Search results for "hippocampal"

Role of endocannabinoids and TRPV1 channels in the bioelectric activity of hippocampal neurons

It has been reported that endocannabinoid system is an important player in the regulation of neuronal bioelectrical activity, relying on receptor-mediated mechanisms. Amongst these, Cannabinoid receptor type 1 (CB1r) and Transient Receptor Potential Vanilloid type 1 (TRPV1) are both modulated by endocannabinoids, involved in the transduction of stimuli in the pre-synaptic neuron and prompt downstream pathways in the post-synaptic neuron. To investigate the role of CB1r/TRPV1 interplay, we applied whole-cell patch clamp technique to visualize the eventual variations in terms of membrane current and action potentials induced by pharmacological manipulation in rat hippocampal neurons. We modul…

Heterogeneous responses of nucleus incertus neurons to corticotrophin-releasing factor and coherent activity with hippocampal theta rhythm in the rat

2013

The nucleus incertus (NI) of the rat hindbrain is a putative node in the ascending control of the septohippocampal system and hippocampal theta rhythm and is stress and arousal responsive. NI contains GABA neurons that express multiple neuropeptides, including relaxin-3 (RLN3) and neuropeptide receptors, including corticotrophin-releasing factor receptor-1 (CRF-R1), but the precise anatomical and physiological characteristics of NI neurons are unclear. Therefore, we examined the firing properties of NI neurons and their responses to CRF, the correlation of these responses with occurrence of relaxin-3, and NI neuron morphology in the rat. Most NI neurons excited by intracerebroventricular CR…

Glial Chloride Homeostasis Under Transient Ischemic Stress

2021

High water permeabilities permit rapid adjustments of glial volume upon changes in external and internal osmolarity, and pathologically altered intracellular chloride concentrations ([Cl–]int) and glial cell swelling are often assumed to represent early events in ischemia, infections, or traumatic brain injury. Experimental data for glial [Cl–]int are lacking for most brain regions, under normal as well as under pathological conditions. We measured [Cl–]int in hippocampal and neocortical astrocytes and in hippocampal radial glia-like (RGL) cells in acute murine brain slices using fluorescence lifetime imaging microscopy with the chloride-sensitive dye MQAE at room temperature. We observed s…

Prenatal Exposure to Δ9-Tetrahydrocannabinol Affects Hippocampus-Related Cognitive Functions in the Adolescent Rat Offspring: Focus on Specific Marke…

2023

Previous evidence suggests that prenatal exposure to THC (pTHC) derails the neurodevelopmental trajectories towards a vulnerable phenotype for impaired emotional regulation and limbic memory. Here we aimed to investigate pTHC effect on hippocampus-related cognitive functions and markers of neuroplasticity in adolescent male offspring. Wistar rats were exposed to THC (2 mg/kg) from gestational day 5 to 20 and tested for spatial memory, object recognition memory and reversal learning in the reinforce-motivated Can test and in the aversion-driven Barnes maze test; locomotor activity and exploration, anxiety-like behaviour, and response to natural reward were assessed in the open field, elevate…

Most hippocampal CA1 pyramidal cells in rabbits increase firing during awake sharp-wave ripples and some do so in response to external stimulation an…

2020

Hippocampus forms neural representations of real-life events including multimodal information of spatial and temporal context. These representations, i.e. organized sequences of neuronal firing are repeated during following rest and sleep, especially when so-called sharp-wave ripples (SPW-Rs) characterize hippocampal local-field potentials. This SPW-R –related replay is thought to underlie memory consolidation. Here, we set out to explore how hippocampal CA1 pyramidal cells respond to the conditioned stimulus during trace eyeblink conditioning and how these responses manifest during SPW-Rs in awake adult female New Zealand White rabbits. Based on reports in rodents, we expected SPW-Rs to ta…

Rats bred for low intrinsic aerobic exercise capacity link obesity with brain inflammation and reduced structural plasticity of the hippocampus.

2021

Abstract BACKGROUND Increasing evidence shows obesity and poor metabolic health are associated with cognitive deficits, but the mechanistic connections have yet to be resolved. We studied rats selectively bred for low and high intrinsic aerobic capacity in order to test the association between low physical fitness, a genetic predisposition for obesity, and brain health. We hypothesized that low-capacity runner (LCR) rats with concurrently greater levels of adiposity would have increased hippocampal inflammation and reduced plasticity compared to the more physically fit high-capacity runner (HCR) rats. METHODS We examined markers for inflammation and brain plasticity in the hippocampi of LCR…

A functional MRI study of happy and sad emotions in music with and without lyrics

2011

Musical emotions, such as happiness and sadness, have been investigated using instrumental music devoid of linguistic content. However, pop and rock, the most common musical genres, utilize lyrics for conveying emotions. Using participants’ self-selected musical excerpts, we studied their behavior and brain responses to elucidate how lyrics interact with musical emotion processing, as reflected by emotion recognition and activation of limbic areas involved in affective experience. We extracted samples from subjects’ selections of sad and happy pieces and sorted them according to the presence of lyrics. Acoustic feature analysis showed that music with lyrics differed from music without lyric…

Special Features of the Hippocampal Formation with Respect to Seizure Conditions

1987

The hippocampus has long been known as a region particularly prone to epileptiform discharges (Kandel et al. 1961). Connections and physiology of this archaic cortical structure are relatively well charac-terized and a wealth of information on features favoring exaggerated neuronal activity has emerged in recent years. The lamellar organization of the hippo-campus (Andersen et al. 1971) may be one of these features; it certainly has facilitated their investigation. Tissue slices cut along the lamellae, perpendicular to the axis of the structure, contain a relatively undisturbed chain of neurons which can be rigorously investigated in vitro. The results from such experiments have allowed mod…

Neurobiology

2016

In the adult mammalian brain, neurogenesis occurs in the dentate gyrus (DG) of the hippocampus throughout the life span. Neurogenesis has been extensively characterized in rodents and to a lesser extent in primates. Within the hippocampus, the adult neurogenic niche is specifically located in the subgranular zone of the DG, where neural stem/progenitor cells (NSPCs) reside. It has been confirmed that these stem cells, which possess astrocytic features, give rise to intermediate progenitors, immature neurons, and neurons. The NSPCs have radial glia-like morphology and electrolucid cytoplasm, in contrast to the immature neurons whose cytoplasm is electrodense, containing abundant polyribosome…

Glutamatergic activation of hippocampal phospholipase D: postnatal fading and receptor desensitization.

2002

Abstract: Phospholipase D (PLD) activity was determined in rat hippocampal slices between postnatal days 3 and 35. After birth, basal PLD activity was low and, within 2 weeks, increased to reach a plateau that was maintained up to the adult age. Likewise the response to glutamate developed postnatally to reach a maximum at day 8, but then faded rapidly and was almost absent at day 35. Activation of PLD by 4β-phorbol 12β,13α-dibutyrate (PDB) was independent of age, whereas the effect of aluminum fluoride (AlF4−) increased to a plateau within the first week. At day 8, PLD stimulation by glutamate via metabotropic receptors involved protein kinase C activation, but was independent of Ca2+ infl…