Task-Evoked Theta Oscillation Dysregulation Underlies Attention Network Deficits in Left Temporal Lobe Drug-Resistant Epilepsy

Aims

This study investigated the neural mechanisms of left temporal lobe drug-resistant epilepsy (DRE) with attention network dysfunction using the attention network test (ANT) and synchronous electroencephalography (EEG).

Methods

This study enrolled three cohorts: 20 patients with left temporal lobe drug-resistant epilepsy (DRE group), 20 left temporal lobe drug-sensitive epilepsy (DSE group) patients, and 20 age-/sex-matched healthy controls (Ctrl group). Participants completed standardized ANT tasks while scalp EEG was recorded at a 1000 Hz sampling rate. We computed power spectral density (PSD) of neural oscillations from ANT-task EEG epochs.

Results

DRE patients exhibited significantly impaired network efficiency across executive control (EC), alerting, and orienting networks. Compared to the Ctrl group, both DRE and DSE groups demonstrated reduced frontal theta PSDs in EC, alerting, and orienting networks (all p < 0.001), with the DRE group showing greater deficits than the DSE group in the EC network (p < 0.001). Additionally, Significant correlations emerged between frontal theta PSD and behavior in Ctrl (EC_{_effect}: r = −0.659, p = 0.002; Alerting_{_effect}: r = 0.690, p = 0.001; Orienting_{_effect}: r = 0.649, p = 0.002) and DSE (EC_{_effect}: r = −0.595, p = 0.006; Alerting_{_effect}: r = 0.592, p = 0.006; Orienting_{_effect}: r = 0.588, p = 0.006). In the DRE group, however, The theta band PSDs of the attention network show no significant correlation with behavioral response effects.

Conclusion

Drug-resistant epilepsy patients have dysfunctional attention network behavior and decreased theta band PSDs in the frontal lobe. It is possible that decreased theta oscillations in the frontal lobe may contribute to ANT behavior dysfunction in drug-resistant epilepsy patients.