Long-term proper name anomia after removal of the uncinate fasciculus

Abstract

The functional organization of left and right hemispheres is different, and hemispheric asymmetries are thought to underlie variations in brain function across individuals. In this study, we assess how differences between hemispheres are reflected in Asymmetric Functional Connectivity (AFC), which provides a full description of how the brain's connectivity structure during resting state differs from that of the same brain mirrored over the longitudinal fissure. In addition, we assess how AFC varies across subjects. Data were provided by the Human Connectome Project, including 423 resting state and combined language task fMRI data sets, and the pattern of AFC was established for all subjects. While we could quantify the symmetry of brain connectivity at 95%, significant asymmetries were observed, consisting foremost of: (1) higher correlations between language areas in the left hemisphere than between their right hemisphere homologues. (2) Higher correlations between language homologue areas in the right hemisphere and left default mode network, than between language areas in the left hemisphere and the default mode network in the right hemisphere. The extent to which subjects exhibited this pattern correlated with language lateralization and handedness. Further exploration in intersubject variation in AFC revealed several additional patterns, one involving entire hemispheres, and another correlations with limbic areas. These results show that language is an important, but not only determinant of AFC. The additional patterns of AFC require further research to be linked to specific asymmetric neuronal states or events.

A Novel Technique for Region and Linguistic Specific nTMS-based DTI Fiber Tracking of Language Pathways in Brain Tumor Patients

“…Yet, such a distribution can be attributed to the role of the UF in the semantic processing (Dick and Tremblay, 2012; Chang et al, 2015) and in the proper name retrieval process (Papagno, 2011). Therefore, if semantic connections reflect its role in the ventral stream, hesitation and no response errors could be interpreted as an expression of anomia, that has been reported as a consequence of UF resection or damage (Papagno et al, 2011, 2016). These data further increased our confidence in the nTMS-based approach.…”

Inter-individual variation in fronto-temporal connectivity predicts the ability to learn different types of associations

“…Studies conducted on patients during awake neurosurgery for left lateralized gliomas have demonstrated that removal of the UF leads to severe impairment in the ability to retrieve the names of famous faces, both post-surgery and at a 3 month follow-up (Papagno et al, 2011). In a recent extension by the same research group, proper naming deficits remained 12 months post-surgery (Papagno et al, 2014). Similar findings have been reported in other laboratories and replicated across different techniques (Damasio, Grabowski, Tranel, Hichwa, & Damasio, 1996; Drane et al, 2008; Grabowski et al, 2001; Nomura et al, 2013; Tranel, Damasio, & Damasio, 1997), suggesting a robust link between proper name retrieval and the UF.…”

Individual differences in white matter microstructure predict semantic control

“…It has been hypothesized that the UF is part of the ventral language pathway, supporting object naming by relaying sensory information about objects, processed in the ventral temporal cortex, to language regions in the inferior-lateral frontal lobes (Papagno et al, 2014a). Evidence for this view is mixed.…”