title: Somatotopic reorganization of hand representation in bilateral arm amputees with or without special foot movement skill.
abstract: Bilateral arm amputees usually are excellent foot users. To explore the plasticity of the primary motor cortex in upper-extremities amputees and to determine if the acquisition of special foot movement skill is related with the bilateral hand amputation, we studied the primary motor cortex by using combined task and resting state functional magnetic resonance imaging (fMRI). We investigated 6 bilateral arm amputees with or without special foot movement skill. In the task fMRI study, we found that toe tapping of all the amputees activated the bilateral hand area, including cases without special foot skill. In addition, cases without special foot skill mainly activated the precentral gyrus, which differed from those with more adept foot motor skill who activated both the precentral and postcentral gyri. To further understand the plasticity of the hand area, the resting state functional connectivity was investigated between the foot and hand regions. One-tailed two-sample t-test suggested that the connections between two areas became significantly stronger in the amputee group. Our study demonstrates that hand region of the cortex does not remain 'silent' after bilateral arm amputation, but rather is recruited by other modalities such as adjacent or nonadjacent cortexes to process motor information in a functionally relevant manner. From the data presented, it seems that the bilateral arm amputees have a strong potential to develop new skills in their remaining extremities and practice may further enhance this potential.
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital Affiliated to Medical College of Zhejiang University, Hangzhou 310016, Zhejiang Province, China. Electronic address: yuxiaojing7@yeah.net.
authors.forename: Xiao Jing
authors.initials: XJ
authors.lastname: Yu
authors.affiliation: Center for Brain Imaging Science and Technology, Department of BME, Zhejiang University, Hangzhou 310027, Zhejiang Province, China.
authors.forename: Hong Jian
authors.initials: HJ
authors.lastname: He
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital Affiliated to Medical College of Zhejiang University, Hangzhou 310016, Zhejiang Province, China.
authors.forename: Qiao Wei
authors.initials: QW
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital Affiliated to Medical College of Zhejiang University, Hangzhou 310016, Zhejiang Province, China; Department of Imaging and Interventional Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Department of Radiology, USC University Hospital, Los Angeles, CA 90033, USA.
authors.forename: Chi Shing
authors.initials: CS
authors.lastname: Zee
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital Affiliated to Medical College of Zhejiang University, Hangzhou 310016, Zhejiang Province, China.
authors.forename: Shi Zheng
authors.initials: SZ
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital Affiliated to Medical College of Zhejiang University, Hangzhou 310016, Zhejiang Province, China.
authors.forename: Xiang Yang
authors.initials: XY
authors.lastname: Gong
mesh_terms: D000328:Adult; D000674:Amputees; D001132:Arm / Q000502:physiology; D001931:Brain Mapping; D005528:Foot / Q000502:physiology*; D006225:Hand / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D034941:Upper Extremity / Q000502:physiology*
keywords: Amputation; Functional magnetic resonance imaging (fMRI); Nonsomatotopic; Primary motor cortex (M1); Reorganization