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Intrinsic Cornu Ammonis Area 1 Theta-Nested Gamma Oscillations Induced by Optogenetic Theta Frequency Stimulation.
- Source :
-
The Journal of neuroscience : the official journal of the Society for Neuroscience [J Neurosci] 2016 Apr 13; Vol. 36 (15), pp. 4155-69. - Publication Year :
- 2016
-
Abstract
- Gamma oscillations (30-120 Hz) are thought to be important for various cognitive functions, including perception and working memory, and disruption of these oscillations has been implicated in brain disorders, such as schizophrenia and Alzheimer's disease. The cornu ammonis area 1 (CA1) of the hippocampus receives gamma frequency inputs from upstream regions (cornu ammonis area 3 and medial entorhinal cortex) and generates itself a faster gamma oscillation. The exact nature and origin of the intrinsic CA1 gamma oscillation is still under debate. Here, we expressed channel rhodopsin-2 under the CaMKIIα promoter in mice and prepared hippocampal slices to produce a model of intrinsic CA1 gamma oscillations. Sinusoidal optical stimulation of CA1 at theta frequency was found to induce robust theta-nested gamma oscillations with a temporal and spatial profile similar to CA1 gamma in vivo The results suggest the presence of a single gamma rhythm generator with a frequency range of 65-75 Hz at 32 °C. Pharmacological analysis found that the oscillations depended on both AMPA and GABAA receptors. Cell-attached and whole-cell recordings revealed that excitatory neuron firing slightly preceded interneuron firing within each gamma cycle, suggesting that this intrinsic CA1 gamma oscillation is generated with a pyramidal-interneuron circuit mechanism.<br />Significance Statement: This study demonstrates that the cornu ammonis area 1 (CA1) is capable of generating intrinsic gamma oscillations in response to theta input. This gamma generator is independent of activity in the upstream regions, highlighting that CA1 can produce its own gamma oscillation in addition to inheriting activity from the upstream regions. This supports the theory that gamma oscillations predominantly function to achieve local synchrony, and that a local gamma generated in each area conducts the signal to the downstream region.<br /> (Copyright © 2016 Butler et al.)
- Subjects :
- Animals
CA1 Region, Hippocampal drug effects
Calcium-Calmodulin-Dependent Protein Kinase Type 2 metabolism
Channelrhodopsins
Entorhinal Cortex drug effects
Entorhinal Cortex physiology
Excitatory Amino Acid Agonists pharmacology
Gamma Rhythm drug effects
In Vitro Techniques
Mice
Mice, Inbred C57BL
Mice, Knockout
Nerve Net drug effects
Nerve Net physiology
Neurons drug effects
Neurons physiology
Photic Stimulation
Promoter Regions, Genetic genetics
Theta Rhythm drug effects
CA1 Region, Hippocampal physiology
Gamma Rhythm physiology
Optogenetics methods
Theta Rhythm physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1529-2401
- Volume :
- 36
- Issue :
- 15
- Database :
- MEDLINE
- Journal :
- The Journal of neuroscience : the official journal of the Society for Neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 27076416
- Full Text :
- https://doi.org/10.1523/JNEUROSCI.3150-15.2016