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At least 883 records · Page 49Linked to original sources
PubMed1983

Retention of conditioned taste aversion in weanling, adult, and old-age rats.

Rats ranging in age from weanling to old age were given a single saccharin/lithium chloride pairing and were tested for saccharin aversion 1 or 28 days later. Weanling, adult, and old-age rats did not differ in their retention of the conditioned aversion at the 1-day retention interval, but weanling rats showed substantially less aversion than adult and old-age rats at the 28-day interval. The old-age rats did not differ from the adults at either retention interval. As old-age rats generally forget a passive avoidance task sooner than adults do, these results lend limited support to the hypothesis that retention of conditioned taste aversion may be mediated by a different memory system than the system that mediates retention of more conventional types of learning.

Aging↗
PubMed1985

Pharmacological evidence of a central effect of naltrexone, morphine, and beta-endorphin and a peripheral effect of met- and leu-enkephalin on retention of an inhibitory response in mice.

Immediate post-training administration of the central acting opioid receptor antagonist naltrexone (0.01-1.00 mg/kg) facilitated 48-h retention of a one-trial inhibitory avoidance task. An inverted-U dose-response curve was obtained. In this dose range naltrexone did not significantly affect response latencies of mice not given a footshock during the training. However, higher doses of naltrexone (3.0 and 10.0 mg/kg) increased latencies of both shocked and unshocked mice. The peripheral-acting opioid receptor blocker, naltrexone methyl bromide (MR 2263) (0.01-10.00 mg/kg), did not significantly influence retention latencies of either shocked or unshocked mice. Further, MR 2263 (0.1, 1.0, or 10.0 mg/kg) did not block the retention impairment produced by concurrently administered morphine (3.0 mg/kg) or beta-endorphin (0.1 microgram/kg). These findings indicate that the effect of these agonists on memory are not due to a peripheral influence. However, MR 2263 does prevent the memory-impairing effect of both metenkephalin (1.0 microgram/kg) and leu-enkephalin (0.3 microgram/kg) on retention. Those results suggest that enkephalins affect retention through influences initiated peripherally. Thus, different sites and mechanisms of action for beta-endorphin and the enkephalins are proposed.

Adrenal Medulla↗
PubMed1988

Psychoneurogenic stress influences upon retention of an inhibitory avoidance response in the rat.

Hormones and peptides involved in the response of an organism to stress play a modulating role in learning and memory processes. We studied whether psychoneurogenic stressors such as sound stimulation or novelty influence retention of an inhibitory avoidance response. An impairing effect on retention was observed when these stressors were applied shortly after the acquisition trial, but not after a 3-h delay. However, sound stimulation and novelty applied shortly before the retention test may facilitate retention behavior. It is suggested that the effect of psychoneurogenic stressors on retention behavior may be linked to influences on consolidation and retrieval processes mediated through the neurohumoral response of the organism to stress.

Acoustic Stimulation↗
PubMed1989

Differential influences of corticotropin-releasing factor on memory retention of aversive learning and appetitive learning in rats.

The effects of intraamygdala injections of corticotropin-releasing factor (CRF) on memory retention of aversive and appetitive learnings were examined in the present study. Other than confirming the results of a previous study that a moderate dose of CRF (0.1 microgram) injected into the amygdala facilitated retention performance of an inhibitory avoidance task (electric shock punishment) 24 h after training, we have further found that this effect lasted for a week. However, CRF produced a differential dose-response effect upon memory of an appetitive learning paradigm (sexual reinforcement). CRF at 0.01 microgram enhanced retention at both 24-h and 1-week intervals, while CRF at 0.1 microgram impaired retention in the same task at 1 week only. These results confirm that the amygdala is important in memory processing and suggest that the mechanisms involved in the action of CRF on memory retention of aversive and appetitive learnings are different. The possible differences are also discussed.

Amygdala↗
PubMed1992

Scopolamine deficits in negative patterning discrimination: evidence for a role of the central cholinergic system in retention but not acquisition of non-spatial configural association learning.

The effects of scopolamine (0.1 mg/kg s.c. and 0.6 mg/kg s.c.) were assessed on the acquisition and retention of a negative patterning discrimination task in rats. At 0.1 mg/kg scopolamine did not affect either acquisition or retention of the task. At 0.6 mg/kg scopolamine did not affect acquisition but did impair retention of the task. This impairment is likely to be centrally mediated as N-methyl scopolamine (0.6 mg/kg s.c.) did not affect retention. Lack of effect of scopolamine on acquisition of the task indicates that the central cholinergic system is not a necessary substrate of the acquisition of non-spatial configural associations. The scopolamine-induced deficit in retention of the task, suggests that there may, however, be a central cholinergic involvement in the retention/retrieval of this type of learning.

Amphetamine↗
PubMed1996

Tuberomammillary nucleus lesion facilitates two-way active avoidance retention in rats.

To evaluate whether the tuberomammillary nucleus might be involved in the acquisition and/or retention of a two-way active avoidance conditioning, rats were given a unilateral lesion of the tuberomammillary nucleus (E2 region) 24 h prior to the first conditioning session. Four learning sessions were performed: one acquisition and 3 retention sessions (short-term, 24 h; and long-term, 8 and 18 days). Results showed that the lesion facilitated the long-term retention of conditioning, but no effects were observed on acquisition and short-term retention. Since rewarding intracranial electrical stimulation seems to be a consistent way to facilitate learning and memory processes, and tuberomammillary lesion has been shown to improve intracranial self-stimulation behavior (ICSS), we suggest that lesions in the present experiment could have facilitated two-way active avoidance retention by enhancing the function of brain reward mechanisms.

Animals↗
PubMed2002

Randomised, placebo controlled, double blind study of alfuzosin SR in patients undergoing trial without catheter following acute urinary retention.

INTRODUCTION: Acute urinary retention caused by bladder outlet obstruction resulting from prostatic enlargement is one of the commonest causes for acute admission to urology wards. More recently, there has been a trend to commence treatment with alpha-blockers after catheterisation followed by a trial without catheter (TWOC), in the hope that surgery may be avoided in a significant proportion of patients. There is no conclusive evidence of the efficacy of this treatment. We conducted a study to evaluate the efficacy of using the alpha-blocker alfuzosin SR in patients with acute urinary retention. PATIENTS AND METHODS: All patients presenting with acute urinary retention to our unit were included in the trial. Exclusion criteria included patients with known bladder or prostate malignancy, bladder calculi, urinary tract infections, urethral stricture or patients on alpha-blockers. A total of 81 patients consented and were randomised. Sixty-two patients completed the study. The retention volume was recorded. Trial medicine was recorded on a twice-daily dose and the first TWOC was carried out after a minimum of three doses or 36 hours after admission. TWOC was considered successful on voiding with a residual volume of <200 ml. Unsuccessful patients were recatheterised and discharged home on trial medication, and called for a second TWOC after 2 weeks. Successful patients were continued on alpha-blockers and failures were put on the operating list for TURP. Patients on active treatments were reviewed at 2 year. RESULTS: Of the 34 patients treated with alfuzosin SR, 17 (50%) resumed voiding and of the 28 patients from placebo group, 16 (57%) voided successfully. All 33 patients were continued open labelled on alfuzosin SR 5mg BD. Out of 33 patients, 13 (43%) had TURP within first year after TWOC and three died due to various medical causes. Out of remaining 17 patients, 15 attended for follow-up. The mean peak flow rate was 8.4 ml/s and the mean residual volume was 112 ml. Six patients (40%) required TURP for severe lower urinary tract symptoms (LUTS). So out of 28 patients followed at 2 year, 19 (68%) had TURP. CONCLUSIONS: These data do not support the routine use of alpha-blockers in patients with acute urinary retention. Also continuing use of alpha-blockers does not seem to prevent further requirements of TURP, although larger studies are needed to support this.

Acute Disease↗
PubMed2001

Kidney ultrasound and Doppler ultrasound findings during and after acute urinary retention.

OBJECTIVE: To evaluate changes in kidney ultrasound and Doppler ultrasound images during and subsequent to acute urinary retention (AUR). METHODS: Twenty-five men with a mean age of 69 years suffering AUR for a mean of 31 h were studied by measuring serum creatinine, creatinine clearance and renal ultrasound. Renal Doppler ultrasound was applied in 19 of these cases and all patients were followed for 6 months after acute retention was relieved. RESULTS: During AUR hydronephrosis was noted in three patients; this disappeared during follow-up. During the acute period, after 1 month and after 6 months the average resistive indexes (RI) were 0.71, 0.70 and 0.69, respectively. The changes were not statistically significant. During follow-up, the proportion of patients with normal RI increased from 42 to 64%. Median serum creatinine was normal during retention and follow-up. Median creatinine clearance was reduced during retention and became normal during follow-up (P < 0.05). No correlation was found between RI and serum creatinine at any time-point, nor was any correlation noted between RI and creatinine clearance during retention or at the 1-month follow-up; at 6 months, however, there was a significant inverse correlation between them (P = 0.01). CONCLUSION: AUR caused elevation of RI, which may be interpreted as diminished renal blood flow. Although in the majority of patients it recovered after treatment, elevated RI was still found in one third of the patients, possibly due to previous chronic bladder outlet obstruction. Our findings stress the importance of both fast release of AUR and effective treatment of its cause.

Acute Disease↗
PubMed1999

A deficit in the short-term retention of lexical-semantic information: forgetting words but remembering a story.

This article examines the long-term memory of a patient, AB, who had previously been reported to have problems in the short-term retention of word meanings. The authors found that AB had a problem not only in the short-term but also in the long-term retention of lexical-semantic information. AB, however, had no problem in the long-term retention of other kinds of information (pictures, shapes, propositional information). This pattern of results was interpreted as evidence that lexical-semantic representations have their own specific memory resources that are involved in the retention of the corresponding representations across different time intervals (e.g., they are involved in short-term as well as long-term retention). Implications for models of memory are discussed.

Adult↗
PubMed1997

Additivity of the effects of retention interval and context change on latent inhibition: toward resolution of the context forgetting paradox.

Three experiments with rats examined retention interval and context switch effects factorially in the latent inhibition paradigm. In Experiment 1, a 28-day retention interval abolished a context switch effect on latent inhibition. In Experiment 2, re-exposure to the contexts before conditioning re-established the context switch effect at the 28-day interval. In this case, the retention interval and context switch effects were additive: Latent inhibition was weakest when the retention interval and context switch were combined. Experiment 3 replicated the context switch effect at the 28-day interval. The results suggest that context switch and retention interval effects may be based on the same process. Context switch effects may weaken over time because physical contexts are embedded in superordinate temporal contexts; animals fail to retrieve physical context when the temporal context changes. This view helps resolve a paradox that has been noted for contextual change theories of forgetting.

Animals↗
PubMed2000

The properties of retention intervals and their affect on retaining prospective memories.

Five experiments were conducted to explore how the character of the retention interval affected event-based prospective memory. According to the canons of retrospective memory, prospective performance should have been worse with increasing delays between intention formation and the time it was appropriate to complete an action. That result did not occur. Rather, prospective memory was better with increasing retention intervals in Experiments 1A, 1B, and 3. In manipulating the nature of the retention interval, the authors found that there were independent contributions of retention interval length and the number of intervening activities, with more activities leading to better prospective memory (Experiments 2 and 3). The identical retention intervals did not improve retrospective memory in Experiment 4. Theoretical explanations for these dissociations between prospective and retrospective memory are considered.

Adult↗
PubMed1983

Presentation- and test-trial effects on acquisition and retention of distance and location.

Acquisition and retention effects of presentation and test trials on movement distance (Experiment 1) and location (Experiment 2) were examined under three multitrial training methods. Three groups of 15 government employees performed three training trial cycles consisting of six trials each. Training methods emphasized either presentation-trial repetition, test-trial repetition, or presentation- and test-trial alternation within cycles. After training, both short- (3 min.) and long-term (24 hr.) retention scores were recorded. Absolute error revealed that (a) presentation-trial repetition promoted acquisition of both distance and location but resulted in extensive short- and long-term forgetting; (b) test-trial repetition produced error increases within cycles, potentiated presentation-trial effectiveness during acquisition, and enhanced long-term retention of both distance and location; (c) presentation- and test-trial alternation promoted distance and location acquisition and produced distance retention intermediate to that of the other two methods. Experiment 3 provided data to support the interpretation that test-trial retention benefits are a function of movement execution mode.

Adult↗
PubMed1998

Ontogenetic differences in the expression of conditioned stimulus conditioning: effects of retention interval.

Preweanling 17-day-old rats were tested for retention of the conditioned emotional response after a 5-min or 24-hr retention interval. For a variety of conditioning parameters (i.e., variation in conditioned stimulus modality, unconditioned stimulus intensity, number of training trials), conditioned responding was consistently weaker after 5 min than after 24 hr. This apparent "incubation," or "hypermnesic," effect was not found in adult rats, even when comparable conditioning levels were indicated on the 24-hr test. The transient short-term retention deficit observed in 17-day-old preweanlings was alleviated by placing the pup in its home cage during the 5-min retention interval or by extending the conditioning session. Fifteen-day-old rat pups did not benefit from home cage exposure or extended training and displayed the transient short-term retention deficit regardless. The results are discussed in terms of age-related effects on time-dependent memory consolidation.

Acoustic Stimulation↗
PubMed1997

Learning and retention in preclinical and early Alzheimer's disease.

Accelerated forgetting has been proposed as the first sign in preclinical and early Alzheimer's disease (AD). The authors investigated learning and retention in participants who later developed AD with free and cued selective reminding (FCSR; H. Buschke, 1984; E. Grober & H. Buschke, 1987), a test that maximizes learning by inducing deep semantic processing and by controlling study and test conditions. AD patients in the preclinical stage recalled significantly fewer words than did matched control participants, indicating an impairment of learning; nonetheless, patients' retention was identical to that of control participants. A retention deficit was documented 3 years later for AD patients but not for control participants, whose retention was still perfect. Thus, a retention deficit is not present in preclinical AD when hallmark learning deficits can be documented. Detection of preclinical and very early AD may be best accomplished by using robust learning tests that control cognitive processing.

Aged↗
PubMed2003

Retention of prefabricated and individually cast root canal posts in vitro.

OBJECTIVES: The aim of the study was to evaluate the retention of prefabricated root canal posts made of a variety of materials that have recently been introduced into dentistry. MATERIALS AND METHODS: The posts studied were CosmoPost, Composipost carbon fibres, Composipost Aestheti-Plus, Composipost Light-Post and Para Post Fiber White. The posts were luted in extracted human premolars and the cores were built up with the resin composites recommended by the manufacturers. The retention of individually cast gold alloy posts luted with zinc-phosphate cement were used as reference. A universal testing machine was used to determine the retention of each cemented post Data were compared using ANOVA supplemented with Fisher's PLSD at a significance level of p < 0.05. RESULTS: Only the CosmoPost system exhibited retention values that were significantly lower than for the conventionally cast gold alloy posts luted with zinc-phosphate cement The force necessary to loosen the CosmoPost specimens was significantly less than that needed to loosen the Composipost. Estheti-Plus (p < 0.05) and the Composipost Ught-Post systems (p < 0.001]. The force necessary to loosen the ParaPost Fiber White specimens was significantly less than for the Composipost Light-Post system (p < 0.01). Other combinations did not differ significantly (p > 0.05). CONCLUSIONS: When zirconium oxide ceramic posts are luted with resin composites the bonding between the ceramic and resin composite seems to be weak. Further studies are thus necessary to achieve improved retention of all-ceramic root canal posts.

Analysis of Variance↗
PubMed2002

Effect of length and diameter of tapered posts on the retention.

The force transmission of tapered unthreaded posts along the root has been reported to be homogenous but their retentive strength was found to be lower compared with those of parallel unthreaded or other kinds of threaded posts. The purpose of this in vitro study was to investigate the effect of length and diameter on the retentive strength of sandblasted tapered prefabricated titanium posts (Erlangen post system). Posts with constant taper angle but with three different lengths (9, 12, 15 mm) and apical diameters (0.5, 0.9, 1.1 mm) were cemented using zinc phosphate cement into the prepared and roughened post spaces of 90 intact anterior teeth. The post retention concerning length and diameter, being independent from each other, was measured by a tensile force test. The retentive strength was found to be proportional to the length as well as to the diameter of the posts. The mean minimum strength (181 +/- 14 N) recorded for the thinnest and shortest post was significantly lower than that of mean maximum strength (612 +/- 85 N) obtained from those of the thickest and longest post. Proportional bond strengths of the posts comprising their surface areas ranged between 6.8 and 7.9 N mm(-2) which were not significantly different between any group. The retention was effected strongly with the increase in the length (approximately 100%) than with the increase in the diameter (approximately 60%). Concerning the posts tested in this study, it is concluded that some caution should be exercised in the choice of post with appropriate length rather than diameter for the tooth concerned.

Cementation↗
PubMed1998

Short communication: long- but not medium-term retention of olfactory memories in honeybees is impaired by actinomycin D and anisomycin.

Although work in a wide variety of species and paradigms has demonstrated that long-term memory is sensitive to the blocking of protein synthesis, previous studies have suggested that the honeybee might represent an exception to this rule. Retention tested one day after training was not impaired by the inhibition of translation by cycloheximide. Using blockers of either transcription (actinomycin D) or translation (anisomycin), we present experiments that reconcile this unusual finding by testing over longer retention periods. Honeybees were conditioned to associate an odourant with a sucrose reward. Typically, this leads to stable retention over days. However, injection of either drug led to lower retention after 4 days, whereas retention after 2 or sometimes even 3 days was unaffected. This dissociates two forms of memory: a protein synthesis-independent, medium-term memory (up to 3 days) and a protein synthesis-dependent, long-term memory lasting for at least 4 days.

Animals↗
PubMed1999

Pre- or post-training injection of buspirone impaired retention in the inhibitory avoidance task: involvement of amygdala 5-HT1A receptors.

The present study investigated the effect of buspirone on memory formation in an aversive learning task. Male Wistar rats were trained on the inhibitory avoidance task and tested for retention 1 day after training. They received peripheral or intra-amygdala administration of buspirone or other 5-HT1A drugs either before or after training. Results indicated that pretraining systemic injections of buspirone caused a dose-dependent retention deficit; 5. 0 mg/kg had a marked effect and 1.0 mg/kg had no effect. Post-training injections of the drug caused a time-dependent retention deficit, which was not due to a state-dependent effect on retrieval. When training in the inhibitory avoidance task was divided into a context-training phase and a shock-training phase, buspirone impaired retention only when administered in the shock-training phase, suggesting that the drug influenced memory processing of affective events. Further results indicated that post-training intra-amygdala infusion of buspirone or the 5-HT1A agonist 8-hydroxy-di-n-propylaminotetralin (8-OH-DPAT) caused a time-dependent and dose-dependent retention deficit. Post-training intra-amygdala infusion of the 5-HT1A antagonist WAY100635 (N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)-N-(2-pyridyl) cyclohexane carboxamine maleate) attenuated the memory-impairing effects of buspirone. These findings suggest that buspirone may modulate memory storage processes in the inhibitory avoidance task through an action on amygdaloid 5-HT1A receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗