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

TITLE=Plasticity of face–hand sensorimotor circuits after a traumatic brachial plexus injury

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 17 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1221777

DOI=10.3389/fnins.2023.1221777

ISSN=1662-453X

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 an 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 handhand SAI was present in both the CG and the TBPI group, 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.Our results indicate that sensorimotor integration involving both hand and face sensorimotor representations are affected by TBPI.