Browse
Submit Data
Databases
API
Help

Dataset Information

35 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Contextual fear memory retrieval by correlated ensembles of ventral CA1 neurons.

ABSTRACT: Ventral hippocampal CA1 (vCA1) projections to the amygdala are necessary for contextual fear memory. Here we used in vivo Ca²⁺ imaging in mice to assess the temporal dynamics by which ensembles of vCA1 neurons mediate encoding and retrieval of contextual fear memories. We found that a subset of vCA1 neurons were responsive to the aversive shock during context conditioning, their activity was necessary for memory encoding, and these shock-responsive neurons were enriched in the vCA1 projection to the amygdala. During memory retrieval, a population of vCA1 neurons became correlated with shock-encoding neurons, and the magnitude of synchronized activity within this population was proportional to memory strength. The emergence of these correlated networks was disrupted by inhibiting vCA1 shock responses during memory encoding. Thus, our findings suggest that networks of cells that become correlated with shock-responsive neurons in vCA1 are essential components of contextual fear memory ensembles.

SUBMITTER: Jimenez JC

PROVIDER: S-EPMC7359370 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Ventral CA1 neurons store social memory.

Project description:The medial temporal lobe, including the hippocampus, has been implicated in social memory. However, it remains unknown which parts of these brain regions and their circuits hold social memory. Here, we show that ventral hippocampal CA1 (vCA1) neurons of a mouse and their projections to nucleus accumbens (NAc) shell play a necessary and sufficient role in social memory. Both the proportion of activated vCA1 cells and the strength and stability of the responding cells are greater in response to a familiar mouse than to a previously unencountered mouse. Optogenetic reactivation of vCA1 neurons that respond to the familiar mouse enabled memory retrieval and the association of these neurons with unconditioned stimuli. Thus, vCA1 neurons and their NAc shell projections are a component of the storage site of social memory.

| S-EPMC5493325 | biostudies-literature

Septal GABAergic inputs to CA1 govern contextual memory retrieval.

Project description:The CA1 output region of the hippocampus plays an essential role in the retrieval of episodic memories. γ-Aminobutyric acid-releasing (GABAergic) long-range projections from the medial septum (MS) densely innervate the hippocampus, but whether septal inputs regulate memory expression remains elusive. We found that the MS to CA1 connection is recruited during recall of a contextual fear memory. Chemogenetic silencing of CA1-projecting MS neurons or septal GABAergic terminals within CA1 blocked memory retrieval. Photostimulation of septal GABAergic terminals in CA1 selectively inhibited interneurons. Abrogating septal GABAergic cells during retrieval disinhibited parvalbumin-rich (PV+) cells in CA1. Direct activation of CA1 PV+ cells impaired memory and prevented the induction of extracellular signal-regulated kinase/mitogen-activated kinase signaling in postsynaptic pyramidal neurons. Opposing disinhibition of hippocampal PV+ cells reversibly restored memory. Our data indicate that suppression of feed-forward inhibition onto CA1 by septal GABAergic neurons is an important mechanism in gating contextual fear behavior.

| S-EPMC7608800 | biostudies-literature

Chemogenetic inactivation of ventral hippocampal glutamatergic neurons disrupts consolidation of contextual fear memory.

Project description:Synaptic consolidation is a process thought to consolidate memory in the brain. Although lesion studies have mainly implicated the hippocampus (HPC) in this process, it is unknown which cell type(s) or regions of the HPC might be essential for synaptic consolidation. To selectively and reversibly suppress hippocampal neuronal activity during this process, we developed a new Gi-DREADD (hM4Di) transgenic mouse for in vivo manipulation of neuronal activity in freely moving animals. We found that CA1 pyramidal neurons could be dose-dependently inactivated by clozapine-n-oxide (CNO). Inactivation of hippocampal neurons within 6 h immediately after conditioned fear training successfully impaired the consolidation of contextual memory, without disturbing cued memory. To anatomically define the brain subregion critical for the behavioral effects, hM4Di viral vectors were transduced and selectively expressed in the glutamatergic neurons in either the dorsal or ventral HPC. Significantly, we found that selective inactivation of ventral but not dorsal glutamatergic hippocampal neurons suppressed the synaptic consolidation of contextual memory.

| S-EPMC4059896 | biostudies-other

Gene expression in rat hippocampal CA1 after the retrieval of contextual fear memory in the absence of extinction.

Project description:Adult rats (male Lister hooded) received a single unsignaled scrambled footshock (0.5 mA for 2 s) 2 min into a 3min exposure to a novel context. 48 hours later, rats were reexopsed to the condition context for 2 min (TEST). One half rats received bilateral microinfusions (1 microlitre/hemisphere) of 2 nmol/microlitre Zif268 antisense ODN (ZIFASO, 5’- GGTAGTTGTCCATGGTGG-3’in PBS, pH 7.4) or Zif268 missense ODN (ZIFMSO, 5’ -GTGTTCGGTAGGGTGTCA-3’in PBS, pH 7.4) into the dorsal hippocampus (AP -3.50, relative to bregma), 90 min before TEST. Infusions were made in awake rats via previously surgically implanted indwelling stainless steel cannula. Rats were housed in the home cages at all times outside the conditioning and TEST procedures. Rats were killed by CO2 inhalation 2 hours after TEST. CA1-enriched dorsal hippocampus was immediately dissected on ice before rapid freezing and storage at -80oC. The ZIFSO-infused group potentially represents reconsolidation-impaired rats.

2015-09-25 | GSE66152 | GEO

Prefrontal cortex neuronal ensembles encoding fear drive fear expression during long-term memory retrieval.

Project description:The prefrontal cortex is an important regulator of fear expression in humans and rodents. Specifically, the rodent prelimbic (PL) prefrontal cortex drives fear expression during both encoding and retrieval of fear memory. Neuronal ensembles have been proposed to function as memory encoding units, and their re-activation is thought to be necessary for memory retrieval and expression of conditioned behavior. However, it remains unclear whether PL cortex neuronal ensembles that encode fear memory contribute to long-term fear expression during memory retrieval. To address this, we employed a viral-mediated TRAP (Targeted Recombination in Active Population) technology to target PL cortex ensembles active during fear conditioning and expressed the inhibitory Gi-DREADD in fear-encoding ensembles. Male and female rats were trained to lever press for food and subjected to Pavlovian delay fear conditioning, then 28 days later, they underwent a fear memory retrieval test. Chemogenetic inhibition of TRAPed PL cortex ensembles reduced conditioned suppression of food seeking in females, but not males. Neither context nor tone freezing behavior was altered by this manipulation during the same retrieval test. Thus, fear-encoding ensembles in PL cortex drive long-term fear expression in a sex and fear modality dependent manner.

| S-EPMC6656710 | biostudies-literature

Contextual fear conditioning induced transcriptional changes in hippocampal CA1 neurons

Project description:The goal of our study was to assess whether the experience can regulate specific lncRNAs within the hippocampus and their role in associative memory. To address this, we carried out unbiased analyses of gene expression in CA1-hippocampal neurons to identify lncRNA changes induced by contextual fear conditioning (CFC).

2023-08-07 | GSE214838 | GEO

High-Frequency Stimulation of Ventral CA1 Neurons Reduces Amygdala Activity and Inhibits Fear.

Project description:The hippocampus can be divided into distinct segments that make unique contributions to learning and memory. The dorsal segment supports cognitive processes like spatial learning and navigation while the ventral hippocampus regulates emotional behaviors related to fear, anxiety and reward. In the current study, we determined how pyramidal cells in ventral CA1 respond to spatial cues and aversive stimulation during a context fear conditioning task. We also examined the effects of high and low frequency stimulation of these neurons on defensive behavior. Similar to previous work in the dorsal hippocampus, we found that cells in ventral CA1 expressed high-levels of c-Fos in response to a novel spatial environment. Surprisingly, however, the number of activated neurons did not increase when the environment was paired with footshock. This was true even in the subpopulation of ventral CA1 pyramidal cells that send direct projections to the amygdala. When these cells were stimulated at high-frequencies (20 Hz) we observed feedforward inhibition of basal amygdala neurons and impaired expression of context fear. In contrast, low-frequency stimulation (4 Hz) did not inhibit principal cells in the basal amygdala and produced an increase in fear generalization. Similar results have been reported in dorsal CA1. Therefore, despite clear differences between the dorsal and ventral hippocampus, CA1 neurons in each segment appear to make similar contributions to context fear conditioning.

| S-EPMC7985556 | biostudies-literature

Limited replicability of drug-induced amnesia after contextual fear memory retrieval in rats.

Project description:With the ultimate goal of investigating boundary conditions for post-reactivation amnesia, we set out to replicate studies in which systemic, post-reactivation administration of midazolam, propranolol, or cycloheximide resulted in amnesia for contextual fear memories. Our experiments involved conceptual as well as exact replications of previously published studies. In most of our experiments, we adopted a procedure that conformed to the standard 3-day protocol typically used in the literature, with contextual fear conditioning on day 1, unreinforced re-exposure to the conditioning context followed by systemic injection of the amnestic drug on day 2, and a memory retention test on day 3. Given the plethora of successful studies with large effects sizes and the absence of any failed replications in the literature, we were surprised to find that we were generally unable to replicate those findings. Our results suggest that post-reactivation amnesia by systemic drug administration in rats is more difficult to obtain than what would be expected based on published empirical reports. At present, it remains unclear which conditions determine the success of this procedure.

| S-EPMC7145453 | biostudies-literature

Gene expression in rat hippocampal CA1 during the extinction of contextual fear memory

Project description:Adult rats (male Lister hooded) were pre-exposed for 3 d for 10 min /d (24 hr interval) to two different novel contexts. On day 4 rats received a single unsignaled scrambled footshock (0.5 mA for 2 s) 2 min into a 3min exposure to one of the two contexts. Rats were either returned to the CS conditioned context (CS+, EXT group) or to the other (CS-, NOR group) context for 10 min, 48h after contextual fear conditioning. Rats were housed in the home cages at all times outside the conditioning and re-exposure components. The novel context chosen to be the conditioned context was counterbalanced across the experimental groups. Rats were killed by CO2 inhalation 2 hours after CS- or CS+ exposure. CA1-enriched dorsal hippocampus was immediately dissected on ice before rapid freezing and storage at -80oC. The CS+ group represents rats that underwent extinction of contextual fear memory.

2015-09-25 | GSE66151 | GEO

Gene expression in rat hippocampal CA1 during the consolidation of contextual fear memory

Project description:Adult rats (male Lister hooded) received a single unsignaled scrambled footshock (0.5 mA for 2 s) 2 min into a 3min exposure to a novel context. One half rats received bilateral microinfusions (1 microlitre/hemisphere) of 2 nmol/microlitre BDNF antisense ODN (BDNFASO, 5’-TCTTCCCCTTTTAATGGT-3’ in PBS, pH 7.4) or BDNF missense ODN (BDNFMSO, 5’ -ATACTTTCTGTTCTTGCC-3’ in PBS, pH 7.4) into the dorsal hippocampus (AP -3.50, relative to bregma), 90 min before contextual fear conditioning (CFC). Infusions were made in awake rats via previously surgically implanted indwelling stainless steel cannula. Rats were housed in the home cages at all times outside the conditioning procedure. Rats were killed by CO2 inhalation 2 hours after CFC. CA1 enriched dorsal hippocampus was immediately dissected on ice before rapid freezing and storage at -80oC. The BDNFASO-infused group represent consolidation-impaired rats.

2015-09-25 | GSE66150 | GEO

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data