Slowing of the Hippocampal θ Rhythm Correlates with Anesthetic-induced Amnesia
Open Access
- 1 December 2010
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Anesthesiology
- Vol. 113 (6), 1299-1309
- https://doi.org/10.1097/aln.0b013e3181f90ccc
Abstract
Background Temporary, antegrade amnesia is one of the core desirable endpoints of general anesthesia. Multiple lines of evidence support a role for the hippocampal θ rhythm, a synchronized rhythmic oscillation of field potentials at 4-12 Hz, in memory formation. Previous studies have revealed a disruption of the θ rhythm at surgical levels of anesthesia. We hypothesized that θ-rhythm modulation would also occur at subhypnotic but amnestic concentrations. Therefore, we examined the effect of three inhaled agents on properties of the θ rhythm considered critical for the formation of hippocampus-dependent memories. Methods We studied the effects of halothane and nitrous oxide, two agents known to modulate different molecular targets (GABAergic [γ-aminobutyric acid] vs. non-GABAergic, respectively) and isoflurane (GABAergic and non-GABAergic targets) on fear-conditioned learning and θ oscillations in freely behaving rats. Results All three anesthetics slowed θ peak frequency in proportion to their inhibition of fear conditioning (by 1, 0.7, and 0.5 Hz for 0.32% isoflurane, 60% N2O, and 0.24% halothane, respectively). Anesthetics inconsistently affected other characteristics of θ oscillations. Conclusions At subhypnotic amnestic concentrations, θ-oscillation frequency was the parameter most consistently affected by these three anesthetics. These results are consistent with the hypothesis that modulation of the θ rhythm contributes to anesthetic-induced amnesia.Keywords
This publication has 58 references indexed in Scilit:
- Distinct contributions of the hippocampus and medial prefrontal cortex to the “what–where–when” components of episodic-like memory in miceBehavioural Brain Research, 2010
- Working memory performance correlates with prefrontal-hippocampal theta interactions but not with prefrontal neuron firing ratesFrontiers in Integrative Neuroscience, 2010
- Theta Oscillations Provide Temporal Windows for Local Circuit Computation in the Entorhinal-Hippocampal LoopNeuron, 2009
- Oscillations, Phase-of-Firing Coding, and Spike Timing-Dependent Plasticity: An Efficient Learning SchemeJournal of Neuroscience, 2009
- Is a New Paradigm Needed to Explain How Inhaled Anesthetics Produce Immobility?Anesthesia & Analgesia, 2008
- Theta synchronizes the activity of medial prefrontal neurons during learningLearning & Memory, 2008
- Amnesic Concentrations of the Nonimmobilizer 1,2-Dichlorohexafluorocyclobutane (F6, 2N) and Isoflurane Alter Hippocampal θ Oscillations In VivoAnesthesiology, 2007
- Hippocampal encoding of non-spatial trace conditioningHippocampus, 1999
- Pavlovian fear conditioning in mice anesthetized with halothanePhysiology & Behavior, 1996
- Acquisition of contextual Pavlovian fear conditioning is blocked by application of an NMDA receptor antagonist D,L-2-amino-5-phosphonovaleric acid to the basolateral amygdala.Behavioral Neuroscience, 1994