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. 2021 Feb 8:2021:6695530.
doi: 10.1155/2021/6695530. eCollection 2021.

Connectivity Analysis during Rubber Hand Illusion-A Pilot TMS-EEG Study in a Patient with SCI

Vanessa N Frey  1   2 , Aljoscha Thomschewski  1   2   3 , Patrick B Langthaler  1   2   3 , Alexander B Kunz  1   4 , Yvonne Höller  1   5 , Eugen Trinka  1   2   3 , Raffaele Nardone  1   2   4   6
Affiliations

Connectivity Analysis during Rubber Hand Illusion-A Pilot TMS-EEG Study in a Patient with SCI

Vanessa N Frey et al. Neural Plast. .

Abstract

Background: Bodily self-perception is an important concept for several neurological disorders, including spinal cord injury (SCI). Changing one's bodily self-perception, e.g., via rubber hand illusion (RHI), induces alterations of bottom-up and top-down pathways and with this the connectivity between involved brain areas. We aim to examine whether (1) this process can be manipulated by changing cortical excitability, (2) connectivity between relevant brain areas differ when the RHI cannot be evoked, and (3) how this projection differs in a patient with SCI.

Method: We applied RHI and facilitatory theta burst stimulation (TBS) on the right primary somatosensory cortex (S1) of 18 healthy participants and one patient with incomplete, cervical SCI. During RHI, we recorded high-density electroencephalography (HD-EEG) and extracted directed and nondirected connectivity measures.

Results: There is no difference in connectivity between sham and real TBS or in the effectivity of RHI. We observed a higher laterality in the patient, i.e., higher connectivity of the right and lower of the left hemisphere. Besides this, connectivity patterns do not differ between healthy participants and the patient.

Conclusion: This connectivity pattern might represent a neuroplastic response in the attempt to overcome the functional impairment of the patient resulting in a similar overall connectivity pattern to the healthy participants, yet with a higher sensitivity towards RHI and a higher laterality. The cortico-cortical communication was not altered depending on whether the illusion was provoked or not; hence, the perceptory illusion could not be observed in the EEG analysis.

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Conflict of interest statement

All the authors declare that they have no conflicts of interest.

Figures

Figure 1
Figure 1
Hierarchical order of the brain areas relevant in this work. EBA: extrastriate body area; S1: primary somatosensory cortex; M1: primary motor cortex; IPS: intraparietal sulcus; PMC: premotor cortex.
Figure 2
Figure 2
Four sessions with one week interval. EPT: electrical perception test; rTBS: real theta burst stimulation; sTBS: sham theta burst stimulation; rRHI: real rubber hand illusion; sRHI: sham rubber hand illusion.
Figure 3
Figure 3
Directed connectivity (ffDTF) after sham transcranial magnetic stimulation. The values show the percentile of the patients' data within the data of the control group (from 0 to 1). M1: primary motor cortex; S1: primary somatosensory cortex; EBA: extrastriate body area; PMC: premotor cortex; IPS: intraparietal sulcus; r: right; l: left.
See this image and copyright information in PMC

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