Connectomics of language

Mapping the Structural Connectivity of Language with DTI Tractography

We used functional-based DTI tractography to map the subcortical connectivity of language in healthy subjects We provided new insights into the location and inter-subject variability of eight white matter fascicles involved in language. This body of knowledge was transposed to brain tumor surgery, by using patient-specific tractography images incorporated into an intraoperative navigation to localize the functional limits of resection. The combination with transient language deficits induced by subcortical electrical stimulation mapping allowed accurate, real-time anatomofunctional correlations. The findings enhanced our comprehension of brain language organization.

Fig. 1: DTI tractography reconstruction of the language connectome in 20 healthy subjects: (blue) frontal aslant fascicle; (green) arcuate fascicle; (turquoise) anterior and (light blue) posterior segments of the superior longitudinal fascicle; (red) uncinate fascicle; (yellow) inferior fronto-occipital fascicle; (orange) inferior longitudinal fascicle; (purple) middle longitudinal fascicle.

Fig. 2: 3D rendering of fMRI clusters (red) following reading comprehension task (individual brain): fibers of the arcuate fascicle (green) directly connect the frontal and temporal language-related areas. Pars op: pars opercularis of inferior frontal gyrus; vPMC: ventral premotor cortex; STG and MTG: superior and middle temporal gyrus; SF: Sylvian fissure.

Fig. 3: Example of anatomofunctional correlation. (A) Intraoperative photograph during the removal of a left frontal glioma. Tag 27 (arrowhead) indicates the subcortical site where DES induced delayed speech planning (initiation disorder). (B and C) Intraoperative screen shot: the green cursor indicates the location where such a response was obtained, showing good correspondence with the subcortical course of the frontal aslant fascicle (turquoise).