Data from: Thalamus and focal to bilateral seizures: a multi-scale cognitive imaging study

Objective To investigate the functional correlates of recurrent
secondarily generalized seizures in temporal lobe epilepsy (TLE), using
task-based fMRI as a framework to test for epilepsy-specific network
rearrangements. As the thalamus modulates propagation of temporal-lobe
onset seizures and promotes cortical synchronization during cognition, we
hypothesized that occurrence of secondarily generalized, i.e. focal to
bilateral tonic-clonic seizures (FBTCS), would relate to thalamic
dysfunction, altered connectivity and whole-brain network centrality.
Methods FBTCS occur in a third of patients with TLE and are a major
determinant of disease severity. In this cross-sectional study, we
analyzed 113 patients with drug-resistant TLE (55 left/58 right), who
performed a verbal fluency fMRI task that elicited robust thalamic
activation. Thirty-three patients (29%) had experienced at least one FBTCS
in the year preceding the investigation. We compared patients with
TLE-FBTCS to those without FBTCS via a multi-scale approach, entailing
analysis of SPM12-derived measures of activation, task-modulated thalamic
functional connectivity (psychophysiological interaction), and
graph-theoretical metrics of centrality.  Results Individuals
with TLE-FBTCS had less task-related activation of bilateral thalamus,
with left-sided emphasis, and left hippocampus than those without FBTCS.
In TLE-FBTCS, we also found greater task-related thalamotemporal and
thalamo-motor connectivity, and higher thalamic degree and betweenness
centrality. Receiver operating characteristic curves, based on a combined
thalamic functional marker, accurately discriminated individuals with and
without FBTCS. Conclusions In TLE-FBTCS, impaired task-related thalamic
recruitment coexists with enhanced thalamotemporal connectivity and
whole-brain thalamic network embedding. Altered thalamic functional
profiles are proposed as imaging biomarkers of active secondary
generalization.