Job ID: 119162
PhD Student: Classification of epileptic signals and its relation to navigational behavior in a virtual environment
Position: Ph.D. Student
Deadline: 30 June 2024
Employment Start Date: 1 October 2024
Contract Length: 3 years
City: Paris
Country: France
Institution: Sorbonne Université
Department: Neuroscience Paris Seine - IBPS
Description:
The objective of this thesis project is to assess the potential link between epileptic activity observed in intracerebral EEG and a navigation task performed in a virtual environment.
Epileptic patients with focal epilepsy starting in the hippocampus have memory problems, including difficulties in forming new memories [1]. In addition, studies have revealed a close relationship between the hippocampus, spatial representation, and navigation strategy, highlighting the importance of this brain region in navigation and spatial orientation [2, 3]. This project aims to investigate how epileptic activity (ictal discharges and interictal activity) affects or is modulated by navigation processes in order to better understand the links between epilepsy, memory and navigation.
First, the work will consist in analyzing intracranial electrophysiological recordings (sEEG) in patients implanted as part of a pre-surgical diagnosis in order to classify and quantify the different epileptic activities. In addition, microelectrodes implanted in the hippocampus allow to record action potentials and to isolate the activity of individual neurons by subsequent spike sorting. Thus, a first part of the work will be to characterize epileptic activity not only at the level of local field potentials, but also at the level of unit activity, using various algorithms, including machine learning methods (see [4]).
Second, we will investigate the relationship between epileptic activity and oculomotor and spatial orientation behavior recorded during a navigation task in a virtual environment. In each patient, we aim to correlate the occurrence of these different types of epileptic activity with specific trial-level behaviors (success, strategy choice) or on a finer time scale (e.g., changes in oculomotor activity, changes in speed in the virtual environment during a trial).
We will also seek to determine, at the patient group level, whether there are reproducible patterns linking specific types of epileptic activity (identified in terms of localization, frequency, power, duration, etc.) to specific types of behaviors or deficits. Given that a recent study has demonstrated an impact of sex on theta rhythm and spatial performance has been demonstrated in a recent study [5], we will specifically test the effect of sex on potential vulnerability to spatial orientation and navigation deficits in epilepsy.
Ultimately, this project aims to automatically identify different types of epileptic activity and behaviors associated with them. This could lead to the characterization of new behavioral indicators of the pathology and its evolution. Conversely, the detection of specific epileptic activities could help to predict certain deficits and improve patient care management.
[1] Fadaie F, Lee HM, Caldairou B, Gill RS, Sziklas V, Crane J, Bernhardt BC, Hong SJ, Bernasconi A, Bernasconi N. Atypical functional connectome hierarchy impacts cognition in temporal lobe epilepsy. Epilepsia (2021) 11:2589-2603. doi: 10.1111/epi.17032. [2] Igloi K, Doeller CF, Paradis AL, Benchenane K, Berthoz A, Burgess N & Rondi-Reig L (2015). Interaction Between Hippocampus and Cerebellum Crus I in Sequence-Based but not Place-Based Navigation. Cerebral Cortex 25(11): 4146-54. DOI: 10.1093/cercor/bhu132. [3] Goodroe SC, Starnes J, Brown TI (2018) The Complex Nature of Hippocampal-Striatal Interactions in Spatial Navigation. Front Hum Neurosci 250. [4] Cousyn L, Dono F, Navarro V, Chavez M. Can heart rate variability identify a high-risk state of upcoming seizure? Epilepsy Res. 2023 Nov;197:107232. doi: 10.1016/j.eplepsyres.2023.107232. Epub 2023 Sep 22. PMID: 37783038. [5] Pu Y, Cornwell BR, Cheyne D, Johnson BW (2020) Gender differences in navigation performance are associated with differential theta and high-gamma activities in the hippocampus and parahippocampus. Behav. Brain Res. 391