Interhemispheric transfer of post-amputation cortical plasticity within the human somatosensory cortex
Kenneth F. Valyear,
Benjamin A. Philip,
Carmen M. Cirstea,
Pin-Wei Chen,
Nathan A. Baune,
Noah Marchal,
Scott H. Frey
Affiliations
Kenneth F. Valyear
Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; School of Psychology, Bangor University, Bangor, UK
Benjamin A. Philip
Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, USA
Carmen M. Cirstea
Department of Physical Medicine and Rehabilitation, University of Missouri School of Medicine, Columbia, MO, USA
Pin-Wei Chen
Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, USA
Nathan A. Baune
Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, USA
Noah Marchal
Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; College of Engineering, University of Missouri, Columbia, MO, USA
Scott H. Frey
Department of Psychological Sciences, University of Missouri, Columbia, MO, USA; Department of Physical Medicine and Rehabilitation, University of Missouri School of Medicine, Columbia, MO, USA; Corresponding author. University of Missouri, Department of Psychological Sciences, McAlester Hall, Columbia, MO, 65211, USA.
Animal models reveal that deafferenting forelimb injuries precipitate reorganization in both contralateral and ipsilateral somatosensory cortices. The functional significance and duration of these effects are unknown, and it is unclear whether they also occur in injured humans. We delivered cutaneous stimulation during functional magnetic resonance imaging (fMRI) to map the sensory cortical representation of the intact hand and lower face in a group of chronic, unilateral, upper extremity amputees (N = 19) and healthy matched controls (N = 29). Amputees exhibited greater activity than controls within the deafferented former sensory hand territory (S1f) during stimulation of the intact hand, but not of the lower face. Despite this cortical reorganization, amputees did not differ from controls in tactile acuity on their intact hands. S1f responses during hand stimulation were unrelated to tactile acuity, pain, prosthesis usage, or time since amputation. These effects appeared specific to the deafferented somatosensory modality, as fMRI visual mapping paradigm failed to detect any differences between groups. We conclude that S1f becomes responsive to cutaneous stimulation of the intact hand of amputees, and that this modality-specific reorganizational change persists for many years, if not indefinitely. The functional relevance of these changes, if any, remains unknown.
