Learning during Sleep: An Indirect Test of the Erasure-Theory of Dreaming

1989 ◽  
Vol 69 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Dick Bierman ◽  
Oscar Winter
Keyword(s):  
Paired Associate ◽  
Stimulus Frequency ◽  
Threshold Effect ◽  
Critical Number ◽  
Indirect Test ◽  
Long Term Effects ◽  
Suggestive Evidence ◽  
Last Stage ◽  
Frequency Threshold

In this study the hypothesis, put forward elsewhere, that dreams are functional through the erasure of ‘incidental’ and weakly represented information was indirectly explored. 12 subjects were presented paired-associate word lists during each Stage-2 period of their sleep. According to the erasure-hypothesis these associations are destroyed during the subsequent dream if their representation is weak. Two effects might be expected. Firstly, associations which are formed during the last Stage-2 period (which is not followed by a dream-stage) will not be destroyed. Secondly, a stimulus frequency threshold-effect could be expected. Associations which are repeatedly presented (more often than a certain critical number) might become strong enough to withstand the ‘erasure.’ In the present study no indication was found for the latter expectation but a significant effect was found for those associations presented during the last Stage-2 period. Furthermore, there was suggestive evidence that sleep-rehearsal (of previously learned associations) yielded long-term effects.

Long-term Effects of Single or Multiple Neonatal Sevoflurane Exposures on Rat Hippocampal Ultrastructure

2015 ◽  
Vol 122 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Levana G. Amrock ◽  
Mathew L. Starner ◽  
Kathy L. Murphy ◽  
Mark G. Baxter
Keyword(s):  
Threshold Effect ◽  
Epidemiological Studies ◽  
Population Based ◽  
Male Rat ◽  
General Anesthetics ◽  
Long Term Effects ◽  
General Anesthetic ◽  
Synaptic Loss ◽  
Rat Pups

Abstract Background: Neonatal exposure to general anesthetics may pose significant neurocognitive risk. Human epidemiological studies demonstrate higher rates of learning disability among children with multiple, but not single, exposures to anesthesia. The authors employ a rat model to provide a histological correlate for these population-based observations. The authors examined long-term differences in hippocampal synaptic density, mitochondrial density, and dendritic spine morphology. Methods: Twenty male rat pups (n = 5/condition) were exposed to 2.5% sevoflurane under one of four conditions: single 2-h exposure on postnatal day 7 (P7); single 6-h exposure on P7; repeated 2-h exposures on P7, P10, and P13 for a cumulative 6 h of general anesthetics; or control exposure to 30% oxygen on P7, P10, and P13. Results: Repeated exposure to general anesthetics resulted in greater synaptic loss relative to a single 2-h exposure (P < 0.001). The magnitude of synaptic loss induced by three 2-h exposures (1.977 ± 0.040 μm3 [mean ± SEM]) was more profound than that of a single 6-h exposure (2.280 ± 0.045 μm3, P = 0.022). Repeated exposures did not alter the distribution of postsynaptic density length, indicating a uniform pattern of loss across spine types. In contrast, mitochondrial toxicity was best predicted by the cumulative duration of exposure. Relative to control (0.595 ± 0.017), both repeated 2-h exposures (0.479 ± 0.015) and a single 6-h exposure (0.488 ± 0.013) were associated with equivalent reductions in the fraction of presynaptic terminals containing mitochondria (P < 0.001). Conclusion: This suggests a “threshold effect” for general anesthetic–induced neurotoxicity, whereby even brief exposures induce long-lasting alterations in neuronal circuitry and sensitize surviving synapses to subsequent loss.

scholarly journals Is the Focal Muscle Vibration an Effective Motor Conditioning Intervention? A Systematic Review

2021 ◽  
Vol 6 (2) ◽  
pp. 39
Author(s):  
Luigi Fattorini ◽  
Angelo Rodio ◽  
Vito E. Pettorossi ◽  
Guido M. Filippi
Keyword(s):  
Mechanical Vibration ◽  
Stimulus Frequency ◽  
Muscle Spindles ◽  
Long Term Effects ◽  
Time Analysis ◽  
Muscle Belly ◽  
After Effects ◽  
Motor Conditioning ◽  
Short And Long Term

Mechanical vibration, applied to single or few muscles, can be a selective stimulus for muscle spindles, able to modify neuromuscular management, inducing short and long-term effects, are now mainly employed in clinic studies. Several studies reported as treatments with focal vibratory (FVT) can influence neuromuscular parameters also in healthy people. However, the application modalities and the consequent effects are remarkably fragmented. This paper aims to review these studies and to characterize the FVT effectiveness on long-term conditional capacities in relation to FVT characteristics. A systematic search of studies published from 1985 to 2020 in English on healthcare databases was performed. Articles had to meet the following criteria: (1) treatment based on a locally applied vibration on muscle belly or tendon; (2) healthy adults involved; (3) outcomes time analysis enduring for more than 24 h. Twelve studies were found, all of them presented an excellent quality score of ≥75%. All selected papers reported positive changes, comparable with traditional long-lasting training effects. Muscle force and power were the most investigated parameters. The after-effects persisted for up to several months. Among the different FV administration modalities, the most effective seems to show a stimulus frequency of ≈100 Hz, repeated more times within three-five days on a voluntary contracted muscle.

Ovarian Dysfunction in Fetally Irradiated Beagles

1977 ◽  
Vol 35 ◽  
pp. 658-659
Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Low Dose ◽  
Long Term Effects ◽  
Ovarian Dysfunction ◽  
Dose Rates ◽  
Highly Sensitive ◽  
Microscopic Evaluation ◽  
Ovarian Pathology ◽  
Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

Long-Term Effects of Head Lice Tx Unknown

2012 ◽  
Vol 43 (3) ◽  
pp. 42
Author(s):  
MITCHEL L. ZOLER
Keyword(s):  
Head Lice ◽  
Long Term Effects

The response of skin perfusion and of rheological and immunological variables to intravenous prostanoid administration in Raynaud’s phenomenon secondary to collagenosis

VASA ◽  
2005 ◽  
Vol 34 (4) ◽  
pp. 243-249 ◽  
Author(s):  
Drinda ◽  
Neumann ◽  
Pöhlmann ◽  
Vogelsang ◽  
Stein ◽  
...  
Keyword(s):  
Laser Doppler Flowmetry ◽  
Raynaud’S Phenomenon ◽  
Raynaud's Phenomenon ◽  
Plasma Viscosity ◽  
Laser Doppler ◽  
Erythrocyte Aggregation ◽  
Control Group ◽  
Long Term Effects ◽  
Doppler Flowmetry

Background: Prostanoids are used in the treatment of Raynaud’s phenomenon and acral perfusion disorders secondary to collagenosis. In subjective terms, intravenous administration of these agents produces success in more than 50% of patients. The therapeutic outcome of clinical administration of alprostadil or iloprost may vary from individual to individual. Patients and methods: The following variables were analysed in a cross-over study in 27 patients with collagenosis and Raynaud’s phenomenon: plasma viscosity and erythrocyte aggregation (rheological variables), partial pressure of oxygen and laser Doppler flowmetry in the finger region, and lymphocyte phenotyping and interleukin (IL) determinations (immunological variables). Results: Laser Doppler flowmetry revealed significant differences between patients with secondary Raynaud’s phenomenon and a control group of 25 healthy subjects. Laser Doppler readings did not change significantly as a result of the treatments. Therapy with iloprost produced a reduction in IL-1beta, L-selectin (CD 62 L) and IL-6. Conclusion: The change in immunological variables due to iloprost may explain the long-term effects of prostaglandins in the treatment of Raynaud’s phenomenon. From our results it is not possible to infer any preference for iloprost or alprostadil.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Sign in / Sign up

Export Citation Format

Share Document