Plasticity of face-hand sensorimotor circuits after a traumatic brachial plexus injury

Fernanda de Figueiredo Torres; Bia Lima Ramalho; Marcelle Ribeiro Rodrigues; Ana Carolina Schmaedeke; Victor Hugo Moraes; Karen T Reilly; Raquel de Paula Carvalho; Claudia D Vargas

doi:10.3389/fnins.2023.1221777

Plasticity of face-hand sensorimotor circuits after a traumatic brachial plexus injury

Front Neurosci. 2023 Aug 7:17:1221777. doi: 10.3389/fnins.2023.1221777. eCollection 2023.

Authors

Fernanda de Figueiredo Torres^{1

2}, Bia Lima Ramalho^{1

2

3}, Marcelle Ribeiro Rodrigues^{1

2}, Ana Carolina Schmaedeke^{1

2}, Victor Hugo Moraes^{1

2}, Karen T Reilly^{4

5}, Raquel de Paula Carvalho^{2

3

6}, Claudia D Vargas^{1

2

3}

Affiliations

¹ Laboratory of Neurobiology of Movement, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
² Laboratory of Neuroscience and Rehabilitation, Institute of Neurology Deolindo Couto, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
³ Research, Innovation and Dissemination Center for Neuromathematics, Institute of Mathematics and Statistics, University of São Paulo, São Paulo, Brazil.
⁴ Trajectoires Team, Lyon Neuroscience Research Center, Lyon, France.
⁵ University UCBL Lyon 1, University of Lyon, Lyon, France.
⁶ Laboratory of Child Development and Motricity, Department of Human Movement Science, Institute of Health and Society, Universidade Federal de São Paulo, Santos, Brazil.

Abstract

Background: Interactions between the somatosensory and motor cortices are of fundamental importance for motor control. Although physically distant, face and hand representations are side by side in the sensorimotor cortex and interact functionally. Traumatic brachial plexus injury (TBPI) interferes with upper limb sensorimotor function, causes bilateral cortical reorganization, and is associated with chronic pain. Thus, TBPI may affect sensorimotor interactions between face and hand representations.

Objective: The aim of this study was to investigate changes in hand-hand and face-hand sensorimotor integration in TBPI patients using an afferent inhibition (AI) paradigm.

Method: The experimental design consisted of electrical stimulation (ES) applied to the hand or face followed by transcranial magnetic stimulation (TMS) to the primary motor cortex to activate a hand muscle representation. In the AI paradigm, the motor evoked potential (MEP) in a target muscle is significantly reduced when preceded by an ES at short-latency (SAI) or long-latency (LAI) interstimulus intervals. We tested 18 healthy adults (control group, CG), evaluated on the dominant upper limb, and nine TBPI patients, evaluated on the injured or the uninjured limb. A detailed clinical evaluation complemented the physiological investigation.

Results: Although hand-hand SAI was present in both the CG and the TBPI groups, hand-hand LAI was present in the CG only. Moreover, less AI was observed in TBPI patients than the CG both for face-hand SAI and LAI.

Conclusion: Our results indicate that sensorimotor integration involving both hand and face sensorimotor representations is affected by TBPI.

Keywords: afferent inhibition; brachial plexus lesion; corticospinal excitability; deafferentation; pain; transcranial magnetic stimulation.

Grants and funding

This study was part of the Research, Innovation, and Diffusion in Neuromathematics project (CEPID NeuroMat, FAPESP 2013/07699-0) and the Brain Plasticity after Brachial Plexus Injury projects (FAPERJ E-26/010.002474/2016, CNE 202.785/2018, and E-26/010.002418/2019). It received funding from FINEP (PROINFRA HOSPITALAR 18.569-8). This research was also supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq (grant number 310397/2021). FT was supported by a doctoral grant (CAPES 88882.332096/2019-01) and a postdoctoral grant (FAPERJ E-26/200.214/2022). BR was supported by a FAPESP grant (#2022/00582-9).