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 × 103 bits and interaction entropy from 0.44 ± 0.11 to 2.18 ± 0.72 × 103 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.
Highlights
Information integration is fundamental to the proper functioning of the cerebral cortex in the wakeful conscious subject (Tononi, 2004)
Power spectral analysis of the spontaneous local field potentials (LFP) revealed that δ power was highest at 4.5% [F(2,31) = 3.52, p = 0.042, and p < 0.05, T–K test] β power was reduced at desflurane concentrations exceeding 3.5% in both cortical regions [F(2,31) = 17.72, p < 0.0001, and p < 0.05, T–K test)
In this work we examined the ability of PnO stimulation to modulate spontaneous and visual stimulus-evoked information www.frontiersin.org integration in local cortical neuronal networks at three levels of anesthesia in vivo
Summary
Information integration is fundamental to the proper functioning of the cerebral cortex in the wakeful conscious subject (Tononi, 2004). Traditionally viewed as a function of the wakesleep cycle, is under the precise control of the ascending arousal system (AAS; Lee and Dan, 2012) with origins in brainstem nuclei and extensive projections to the thalamus, basal forebrain, hypothalamus, and neocortex via ventral and dorsal pathways (Jones and Yang, 1985; Holstege and Kuypers, 1987). These states fall on a continuum that is heavily influenced and determined by fluctuations in spontaneous neuronal activity (Harris and Thiele, 2011). PnO electrical stimulation had a significant modulatory effect on cortical information integration under anesthesia
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