Evaluation of brain plasticity in limb and tissue losses with fmrg

This thesis evaluated the cortical plasticity processes occurring in the human brain following tissue and limb loss, utilizing functional magnetic resonance imaging (fMRI). The study included several patient groups: 3 individuals with face transplantation, 2 with bilateral arm transplantation, 5 with facial lesions, 2 who underwent replantation, 4 with congenital limb deficiency, 13 with peripheral nerve blockade, and 5 with lower extremity amputation. Additionally, two control groups, each consisting of 10 healthy individuals, were evaluated for sensory tasks and lower extremity tasks, respectively. All data underwent standard preprocessing steps using SPM12 software, including alignment, normalization, and smoothing, and were then analyzed with a general linear model. Subsequently, activation maps were generated after statistical thresholding. Individual maps were then used to determine group-level activations and were comparatively interpreted using the Human Motor Area Template and an anatomical labeling atlas. The results indicated that in individuals who underwent transplantation, cortical representations were reorganized, and this process was shaped by both usage experience and the rehabilitation process. For individuals who had replantation, plasticity was observed to gradually approach classical sensorimotor organization over time. In those with congenital limb deficiency, facial representations were found to expand into hand areas. Even when movement was inhibited in individuals subjected to peripheral blockade, an increase in activity was observed in certain cortical areas; this particularly highlighted the functions of premotor and parietal areas related to movement intention. In individuals with lower extremity amputation, cortical activity was found to deviate from classical foot representations, spreading to wider areas. Additionally, motor imagery tasks in this group produced significant activations similar to those in the control group. These findings reveal that cortical plasticity is a dynamic process that is reshaped not only structurally but also functionally and experientially. These results provide a scientific basis for the individualization of neurorehabilitation applications and the development of brain-computer interface systems.