My Account

Poster A50, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall

GEREC protocol for interactive mapping of language and memory processes in temporal lobe epilepsy

Sonja Banjac1, Elise Roger1, Emilie Cousin1,2, Marcela Perrone-Bertolotti1, Cédric Pichat1,2, Laurent Lamalle2, Lorella Minotti3, Philippe Kahane3, Monica Baciu1;1Université Grenoble Alpes, CNRS LPNC UMR 5105, 2Université Grenoble Alpes, UMS IRMaGe CHU Grenoble, 3Université Grenoble Alpes, GIN ‘Synchronisation et modulation des réseaux neuronaux dans l'épilepsie’ & Neurology Department

Introduction: In patients with temporal lobe epilepsy (TLE) the benefit of temporal surgery must be carefully evaluated taking into consideration the risk of inducing the impairments since surgery can lead to postoperative memory (Baxendale et al., 2006) and language deficits (Davies et al., 1998). A number of protocols have been proposed for evaluating language and memory preoperatively in these patients (e.g. Aldenkamp et al., 2003), however, they tested language and memory separately. Considering that mesial temporal regions are implied in both of these processes, it should be essential to evaluate the neural basis of language-and-memory jointly in TLE patients that are being considered for surgery. The present protocol was designed to do so. Methods: The GEREC protocol consists of three runs: (1) block-based run, Generation (GE), during which participants should covertly generate a sentence after hearing a word; (2) event-based run, Recognition (REC), during which, after being presented with an image, participants respond whether they have heard the object from the picture in the first run or not; and (3) block-based run, Recall (RA), in which participants should, after hearing the same words from the first run, remember and covertly generate the same sentences they did in the GE. The GE and RA runs are designed to activate intermixed language-and-memory network by engaging episodic memory encoding and retrieval respectively. Moreover, the protocol is ecological and adapted to patients (easy to perform and has a short duration). Before using it with patients, the protocol needs to be tested in healthy participants, which is the objective of this work. Twenty healthy adults aged 18 to 30 completed the experimental protocol. The fMRI data were acquired at 3T and the manufacturer-provided gradient-echo/T2* weighted EPI method was used. Images were first spatially pre-processed. Results: The statistical analyses revealed that GE run (P<0.05, FWE-corrected) activated the expected frontotemporal network including left inferior frontal, bilateral middle and superior temporal regions and temporal pole as well as the contralateral cerebellum, specifically 6 and Crus 1. Encoding activated (P<0.001, uncorrected) left hippocampus and middle temporal gyrus. Initially designed as a memory task, REC activated (P<0.05, FWE-corrected) a large language-and-memory network, including bilateral inferior ocipito-temporal, left parietal and hippocampal regions, but also the left frontal inferior, bilateral SMA and cerebellum. It could be that, despite not being explicitly instructed to do so, when seeing the images, participants automatically performed picture naming. The RA run, on the other hand, activated (P<0.05, FWE-corrected) more strongly the language network consisting of left frontal inferior and bilateral temporal regions. Conclusion: Our findings support the utility of GEREC protocol for mapping a shared language-and-memory network. The main intention of this protocol is to reliably map this network in patients with TLE and, in conjunction with the results of neuropsychological testing, it can provide valuable information for planning the reconstructive surgery. Finally, it can also be considered as a practical foundation for exploration of language and memory interconnection.

Themes: Methods, Language Production
Method: Functional Imaging

Back