Auditory gamma-band synchronization and attentional performance in juvenile myoclonic epilepsy

Cognitive difficulties in juvenile myoclonic epilepsy (JME) are part of the clinical phenotype alongside epileptic seizures; however, the underlying neurophysiological mechanisms remain unclear. Auditory steady-state responses (ASSRs) to repetitive 40- and 80-Hz stimuli are widely used measures of gamma-band oscillations (GBOs) relevant to cognition, but have not yet been investigated in JME. To address this gap, we examined 40- and 80-Hz ASSRs using magnetoencephalography and their relationship with cognitive function in JME.

In this cross-sectional case-control study, we recorded ASSRs in 16 patients with JME and 16 age- and sex-matched healthy controls (HC). Evoked power and phase-locking factor (PLF) were quantified from magnetic resonance imaging-based source estimates in the bilateral primary auditory cortices and compared between groups using linear mixed-effects models (LMMs). Cognitive function was assessed with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Within the JME group, associations between RBANS indices and ASSR measures were examined using age- and sex-adjusted linear regression. Where applicable, p values were adjusted using the Benjamini-Hochberg false discovery rate (FDR) procedure.

LMMs showed lower evoked power and PLF in JME than in HC (both group effects p < 0.001). Among the five RBANS indices, only the Attention Index was lower in JME (FDR-adjusted p = 0.02). Within the JME group, the Attention Index was positively associated with both measures (evoked power: B = 16.65, 95% confidence interval [CI], 5.81 to 27.49; PLF: B = 38.82, 95% CI, 13.82 to 63.83; both FDR-adjusted p = 0.03), whereas other indices showed no significant associations.

Gamma-band ASSRs were reduced in JME and were consistently associated with attentional performance across evoked power and PLF. These exploratory findings suggest that gamma-band ASSRs may help investigate network-level mechanisms, potentially involving thalamocortical dysfunction that link gamma synchronization to attentional performance in JME.

Juvenile myoclonic epilepsy (JME) is associated with cognitive difficulties beyond seizures, but the underlying brain physiology is not fully understood. Using magnetoencephalography, we found that patients with JME showed weaker gamma-band auditory steady-state responses (ASSRs) than healthy participants. Within the JME group, stronger and more synchronized responses were associated with better attention scores, suggesting that gamma-band brain activity may be linked to attentional performance in JME. Together, these findings indicate that ASSRs may provide a useful window into brain mechanisms related to cognitive difficulties, particularly those involving attention, in JME.