Functional connectivity networks are disrupted in left temporal lobe epilepsy

TLDR

Functional connectivity maps the distributed network of brain regions fluctuating synchronously during a continuous brain state. This study investigated whether patients with left temporal lobe epilepsy differ from controls in resting‑state functional connectivity between typical language regions. The authors used seeded functional connectivity in 17 left TLE patients and eight healthy controls, defining seed regions from language fMRI activation and deactivation in a separate cohort of 30 controls. Resting‑state functional connectivity between language areas was markedly reduced in left TLE patients compared to controls, with patients showing connectivity only to a few areas, especially the seed region, while language fMRI activation patterns were unchanged. Published in Annals of Neurology, 2006.

Abstract

Abstract Objective Functional connectivity maps the distributed network of brain regions fluctuating synchronously during a continuous brain state. This study sought to investigate whether patients with left temporal lobe epilepsy (TLE) differ from controls in their resting‐state functional connectivity between typical language regions. Methods We studied 17 patients with left TLE, together with eight healthy controls, using seeded functional connectivity. Seed regions were defined using the regions of maximal activation and deactivation during a language functional magnetic resonance imaging (fMRI) task in a separate cohort of 30 controls. Results Language fMRI produced the expected activation pattern, which was not different between patients and controls. However, functional connectivity between language areas during rest was markedly different; whereas controls showed connectivity between each of the seed areas and the majority of the language areas, patients showed connectivity only with a few areas, particularly the seed area itself. This difference was significant in the direct comparison of patients and control connectivity maps. Interpretation We suggest that this reduced connectivity in left temporal lobe epilepsy may reflect a disturbance of the language network during resting state in patients and may be related to subtle language difficulties in this patient population. Ann Neurol 2006