期刊
JOURNAL OF NEUROSCIENCE
卷 29, 期 5, 页码 1381-1394出版社
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.4339-08.2009
关键词
hippocampal function; theta rhythm; oscillator; CA1; CA3; dentate gyrus; memory; synchrony; network
资金
- NIMH NIH HHS [R01 MH054671, MH54671, R01 MH054671-10] Funding Source: Medline
- NINDS NIH HHS [R01 NS034994-10, R01 NS034994-11, NS34994, R01 NS034994] Funding Source: Medline
Theta (4-10 Hz) oscillations in the hippocampus are thought to be important for plasticity, temporal coding, learning, and memory. The hippocampal system has been postulated to have two (or more) rhythmic sources of theta oscillations, but little is known about the behavior-dependent interplay of theta oscillations in different subregions and layers of the hippocampus. We tested rats in a hippocampus-dependent delayed spatial alternation task on a modified T-maze while simultaneously recording local field potentials from dendritic and somatic layers of the dentate gyrus, CA3, and CA1 regions using high- density, 96-site silicon probes. We found that while theta oscillations were generally coherent throughout the hippocampus, the power, coherence, and phase of theta oscillations fluctuated in a layer-specific manner, confirming the presence of multiple interdependent dipoles. Layer-dependent changes in the power and coherence of theta oscillations varied with aspects of both the memory and control (non-mnemonic) tasks, but only a small fraction of the variance could be explained by running speed or acceleration. Furthermore, the phase lag between theta oscillations in the CA3 and CA1 pyramidal layers was significantly smaller on the maze arm approaching the T-junction than on other arms of the alternation task or on comparable segments of control tasks. Overall, our findings reveal a consortium of layer-specific theta dipoles ( current sinks and sources) generated by the rhythmic flow of ions into and out of hippocampal cells. Moreover, our data suggest that these different theta generators flexibly coordinate hippocampal regions and layers to support behavioral task performance.
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