Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0598853 (forgetting)
 3,232 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Induction of long-term potentiation within the hippocampal formation can be modulated by afferent influences from a number of subcortical structures known to be involved in hippocampal-dependent learning and memory. This study performed on freely moving rats investigated the effects of stimulation of the noradrenergic locus coeruleus nucleus and the serotonergic dorsal raphe nucleus on spontaneously decaying posttetanic long-term potentiation in the dentate gyrus and the hippocampal CA1 area, respectively. High-frequency electrical stimulation of the locus coeruleus or the dorsal raphe elicited a well-expressed behavioural reaction of exploratory or defensive type, respectively, but did not significantly alter transmission at perforant path-dentate gyrus or Schaffer collateral-CA synapses, when delivered either before tetanic stimulation of the perforant path or the Schaffer collaterals or long (hours and days) after previously induced long-term potentiation had completely decayed. However, when locus coeruleus or dorsal raphe stimulation was delivered with the same parameters during a limited time (minutes and hours) after marked or even complete decay of tetanus-induced long-term potentiation at perforant path-dentate gyrus or Schaffer collateral-CA1 synapses, the potentiation was partially or entirely restored but never increased beyond the initial level of potentiation. In CA1, stimulation of ipsilateral and contralateral Schaffer collaterals demonstrated that the restoration of previously existing long-term potentiation by dorsal raphe stimulation was input-specific, occurring, like tetanus-induced potentiation, only in the pathway which had previously been tetanized. These findings suggest that the noradrenergic locus coeruleus and the serotonergic dorsal raphe can influence not only induction, but also spontaneous decay of long-term potentiation in the hippocampal formation. Since hippocampal long-term potentiation is thought to play a role in certain kinds of learning and memory, and association of tetanic stimulation with activation of ascending neuromodulatory systems is required for full expression of long-term potentiation, the restoration of hippocampal long-term potentiation by activation of a neuromodulatory system alone may serve as a mechanism of associative reminder which may underlie facilitation of memory retrieval after a period of forgetting, as has been observed in trained rats under similar conditions.
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PMID:Restoration of decaying long-term potentiation in the hippocampal formation by stimulation of neuromodulatory nuclei in freely moving rats. 1036 14

This study tested questions of ecological validity by comparing the eyewitness testimonies of children directly experiencing a painful inoculation experience those of children in a yoked-control group who vicariously experienced the inoculation onwith videotape. The study involved 86 5-year-olds, divided between 2 groups: the experiential and yoked control. The experiential group was followed through a health department with a video camera as they received diphtheria, pertussis, tetanus (DPT), and oral polio inoculations. They were tested immediately, 20 min later, and 1 month later. Each child in the yoked-control group merely watched the videotape of his or her counterpart in the experiential group, made similar ratings of pain, and was given the same tests and suggestions. Stress and personal experience affected items congruent with the stressor to produce flashbulb-like memories, with slower rates of forgetting for some items, such as nurse identifications, and greater suggestibility for other items, such as estimates of needle size. These and the apparently conflicting results in the literature were said to make sense when personally experienced stress was viewed from S.-A. Christianson's (1992) interactive perspective rather than as a single ubiquitous variable.
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PMID:Similarities and differences in eyewitness testimonies of children who directly versus vicariously experience stress. 1167 66

Inhibition of phosphodiesterase 9 (PDE9) has been reported to enhance rodent cognitive function and may represent a potential novel approach to improving cognitive dysfunction in Alzheimer's disease. PF-04447943, (6-[(3S,4S)-4-methyl-1-(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-1-(tetrahydro-2H-pyran-4-yl)-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one), a recently described PDE9 inhibitor, was found to have high affinity (Ki of 2.8, 4.5 and 18 nM) for human, rhesus and rat recombinant PDE9 respectively and high selectivity for PDE9 versus PDEs1-8 and 10-11. PF-04447943 significantly increased neurite outgrowth and synapse formation (as indicated by increased synapsin 1 expression) in cultured hippocampal neurons at low (30-100 nM) but not high (300-1000 nM) concentrations. PF-04447943 significantly facilitated hippocampal slice LTP evoked by a weak tetanic stimulus at a concentration of 100 nM but failed to affect response to the weak tetanus at either 30 or 300 nM, or the LTP produced by a theta burst stimulus. Systemic administration of PF-04447943 (1-30 mg/kg p.o.) dose-dependently increased cGMP in the cerebrospinal fluid 30 min after administration indicating target engagement in the CNS of rats. PF-04447943 (1-3 mg/kg p.o.) significantly improved cognitive performance in three rodent cognition assays (mouse Y maze spatial recognition memory model of natural forgetting, mouse social recognition memory model of natural forgetting and rat novel object recognition with a scopolamine deficit). When administered at a dose of 3 mg/kg p.o., which improved performance in novel object recognition, PF-04447943 significantly increased phosphorylated but not total GluR1 expression in rat hippocampal membranes. Collectively these data indicate that PF-04447943 is a potent, selective brain penetrant PDE9 inhibitor that increased indicators of hippocampal synaptic plasticity and improved cognitive function in a variety of cognition models in both rats and mice. Results with PF-04447943 are consistent with previously published findings using a structurally diverse PDE9 inhibitor, BAY73-6199, and further support the suggestion that PDE9 inhibition may represent a novel approach to the palliative remediation of cognitive dysfunction.
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PMID:The selective phosphodiesterase 9 (PDE9) inhibitor PF-04447943 (6-[(3S,4S)-4-methyl-1-(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-1-(tetrahydro-2H-pyran-4-yl)-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one) enhances synaptic plasticity and cognitive function in rodents. 2161 87