Fig. 2.

Shifted lip representation in the deprived cortex correlates with phantom limb pain (PLP). (A) Pictures illustrating the sensory stimulation applied over the thumb (top) and the lips (bottom). (B) fMRI activity during sensory stimulation applied over the intact thumb (blue), the lip on the deprived hemisphere (red) and the lip on the intact hemisphere (green) in amputees with PLP (n ​= ​10); projected to one hemisphere. The yelllow line shows a probabilistic deliniation of Broadmann areas 3b and 1 of S1. The stimulations were applied in different sessions in pseudorandomized order. The colored patches show the location of peak activity for the individual patients. The patches were sligthly enlarged (4 ​mm) for visualization purposes. The projections are carried out on a semi-inflated surface (all using surface-based analyses). C) Correlation between PLP severity (based on the Pain Intensity scale of the West Haven-Yale Multidimensional Pain Inventory adapted for PLP and Euclidean distances between the cortical representation of the thumb and the lips in the deafferented hemisphere (r ​= ​−0.79, p ​= ​0.006). These distances are measured between the lip representation (deafferented hemisphere) and intact thumb (with x-axis flipped to match the hemisphere of the lip). They are in mm and are calculated in the folded brain in standard space (i.e. standard brain). Based on HF’s unpublished data.