title: Primary motor cortex changes after amputation correlate with phantom limb pain and the ability to move the phantom limb.
abstract: A substantial body of evidence documents massive reorganization of primary sensory and motor cortices following hand amputation, the extent of which is correlated with phantom limb pain. Many therapies for phantom limb pain are based upon the idea that plastic changes after amputation are maladaptive and attempt to normalize representations of cortical areas adjacent to the hand area. Recent data suggest, however, that higher levels of phantom pain are associated with stronger local activity and more structural integrity in the missing hand area rather than with reorganization of neighbouring body parts. While these models appear to be mutually exclusive they could co-exist, and one reason for the apparent discrepancy between them might be that no single study has examined the organisation of lip, elbow, and hand movements in the same participants. In this study we thoroughly examined the 3D anatomy of the central sulcus and BOLD responses during movements of the hand, elbow, and lips using MRI techniques in 11 upper-limb amputees and 17 healthy control subjects. We observed different reorganizational patterns for all three body parts as the former hand area showed few signs of reorganization, but the lip and elbow representations reorganized and shifted towards the hand area. We also found that poorer voluntary control and higher levels of pain in the phantom limb were powerful drivers of the lip and elbow topological changes. In addition to providing further support for the maladaptative plasticity model, we demonstrate for the first time that motor capacities of the phantom limb correlate with post-amputation reorganization, and that this reorganization is not limited to the face and hand representations but also includes the proximal upper-limb.
authors: Department of Physical Medicine and Rehabilitation, Faculty of Medicine, University Jean Monnet of Saint Etienne, F-42023 Saint-Etienne, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000 Grenoble, France; Inserm, U1216, F-38000 Grenoble, France; Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark. Electronic address: estelle.raffin@ujf-grenoble.fr.
authors: Estelle
authors: E
authors: Raffin
authors: Center for Cognitive Neuroscience, UMR 5229, CNRS, Lyon, France; University Claude Bernard Lyon 1, F-69000 Lyon, France.
authors: Nathalie
authors: N
authors: Richard
authors: Department of Physical Medicine and Rehabilitation, Faculty of Medicine, University Jean Monnet of Saint Etienne, F-42023 Saint-Etienne, France.
authors: Pascal
authors: P
authors: Giraux
authors: University Claude Bernard Lyon 1, F-69000 Lyon, France; INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Centre, ImpAct Team, F-69000 Lyon, France. Electronic address: karen.reilly@inserm.fr.
authors: Karen T
authors: KT
authors: Reilly
mesh_terms: D000328:Adult; D000368:Aged; D000674:Amputees; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement / Q000502:physiology; D010591:Phantom Limb / Q000503:physiopathology*; D055815:Young Adult
keywords: Motor control; Motor cortex; Phantom movements; Phantom pain; Reorganization; fMRI