title: Reassessing cortical reorganization in the primary sensorimotor cortex following arm amputation.
abstract: The role of cortical activity in generating and abolishing chronic pain is increasingly emphasized in the clinical community. Perhaps the most striking example of this is the maladaptive plasticity theory, according to which phantom pain arises from remapping of cortically neighbouring representations (lower face) into the territory of the missing hand following amputation. This theory has been extended to a wide range of chronic pain conditions, such as complex regional pain syndrome. Yet, despite its growing popularity, the evidence to support the maladaptive plasticity theory is largely based on correlations between pain ratings and oftentimes crude measurements of cortical reorganization, with little consideration of potential contributions of other clinical factors, such as adaptive behaviour, in driving the identified brain plasticity. Here, we used a physiologically meaningful measurement of cortical reorganization to reassess its relationship to phantom pain in upper limb amputees. We identified small yet consistent shifts in lip representation contralateral to the missing hand towards, but not invading, the hand area. However, we were unable to identify any statistical relationship between cortical reorganization and phantom sensations or pain either with this measurement or with the traditional Euclidian distance measurement. Instead, we demonstrate that other factors may contribute to the observed remapping. Further research that reassesses more broadly the relationship between cortical reorganization and chronic pain is warranted.
authors.affiliation: 1 Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB Centre), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK tamar.makin@ndcn.ox.ac.uk.
authors.forename: Tamar R
authors.initials: TR
authors.lastname: Makin
authors.affiliation: 1 Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB Centre), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK 2 The Hospital for Sick Children, 555 University Avenue, Toronto M5G 1X8, Ontario, Canada.
authors.forename: Jan
authors.initials: J
authors.lastname: Scholz
authors.affiliation: 1 Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB Centre), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK 3 Oxford Centre for Enablement, Nuffield Orthopaedic Centre, Oxford OX3 7HE, UK.
authors.forename: David
authors.initials: D
authors.lastname: Henderson Slater
authors.affiliation: 1 Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB Centre), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
authors.forename: Heidi
authors.initials: H
authors.lastname: Johansen-Berg
authors.affiliation: 1 Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB Centre), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK 4 Nuffield Division Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
authors.forename: Irene
authors.initials: I
authors.lastname: Tracey
mesh_terms: D000328:Adult; D000671:Amputation, Surgical / Q000379:methods; D001132:Arm / Q000601:surgery*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D010591:Phantom Limb / Q000503:physiopathology; D066191:Sensorimotor Cortex / Q000473:pathology / Q000503:physiopathology*; D055815:Young Adult
keywords: amputees; functional MRI; pain; phantom pain; plasticity