Soutenance de thèse –Léa Chibany

Name: <span>Soutenance de thèse –</span>Léa Chibany
Start: 2026-12-11T10:00:00+01:00
End: 2026-12-11T10:00:00+01:00

Friday 11 December / 10:00

Venue : CARF

Thesis defended in english

IMN
Team : Network dynamics for procedural learning

Thesis directed by Jérôme Aupy

Title

Cortico-striatal dynamics during ictal motor manifestations and voluntary movement in focal epilepsy

Abstract

Focal epilepsy is increasingly understood as a network disorder that affects both cortical and subcortical structures. Seizure semiology reflects interactions between pathological discharges and distributed cortical and subcortical networks, yet how seizure discharge produces these clinical expressions remains incompletely characterized, partly because the neural mechanisms underlying typical motor control are not fully established. Research on subcortical contributions has primarily focused on the thalamus, whereas the basal ganglia remain comparatively underexplored, and the contribution of the striatum to epileptic networks remains insufficiently characterized.

In this work, we examined the putamen and its cortical connections in motor networks, first during seizures and then during voluntary movement, with stereoelectroencephalographic (SEEG) recordings in patients with drug-resistant epilepsy. Our objectives were to determine whether the putamen participates in focal seizures, to characterize its role in ictal motor expression, and to investigate the broader motor regions involved together with cortico-striatal dynamics during voluntary movement. Investigating physiological motor processing alongside helps clarify how the network’s pathological manifestations diverge from normal motor functioning.

We found that 84% of 68 focal seizures from 31 patients spread to the ipsilateral striatum, mostly late, and that striatal epileptogenicity was low. Functional connectivity between the striatum and the broader network was lowest in the background period and higher in the ictal and postictal periods, and seizures evolving into focal to bilateral tonic-clonic seizures (FBTCS) tended to show higher connectivity between the epileptogenic zone and the striatum at termination. In 19 patients, a focal, multi-band increase in insular spectral power accompanied the onset of gestural and oroalimentary automatisms, and a broader power increase including the putamen in beta, accompanied FBTCS. No region showed a significant change in coherence or imaginary coherence with the putamen for any semiology. During voluntary movement, in eight patients performing a Go/No-Go task, putamen beta power was below the resting level in every epoch and below the pre-cue level from the cue to movement completion. In all regions, high gamma increased after each task event relative to the pre-cue interval, while remaining below the level of the pre-task rest, and delta and theta increased relative to the pre-cue interval while the movement was being withheld. When compared with rest only, high gamma was higher on failed than on successful withholding, in the putamen and the Rolandic operculum.

Across the studies, the putamen is engaged in both states, with a beta decrease during voluntary movement and a beta increase during FBTCS, and the reference period or analysis window determines which effects are detected. The Rolandic operculum and the insula are the cortical regions most consistently linked to the putamen in both states. Overall, the putamen is recruited late and exhibits low epileptogenicity during seizures, but it shows semiology-dependent changes, and its physiological beta desynchronization during movement provides a reference for the interpretation of ictal findings. Understanding physiological motor processes contributes to understanding pathological ones: these observations define candidate targets, seizure phases and semiologies for future studies of striatal and basal ganglia modulation. The main limitation of this work is the heterogeneity of electrode implantation and the incomplete sampling of the motor network.