Project

Epilepsy is a frequent chronic neurological condition affecting around 1% of the general population. It is accompanied by severe disability, related to seizures, as well as associated cognitive and psychiatric disorders. In the majority of epilepsies, seizures are initiated in one localised region of the brain (focal epilepsy) and then spread to other regions. However, epileptic activity is increasingly considered to reflect the abnormal function of a neuronal network comprising several regions rather than one single brain region. The interactions within the network allow the initiation and spread of epileptic activity. Epileptic activity affecting the brain cortex is only partially detected by scalp electroencephalography (EEG) in the form of epileptic discharges and new markers for the epileptic activity between seizures (interictal activity) are needed to achieve a better understanding of how epileptic activity affects brain functions, notably with respect to cognition.

We will investigate functional brain networks non-invasively in humans with different brain imaging techniques based on recording abnormal electrical activity of the brain: 1) Electric Source Imaging (ESI) that estimates the cerebral generators of electrical activity recorded on the scalp using high density EEG; 2) simultaneous EEG and functional magnetic resonance imaging (EEG-fMRI) that maps regions involved in epileptic activity over the whole brain. The combination of these techniques allows studying epileptic activity in the brain with a unique spatial and temporal resolution.

This project builds on our recent work that contributed to mapping the key regions involved in such networks. The first goal is to better understand the interaction between the electrical activity (EEG) and the haemodynamic changes (fMRI) (negative or early fMRI changes related to epileptic activity). The second goal is to investigate how the presence of these epileptic networks alters neuronal networks that are responsible for normal brain functions. The third goal is to understand how regions of the epileptic network interact with each other and how these interactions are modified by the occurrence of epileptic discharges.

The identification of new bio-markers of epileptic activity using multimodal imaging with high spatial and temporal resolution would help monitor disease activity and decide whether more aggressive treatment is needed in order to minimize cognitive impairment. Moreover, in selected patients with pharmaco-resistant seizures, surgical removal of a well-identified epileptic focus, sometimes after intracranial EEG recordings, can lead to seizure-freedom. A comprehensive understanding of the organisation of the epileptic network is crucial for the success of surgery.  On another level, the follow-up of patients after surgery and/or the results intracranial EEG recordings for the delineation of their epileptic focus offer a unique validation for new neuro-imaging techniques in humans.