scholarly journals Reduced Synaptic Plasticity in the Lateral Perforant Path Input to the Dentate Gyrus of Aged C57BL/6 Mice

2003 ◽  
Vol 90 (1) ◽  
pp. 32-38 ◽  
Author(s):  
David J. Froc ◽  
Brennan Eadie ◽  
Amanda M. Li ◽  
Karl Wodtke ◽  
Maric Tse ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Dentate Gyrus ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Significant Degree ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Synaptic Efficacy ◽  
Term Potentiation ◽  
Effects Of Aging

Hippocampal slices obtained from C57BL/6 mice (3–25 mo) were used to investigate the effects of aging on excitatory postsynaptic potentials (EPSPs) elicited in dentate gyrus with lateral perforant path stimulation. The maximal amplitude of the EPSP, as well as the degree of paired-pulse facilitation, was significantly reduced in animals aged 12 mo or more compared with younger animals (<12 mo). Although all animals showed equivalent short-term potentiation (STP) in response to high-frequency stimulation, this did not translate into a long-lasting increase in synaptic efficacy in the older animals. A significant degree of long-term potentiation (LTP) of synaptic efficacy was only observed in animals <12 mo of age when measured 30 min after induction. Blocking GABAA-mediated inhibition significantly enhanced STP in younger and older animals; however, a significant degree of LTP was again only observed in slices taken from younger animals. These data indicate that the lateral perforant path input to the dentate gyrus is altered by the aging process, and that this results in a reduction in the capacity of this input to exhibit long-lasting synaptic plasticity.

Low-frequency stimulation of the perforant path produces long-term potentiation in the dentate gyrus of unanesthetized rats

1983 ◽  
Vol 61 (10) ◽  
pp. 1156-1161 ◽  
Author(s):  
R. W. Skelton ◽  
J. J. Miller ◽  
A. G. Phillips
Keyword(s):  
Dentate Gyrus ◽  
Low Frequency ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Synaptic Efficacy ◽  
Term Potentiation ◽  
Frequency Stimulation ◽  
Stimulation Of

Brief periods of high-frequency stimulation of hippocampal afferents produce long-term potentiation (LTP) of synaptic transmission, but the minimum frequency capable of inducing this alteration in synaptic efficacy has not been specified. The present study used the repeated measurement of input–output curves in the perforant path – dentate gyrus system of freely moving rats to monitor synaptic efficacy and found that stimulation at 0.2 Hz, but not 0.04 Hz produced LTP. These results suggest that the minimum stimulation frequency capable of producing LTP is lower than previously described. Possible reasons for the discrepancy between the present and previous findings are discussed, along with the implications of low-frequency potentiation.

Attenuated LTP in Hippocampal Dentate Gyrus Neurons of Mice Deficient in the PAF Receptor

2001 ◽  
Vol 85 (1) ◽  
pp. 384-390 ◽  
Author(s):  
Chu Chen ◽  
Jeffrey C. Magee ◽  
Victor Marcheselli ◽  
Mattie Hardy ◽  
Nicolas G. Bazan
Keyword(s):  
Synaptic Plasticity ◽  
Dentate Gyrus ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Wild Type ◽  
In The Wild ◽  
Paf Receptor ◽  
Deficient Mice

Platelet-activating factor (PAF), a bioactive lipid (1- O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) derived from phospholipase A2and other pathways, has been implicated in neural plasticity and memory formation. Long-term potentiation (LTP) can be induced by the application of PAF and blocked by a PAF receptor (PAF-R) inhibitor in the hippocampal CA1 and dentate gyrus. To further investigate the role of PAF in synaptic plasticity, we compared LTP in dentate granule cells from hippocampal slices of adult mice deficient in the PAF-R and their age-matched wild-type littermates. Whole cell patch-clamp recordings were made in the current-clamp mode. LTP in the perforant path was induced by a high-frequency stimulation (HFS) and defined as >20% increase above baseline of the amplitude of excitatory postsynaptic potentials (EPSPs) from 26 to 30 min after HFS. HFS-induced enhancement of the EPSP amplitude was attenuated in cells from the PAF-R-deficient mice (163 ± 14%, mean ± SE; n = 32) when compared with that in wild-type mice (219 ± 17%, n = 32). The incidence of LTP induction was also lower in the cells from the deficient mice (72%, 23 of 32 cells) than in the wild-type mice (91%, 29 of 32 cells). Using paired-pulse facilitation as a synaptic pathway discrimination, it appeared that there were differences in LTP magnitudes in the lateral perforant path but not in the medial perforant path between the two groups. BN52021 (5 μM), a PAF synaptosomal receptor antagonist, reduced LTP in the lateral path in the wild-type mice. However, neither BN52021, nor BN50730 (5 μM), a microsomal PAF-R antagonist, reduced LTP in the lateral perforant path in the receptor-deficient mice. These data provide evidence that PAF-R-deficient mice are a useful model to study LTP in the dentate gyrus and support the notion that PAF actively participates in hippocampal synaptic plasticity.

scholarly journals Long-term potentiation expands information content of hippocampal dentate gyrus synapses

2018 ◽  
Vol 115 (10) ◽  
pp. E2410-E2418 ◽  
Author(s):  
Cailey Bromer ◽  
Thomas M. Bartol ◽  
Jared B. Bowden ◽  
Dusten D. Hubbard ◽  
Dakota C. Hanka ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Dentate Gyrus ◽  
Storage Capacity ◽  
Unit Length ◽  
Long Term Potentiation ◽  
Information Storage ◽  
Perforant Path ◽  
Hippocampal Dentate Gyrus ◽  
Term Potentiation

An approach combining signal detection theory and precise 3D reconstructions from serial section electron microscopy (3DEM) was used to investigate synaptic plasticity and information storage capacity at medial perforant path synapses in adult hippocampal dentate gyrus in vivo. Induction of long-term potentiation (LTP) markedly increased the frequencies of both small and large spines measured 30 minutes later. This bidirectional expansion resulted in heterosynaptic counterbalancing of total synaptic area per unit length of granule cell dendrite. Control hemispheres exhibited 6.5 distinct spine sizes for 2.7 bits of storage capacity while LTP resulted in 12.9 distinct spine sizes (3.7 bits). In contrast, control hippocampal CA1 synapses exhibited 4.7 bits with much greater synaptic precision than either control or potentiated dentate gyrus synapses. Thus, synaptic plasticity altered total capacity, yet hippocampal subregions differed dramatically in their synaptic information storage capacity, reflecting their diverse functions and activation histories.

Medial amygdala enhances synaptic transmission and synaptic plasticity in the dentate gyrus of rats in vivo

1995 ◽  
Vol 74 (5) ◽  
pp. 2201-2203 ◽  
Author(s):  
Y. Ikegaya ◽  
K. Abe ◽  
H. Saito ◽  
N. Nishiyama
Keyword(s):  
Synaptic Plasticity ◽  
Synaptic Transmission ◽  
Dentate Gyrus ◽  
High Frequency ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
High Frequency Stimulation ◽  
Medial Amygdala ◽  
Frequency Stimulation ◽  
Stimulation Of

1. The present experiment was designed to test whether synaptic transmission and synaptic plasticity in the dentate gyrus were modulated by the medial amygdala (MeA). Field potentials in the dentate gyrus (DG) evoked by stimulations of the medial perforant path (PP) were extracellularly recorded in anesthetized rats. 2. Although single-pulse stimulation of the MeA augmented PP stimulation-evoked population spike amplitude in the DG transiently, high-frequency stimulation (100 Hz for 1 s) of the MeA induced long-lasting enhancement of synaptic transmission that was not occluded by PP tetanus-induced long-term potentiation (LTP). 3. When high-frequency stimulation of the MeA was applied concurrently with weak tetanus of the PP, which alone induced only marginal LTP, the magnitude of LTP increased considerably. 4. These results demonstrate that neuron activities in the MeA induce short- and long-lasting changes in the excitability of the PP-DG synapses and thereby enhance their synaptic plasticity.

scholarly journals Imaging spatio-temporal patterns of long-term potentiation in mouse hippocampus

2003 ◽  
Vol 358 (1432) ◽  
pp. 689-693 ◽  
Author(s):  
Toshiyuki Hosokawa ◽  
Masaki Ohta ◽  
Takeshi Saito ◽  
Alan Fine
Keyword(s):  
Hippocampal Slices ◽  
Temporal Patterns ◽  
Long Term Potentiation ◽  
Optical Recording ◽  
Stratum Radiatum ◽  
High Frequency Stimulation ◽  
Optical Signals ◽  
Term Potentiation ◽  
Spatio Temporal

Spatio-temporal patterns of neuronal activity before and after the induction of long-term potentiation in mouse hippocampal slices were studied using a real-time high-resolution optical recording system. After staining the slices with voltage-sensitive dye, transmitted light images and extracellular field potentials were recorded in response to stimuli applied to CA1 stratum radiatum. Optical and electrical signals in response to single test pulses were enhanced for at least 30 minutes after brief high-frequency stimulation at the same site. In two-pathway experiments, potentiation was restricted to the tetanized pathway. The optical signals demonstrated that both the amplitude and area of the synaptic response were increased, in patterns not predictable from the initial, pretetanus, pattern of activation. Optical signals will be useful for investigating spatio-temporal patterns of synaptic enhancement underlying information storage in the brain.

Effects of Adult Neurogenesis on Synaptic Plasticity in the Rat Dentate Gyrus

2001 ◽  
Vol 85 (6) ◽  
pp. 2423-2431 ◽  
Author(s):  
J. S. Snyder ◽  
N. Kee ◽  
J. M. Wojtowicz
Keyword(s):  
Synaptic Plasticity ◽  
Dentate Gyrus ◽  
Adult Neurogenesis ◽  
Long Term Potentiation ◽  
Receptor Blocker ◽  
Granule Neurons ◽  
Term Potentiation ◽  
Cell Recording ◽  
Similar Preparation ◽  
Nmda Receptor Blocker

Ongoing neurogenesis in the adult hippocampal dentate gyrus (DG) generates a substantial population of young neurons. This phenomenon is present in all species examined thus far, including humans. Although the regulation of adult neurogenesis by various physiologically relevant factors such as learning and stress has been documented, the functional contributions of the newly born neurons to hippocampal functions are not known. We investigated possible contributions of the newly born granule neurons to synaptic plasticity in the hippocampal DG. In the standard hippocampal slice preparation perfused with artificial cerebrospinal fluid (ACSF), a small (10%) long-term potentiation (LTP) of the evoked field potentials is seen after tetanic stimulation of the afferent medial perforant pathway (MPP). The induction of this ACSF-LTP is resistant to a N-methyl-d-aspartate (NMDA) receptor blocker,d,l-2-amino-5-phosphonovaleric acid (APV), but is completely prevented by ifenprodil, a blocker of NR2B subtype of NMDA receptors. In contrast, slices perfused with picrotoxin (PICRO), a GABA-receptor blocker, revealed a larger (40–50%), APV-sensitive but ifenprodil-insensitive LTP. The ACSF-LTP required lower frequency of stimulation and fewer stimuli for its induction than the PICRO-LTP. All these characteristics of ACSF-LTP are in agreement with the properties of the putative individual new granule neurons examined previously with the use of the whole cell recording technique in a similar preparation. A causal relationship between neurogenesis and ACSF-LTP was confirmed in experiments using low dose of gamma radiation applied to the brain 3 wk prior to the electrophysiological experiments. In these experiments, the new cell proliferation was drastically reduced and ACSF-LTP was selectively blocked. We conclude that the young, adult-generated granule neurons play a significant role in synaptic plasticity in the DG. Since DG is the major source of the afferent inputs into the hippocampus, the production and the plasticity of new neurons may have an important role in the hippocampal functions such as learning and memory.

scholarly journals PKA and Ube3a regulate SK2 channel trafficking to promote synaptic plasticity in hippocampus: Implications for Angelman Syndrome

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiandong Sun ◽  
Yan Liu ◽  
Guoqi Zhu ◽  
Caleb Cato ◽  
Xiaoning Hao ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Angelman Syndrome ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Synaptic Membranes ◽  
Channel Trafficking ◽  
Over Expression ◽  
Terminal Domain ◽  
Complex Interactions ◽  
Term Potentiation

Abstract The ubiquitin ligase, Ube3a, plays important roles in brain development and functions, since its deficiency results in Angelman Syndrome (AS) while its over-expression increases the risk for autism. We previously showed that the lack of Ube3a-mediated ubiquitination of the Ca2+-activated small conductance potassium channel, SK2, contributes to impairment of synaptic plasticity and learning in AS mice. Synaptic SK2 levels are also regulated by protein kinase A (PKA), which phosphorylates SK2 in its C-terminal domain, facilitating its endocytosis. Here, we report that PKA activation restores theta burst stimulation (TBS)-induced long-term potentiation (LTP) in hippocampal slices from AS mice by enhancing SK2 internalization. While TBS-induced SK2 endocytosis is facilitated by PKA activation, SK2 recycling to synaptic membranes after TBS is inhibited by Ube3a. Molecular and cellular studies confirmed that phosphorylation of SK2 in the C-terminal domain increases its ubiquitination and endocytosis. Finally, PKA activation increases SK2 phosphorylation and ubiquitination in Ube3a-overexpressing mice. Our results indicate that, although both Ube3a-mediated ubiquitination and PKA-induced phosphorylation reduce synaptic SK2 levels, phosphorylation is mainly involved in TBS-induced endocytosis, while ubiquitination predominantly inhibits SK2 recycling. Understanding the complex interactions between PKA and Ube3a in the regulation of SK2 synaptic levels might provide new platforms for developing treatments for AS and various forms of autism.

Priming-Induced Shift in Synaptic Plasticity in the Rat Hippocampus

1999 ◽  
Vol 82 (4) ◽  
pp. 2024-2028 ◽  
Author(s):  
Hongyan Wang ◽  
John J. Wagner
Keyword(s):  
Synaptic Plasticity ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Crossover Point ◽  
Term Potentiation ◽  
Before And After ◽  
History Of ◽  
The Brain ◽  
Dependent Mechanism

The activity history of a given neuron has been suggested to influence its future responses to synaptic input in one prominent model of experience-dependent synaptic plasticity proposed by Bienenstock, Cooper, and Munro (BCM theory). Because plasticity of synaptic plasticity (i.e., metaplasticity) is similar in concept to aspects of the BCM proposal, we have tested the possibility that a form of metaplasticity induced by a priming stimulation protocol might exhibit BCM-like characteristics. CA1 field excitatory postsynaptic potentials (EPSPs) obtained from rat hippocampal slices were used to monitor synaptic responses before and after conditioning stimuli (3–100 Hz) of the Schaffer collateral inputs. A substantial rightward shift (>5-fold) in the frequency threshold between long-term depression (LTD) and long-term potentiation (LTP) was observed <1 h after priming. This change in the LTD/P crossover point occurred at both primed and unprimed synaptic pathways. These results provide new support for the existence of a rapid, heterosynaptic, experience-dependent mechanism that is capable of modifying the synaptic plasticity phenomena that are commonly proposed to be important for developmental and learning/memory processes in the brain.

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