Decoupling between the hand territory and the default mode network after bilateral arm transplantation: four-year follow-up case study
Several studies have suggested both a local and network reorganization of the sensorimotor system following amputation. Transplantation of a new limb results in a new shifting of cortical activity in the local territory of the transplanted limb. However, there is a lack of information about the reversibility of the abnormalities at the network level. The objective of this study was to characterize the functional connectivity changes between the cortical territory of the new hand and two intrinsic network of interest: the sensorimotor network (SMN) and the default mode network (DMN) of one patient whom received bilateral forearm transplants. Using resting-state fMRI these two networks were identified across four different time points, starting four months after the transplantation surgery and during three consecutive years while the patient underwent physical rehabilitation. The topology of the SMN was disrupted at the first acquisition and over the years returned to its canonical pattern. Analysis of the DMN showed the normal topology with no significant changes across acquisitions. Functional connectivity between the missing hand’s cortical territory and the SMN increased over time. Accordingly, functional connectivity between the missing hand’s cortical territory and the DMN became anticorrelated over time. Our results suggest that after transplantation a new reorganization occurs at the network level, supporting the idea that extreme behavioral changes can affect not only the local rewiring but also the intrinsic network organization in neurologically healthy subjects. Overall this study provides new insight on the complex dynamics of brain organization.
KeywordsResting state Motor network Transplantation Hand Default mode network
Compliance with ethical standards
This study was funded by Consejo Nacional De Ciencia y Tecnologia (3157 to CRHC).
Conflict of interest
The Authors declare they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the Instituto Nacional de Neurología y Neurocirugía in Mexico City and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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