Theta Power and Phase Connectivity During Verbal Memory Processes in Idiopathic Generalized Epilepsy
Abstract number :
3.103
Submission category :
11. Behavior/Neuropsychology/Language / 11A. Adult
Year :
2024
Submission ID :
358
Source :
www.aesnet.org
Presentation date :
12/9/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Yun Lien, MSc – University of Alabama at Birmingham
Jerzy Szaflarski, MD, PhD – University of Alabama
Lawrence Ver Hoef, MD – The University of Alabama at Birmingham
Anna Moyana, BS – University of Alabama at Birmingham
Jennifer Pilkington, BS – University of Alabama at Birmingham
Brandon Mitchell, BS – University of Alabama at Birmingham
Roy Martin, PhD – University of Alabama at Birmingham
Jane B. Allendorfer, PhD – University of Alabama at Birmingham
Rationale: Adults with idiopathic generalized epilepsy (IGEs) often exhibit cognitive impairments, but research has shown inconsistent verbal memory results. Some found impaired verbal working memory in IGEs compared to controls, while others found cognitive dysfunction but not in verbal memory. Further, there is neuroimaging evidence for altered memory-related functional networks, particularly for medial frontal areas, in IGEs compared to controls. However, few have investigated the functional connectivity during memory processing in IGEs with electroencephalography (EEG). In this study, we focused on theta frequency (4-8 Hz), which is involved in learning and memory. We hypothesized differences in theta power and phase connectivity between different aspects of verbal memory in IGEs.
Methods: Fifteen adults with clinician-confirmed IGE diagnosis (9 males; mean age±SD of 29±8 years) were administered the California Verbal Learning Test (CVLT-II) while undergoing EEG using CURRY7 (NeuroScan Compumedics). Participants were aurally presented a list of words and instructed to recall them during learning trials (Learning), after an interference list (short delay free recall (SDFR)), and after 20 minutes (long delay free recall (LDFR)). EEG data were recorded from 63 active channels (Cz as reference) and continuously sampled at 1000 Hz. Start and end times for Learning, SDFR, and LDFR were marked during EEG acquisition. EEG data were analyzed using EEGLAB (ver. 2024.0). Bandpass filters were utilized to isolate theta waves. Hilbert transform was applied to determine the theta power and phase. Left (L), right (R), and medial regions of interest (ROIs) were defined: L dorsolateral prefrontal cortex (LDLPFC; F3,5,7), RDLPFC (F4,6,8), L inferior frontal gyrus (LIFG; F11, FT11), RIFG (F12, FT12), L temporal (LT; T7, TP7, P7), R temporal (RT; T8, TP8, P8), medial prefrontal (MPF; Fz, F1-2), central (C; Cz, C1-4), frontocentral (FC; FCz, FC1-4), and parietal (P; Pz, P1-4, CPz, CP1-4). Phase lag index (PLI) was used to measure the phase connectivity between ROIs. SDFR and LDFR T-scores were compared to assess memory performance differences. Theta power and PLI for SDFR and LDFR were compared to Learning periods to assess differences in verbal memory retrieval versus encoding.
Results: SDFR and LDFR scores were not significantly different (p=0.076). Theta power significantly decreased in RDLPFC (p=0.038), LIFG (p=0.045), LT (p=0.012), RT (p=0.007), MPF (p=0.032), FC (p=0.009), central (p=0.005), and parietal (p=0.016) areas during LDFR compared to Learning. PLI was significantly decreased in MPF-RT connectivity (p=0.045) during SDFR compared to Learning and significantly increased in MPF-parietal (p=0.048), MPF-LT (p=0.03), MPF-RT (p=0.044), and MPF-LIFG (p=0.036) connectivity during LDFR compared to SDFR.
Conclusions: Our results suggest involvement of theta oscillations in memory retrieval after a long delay. Theta phase connectivity differences, particularly between short- and long-delay recall, provide support for a critical role of medial prefrontal areas during memory retrieval processes in IGEs.
Funding: This work was supported by NIH R01HD102723 to JBA
Behavior