Where in the Brain is "the Other's" Hand? Mapping Dysfunctional Neural Networks in Somatoparaphrenia. (10th November 2021)

• Record Type: Journal Article
• Authors: Saetta, Gianluca; Michels, Lars; Brugger, Peter
• Is Part Of: Neuroscience. Volume 476(2021)
• Page Start: 21
• Page End: 33
• Publication Date: 2021-11-10
• Subjects: somatoparaphrenia -- fMRI -- rs-fMRI -- interhemisperic disconnection -- motor imagery -- opercular part of the right inferior frontal gyrus; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2021.09.007
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Limb misattribution in somatoparaphrenia is linked to the activity of the right inferior frontal gyrus, pars opercularis (rIFG). The rIFG resting-state activity negatively correlated with that of the Broca area and the left temporo-parietal junction. The affected right limb resting-state somatosensory network was functionally disconnected from the left SII. Limb disownership and misattribution might be due to a deficit of multisensory integration in the brain. Delusional disownership may relate to functional disconnection of language areas from areas representing the left hemibody. Abstract: Somatoparaphrenia refers to the delusional belief, typically observed in right brain-damaged patients, that the contralesional limbs belong to someone else. Here, we aimed to uncover the neural activity associated with this productive, i.e. confabulatory, component in a patient, S.P.P., with a large right-sided lesion of both cortical and subcortical gray and white matter. He claimed that his left paralyzed hand belonged to his mother. In a block-design functional magnetic resonance (fMRI) experiment, S.P.P. imagined that the mother would move her (i.e. his left) hand (condition "mother"). Subtraction of the activity elicited by control conditions (imagery of self-generated movement of either left or right hand) from that in the "mother" condition resulted in the focal activation of the pars opercularis of the right inferior frontal gyrus (rIFG). In a separate, resting-state fMRI experiment with S.P.P. and 21 healthy controls, we examined the functional connectivity of the rIFG and the affected hand somatosensory network to the rest of the brain. We found a negative correlation between the activity in the rIFG and that of Broca area and the temporo-parietal junction in the left hemisphere. Furthermore, the affected hand somatosensory network was disconnected from the left secondary somatosensory cortex. Our results link the productive component of somatoparaphrenia to the activity of crucial hubs for integrating the multimodal signals of the affected hand. Furthermore, they provide the first direct evidence supporting the "left narrator model", proposed by Halligan et al. (1995), according to which the confabulations of somatoparaphrenia are due to a disconnection of left hemisphere language areas from right hemisphere parieto-temporal cortex.