Cone photoreceptors and horizontal cells (HCs) have a reciprocal synapse that underlies lateral inhibition and establishes the antagonistic center-surround organization of the visual system. Cones transmit to HCs through an excitatory synapse and HCs feed back to cones through an inhibitory synapse. Here we report that HCs also transmit to ...

Long-term potentiation (LTP) has received attention because of its proposed role in learning and memory. Despite substantial effort the pre- or postsynaptic expression site of LTP remains unsettled. It has been proposed that LTP is expressed postsynaptically through the functional conversion of "silent synapses." We had shown that Schaffer collateral ...

1. Nitric oxide (NO), a gas transmitter, modulates many physiological processes, including the central regulation of cardiovascular activity. However, the mechanisms underlying the regulation of cardiovascular activity remain relatively unexplored. In the present study, we hypothesized that central NO-dependent sympathetic inhibition is mediated by activation of adenosine A(2A) receptors (A(2A) ...

The posterior bed nuclei of the stria terminalis (BST) are important neural substrate for relaying limbic influences to the paraventricular nucleus (PVN) of the hypothalamus to inhibit hypothalamic-pituitary-adrenal (HPA) axis responses to emotional stress. Androgen receptor-expressing cells within the posterior BST have been identified as projecting to the PVN region. ...

Long-term potentiation (LTP) at hippocampal mossy fiber-CA3 pyramidal neuron synapses was induced in the field excitatory postsynaptic potential (EPSP) by the delivery of HFS (a tetanus of two trains of 100 pulses at 100Hz with a 10s interval) and was reversed (depotentiated) by a train of LFS of 1000 pulses ...

The impact of theta patterning of the stimulation on the kindling effects of pentylenetetrazol (PTZ) was studied in rat hippocampus area CA1 in vitro. A potential involvement of adenosine A1 receptors was also examined. Primed-bursts stimulation (PBs) and theta pulse stimulation (TPS) were used as patterned activities. Stimulus patterns were ...

It is well known that hippocampus plays important roles in learning and memory. Both calcitonin gene-related peptide (CGRP) and CGRP receptors are found in hippocampus. In the present study we explored the influence of CGRP on long term potentiation (LTP) in hippocampal Schaffer collateral-CA1. Our results demonstrated that CGRP inhibited ...

Natural rewards and addictive drugs are believed to exert their reinforcing actions by influencing synaptic plasticity in reward-related brain regions such as the nucleus accumbens (NAc). Long-lasting changes in the efficacy of excitatory synaptic transmission in the NAc are critically dependent on efficient interactions between the dopaminergic and the glutamatergic ...

Modulation of Cys-loop receptors by steroids is of physiological and therapeutical relevance. Nonetheless, its molecular mechanism has not been elucidated for serotonin (5-HT) type 3 receptors. We deciphered the mechanism of action of hydrocortisone (HC) at 5-HT type 3A receptors. Single-channel currents from the high-conductance form (∼4.7 pA, -70 mV) ...

Ghrelin, an orexigenic hormone, is mainly produced by the stomach and released into the circulation. Ghrelin receptors (growth hormone secretagogue receptors) are expressed throughout the brain, including the hippocampus. The activation of ghrelin receptors facilitates high-frequency stimulation (HFS)-induced long-term potentiation (LTP) in vitro, and also improves learning and memory. Herein, ...

Acetylcholine (ACh) is the major neurotransmitter released from vestibular efferent terminals onto hair cells and afferents. Previous studies indicate that the two classes of acetylcholine receptors, nicotinic (nAChRs) and muscarinic receptors (mAChRs), are expressed by vestibular hair cells (VHCs). To identify if both classes of receptors are present in VHCs, ...

Spinal astrocytes are coupled by connexin (Cx) gap junctions and express pannexin 1 (Px1) and purinergic receptors. Fibroblast growth factor 1 (FGF-1), which is released in spinal cord injury, activated spinal astrocytes in culture, induced secretion of ATP, and permeabilized them to relatively large fluorescent tracers [ethidium (Etd) and lucifer ...

Neuregulin 1 (NRG1) is a trophic factor that acts by stimulating ErbB receptor tyrosine kinases and has been implicated in neural development and synaptic plasticity. In this study, we investigated mechanisms of its suppression of long-term potentiation (LTP) in the hippocampus. We found that NRG1 did not alter glutamatergic transmission ...

The capacity for long-term changes in synaptic efficacy can be altered by prior synaptic activity, a process known as "metaplasticity." Activation of receptors for modulatory neurotransmitters can trigger downstream signaling cascades that persist beyond initial receptor activation and may thus have metaplastic effects. Because activation of β-adrenergic receptors (β-ARs) strongly ...

Amphetamine can improve cognition in healthy subjects and patients with schizophrenia, attention-deficit hyperactivity disorder, and other neuropsychiatric diseases; higher doses, however, can impair cognitive function, especially those mediated by the prefrontal cortex. We investigated how amphetamine affects prefrontal cortex long-term potentiation (LTP), a cellular correlate of learning and memory, in ...

The ventral hippocampus (VH) was recently shown to express lower magnitude LTP compared to the dorsal hippocampus (DH). Exposure to acute stress reversed this difference, and VH slices from stressed rats expressed larger LTP than that produced in the DH, which was reduced by stress. In an attempt to uncover ...

Purpose:  Temporal lobe epilepsy (TLE) is associated with changes in hippocampal function/morphology. These changes often manifest as a decline in cognitive abilities, which in animal models is reflected in reduced spatial learning and up-regulation or down-regulation of synaptic plasticity. Beyond this, however, changes also occur in other, extralimbic structures, as ...

Diacylglycerol (DAG) is an important signaling molecule at neuronal synapses. Generation of synaptic DAG is triggered by the activation of diverse surface receptors including N-methyl-D-aspartate (NMDA) receptors and metabotropic glutamate receptors. The action of DAG is terminated by enzymatic conversion of DAG to phosphatidic acid (PA) by DAG kinases (DGKs). ...

Brain-derived neurotrophic factor (BDNF) facilitates the formation of long-term potentiation (LTP) in hippocampus, but whether this involves release from presynaptic versus postsynaptic pools is unclear. We therefore tested whether BDNF is essential for LTP in dorsal striatum, a structure in which the neurotrophin is present only in afferent terminals. Whole-cell ...

Synaptic rules that may determine the interaction between coexisting forms of long-term potentiation (LTP) at glutamatergic central synapses remain unknown. Here, we show that two mechanistically distinct forms of LTP could be induced in thalamic input to the lateral nucleus of the amygdala (LA) with an identical presynaptic stimulation protocol, ...

Proper expression of synaptic NMDA receptors (NMDARs) is necessary to regulate synaptic Ca²(+) influx and the induction the long-term potentiation (LTP) in the mammalian hippocampus. Previously we reported that expressing the A-type K(+) channel subunit Kv4.2 in CA1 neurons of organotypic slice cultures reduced synaptic NR2B-containing NMDAR expression and completely ...

Currently, the underlying neurobiological mechanism as to how repetitive transcranial magnetic stimulation (rTMS) can alter depressive states remains unclear. Animal data suggest that its influence could occur at the neurotransmitter level, such as modulation of the serotonin system. Twenty-one antidepressant-free medication-resistant unipolar depressed patients, and 21 age- and gender-matched healthy ...

The hippocampus plays a central role in memory formation in the mammalian brain. The subiculum is the principal target of CA1 pyramidal cells and thus serves as the major relay station for the outgoing hippocampal information. Pyramidal cells in the subiculum have been classified as burst-spiking (BS) and regular-spiking (RS) ...

Norepinephrine receptors have been studied in emotion, memory, and attention. However, the role of alpha1-adrenergic receptors in fear conditioning, a major model of emotional learning, is poorly understood. We examined the effect of terazosin, an alpha1-adrenergic receptor antagonist, on cued fear conditioning. Systemic or intra-lateral amygdala terazosin delivered before conditioning ...

Alterations in curvature of the post synaptic density (PSD) and apposition zone (AZ), are believed to play an important role in determining synaptic efficacy. In the present study we have examined curvature of PSDs and AZs 24 h following homosynaptic long-term potentiation (LTP), and heterosynaptic long-term depression (LTD) in vivo, ...

Long-term potentiation (LTP) defines persistent increases in neurotransmission strength at synapses that are triggered by specific patterns of neuronal activity. LTP, the most widely accepted molecular model for learning, is best characterised at glutamatergic synapses on dendritic spines. In this context, LTP involves increases in dendritic spine size and the ...

Vascular dementia is one of the most important causes that account for 20-40% of all dementia cases. The aim of this study was to investigate whether electroacupuncture can reduce behavior deficit and long-term potentiation (LTP) in vascular dementia. Here we used a middle cerebral artery occlusion (MCAo) technique to induce ...

Dopamine release associated with motivational arousal is thought to drive goal-directed learning and consolidation of acquired memories. This dopamine hypothesis of learning and motivation directly suggests that dopamine is necessary for modifications of excitatory synapses in dopamine terminal fields, including the prefrontal cortex (PFC), to "stamp in" posttrial memory traces. ...

Spike timing-dependent long-term potentiation (t-LTP) is the embodiment of Donald Hebb's postulated rule for associative memory formation. Pre- and postsynaptic action potentials need to be precisely correlated in time to induce this form of synaptic plasticity. NMDA receptors have been proposed to detect correlated activity and to trigger synaptic plasticity. ...

Orexin neurons, localized in the lateral hypothalamus area, synthesize two neuropeptides called orexin A and orexin B and send their axons to hippocampal formation including dentate gyrus (DG). Orexin A and orexin B act as endogenous ligands for two G-protein coupled receptors called orexin-1 and orexin-2 receptors (OX1R and OX2R). ...

We had described a muscarinic-mediated long-term synaptic enhancement at Schaffer collateral synapses caused by the insertion of AMPARs in spines of rat hippocampal CA1 pyramidal neurons that requires Ca(2+) release from IP3-sensitive stores (Fernández de Sevilla et al., 2008). We now show that this AMPA-mediated LTP(IP3) is precisely matched by ...

N-methyl-D-aspartate (NMDA) receptor-mediated currents are enhanced by phosphorylation. We have investigated effects of phosphorylation-dependent short-term plasticity of NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) on the induction of long-term depression (LTD). We confirmed in whole cell clamped CA1 pyramidal neurons that LTD is induced by pairing stimulus protocols. However, after serine-threonine ...

AKAP79/150 is a protein scaffold that is thought to position specific kinases (protein kinase A and C) and phosphatases (calcineurin) in appropriate synaptic domains so that their activities can regulate excitatory synaptic strength. Using a viral-mediated molecular replacement strategy in rat hippocampal slices, we found that AKAP is required for ...

There is an expanding body of work characterizing dopaminergic modulation of synaptic plasticity in the hippocampus CA1 region, an area known to be involved in learning and memory. However, in vitro studies to date have focused almost exclusively on the proximal and distal apical dendritic layers (strata radiatum and lacunosum ...

Zinc potentiates the induction of NMDA receptor-dependent hippocampal CA1 long-term potentiation (LTP) at low micromolar concentrations, while excessive zinc attenuates it. Homeostasis of synaptic zinc is critical for LTP induction. In the present study, LTP at hippocampal CA1 synapses was analyzed focused on the timing and level of zinc influx ...

It is generally assumed that long lasting synaptic potentiation (long-term potentiation, LTP) and depression (long-term depression, LTD) result from distinct patterns of afferent activity, with high and low frequency activity favouring LTP and LTD, respectively. However, a novel form of N-methyl-d-aspartate (NMDA) receptor-dependent synaptic potentiation in the hippocampal CA1 area ...

Encoding of novel information has been proposed to rely on the time-locked release of dopamine in the hippocampal formation during novelty detection. However, the site of novelty detection in the hippocampus remains a matter of debate. According to current models, the CA1 and the subiculum act as detectors and distributors ...

Corticostriatal projections constitute the main input to the basal ganglia, an ensemble of interconnected subcortical nuclei involved in procedural learning. Thus, long-term plasticity at corticostriatal synapses would provide a basic mechanism for the function of basal ganglia in learning and memory. We had previously reported the existence of a corticostriatal ...

Aversive olfactory learning was established in young rats after odor exposure paired with foot shock through a classical conditioning paradigm. Using behavioral pharmacology and Western blotting, we previously reported that plasticity in the main olfactory bulb (MOB) underlies aversive olfactory learning. Since long-term potentiation (LTP) observed in the hippocampus is ...

How persistent synaptic and spine modification is achieved is essential to our understanding of developmental refinement of neural circuitry and formation of memory. Within a short period after their induction, both types of modifications can either be stabilized or reversed, but how this reversibility is controlled is largely unknown. We ...

Tetanic stimulation of the sciatic nerve (TSS) produces long-term potentiation (LTP) of C-fiber-evoked field potentials in the spinal cord. This potentiation is considered to be a substrate for long-lasting sensitization in the spinal pain pathway. Because microglia have previously been shown to regulate the induction of spinal LTP, we hypothesize ...

Learning-facilitated synaptic plasticity describes the ability of hippocampal synapses to respond with persistent synaptic plasticity to the coupling of weak afferent stimulation, which is subthreshold for the induction of plasticity, with a spatial learning experience. The metabotropic glutamate receptor subtype 5 (mGluR5) is critically involved in enabling the persistency of ...

The induction of long-term potentiation (LTP) of CA3-CA1 synapses requires activation of postsynaptic N-methyl-D-aspartate receptors (GluNRs). At resting potential, the contribution of GluNRs is limited by their voltage-dependent block by extracellular Mg(2+) . High-frequency afferent stimulation is required to cause sufficient summation of excitatory synaptic potentials (EPSPs) to relieve this ...

NMDA receptor-dependent synaptic modifications, such as long-term potentiation (LTP) and long-term depression (LTD), are essential for brain development and function. LTD occurs mainly by the removal of AMPA receptors from the postsynaptic membrane, but the underlying molecular mechanisms remain unclear. Here, we show that activation of caspase-3 via mitochondria is ...

C-type natriuretic peptide (CNP) and the natriuretic peptide receptor B (NPR-B) are expressed throughout the hippocampus. We tested whether CNP affected long-term potentiation (LTP) or long-term depression (LTD) in area CA1. Field potentials (FP) were simultaneously recorded in stratum pyramidale (SP) and stratum radiatum (SR) of area CA1 in rat ...

Although an increasing number of studies have demonstrated the plasticity of NMDA receptor-mediated synaptic transmission, little is known about the molecular mechanisms that underlie this neurologically important process. In a study of NMDAR-mediated synaptic responses in hippocampal Schaffer-CA1 synapses whose AMPA receptor (AMPAR) activity is totally blocked, we uncovered differences ...

The interest on the physiology of the nucleus accumbens (NAcc) has grown in recent years given its relationship to addictive behaviours, and the possibility to treat them by interacting with NAcc function. We have shown that the prior stimulation of the core region blocks induction of long-term potentiation (LTP) at ...

Opioids remain the mainstay of treatment for severe pain, but the associated hyperalgesia and tolerance are significant impediments to achieving adequate pain relief with opioids. Here we show that in the spinal cord, brief application of the mu-opioid receptor agonist (D-Ala(2),N-Me-Phe(4),Gly-ol(5))-enkephalin (DAMGO) at 1 mum, but not at 1-10 nm, ...

The insertion of amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors into the plasma membrane and removal via internalization are essential for regulating synaptic strength, which underlies the basic mechanism of learning and memory. The retinocollicular pathway undergoes synaptic refinement during development and shows a wide variety of long-term synaptic changes; however, still ...

The onset of puberty defines a developmental stage when some learning processes are diminished, but the mechanism for this deficit remains unknown. We found that, at puberty, expression of inhibitory alpha4betadelta gamma-aminobutyric acid type A (GABAA) receptors (GABAR) increases perisynaptic to excitatory synapses in CA1 hippocampus. Shunting inhibition via these ...