Résumé
Difficulty in retrieving proper name (PN) is a persistent impairment characterizing various neurological conditions and leading to significant consequences on patients’ quality of life. While the role of cortical regions associated with PN retrieval process is relatively well-established, current knowledge about the underlying white matter connections remains elusive. Recently, exploratory works have suggested the involvement of the occipitotemporal connectivity, especially the left inferior longitudinal fasciculus (ILF). However, its anatomical proximity with left the uncinate fasciculus (UF) makes the exact role of left ILF difficult to dissociate, especially because of the rather limited sample of patients recruited in these works thus limiting result interpretability. In the current study, 44 patients presenting with diffuse low-grade glioma and having undergone an “awake” surgery were split into 4 subgroups, depending on the location of the surgical resection: (i) the left ILF group with spared left UF (n=8), (ii) the temporal cortex group including the temporal pole (n=8), (iii) the fronto-temporo-insular group (n=13) and (iv) the control prefrontal group (without damage to left UF) (n=15). Patients underwent a neuropsychological protocol including a specific assessment of proper name retrieval. A neurologically healthy population group underwent the same protocol in order to calibrate the proper name denomination task and to compare individual patients’ scores to normative scores. After correcting for socio-demographic and other neuropsychological variables (such as socio-educational level, age, memory, and common names naming performances and so on), the influence of which may bias the output statistical analyses, the results clearly indicate that resection of the left ILF is associated with a severe decrease in the ability to retrieve proper name compared with subgroups without damage to this pathway. Moreover, whereas 100% of patients of the ILF group showed PN retrieval deficit, only 38% of them had a deficit in common name retrieval. Taken as a whole, these findings suggest that the left ILF is a major connectivity for PN retrieval, this white matter fasciculus also contributing more occasionally to common name retrieval. This pattern of results provides new insight into the networking organization of the PN retrieval network, and are clinically useful for guiding neurorehabilitation strategies.