Effect of low frequency electrical stimulation on seizure-induced short- and long-term impairments in learning and memory in rats

✓ The histological, histochemical, and ultrastructural features of canine diaphragms subjected to pacing by high-frequency electrical stimulation (27 to 33 Hz) of the phrenic nerve are compared with unstimulated diaphragms and with diaphragms subjected to pacing by low-frequency stimulation (11 to 13 Hz). The high-frequency group showed a reduced tidal volume (fatigue) after long-term stimulation, and myopathic changes which included enlarged internal and sarcolemmal nuclei, ring fibers, moth-eaten fibers with irregular histochemical staining, core/targetoid fibers, and smearing and aggregation of Z-band material with electron microscopy. The low-frequency group did not develop a significant degree of fatigue or pathological changes, and showed histochemical evidence of transformation to fast-twitch (type II) fibers. Possible pathogenic mechanisms and their similarity to those in certain human neuromuscular diseases are discussed. The application of the findings resulting from high- and low-frequency stimulation to long-term diaphragm pacing in humans with chronic ventilatory insufficiency is also discussed.

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Effect of Short- and Long-Term Administration of Baclofen on Spatial Learning and Memory in Rats

Physiological Research ◽

10.33549/physiolres.933554 ◽

2018 ◽

pp. 133-141 ◽

Cited By ~ 1

Author(s):

M. HOLAJOVA ◽

M. FRANEK

Keyword(s):

Learning And Memory ◽

Spatial Learning ◽

Receptor Agonist ◽

Gabab Receptor ◽

Spatial Learning And Memory ◽

Adult Rats ◽

Treatment Groups ◽

Term Administration ◽

Short And Long Term

Baclofen is the only clinically available metabotropic GABAB receptor agonist. In our experiment, we tested the hypothesis that long-term baclofen administration can impair learning and memory in rats. The experiment consisted of three parts. In the first part of the study the drug was administered simultaneously with the beginning of the behavioral tests. In the second and third part of the experiment baclofen was administered daily for 14 days and for one month before the tests. In each part of the experiment, adult rats were randomly divided into four treatment groups. Three groups were given an injection of baclofen at doses of 1 mg/kg, 5 mg/kg, 10 mg/kg, while the fourth group was injected with saline. The injections were given after each session. Spatial learning and memory were tested using the Morris water maze, involving three types of tests: Acquisition, Probe, and Re-acquisition. This work reveals that baclofen did not affect spatial learning at any of the tested doses and regardless of the length of administration. Memory was observed to be affected, but only at the highest dose of baclofen and only temporarily. This conclusion is in line with previously published clinical cases.

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Engines of change: Transposable element mutation rates are high and variable within Daphnia magna

PLoS Genetics ◽

10.1371/journal.pgen.1009827 ◽

2021 ◽

Vol 17 (11) ◽

pp. e1009827

Author(s):

Eddie K. H. Ho ◽

Emily S. Bellis ◽

Jaclyn Calkins ◽

Jeffrey R. Adrion ◽

Leigh C. Latta IV ◽

...

Keyword(s):

Daphnia Magna ◽

Insertion Site ◽

Low Frequency ◽

Interspecific Variation ◽

Mutation Rates ◽

Evolutionary Forces ◽

Genome Wide ◽

Short And Long Term ◽

Powerful Mechanism

Transposable elements (TEs) represent a major portion of most eukaryotic genomes, yet little is known about their mutation rates or how their activity is shaped by other evolutionary forces. Here, we compare short- and long-term patterns of genome-wide mutation accumulation (MA) of TEs among 9 genotypes from three populations of Daphnia magna from across a latitudinal gradient. While the overall proportion of the genome comprised of TEs is highly similar among genotypes from Finland, Germany, and Israel, populations are distinguishable based on patterns of insertion site polymorphism. Our direct rate estimates indicate TE movement is highly variable (net rates ranging from -11.98 to 12.79 x 10−5 per copy per generation among genotypes), differing both among populations and TE families. Although gains outnumber losses when selection is minimized, both types of events appear to be highly deleterious based on their low frequency in control lines where propagation is not limited to random, single-progeny descent. With rate estimates 4 orders of magnitude higher than base substitutions, TEs clearly represent a highly mutagenic force in the genome. Quantifying patterns of intra- and interspecific variation in TE mobility with and without selection provides insight into a powerful mechanism generating genetic variation in the genome.

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Endocannabinoid dynamics gate spike-timing dependent depression and potentiation

eLife ◽

10.7554/elife.13185 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 24

Author(s):

Yihui Cui ◽

Ilya Prokin ◽

Hao Xu ◽

Bruno Delord ◽

Stephane Genet ◽

...

Keyword(s):

Mathematical Modeling ◽

Synaptic Plasticity ◽

Learning And Memory ◽

Long Term Potentiation ◽

Cellular Mechanism ◽

Spike Timing ◽

Long Term Depression ◽

Term Potentiation ◽

Short And Long Term

Synaptic plasticity is a cardinal cellular mechanism for learning and memory. The endocannabinoid (eCB) system has emerged as a pivotal pathway for synaptic plasticity because of its widely characterized ability to depress synaptic transmission on short- and long-term scales. Recent reports indicate that eCBs also mediate potentiation of the synapse. However, it is not known how eCB signaling may support bidirectionality. Here, we combined electrophysiology experiments with mathematical modeling to question the mechanisms of eCB bidirectionality in spike-timing dependent plasticity (STDP) at corticostriatal synapses. We demonstrate that STDP outcome is controlled by eCB levels and dynamics: prolonged and moderate levels of eCB lead to eCB-mediated long-term depression (eCB-tLTD) while short and large eCB transients produce eCB-mediated long-term potentiation (eCB-tLTP). Moreover, we show that eCB-tLTD requires active calcineurin whereas eCB-tLTP necessitates the activity of presynaptic PKA. Therefore, just like glutamate or GABA, eCB form a bidirectional system to encode learning and memory.

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Dictionary-unsanctioned Anglicisms

10.1093/acprof:oso/9780190625542.003.0004 ◽

2017 ◽

Author(s):

Valérie Saugera

Keyword(s):

Life Cycle ◽

Low Frequency ◽

Short Life ◽

Global English ◽

Very Low Frequency ◽

Short And Long Term

This core chapter reports on the findings from the investigation of the Libération corpus. Systematic tracking of dictionary-unattested Anglicisms occurring over a year of press language reveals that contact with global English has resulted in new patterns of borrowing and processes for extending the French lexicon, for the short and long term. A major finding is that the database includes many types of Anglicisms with very few tokens: global English is a robust supplier of transient words (nonce borrowings and very low-frequency items) which complement the more durable lexicon. Diachronic comparisons show that these Anglicisms typically have a short life cycle in the French lexicon, though some Anglicisms from the corpus entered subsequent editions of the dictionary. The data also reveal the less common borrowing of items from closed classes, including pronoun himself, stressed article the, and the preposition-like series starring/featuring/including.

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Loss of Long-Lasting Potentiation Mediated by Group III mGluRs in Amygdala Neurons in Kindling-Induced Epileptogenesis

Journal of Neurophysiology ◽

10.1152/jn.1997.78.6.3475 ◽

1997 ◽

Vol 78 (6) ◽

pp. 3475-3478 ◽

Cited By ~ 20

Author(s):

Volker Neugebauer ◽

N. Bradley Keele ◽

Patricia Shinnick-Gallagher

Keyword(s):

Electrical Stimulation ◽

Synaptic Transmission ◽

Learning And Memory ◽

Metabotropic Glutamate Receptors ◽

Long Term Potentiation ◽

Group Iii ◽

Brain Functions ◽

Group Ii ◽

Mglur Antagonist

Neugebauer, Volker, N. Bradley Keele, and Patricia Shinnick-Gallagher. Loss of long-lasting potentiation mediated by group III mGluRs in amygdala neurons in kindling-induced epileptogenesis. J. Neurophysiol. 78: 3475–3478, 1997. Long-lasting modifications of synaptic transmission can be induced in the amygdala by electrical stimulation as done in the long-term potentiation (LTP) model of learning and memory and the kindling model of epilepsy. The present study reports for the first time a long-lasting potentiation (LLP) of synaptic transmission that is induced pharmacologically by the activation of group III metabotropic glutamate receptors (mGluRs) in basolateral amygdala (BLA) neurons. In whole cell voltage-clamp mode, BLA neurons were recorded in brain slices from control rats and rats with amygdala-kindled seizures. The group III mGluR agonist l-2-amino-4-phosphonobutyrate (l-AP4, 10 μM) induced LLP of monosynaptic excitatory postsynaptic currents (EPSCs) evoked by electrical stimulation in the lateral amygdala (maximum 258 ± 50% of predrug control; means ± SE) in control ( n = 7) but not in kindled neurons( n = 6). LLP was measured 15 min after the superfusion of l-AP4, lasted for >45 min, and was not accompanied by postsynaptic membrane changes. l-AP4 induced LLP was prevented by the group III mGluR antagonist (S)-2-methyl-2-amino-4-phosphonobutyrate (MAP4; 100 μM, n = 6) but not the group II mGluR antagonist (2S,3S,4S)-2-methyl-2-carboxycyclopropylglycine (MCCG; 100 μM, n = 3). LLP was not observed after superfusion of the group II mGluR agonist (2S,3S,4S)-2-(carboxycyclopropyl)glycine (l-CCG; 1.0 and 10 μM) in either control ( n = 13) or kindled ( n = 10) neurons. If the underlying mechanisms and the functional significance of pharmacologically induced LLP are similar to those of LTP, the loss of l-AP4 induced LLP in kindled neurons may be a neurobiological correlate of learning and memory deficits in kindled animals and long-term alterations of brain functions in patients with epilepsies.

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