The Long-Term Memory Network Plasticity After Anterior Temporal Lobe Resection
Abstract number :
3.238
Submission category :
5. Neuro Imaging / 5B. Functional Imaging
Year :
2023
Submission ID :
959
Source :
www.aesnet.org
Presentation date :
12/4/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: Marine Fleury, BSc, MRes – UCL Queen Square Institute of Neurology
Lawrence Binding, BSc, MSc – Ph.D. student, Department of Computer Science, UCL Centre for Medical Image Computing; Fenglai Xiao, MD, Ph.D. – Research Fellow, Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Davide Giampiccolo, MD – Ph.D. student, Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Lorenzo Caciagli, MD, Ph.D. – Research Fellow, Department of Bioengineering, University of Pennsylvania; Gavin Winston, BSc MA BMBCh PhD – Associate Professor, Department of Medicine, Queen's University, Kingston; Pamela Thompson, Ph.D. – Consultant Neuropsychologist, Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Sallie Baxendale, Ph.D. – Professor of Clinical Neuropsychology, Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; Matthias Koepp, MD, PhD, FRCP – Professor of Neurology, Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology; John Duncan, MA DM FRCP FMedSci – Principal Clinical Research Fellow, Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology,; Meneka Sidhu, MD PhD MRCP – Consultant neurologist, Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology
Rationale:
Episodic memory decline is observed in up to 40% of cases following anterior temporal lobe resection (ATLR). Functional MRI (fMRI) studies have shown reorganization of functional memory networks up to one year after ATLR, but longer-term plasticity and its impact on memory function remain underexplored. This study aims to identify biomarkers of long-term functional connectivity changes in the encoding memory network, and their relationship with changes in memory function in the longer term after ATLR.
Methods:
A memory fMRI paradigm was conducted on 25 temporal lobe epilepsy (TLE) patients undergoing ATLR (12 left-sided), and 10 healthy controls. Memory fMRI and standardized neuropsychometry were performed pre-, one year, and 10 years post-operatively in patients and similar intervals in controls. The paradigm involved word and face encoding inside the scanner, followed by an out-of-scanner recognition test. Encoded items were sorted to remembered, forgotten, and familiar accordingly. Changes in task-modulated functional connectivity of remembered items were assessed using generalized context-dependent psychophysiological interaction (gPPI) analysis. Seeds for gPPI analysis included a MTL mask (contralesional hippocampus) and a remnant MTL mask (remnant hippocampus and parahippocampal gyrus). Memory change was assessed via a reliable change index (RCI; clinically significant change). Mixed ANOVA using flexible factorial design and analyses of covariance were run to model longitudinal changes in MTL-to-whole-brain functional connectivity in TLE, over and above those seen in controls, and their relationship with memory scores from one–10 years after ATLR.
Results:
In patients who had left ATLR, verbal memory significantly improved as a group from short to long-term follow-ups (Figure 1). After right ATLR, 38% of individuals showed significant visual memory improvement, although not reaching group significance. Regardless of resection side, long-term functional plasticity involved systematic memory reorganization to the contralesional MTL. Compared to the short-term, connectivity was increased at the long-term follow-up from both MTL seeds to contralesional posterior fusiform and parahippocampal gyri, for visual and verbal memory respectively. Increased MTL seeds connectivity to contralateral fusiform and right parahippocampal gyri was associated with long-term improvement in visual and verbal memory (Figure 2, A and B).
Conclusions:
Our ROI-to-whole-brain task-based connectivity analysis revealed that plasticity in the encoding memory network continues for years after ATLR, with key connectivity changes to contralesional fusiform and parahippocampal gyri. These findings suggest potential clinical interventions such as rehabilitation years after ATLR may still be of benefit to promote long-term cognitive recovery.
Funding:
National Institute for Health Research UCLH Biomedical Research Centre (grant 229811), The Wellcome Trust (grant 083148), Wellcome Trust Innovation Program (106882/Z/15/Z, 218380/Z/19/Z) and MRC (G0802012, MR/M00841X/1) support this work.
Neuro Imaging