Theta Phase Segregation of Input-Specific Gamma Patterns in Entorhinal-Hippocampal Networks
Precisely how rhythms support neuronal communication remains obscure. We investigated interregional coordination of gamma oscillations using high-density electrophysiological recordings in the rat hippocampus and entorhinal cortex. We found that 30–80 Hz gamma dominated CA1 local field potentials (L...
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Veröffentlicht in: | Neuron (Cambridge, Mass.) Mass.), 2014-10, Vol.84 (2), p.470-485 |
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Zusammenfassung: | Precisely how rhythms support neuronal communication remains obscure. We investigated interregional coordination of gamma oscillations using high-density electrophysiological recordings in the rat hippocampus and entorhinal cortex. We found that 30–80 Hz gamma dominated CA1 local field potentials (LFPs) on the descending phase of CA1 theta waves during navigation, with 60–120 Hz gamma at the theta peak. These signals corresponded to CA3 and entorhinal input, respectively. Above 50 Hz, interregional phase-synchronization of principal cell spikes occurred mostly for LFPs in the axonal target domain. CA1 pyramidal cells were phase-locked mainly to fast gamma (>100 Hz) LFP patterns restricted to CA1, which were strongest at the theta trough. While theta phase coordination of spiking across entorhinal-hippocampal regions depended on memory demands, LFP gamma patterns below 100 Hz in the hippocampus were consistently layer specific and largely reflected afferent activity. Gamma synchronization as a mechanism for interregional communication thus rapidly loses efficacy at higher frequencies.
•CA1 dendritic layer gamma rhythms reflect driving afferent patterns•CA3 input to CA1 typically occurs later in the theta cycle than EC input•CA1 output patterns are not coherently entrained by fast input rhythms•CA1 pyramidal cell activity is locally coordinated at high frequencies
How brain rhythms support information exchange remains obscure. Schomburg et al. employ large-scale electrophysiological recordings in the hippocampus and entorhinal cortex of behaving rats to investigate the coordination and synchrony of gamma oscillations within and between regions. |
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ISSN: | 0896-6273 1097-4199 |
DOI: | 10.1016/j.neuron.2014.08.051 |