Resting-state EEG network change in alpha and beta bands after upper limb amputation.

To investigate the reorganization of functional brain network following amputation, twenty-two right-hand amputees and twenty-four age- and education-matched controls participated in a resting-state EEG study. EEG networks in alpha and beta bands were constructed using phase synchronization. Both global and local network parameters were compared between amputees and healthy controls. In the aspect of global connectivity, amputees showed increased clustering coefficient (C), decreased characteristic path length (L) and increased small worldness (S) in alpha band, and an increase of L in beta band. Meanwhile, in comparison with the controls, the right-hand amputees have lower nodal degree (k) in the sensorimotor cortex but higher k in the parietal area in the right hemisphere in alpha band. These alterations of network following amputation implied a decreased inhibition from the intact sensorimotor area and increased connections in the right parietal area, which supported the unmasking theory. Such connectivity changes might also relate to the phantom limb phenomenon.