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Concina G, Milano L, Renna A, Manassero E, Stabile F, Sacchetti B. Hippocampus-to-amygdala pathway drives the separation of remote memories of related events. Cell Rep 2024; 43:114151. [PMID: 38656872 DOI: 10.1016/j.celrep.2024.114151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 02/21/2024] [Accepted: 04/09/2024] [Indexed: 04/26/2024] Open
Abstract
The mammalian brain can store and retrieve memories of related events as distinct memories and remember common features of those experiences. How it computes this function remains elusive. Here, we show in rats that recent memories of two closely timed auditory fear events share overlapping neuronal ensembles in the basolateral amygdala (BLA) and are functionally linked. However, remote memories have reduced neuronal overlap and are functionally independent. The activity of parvalbumin (PV)-expressing neurons in the BLA plays a crucial role in forming separate remote memories. Chemogenetic blockade of PV preserves individual remote memories but prevents their segregation, resulting in reciprocal associations. The hippocampus drives this process through specific excitatory connections with BLA GABAergic interneurons. These findings provide insights into the neuronal mechanisms that minimize the overlap between distinct remote memories and enable the retrieval of related memories separately.
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Affiliation(s)
- Giulia Concina
- Rita Levi-Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Luisella Milano
- Rita Levi-Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Annamaria Renna
- Rita Levi-Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Eugenio Manassero
- Rita Levi-Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Francesca Stabile
- Rita Levi-Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Benedetto Sacchetti
- Rita Levi-Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy.
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Concina G, Gurgone A, Boggio EM, Raspanti A, Pizzo R, Morello N, Castroflorio E, Pizzorusso T, Sacchetti B, Giustetto M. Stabilizing Immature Dendritic Spines in the Auditory Cortex: A Key Mechanism for mTORC1-Mediated Enhancement of Long-Term Fear Memories. J Neurosci 2023; 43:8744-8755. [PMID: 37857485 PMCID: PMC10727119 DOI: 10.1523/jneurosci.0204-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 10/21/2023] Open
Abstract
Mammalian target of rapamycin (mTOR) pathway has emerged as a key molecular mechanism underlying memory processes. Although mTOR inhibition is known to block memory processes, it remains elusive whether and how an enhancement of mTOR signaling may improve memory processes. Here we found in male mice that the administration of VO-OHpic, an inhibitor of the phosphatase and tensin homolog (PTEN) that negatively modulates AKT-mTOR pathway, enhanced auditory fear memory for days and weeks, while it left short-term memory unchanged. Memory enhancement was associated with a long-lasting increase in immature-type dendritic spines of pyramidal neurons into the auditory cortex. The persistence of spine remodeling over time arose by the interplay between PTEN inhibition and memory processes, as VO-OHpic induced only a transient immature spine growth in the somatosensory cortex, a region not involved in long-term auditory memory. Both the potentiation of fear memories and increase in immature spines were hampered by rapamycin, a selective inhibitor of mTORC1. These data revealed that memory can be potentiated over time by the administration of a selective PTEN inhibitor. In addition to disclosing new information on the cellular mechanisms underlying long-term memory maintenance, our study provides new insights on the molecular processes that aid enhancing memories over time.SIGNIFICANCE STATEMENT The neuronal mechanisms that may help improve the maintenance of long-term memories are still elusive. The inhibition of mammalian-target of rapamycin (mTOR) signaling shows that this pathway plays a crucial role in synaptic plasticity and memory formation. However, whether its activation may strengthen long-term memory storage is unclear. We assessed the consequences of positive modulation of AKT-mTOR pathway obtained by VO-OHpic administration, a phosphatase and tensin homolog inhibitor, on memory retention and underlying synaptic modifications. We found that mTOR activation greatly enhanced memory maintenance for weeks by producing a long-lasting increase of immature-type dendritic spines in pyramidal neurons of the auditory cortex. These results offer new insights on the cellular and molecular mechanisms that can aid enhancing memories over time.
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Affiliation(s)
- Giulia Concina
- Department of Neuroscience, University of Turin, Turin, 10125, Italy
| | - Antonia Gurgone
- Department of Neuroscience, University of Turin, Turin, 10125, Italy
| | - Elena M Boggio
- Institute of Neuroscience, National Research Council, Pisa, 56124, Italy
| | | | - Riccardo Pizzo
- Department of Neuroscience, University of Turin, Turin, 10125, Italy
| | - Noemi Morello
- Department of Neuroscience, University of Turin, Turin, 10125, Italy
| | | | - Tommaso Pizzorusso
- Institute of Neuroscience, National Research Council, Pisa, 56124, Italy
- Scuola Normale Superiore, Biology Laboratory BIO@SNS, Pisa, 56124, Italy
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Asokan MM, Watanabe Y, Kimchi EY, Polley DB. Potentiation of cholinergic and corticofugal inputs to the lateral amygdala in threat learning. Cell Rep 2023; 42:113167. [PMID: 37742187 PMCID: PMC10879743 DOI: 10.1016/j.celrep.2023.113167] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 07/07/2023] [Accepted: 09/07/2023] [Indexed: 09/26/2023] Open
Abstract
The amygdala, cholinergic basal forebrain, and higher-order auditory cortex (HO-AC) regulate brain-wide plasticity underlying auditory threat learning. Here, we perform multi-regional extracellular recordings and optical measurements of acetylcholine (ACh) release to characterize the development of discriminative plasticity within and between these brain regions as mice acquire and recall auditory threat memories. Spiking responses are potentiated for sounds paired with shock (CS+) in the lateral amygdala (LA) and optogenetically identified corticoamygdalar projection neurons, although not in neighboring HO-AC units. Spike- or optogenetically triggered local field potentials reveal enhanced corticofugal-but not corticopetal-functional coupling between HO-AC and LA during threat memory recall that is correlated with pupil-indexed memory strength. We also note robust sound-evoked ACh release that rapidly potentiates for the CS+ in LA but habituates across sessions in HO-AC. These findings highlight a distributed and cooperative plasticity in LA inputs as mice learn to reappraise neutral stimuli as possible threats.
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Affiliation(s)
- Meenakshi M Asokan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Division of Medical Sciences, Harvard Medical School, Boston, MA 02114, USA.
| | - Yurika Watanabe
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA
| | - Eyal Y Kimchi
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Division of Medical Sciences, Harvard Medical School, Boston, MA 02114, USA; Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA
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Asokan MM, Watanabe Y, Kimchi EY, Polley DB. Potentiated cholinergic and corticofugal inputs support reorganized sensory processing in the basolateral amygdala during auditory threat acquisition and retrieval. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.31.526307. [PMID: 36778308 PMCID: PMC9915656 DOI: 10.1101/2023.01.31.526307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Reappraising neutral stimuli as environmental threats reflects rapid and discriminative changes in sensory processing within the basolateral amygdala (BLA). To understand how BLA inputs are also reorganized during discriminative threat learning, we performed multi-regional measurements of acetylcholine (ACh) release, single unit spiking, and functional coupling in the mouse BLA and higher-order auditory cortex (HO-AC). During threat memory recall, sounds paired with shock (CS+) elicited relatively higher firing rates in BLA units and optogenetically targeted corticoamygdalar (CAmy) units, though not in neighboring HO-AC units. Functional coupling was potentiated for descending CAmy projections prior to and during CS+ threat memory recall but ascending amygdalocortical coupling was unchanged. During threat acquisition, sound-evoked ACh release was selectively enhanced for the CS+ in BLA but not HO-AC. These findings suggest that phasic cholinergic inputs facilitate discriminative plasticity in the BLA during threat acquisition that is subsequently reinforced through potentiated auditory corticofugal inputs during memory recall.
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Affiliation(s)
- Meenakshi M. Asokan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
- Division of Medical Sciences, Harvard Medical School, Boston MA 02114 USA
| | - Yurika Watanabe
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
| | - Eyal Y. Kimchi
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Daniel B. Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114 USA
- Division of Medical Sciences, Harvard Medical School, Boston MA 02114 USA
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School, Boston MA 02114 USA
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