PT  - JOURNAL ARTICLE
AU  - Maëva Ferraris
AU  - Antoine Ghestem
AU  - Ana F. Vicente
AU  - Lauriane Nallet-Khosrofian
AU  - Christophe Bernard
AU  - Pascale P. Quilichini
TI  - The Nucleus Reuniens Controls Long-Range Hippocampo–Prefrontal Gamma Synchronization during Slow Oscillations
AID  - 10.1523/JNEUROSCI.3058-17.2018
DP  - 2018 Mar 21
TA  - The Journal of Neuroscience
PG  - 3026--3038
VI  - 38
IP  - 12
4099  - http://www.jneurosci.org/content/38/12/3026.short
4100  - http://www.jneurosci.org/content/38/12/3026.full
SO  - J. Neurosci.2018 Mar 21; 38
AB  - Gamma oscillations are involved in long-range coupling of distant regions that support various cognitive operations. Here we show in adult male rats that synchronized bursts of gamma oscillations bind the hippocampus (HPC) and prefrontal cortex (mPFC) during slow oscillations and slow-wave sleep, a brain state that is central for consolidation of memory traces. These gamma bursts entrained the firing of the local HPC and mPFC neuronal populations. Neurons of the nucleus reuniens (NR), which is a structural and functional hub between HPC and mPFC, demonstrated a specific increase in their firing before gamma burst onset, suggesting their involvement in HPC–mPFC binding. Chemical inactivation of NR disrupted the temporal pattern of gamma bursts and their synchronization, as well as mPFC neuronal firing. We propose that the NR drives long-range hippocampo–prefrontal coupling via gamma bursts providing temporal windows for information exchange between the HPC and mPFC during slow-wave sleep.SIGNIFICANCE STATEMENT Long-range coupling between hippocampus (HPC) and prefrontal cortex (mPFC) is believed to support numerous cognitive functions, including memory consolidation occurring during sleep. Gamma-band synchronization is a fundamental process in many neuronal operations and is instrumental in long-range coupling. Recent evidence highlights the role of nucleus reuniens (NR) in consolidation; however, how it influences hippocampo–prefrontal coupling is unknown. In this study, we show that HPC and mPFC are synchronized by gamma bursts during slow oscillations in anesthesia and natural sleep. By manipulating and recording the NR–HPC–mPFC network, we provide evidence that the NR actively promotes this long-range gamma coupling. This coupling provides the hippocampo–prefrontal circuit with a novel mechanism to exchange information during slow-wave sleep.