Upper limb cortical maps in amputees with targeted muscle and sensory reinnervation

Andrea Serino, Michel Akselrod, Roy Salomon, Roberto Martuzzi, Maria Laura Blefari, Elisa Canzoneri, Giulio Rognini, W. Van der Zwaag, Maria Iakova, François Luthi, Amedeo Amoresano, Todd Kuiken, Olaf Blanke

Research output: Contribution to journal/periodicalArticleScientificpeer-review

Abstract

Neuroprosthetics research in amputee patients aims at developing new prostheses that move and feel like real limbs. Targeted muscle and sensory reinnervation (TMSR) is such an approach and consists of rerouting motor and sensory nerves from the residual limb towards intact muscles and skin regions. Movement of the myoelectric prosthesis is enabled via decoded electromyography activity from reinnervated muscles and touch sensation on the missing limb is enabled by stimulation of the reinnervated skin areas. Here we ask whether and how motor control and redirected somatosensory stimulation provided via TMSR affected the maps of the upper limb in primary motor (M1) and primary somatosensory (S1) cortex, as well as their functional connections. To this aim, we tested three TMSR patients and investigated the extent, strength, and topographical organization of the missing limb and several control body regions in M1 and S1 at ultra high-field (7 T) functional magnetic resonance imaging. Additionally, we analysed the functional connectivity between M1 and S1 and of both these regions with fronto-parietal regions, known to be important for multisensory upper limb processing. These data were compared with those of control amputee patients (n = 6) and healthy controls (n = 12). We found that M1 maps of the amputated limb in TMSR patients were similar in terms of extent, strength, and topography to healthy controls and different from non-TMSR patients. S1 maps of TMSR patients were also more similar to normal conditions in terms of topographical organization and extent, as compared to non-targeted muscle and sensory reinnervation patients, but weaker in activation strength compared to healthy controls. Functional connectivity in TMSR patients between upper limb maps in M1 and S1 was comparable with healthy controls, while being reduced in non-TMSR patients. However, connectivity was reduced between S1 and fronto-parietal regions, in both the TMSR and non-TMSR patients with respect to healthy controls. This was associated with the absence of a well-established multisensory effect (visual enhancement of touch) in TMSR patients. Collectively, these results show how M1 and S1 process signals related to movement and touch are enabled by targeted muscle and sensory reinnervation. Moreover, they suggest that TMSR may counteract maladaptive cortical plasticity typically found after limb loss, in M1, partially in S1, and in their mutual connectivity. The lack of multisensory interaction in the present data suggests that further engineering advances are necessary (e.g. the integration of somatosensory feedback into current prostheses) to enable prostheses that move and feel as real limbs.

Original languageEnglish
Pages (from-to)2993-3011
Number of pages19
JournalBrain
Volume140
Issue number11
DOIs
Publication statusPublished - 01 Nov 2017

Keywords

  • Adult
  • Aged
  • Amputation
  • Artificial Limbs
  • Brain Mapping
  • Electromyography
  • Female
  • Functional Neuroimaging
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Motor Cortex
  • Movement
  • Muscle, Skeletal
  • Neuronal Plasticity
  • Skin
  • Somatosensory Cortex
  • Touch
  • Upper Extremity
  • Journal Article

Fingerprint Dive into the research topics of 'Upper limb cortical maps in amputees with targeted muscle and sensory reinnervation'. Together they form a unique fingerprint.

  • Cite this

    Serino, A., Akselrod, M., Salomon, R., Martuzzi, R., Blefari, M. L., Canzoneri, E., Rognini, G., Van der Zwaag, W., Iakova, M., Luthi, F., Amoresano, A., Kuiken, T., & Blanke, O. (2017). Upper limb cortical maps in amputees with targeted muscle and sensory reinnervation. Brain, 140(11), 2993-3011. https://doi.org/10.1093/brain/awx242