New PhysioNet Paper: The nucleus reuniens controls long-range hippocampo-prefrontal gamma synchronization during slow oscillations

Check our new paper in Journal of Neuroscience - HERE.

Ferraris M, Ghestem A, Vicente AF, Nallet-Khosrofian L, Bernard C, Quilichini PP.

The nucleus reuniens controls long-range hippocampo-prefrontal gamma synchronization during slow oscillations. Journal of Neuroscience 19 February 2018, 3058-17;

DOI: https://doi.org/10.1523/JNEUROSCI.3058-17.2018

ABSTRACT

Gamma oscillations are involved in long-range coupling of distant regions which 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 prior to 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 nucleus reuniens 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.