SU79. The Pathway to Hearing Voices? The Arcuate Fasciculus in Adolescents Reporting Psychotic Experiences

Amy Adair, Erik O'Hanlon
2017 Schizophrenia Bulletin  
A few studies have investigated resting-state functional connectivity (RSFC) between the cerebral cortex and cerebellar cortex in schizophrenia, but evidence on the contribution of cerebellar efferents to the striatum and cerebral cortex has been lacking. Methods: We investigated resting-state fMRI in 40 patients with their first episode of psychosis (FEP) and 40 age-and gender-matched healthy controls (HC). RSFC between cerebellar nuclei (dorsal dentate/DNd, ventral dentate/DNv, interpositus
more » ... DNv, interpositus nucleus/IN, and fastigial nucleus/FN) and striatal regions (caudate, putamen, and nucleus accumbens/NAc) was examined using a regions of interest (ROI) approach. Each ROI's unique influence to the whole brain was examined using a seed-to-voxel semipartial correlation (height P < .001 uncorrected; extent P < .05 FWE-corrected). We investigated the white matter integrity of superior cerebellar peduncle (SCP for possible structural-functional constraints), clinical ratings, and a cerebellar-sensitive cognitive measure (verbal fluency). Results: FEP patients exhibited decreased RSFC between the left FN and right putamen compared with HCs (P = .016, corrected). The strength was correlated with letter fluency performance (r = 0.36, P = .021) and global assessment of functioning (both current and past year: r = 0.38, P = .015, and r = 0.40, P = .010). At network level, patients showed relatively increased activity of the left NAc linking right-sided cerebellar nuclei (P = .035, corrected). Our unique RSFC analysis produced 3 clusters: patients showed (1) decreased RSFC between the left IN and right-sided Broca's area; (2) increased RSFC between the right DNv and left lateral frontopolar area; and (3) increased RSFC of right IN with the left inferior parietal and right premotor areas. No striatal regions produced such differences. Finally, we found significantly increased left SCP mean diffusivity in patients compared with HCs (P = .026). Conclusion: We for the first time provide evidence on disordered RSFC of left-sided cerebellar output nuclei to the striatum and neocortex at the early stage of schizophrenia. Accordingly, the integrity of left-sided cerebellar efferent fibers was lowered in patients. The relatively increased left NAc network activity would need to be investigated to test whether this represents a secondary, compensatory mechanism. Overall, we highlighted the role of cerebellar output nuclei in schizophrenia pathophysiology above and beyond striatal dysfunction.
doi:10.1093/schbul/sbx024.076 fatcat:lsgolz2qpbhjjoiezdtuabtgpm