Differential Effects of Lateralization-Task and Training on Low-Frequency EEG Oscillations in Upper- and Lower-Limb Amputees.

Amputation may disrupt body schema through impairments in attentional mechanisms within the central nervous system. This study examined behavioral performance and low-frequency oscillatory (LFO) activity in individuals with upper-limb amputations (ULA), lower-limb amputations (LLA), and healthy controls (HC). Participants included six ULA (5 Male, 1 Female), nine LLA (7 Male, 2 Female), and eleven HC (8 Male, 3 Female). During electroencephalography (EEG) recording, participants performed a hand laterality task with stimuli varying in laterality (right vs. left) and angular orientation (0° vs. 180°). EEG was recorded before and after lateralization training. Accuracy was higher for stimuli presented at 0° than at 180° (p < .05), and overall accuracy significantly improved following training (p < .001). ULA exhibited slower reaction times than LLA (p < .05). EEG results showed a greater increase in delta (1.5-3 Hz) power in ULA compared with HC (p < .05). Right-hand stimuli and those presented at 0° modulated delta phase responses (p < .05). Increased theta (4-7 Hz) power and phase responses after training suggest enhanced oscillatory entrainment through attentional engagement (p < .05). Overall, behavioral and electrophysiological findings provide insight into bodily attention mechanisms in amputees and have implications for neurorehabilitation. Future studies with larger and more homogeneous samples are needed to improve generalizability and clarify underlying mechanisms.