Connectivity of Episodic Memory Networks in Temporal Lobe Epilepsy
Abstract number :
2.196
Submission category :
5. Neuro Imaging / 5B. Functional Imaging
Year :
2022
Submission ID :
2204637
Source :
www.aesnet.org
Presentation date :
12/4/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:26 AM
Authors :
Marine Fleury, MRes – Queen Square Institute of Neurology; Sarah Buck, PhD – Postdoctoral fellow, Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Lawrence Binding, MSc – PhD Candidate, Computer Science, UCL Centre for Medical Image Computing; Lorenzo Caciagli, MD, PhD – Postdoctoral Fellow, Department of Bioengineering, UPenn Complex Systems Lab; Sjoerd Vos, PhD – Research Associate, Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Gavin Winston, MD, Professor – Honorary Associate Professor, Department of Medicine, UCL Queen Square Institute of Neurology; Pamela Thompson, Dr – Honorary Associate Professor, Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Matthias Koepp, MD, Professor – Consultant Neurologist and Professor of Neurology, Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; John Duncan, MD, Professor – Consultant Neurologist and Principal Clinical Research Fellow, Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Meneka Sidhu, MD, PhD – Consultant Neurologist and Honorary Senior Lecturer, Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology
Rationale: Temporal Lobe Epilepsy (TLE) affects brain networks and is associated with deficits in episodic memory. Anterior temporal lobe resection (ATLR) is a common surgical intervention for treating drug-refractory TLE. Functional magnetic resonance imaging (fMRI) studies have described temporal and extra-temporal reorganisation of memory functions at the local activation-level, however, network-level alterations have been under-investigated. We probed the functional anatomy of memory networks using memory fMRI and determined how this relates to post-operative memory functions in TLE._x000D_
Methods: Ninety patients with unilateral TLE (43 left) and 29 controls performed a memory-encoding fMRI paradigm of faces and words followed with out-of-scanner recognition tests. Subsequent memory event-related contrasts of words and faces remembered were generated. Psychophysiological interaction (PPI) analyses probed task-associated changes in functional connectivity seeding from the mesial temporal lobes (MTLs). We correlated changes in connectivity with clinical memory scores, epilepsy duration, age at epilepsy onset, and seizure frequency. We assessed connectivity differences between controls and TLE groups. We then correlated preoperative connectivity measures with postoperative memory outcome in 18 TLE (8 left) who underwent standard neuropsychometry (list and design learning) 3 months after ATLR. _x000D_
Results: Compared to controls, individuals with TLE showed widespread decreased connectivity between the MTLs bilaterally and frontal lobes, and increased local connectivity between the anterior MTLs bilaterally. Increased intrinsic connectivity within the bilateral MTL was associated with better out-of-scanner memory performance in both TLE groups. Longer epilepsy duration and higher seizure frequency correlated with decreased connectivity between bilateral MTLs and orbitofrontal (OFC) and left inferior frontal gyri (IFG) in RTLE. TLE with HS was associated with greater connectivity disruption within the MTL and extra-temporally. Stronger preoperative connectivity between right MTL and contra-lesional OFC and insula correlated with better verbal memory outcome 3 months after left and right-sided ATLR._x000D_
Conclusions: Connectivity analyses showed that TLE is associated with temporal and extra-temporal memory network reorganisation. Increased bilateral functional connectivity within the MTL and connectivity to the OFC and IFG is efficient, and is disrupted by longer epilepsy duration and higher seizure burden. Contralateral frontal reorganisation pre-operatively is supportive of verbal memory functions post-operatively._x000D_
Funding: National Institute for Health Research UCL Hospitals Biomedical Research Centre, UCLH BRC (grant number 229811), The Wellcome Trust (grant number 083148), The Wellcome Trust Innovation Program (106882/Z/15/Z and 218380/Z/19/Z) and the Medical Research Council (G0802012, MR/M00841X/1) support this work; Brain Research UK PhD scholarship (award 14181) supports LC; and UCLH BRC and ES supports MKS.
Neuro Imaging