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Factors affecting reorganisation of memory encoding networks in temporal lobe epilepsy.

Sidhu, MK; Stretton, J; Winston, GP; Symms, M; Thompson, PJ; Koepp, MJ; Duncan, JS; (2015) Factors affecting reorganisation of memory encoding networks in temporal lobe epilepsy. Epilepsy Research , 110 1 - 9. 10.1016/j.eplepsyres.2014.11.001. Green open access

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Abstract

Aims: In temporal lobe epilepsy (TLE) due to hippocampal sclerosis reorganisation in the memory encoding network has been consistently described. Distinct areas of reorganisation have been shown to be efficient when associated with successful subsequent memory formation or inefficient when not associated with successful subsequent memory. We investigated the effect of clinical parameters that modulate memory functions: age at onset of epilepsy, epilepsy duration and seizure frequency in a large cohort of patients. / Methods: We studied 53 patients with unilateral TLE and hippocampal sclerosis (29 left). All participants performed a functional magnetic resonance imaging memory encoding paradigm of faces and words. A continuous regression analysis was used to investigate the effects of age at onset of epilepsy, epilepsy duration and seizure frequency on the activation patterns in the memory encoding network. / Results: Earlier age at onset of epilepsy was associated with left posterior hippocampus activations that were involved in successful subsequent memory formation in left hippocampal sclerosis patients. No association of age at onset of epilepsy was seen with face encoding in right hippocampal sclerosis patients. In both left hippocampal sclerosis patients during word encoding and right hippocampal sclerosis patients during face encoding, shorter duration of epilepsy and lower seizure frequency were associated with medial temporal lobe activations that were involved in successful memory formation. Longer epilepsy duration and higher seizure frequency were associated with contralateral extra-temporal activations that were not associated with successful memory formation. / Conclusion: Age at onset of epilepsy influenced verbal memory encoding in patients with TLE due to hippocampal sclerosis in the speech-dominant hemisphere. Shorter duration of epilepsy and lower seizure frequency were associated with less disruption of the efficient memory encoding network whilst longer duration and higher seizure frequency were associated with greater, inefficient, extra-temporal reorganisation.

Type: Article
Title: Factors affecting reorganisation of memory encoding networks in temporal lobe epilepsy.
Location: Netherlands
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.eplepsyres.2014.11.001
Publisher version: http://dx.doi.org/10.1016/j.eplepsyres.2014.11.001
Language: English
Additional information: © 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).
Keywords: Duration, Episodic memory, Functional MRI, Seizure frequency, Temporal lobe epilepsy
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Clinical and Experimental Epilepsy
URI: https://discovery.ucl.ac.uk/id/eprint/1462339
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