Shahrzad Damercheli, Elektronikmaterial

Phantom limb pain (PLP) affects up to 80% of amputees, remains difficult to treat, and is often associated with maladaptive cortical reorganization. This dissertation investigates plasticity-guided interventions that target abnormal sensorimotor processing through a unified framework combining transcranial direct current stimulation (tDCS), sensory discrimination training, and phantom sensorimotor execution (imagery and active movement). First, a systematic review of PLP and tDCS literature (Article I) establishes the therapeutic potential of neuromodulation while identifying gaps in mechanistic understanding. Further, controlled experimental work in able-bodied individuals (Articles II and III) demonstrates dissociable effects of task-specific sensory training on somatosensory plasticity. Discrimination-based training improved spatial acuity (two-point discrimination) in the stimulated skin areas (p = 0.047) with effects sustained at follow-up, while the control skin areas showed delayed yet comparable improvement. In contrast, detection sensitivity (monofilament force thresholds) demonstrated short-term state changes without persistent effects, suggesting distinct plasticity mechanisms: fine spatial discrimination engages lasting receptive-field sharpening, whereas detection sensitivity reflects transient excitability modulation. Concurrently, anodal tDCS enhanced motor learning in a cross-over study (Article IV) with the non-dominant limb showing a 28% increase in motor performance completion rate (p = 0.023), indicating mechanisms relevant to prosthesis control. Building on these mechanistic insights, a clinical protocol integrating tDCS with mindful sensor and motor training (Article V) is proposed for individuals with PLP to promote durable somatosensory map refinement and evaluate pain reduction. Collectively, this work introduces an integrated neuromodulatory and behavioral framework by demonstrating how task-specific sensory training and motor training interact with sensory acuity and motor learning, respectively, and potentially alleviate PLP. Rigorous validation through a clinically balanced trial design that controls for amputation level, pain severity, and demographic factors will be essential to confirm mechanism translation and achieve targeted and lasting relief from PLP.