A cortical source localization analysis of resting EEG data after remifentanil infusion

To explore changes in current source density locations after remifentanil infusion in healthy volunteers using source localization of the electroencephalography (EEG).

EEG data was collected from 21 males using a 62-electrode system. Additionally, cognitive performance was evaluated by a continuous reaction time paradigm, and pain scores were obtained for experimental bone and heat stimuli. Data were recorded before and during treatment with remifentanil and placebo. Source localization was performed by sLORETA at delta (1-3.9 Hz), theta (4-7.9 Hz), alpha (8-12 Hz), beta1 (12.1-18 Hz), and beta2 (18.1-30 Hz) frequency bands.

Pre-treatment recordings demonstrated reproducible source characteristics. The alterations (i.e., pre- versus post-treatment) due to remifentanil were significantly and robustly different from placebo infusions. The results indicated that neurons in several brain areas including inferior frontal gyrus and insula at frontal lobe oscillated more strongly after remifentanil infusion compared to placebo. Furthermore, the source activity at delta band was correlated with continuous reaction time index.

These results indicate that alterations in brain oscillations during remifentanil are mostly localized to frontal, fronto-temporal and fronto-central lobes and related to cognitive function.

The approach offers the potential to be used for understanding the underlying mechanism of action of remifentanil on brain activity.