski and Blankenburg, 2015a). Interestingly, slightly different portions of the EBA were activated by arm versus object vision (posterior) and passive arm rotation (anterior), which might support proposals of multiple functionally distinct body representations (Weiner and Grill-Spector, 2011) or functional gradients (Lingnau and Downing, 2015) in the EBA.…”

“…The PMv might instantiate "higher-level" functions such as representing the (fake) hand for action on nearby objects (Graziano, 1999;Graziano et al, 2000;Ehrsson et al, 2004), whereas multisensory integration may occur at an "earlier stage" in the PPC (Gentile et al, 2013;Limanowski and Blankenburg, 2015a). However, a potential limitation of fMRI experiments, including our study, is their relatively low spatiotemporal resolution compared with electrophysiological recordings in monkeys.…”

Behavioral, Neural, and Computational Principles of Bodily Self-Consciousness

“…During the rubber hand illusion, however, the incongruence between tactile and visual inputs (due to the proprioceptive mismatch between the position of the real and the rubber hand, or by the appearance of the rubber hand) generates a strong prediction error, which needs to be minimized. This is done by changing predictions and modulating sensory inputs so that the proprioceptive mismatch (proprioceptive drift) and the perceptual difference between the real and the rubber hand is reduced, resulting in the new prediction that ''the rubber hand is my hand,'' thus supporting embodiment (see Limanowski and Blankenburg, 2015 for recent neuroimaging data supporting this model).…”

Mentalizing homeostasis: The social origins of interoceptive inference

“…They argued that one's body is processed in a probabilistic manner as the most likely to be "me" (see Limanowski & Blankenburg, 2015 for empirical support). Such probabilistic representations are created through the integration of top-down 'predictions' about the body and of bottom-up "prediction errors" from unimodal sensory systems that are then explained away.…”