Hippocampal theta-driving cells revealed by Granger causality

Authors

  • Lu Zhang,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Guifen Chen,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Ruifang Niu,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Wei Wei,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Xiaoyu Ma,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Jiamin Xu,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Jingyi Wang,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Zhiru Wang,

    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
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  • Longnian Lin

    Corresponding author
    1. Key Laboratory of Brain Functional Genomics (Ministry of Education), Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road N., Shanghai, China
    • Institute of Brain Functional Genomics, East China Normal University, Shanghai 200062, China
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Abstract

The two-dipole model of theta generation in hippocampal CA1 suggests that the inhibitory perisomatic theta dipole is generated by local GABAergic interneurons. Various CA1 interneurons fire preferentially at different theta phases, raising the question of how these theta-locked interneurons contribute to the generation of theta oscillations. We here recorded interneurons in the hippocampal CA1 area of freely behaving mice, and identified a unique subset of theta-locked interneurons by using the Granger causality approach. These cells fired in an extremely reliable theta-burst pattern at high firing rates (∼90 Hz) during exploration and always locked to ascending phases of the theta waves. Among theta-locked interneurons we recorded, only these cells generated strong Granger causal influences on local field potential (LFP) signals within the theta band (4–12 Hz), and the influences were persistent across behavioral states. Our results suggest that this unique type of theta-locked interneurons serve as the local inhibitory theta dipole control cells in shaping hippocampal theta oscillations. © 2012 Wiley Periodicals, Inc.

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