Abstract
We used functional magnetic resonance imaging to investigate how causal influences between brain regions during the rubber hand illusion (RHI) are modulated by tactile and visual stimuli. We applied needle rotations during the RHI in two different ways: one was with the real hand (reinstantiation by tactile stimuli, R-TS) and the other was with the rubber hand (reinstantiation by visual stimuli, R-VS). We used dynamic causal modeling to investigate interactions among four relevant brain regions: the ventral premotor cortex (PMv), the intraparietal sulcus (IPS), the secondary somatosensory cortex (SII), and the lateral occipitotemporal cortex (LOC). The tactile aspects of needle rotations changed the effective connectivity by directly influencing activity in the SII, whereas visual aspects of needle rotation changed the effective connectivity by influencing both the SII and the LOC. The endogenous connectivity parameters between the IPS and the PMv were reduced significantly in the R-TS condition. The modulatory parameters between the IPS and the PMv were enhanced significantly in the R-TS condition. The connectivity patterns driven by disowned bodily states could be differentially modulated by tactile and visual afferent inputs. Effective connectivity between the parietal and frontal multimodal areas may play important roles in the reinstantiation of body ownership.
Highlights
The “rubber hand illusion” (RHI) is an experimental paradigm that can manipulate body ownership via congruent touching on the rubber hand and the subject’s real hand [1]
Several functional magnetic resonance imaging studies have demonstrated that the illusory body ownership during the RHI was highly associated with the parietal and frontal multimodal areas [2, 3] and the lateral occipitotemporal cortex (LOC) [4]
Limanowski and Blankenburg used dynamic causal modeling (DCM) and revealed the effective connectivity underlying the illusory self-attribution of the rubber hand among four relevant brain regions: the ventral premotor cortex (PMv), the intraparietal sulcus (IPS), the secondary somatosensory cortex (SII), and the LOC [5]
Summary
The “rubber hand illusion” (RHI) is an experimental paradigm that can manipulate body ownership via congruent touching on the rubber hand and the subject’s real hand [1]. Illusory body ownership during the RHI is known to induce a disowned bodily state for the subject’s own hand. Neural Plasticity integration as the key mechanism underlying self-attribution of the body [9], we propose two plausible reinstantiation methods from the disowned bodily states: one involves novel tactile information from the real hand and the other involves novel visual information about the artificial hand. When needle rotations are provided to the real hand as tactile stimuli, the subject could recover from the disowned bodily state with direct tactile information from his/her own body [11]. When needle rotations are provided to the rubber hand as visual stimuli, the subject may recover from the disowned bodily state because visual information from the rubber hand does not correspond to tactile input from the real hand [13]. Using DCM, we conducted a data-driven estimation of the effective connectivity (causal influence of the activities of certain brain regions on the activities of others), including endogenous connectivity (endogenous connectivity strength independent of experimental condition), and its changes (modulatory effects), under experimental conditions (driving input) between brain regions
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