Figure 1
(A) Diffusion tensor imaging (DTI) demonstrates a clear U-fibre density reduction in the left frontal area, illustrated by high signal in the colour scale. (B) Three-dimensional reconstructed brain surface created by coregistration of preoperative MRI and post-implantation CT shows placement of intracranial depth electrodes on the left hemisphere. Electrode 1 represents the innermost contact; A1-A12: left superior frontal gyrus (frontobasal, anterior); B1-B8: left superior frontal gyrus (frontobasal); C1-C10: left superior frontal gyrus (medial); D1-D8: left superior frontal gyrus (posterior); E1-E12: left middle frontal gyrus (anterior); F1-F8: left middle frontal gyrus (posterior); G1-G8: left inferior frontal gyrus; H1-H8: left anterior insula; J1-J6: left posterior insula; K1-K8: left anterior temporal lobe; L1-11: right superior frontal gyrus (frontobasal); and M1-12: right middle frontal gyrus. (C) Results of extraoperative electrical stimulation mapping (monopolar stimulation was performed with a distant reference electrode overlying non-eloquent cortex). C6-C8: continuous prolongation of a monotonous vowel extended for the duration of stimulation; D1-D7, C2-C10: tonic reaction of the right arm and shoulder and right foot; G6-G8: speech arrest during a naming task; and H2-H4, F1, C1: cessation of bilateral voluntary movements without loss of awareness (negative motor area).