Modulation of cortical interhemispheric interactions by motor facilitation or restraint.
Cortical interhemispheric interactions in motor control are still poorly understood and it is important to clarify how these depend on inhibitory/facilitatory limb movements and motor expertise, as reflected by limb dominance. Here we addressed this problem using functional magnetic resonance imaging (fMRI) and a task involving dominant/nondominant limb mobilization in the presence/absence of contralateral limb restraint. In this way we could modulate excitation/deactivation of the contralateral hemisphere. Blocks of arm elevation were alternated with absent/present restraint of the contralateral limb in 17 participants. We found the expected activation of contralateral sensorimotor cortex and ipsilateral cerebellum during arm elevation. In addition, only the dominant arm elevation (hold period) was accompanied by deactivation of ipsilateral sensorimotor cortex, irrespective of presence/absence of contralateral restraint, although the latter increased deactivation. In contrast, the nondominant limb yielded absent deactivation and reduced area of contralateral activation upon restriction. Our results provide evidence for a difference in cortical communication during motor control (action facilitation/inhibition), depending on the "expertise" of the hemisphere that controls action (dominant versus nondominant). These results have relevant implications for the development of facilitation/inhibition strategies in neurorehabilitation, namely, in stroke, given that fMRI deactivations have recently been shown to reflect decreases in neural responses.
University of Lisbon, Faculty of Human Kinetics, CIPER, LBMF, 1499-002 Lisbon, Portugal ; Garcia de Orta Hospital, Pragal, 2801-951 Almada, Portugal.
Ana Cristina
AC
Vidal
Visual Neuroscience Laboratory, Institute for Biomedical Imaging in Life Sciences (IBILI), ICNAS, Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal.
Paula
0000-0001-7617-3635
P
Banca
University of Lisbon, Faculty of Human Kinetics, CIPER, LBMF, 1499-002 Lisbon, Portugal.
Augusto Gil
AG
Pascoal
Stroke Unit, Department of Neurology, Coimbra University Hospital, 3000-075 Coimbra, Portugal.
Gustavo
G
Cordeiro
Stroke Unit, Department of Neurology, Coimbra University Hospital, 3000-075 Coimbra, Portugal.
João
J
Sargento-Freitas
Garcia de Orta Hospital, Pragal, 2801-951 Almada, Portugal ; Visual Neuroscience Laboratory, Institute for Biomedical Imaging in Life Sciences (IBILI), ICNAS, Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal.
Miguel
0000-0003-4364-6373
M
Castelo-Branco
D000328:Adult; D001132:Arm / Q000502:physiology; D002540:Cerebral Cortex / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D015233:Models, Statistical; D009044:Motor Cortex / Q000502:physiology; D009068:Movement / Q000502:physiology*; D012149:Restraint, Physical; D034941:Upper Extremity / Q000502:physiology