@article {69383,
	title = {Hippocampal cholecystokinin-expressing interneurons regulate temporal coding and contextual learning},
	journal = {Neuron},
	year = {2024},
	month = {2024 Apr 17},
	abstract = {<p>Cholecystokinin-expressing interneurons (CCKIs) are hypothesized to shape pyramidal cell-firing patterns and regulate network oscillations and related network state transitions. To directly probe their role in the CA1 region, we silenced their activity using optogenetic and chemogenetic tools in mice. Opto-tagged CCKIs revealed a heterogeneous population, and their optogenetic silencing triggered wide disinhibitory network changes affecting both pyramidal cells and other interneurons. CCKI silencing enhanced pyramidal cell burst firing and altered the temporal coding of place cells: theta phase precession was disrupted, whereas sequence reactivation was enhanced. Chemogenetic CCKI silencing did not alter the acquisition of spatial reference memories on the Morris water maze but enhanced the recall of contextual fear memories and enabled selective recall when similar environments were tested. This work suggests the key involvement of CCKIs in the control of place-cell temporal coding and the formation of contextual memories.</p>
},
	issn = {08966273},
	doi = {10.1016/j.neuron.2024.03.019},
	url = {https://doi.org/10.1016/j.neuron.2024.03.019},
	author = {Rangel Guerrero, D{\'a}maris K. and Balueva, Kira and Barayeu, Uladzislau and Baracskay, Peter and Gridchyn, Igor and Nardin, Michele and Roth, Chiara Nina and Wulff, Peer and Csicsvari, Jozsef}
}
@article {68999,
	title = {Theta oscillations as a substrate for medial prefrontal-hippocampal assembly interactions.},
	journal = {Cell Reports},
	volume = {42},
	year = {2023},
	month = {2023 Aug 24},
	pages = {113015},
	abstract = {<p>The execution of cognitive functions requires coordinated circuit activity across different brain areas that involves the associated firing of neuronal assemblies. Here, we tested the circuit mechanism behind assembly interactions between the hippocampus and the medial prefrontal cortex (mPFC) of adult rats by recording neuronal populations during a rule-switching task. We identified functionally coupled CA1-mPFC cells that synchronized their activity beyond that expected from common spatial coding or oscillatory firing. When such cell pairs fired together, the mPFC cell strongly phase locked to CA1 theta oscillations and maintained consistent theta firing phases, independent of the theta timing of their CA1 counterpart. These functionally connected CA1-mPFC cells formed interconnected assemblies. While firing together with their CA1 assembly partners, mPFC cells fired along specific theta sequences. Our results suggest that upregulated theta oscillatory firing of mPFC cells can signal transient interactions with specific CA1 assemblies, thus enabling distributed computations.</p>
},
	issn = {2211-1247},
	doi = {10.1016/j.celrep.2023.113015},
	author = {Nardin, Michele and Kaefer, Karola and Stella, Federico and Csicsvari, Jozsef}
}
