Topic: dorsal hippocampus

Understanding the mechanisms of statistical learning, where organisms infer structure from sensory observations without explicit instruction, is crucial in comprehending how the brain processes and responds to complex and dynamic environments. This work explores the innate capabilities of mice to discern environmental regularities, focusing on the role of the hippocampus in this unsupervised learning process. The study leverages a novel comparative behavioural paradigm, termed X-detection, to manipulate the statistics of embedded tone sequences (patterns) in an auditory cover task: subjects s

Navigating space to retrieve uncued rewards at remembered locations depends on intact hippocampal function. Indeed, learning novel reward locations in familiar environments requires synaptic plasticity and lasting reorganization of spatial representations in the CA1 area of the dorsal hippocampus. Such reorganization is absent when learning associations between rewards and non-spatial cues, for which spatial memory is not involved. Thus, the rodent brain selectively adjusts weights of hippocampal inputs, plasticity processes, and the stability of spatial representations, supporting adaptive be

Preclinical research into dementia with Lewy bodies (DLB) is challenging due to the lack of α-synucleinopathy animal models that do not also develop Parkinsonism. To address this issue, we have developed a new mouse model for investigating the impact of α-synuclein (α-Syn) overexpression and aggregation on driving cortical and hippocampal circuit dysfunction. Using bilateral stereotaxic injections of adeno-associated virus (AAVs) vectors, we transduced overexpression of human SNCA (encoding α-Syn) with mScarlet (red fluorophore), or an mScarlet-only control vector. We targeted either dorsal hi

The medial (MPP) and lateral perforant path (LPP) inputs to the dentate gyrus (DG) comprise a prominent source of information for the hippocampus. Behavioral and anatomical studies have indicated that the MPP provides information about metric space and the LPP provides information about item identity to the hippocampus. This may influence how information is encoded in MPP and LPP inputs to the hippocampus.Here, we examined the frequency-dependency of synaptic plasticity in MPP-DG and LPP-DG synapses of the dorsal hippocampus of freely behaving adult male rats using patterned afferent stimulati

Background: Hippocampal memory deficit is an important symptom in patients with schizophrenia that responds poorly to antipsychotic treatment. Here, we investigated deficits in hippocampal long-term potentiation/depotentiation changes in the sub-chronic phencyclidine (scPCP) rat model for schizophrenia and how chronic exercise as a non-pharmacological treatment may produce hippocampal synaptic and cognitive improvements.Methods: 60 Female Lister Hooded rats (50 for acute recording and 10 for chronic recording) were dosed with either saline or PCP (2 mg/kg, i.p.) twice daily for seven days foll

Emotional contagion, the capacity to internally simulate another's emotional state, plays a crucial role in modulating prosocial behavior. This includes rescue behaviors, wherein individuals in a safe context intervene to release a trapped conspecific from an aversive context. However, little is known about how the perceived emotional arousal of the distressed individual influences the helper's behavior and the underlying neuronal mechanisms driving prosociability. This study explores the involvement of the dorsal hippocampus (dHPC), associated with contextual learning, in emotionally charged

High-throughput electrophysiological recordings, using multichannel silicon probes, allow simultaneous registration of neural activity from multiple brain regions. However, the difficulty of determining the precise localisation of recording sites within neural subcompartments creates challenges for data analysis and the interpretation of experimental results. While electrode localisation can be achieved to some extent by post-mortem histological reconstruction of the probes, it can be improved by real-time discrimination of the electrophysiological features of the signal: evoked potentials tri

Physical exercise benefits the dorsal hippocampus (dHPC) and promotes learning and memory. We have focused on light exercise (LEX) and have revealed that this accessible form of exercise can effectively increase hippocampal activity and enhance memory performance. However, the circuit mechanism underlying this benefit remains largely undetermined. Our recent findings demonstrate that LEX can stimulate tyrosine hydroxylase-positive (TH+) neurons in the locus coeruleus (LC) and the ventral tegmental area (VTA), and increase noradrenaline (NA) and dopamine (DA) release in the dHPC. This raises th

Excessive alcohol consumption during adolescence is regarded as a risk factor for the development of alcoholism later in life, but the pathophysiological mechanisms that render the adult brain susceptible to alcohol are largely unknown. GABAA receptors are among the targets of alcohol to regulate neural activity in the brain. Work from our lab has demonstrated that activin, a member of the TGF-β family, controls alcohol potentiation of GABAA receptors in adult mouse dorsal hippocampus. Considering the well-known functional segregation along the hippocampal longitudinal axis, we examined here h

In our previous study, we conducted a rescue behavior experiment. In this experiment, mice were trained to rescue a distressed familiar conspecific of the same sex by opening a door under two conditions: when the trapped mouse was in a dry or flooded chamber. We demonstrated that mice exhibit rescue behavior towards a distressed conspecific. Additionally, we discovered that inhibiting the dorsal hippocampus impairs this behavior. However, several questions regarding the specific components of impaired behavior remain. Does the emotional arousal of potential helpers increase when witnessing a d

Cognitive impairments associated with schizophrenia (CIAS) are modelled in rodents using sub-chronic administration of phencyclidine (scPCP). Changes to inflammatory markers have been associated with CIAS in patients, while exercise can improve cognition clinically and pre-clinically. This study aimed to investigate the effect of exercise on cognition and inflammation in the scPCP mouse.Adult female c57 mice were dosed with vehicle (0.9% saline, n=28) or PCP (10mg/kg, n=28) once daily for 10 days and divided into sedentary or exercised groups. Exercised mice had running-wheel access for 1h dai

The process of memory consolidation involves the transfer of information from short-term memory (STM) to long-term memory (LTM). Memory consolidation requires activation of the dorsal hippocampus (dHP), especially under conditions of high memory load. In this study, we asked whether there is a limit to the memory capacity, that is, the amount of information that can be stored during unique experiences. Using male and female outbred CD1 mice subjected to a modified version of the object recognition test, we found that females, despite having the same 6- object STM capacity as males, appear to t

Astrocytes are crucial for modulating synaptic activity and behavior through bidirectional communication with neurons. They sense and respond to neuronal activity by elevating intracellular calcium levels, which display complex spatiotemporal properties. To disclose its implications for behavior, we studied the IP3 receptor type 2 knockout (IP3R2 KO) mouse model that lacks global calcium elevations in astrocytes. We found that mice lacking IP3R2 display enhanced fear memory. Molecular analysis of hippocampal tissues revealed hundreds of up or down-regulated genes, among which 76 of those are m

Creating internal representations of the surrounding context and stabilizing them are essential for safe exploration of the environment. Spatial memories in the dorsal hippocampus (dHPC) are initially encoded by place-cells during awake exploration and stabilized during non-REM sleep fast oscillations (sharp-wave ripples) through place cell reactivation. The hippocampal formation is heterogeneous; the dHPC processes mostly contextual information, while the ventral part (vHPC) encodes valence and anxiety. This functional segregation is supported by the stronger connectivity of the vHPC with oth

Episodic memory formation in the mammalian brain is steered by synaptic plasticity processes in the hippocampus. The dorsal hippocampus is instrumental for spatial learning whereas the ventral hippocampus is required for emotional functions. We studied how GABAergic inhibition regulates spike timing-dependent potentiation (t-LTP) at Schaffer collateral-CA1 synapses along the longitudinal axis of the hippocampus using acute brain slices of male C57Bl/6J mice. To this aim we used two distinct t-LTP protocols that rely on six repeats of paired pre- and postsynaptic firing within 10 seconds, resem

One of the main targets of the vesicular glutamate transporter type 3 (vGluT3)-expressing median raphe neurons, is the dorsal hippocampus, a key node of the brain’s episodic memory circuit. We uncovered previously that the raphe-hippocampal glutamatergic connection selectively and highly efficiently activates certain types of hippocampal inhibitory neurons at very short latency. However, the function of this powerful inhibition-targeting modulation is still elusive. In this study, we combined the selective tagging of either vGluT3 MR neurons or their hippocampus-projecting subgroup and high-de

Sleep-wake disturbances are common in sepsis. We previously hypothesized in an anaesthetized sepsis model, that acute changes in sleep-state dynamics were linked to altered in attractor state dynamics. Here, we studied the acute effects of high-dose LPS injection (5mg/kg) on brain activity in a non-anaesthetized survival model.LFP was recorded from dorsal hippocampus and overlaying cortex of 13 male Long-Evans rats before and after LPS injection. Sleep-wake states were scored for cortex and hippocampus, and analyzed using a 3-D power-spectrum-based state-space approach. Additionally, aperiodic