Causal Dynamics of Scalp Electroencephalography Oscillation During the Rubber Hand Illusion.
Rubber hand illusion (RHI) is an important phenomenon for the investigation of body ownership and self/other distinction. The illusion is promoted by the spatial and temporal contingencies of visual inputs near a fake hand and physical touches to the real hand. The neural basis of this phenomenon is not fully understood. We hypothesized that the RHI is associated with a fronto-parietal circuit, and the goal of this study was to determine the dynamics of neural oscillation associated with this phenomenon. We measured electroencephalography while delivering spatially congruent/incongruent visuo-tactile stimulations to fake and real hands. We applied time-frequency analyses and calculated renormalized partial directed coherence (rPDC) to examine cortical dynamics during the bodily illusion. When visuo-tactile stimulation was spatially congruent, and the fake and real hands were aligned, we observed a reduced causal relationship from the medial frontal to the parietal regions with respect to baseline, around 200 ms post-stimulus. This change in rPDC was negatively correlated with a subjective report of the RHI intensity. Moreover, we observed a link between the proprioceptive drift and an increased causal relationship from the parietal cortex to the right somatosensory cortex during a relatively late period (550-750 ms post-stimulus). These findings suggest a two-stage process in which (1) reduced influence from the medial frontal regions over the parietal areas unlocks the mechanisms that preserve body integrity, allowing RHI to emerge; and (2) information processed at the parietal cortex is back-projected to the somatosensory cortex contralateral to the real hand, inducing proprioceptive drift.
Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami, Hiroshima, 734-8551, Japan. nkanayama@hiroshima-u.ac.jp.
Noriaki
N
Kanayama
Department of Psychology and Cognitive Science, University of Trento, Rovereto, Italy.
Alberto
A
Morandi
Department of General Systems Studies in Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo, 153-8902, Japan.
Kazuo
K
Hiraki
Department of Psychology and Cognitive Science, University of Trento, Rovereto, Italy.|Centre for Mind/Brain Sciences, University of Trento, Rovereto, Italy.
Francesco
F
Pavani
D000328:Adult; D001828:Body Image; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007088:Illusions / Q000502:physiology*; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D012535:Scalp / Q000502:physiology; D055698:Touch Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
Body ownership; Causal relationship; Electroencephalography; Rubber hand illusion