title: Brainstem stimulation augments information integration in the cerebral cortex of desflurane-anesthetized rats.
abstract: States of consciousness have been associated with information integration in the brain as modulated by anesthesia and the ascending arousal system. The present study was designed to test the hypothesis that electrical stimulation of the oral part of the pontine reticular nucleus (PnO) can augment information integration in the cerebral cortex of anesthetized rats. Extracellular unit activity and local field potentials were recorded in freely moving animals from parietal association (PtA) and secondary visual (V2) cortices via chronically implanted microwire arrays at three levels of anesthesia produced by desflurane: 3.5, 4.5, and 6.0% (where 4.5% corresponds to that critical for the loss of consciousness). Information integration was characterized by integration (multiinformation) and interaction entropy, estimated from the statistical distribution of coincident spike patterns. PnO stimulation elicited electrocortical activation as indicated by the reductions in δ- and θ-band powers at the intermediate level of anesthesia. PnO stimulation augmented integration from 1.13 ± 0.03 to 6.12 ± 1.98 × 10(3) bits and interaction entropy from 0.44 ± 0.11 to 2.18 ± 0.72 × 10(3) bits; these changes were most consistent in the PtA at all desflurane concentrations. Stimulation of the retina with discrete light flashes after PnO stimulation elicited an additional 166 ± 25 and 92 ± 12% increase in interaction entropy in V2 during light and intermediate levels. The results suggest that the PnO may modulate spontaneous ongoing and sensory stimulus-related cortical information integration under anesthesia.
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA.
authors.forename: Siveshigan
authors.initials: S
authors.lastname: Pillay
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA.
authors.forename: Jeannette
authors.initials: J
authors.lastname: Vizuete
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA.
authors.forename: Xiping
authors.initials: X
authors.lastname: Liu
authors.affiliation: Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University Budapest, Hungary.
authors.forename: Gabor
authors.initials: G
authors.lastname: Juhasz
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA.
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Hudetz
keywords: anesthesia; ascending arousal system; consciousness; cortical state; information integration; neuronal state repertoire