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Poor Retention (poor + retention)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Fast Mapping but Poor Retention by 24-Month-Old Infants

INFANCY, Issue 2 2008
Jessica S. Horst
Four experiments explored the processes that bridge between referent selection and word learning. Twenty-four-month-old infants were presented with several novel names during a referent selection task that included both familiar and novel objects and tested for retention after a 5-min delay. The 5-min delay ensured that word learning was based on retrieval from long-term memory. Moreover, the relative familiarity of objects used during the retention test was explicitly controlled. Across experiments, infants were excellent at referent selection, but very poor at retention. Although the highly controlled retention test was clearly challenging, infants were able to demonstrate retention of the first 4 novel names presented in the session when referent selection was augmented with ostensive naming. These results suggest that fast mapping is robust for reference selection but might be more transient than previously reported for lexical retention. The relations between reference selection and retention are discussed in terms of competitive processes on 2 timescales: competition among objects on individual referent selection trials and competition among multiple novel name,object mappings made across an experimental session. [source]

Hydrologic versus geomorphic limitation on CPOM storage in stream ecosystems

FRESHWATER BIOLOGY, Issue 8 2008
MELANIE J. SMALL
Summary 1. Stream ecosystems are the products of interactions between hydrology, geomorphology and ecology, but examining all three components simultaneously is difficult and rarely attempted. Frequently, either geomorphology or hydrology is treated as invariable or static. 2. To examine the validity of treating either hydrology or geomorphology as static, we studied the individual and combined effects of hydrology and channel geomorphology on coarse particulate organic matter (CPOM) storage. Using data from an experimental leaf release in a hydrologically regulated stream we created a simple numerical model. This allowed us to quantify the relative influence of CPOM trapping and CPOM retention on total long-term CPOM storage under variable regimes of flood frequency and geomorphic structure. 3. CPOM storage is a function of supply, flood frequency and the type and frequency of in-stream structures. In-stream structures perform two distinct functions, trapping and retention, whose relative importance in leaf storage changes with stream hydrology. Trapping is more important for CPOM storage in streams with few floods, while retention is more important in streams with frequent floods. Different structures (e.g. boulders, large wood, small wood) perform these functions at different efficiencies. We found that large wood trapped two to three times more leaves than the bank, but that the bank retained leaves two to three times more efficiently. 4. A modelled channel with five times the amount of large wood as the study channel (a ,wood restoration') initially stored 14% more leaves than the modelled ,natural' channel. After six floods, however, the modelled wood restoration channel stored 50% less CPOM than the natural channel as the large wood had high trapping but poor retention. The modelled natural channel contained structures that could both trap and retain. Thus, as different structures performed different functions, the structural complexity buffered the stream allochthonous energy base against changes in hydrology through its balance of trapping and retention. 5. As the frequency of floods increased, the spatial distribution of CPOM became increasingly patchy as storage was driven entirely by structures with high retention. Thus, the coupling of flood frequency and geomorphic structure influenced CPOM availability, which in turn has ramifications for the entire stream food web. [source]

A cognitive aid for neonatal resuscitation: a randomized controlled trial

PEDIATRIC ANESTHESIA, Issue 7 2009
M.D. Bould
Introduction:, Anaesthetists are among several health care practitioners responsible for neonatal resuscitation in Canada. The Neonatal resuscitation program (NRP) courses are the North American educational standard. NRP has been shown to be an effective way of learning skills and knowledge but retention has been found to be problematic [1]. The use of cognitive aids is mandatory in industries such as aviation, to avoid dependence on memory when decision making in critical situations. Visual cognitive aids have been studied retrospectively in resuscitation and performance was found to correlate to the frequency of use of the aid [2]. Cognitive aids have been found to be of benefit in an unblinded prospective study [3]. We aimed to conduct the first blinded study on the effect of a cognitive aid on the performance of simulated resuscitation. Methods:, We conducted a single-blind randomized controlled trial to investigate whether the presence of a cognitive aid improved performance in a simulated neonatal resuscitation. After ethics board approval we recruited 32 anaesthesia residents who had previously passed the NRP. Subjects were randomized to an intervention group that had a poster detailing the NRP algorithm and a control group without the poster. The cognitive aid was positioned so that it could not be seen on the video recordings of the simulation that was used to assess performance. The scenario was piloted to confirm adequate blinding. Both groups had their performance in a simulated neonatal resuscitation recorded and subsequently analyzed by a peer, an expert anaesthetist and an expert neonatologist, using a previously validated checklist. A further rater observed the scenario in real time to examine frequency of use of the cognitive aid. Results:, The inter-rater reliability of the checklist was excellent with an intraclass correlation coefficient of 0.88. Consequently the mean of the scores assigned by all three raters was used for analysis. The median checklist score in the control group 18.2 [15.0,20.5 (10.7,25.3)] was not significantly different from that in the intervention group 20.3 [18.3,21.3 (15.0,24.3)] (P = 0.08). Retention of NRP skills and knowledge of was poor: when evaluated by the neonatologist none of the subjects correctly performed all life-saving interventions necessary to pass the checklist. Although only one subject in the intervention group did not use the aid at all, only 26.7% used the aid frequently and none used it extensively. Discussion:, Retention of skills after NRP training was poor. Our study confirms previous findings of poor retention of skills after NRP training: Kaczorowski et al. investigated family medicine trainees and found that none of 44 residents that were retested 6,8 months after an NRP course would have passed the course due to errors in life-saving interventions [1]. Previous research has shown that the presence of a cognitive aid can improve performance in the simulated management of a rare, high stakes scenario: malignant hyperthermia [3]. Our negative findings contrast with this and another previous study [2]. A potential reason for this discrepancy is that the raters in the previous studies were not blinded to group allocation, nor were the rating scales used validated. The infrequent use of the cognitive aid may be the reason that it did not improve performance in. Further research is required to investigate whether cognitive aids can be useful if their use is incorporated into NRP training. Conclusion:, A randomized single-blinded trial found that a cognitive aid did not improve performance at simulated resuscitation, in contrast to previous retrospective and unblended studies. Retention of skills and knowledge after resuscitation training remains an ongoing challenge for medical educators. [source]

Protective effect of quercetin against ICV colchicine-induced cognitive dysfunctions and oxidative damage in rats

PHYTOTHERAPY RESEARCH, Issue 12 2008
Anil Kumar
Abstract Intracerebroventricular (i.c.v.) administration of colchicine, a microtubule-disrupting agent, causes cognitive dysfunction and oxidative stress. The present study was designed to investigate the protective effects of quercetin against colchicine-induced memory impairment and oxidative damage in rats. An i.c.v. cannula was implanted in the lateral ventricle of male Wistar rats. Colchicine was administered at dose of 15 µg/rat. Morris water maze and plus-maze performance tests were used to assess memory tasks. Various biochemical parameters such as lipid peroxidation, reduced glutathione, nitrite level, acetylcholinesterase and proteins were also assessed. Central administration of colchicine (15 µg/rat) showed poor retention of memory. Chronic treatment with quercetin (20 and 40 mg/kg, p.o.) twice daily for a period of 25 days beginning 4 days prior to colchicine injection significantly improved the colchicine-induced cognitive impairment. Biochemical analysis revealed that i.c.v. colchicine injection significantly increased lipid peroxidation, nitrite and depleted reduced glutathione activity in the brains of rats. Chronic administration of quercetin significantly attenuated elevated lipid peroxidation and restored the depleted reduced glutathione, acetylcholinesterase activity and nitrite activity. The results of the present study clearly indicated that quercetin has a neuroprotective effect against colchicine-induced cognitive dysfunctions and oxidative damage. This article was published online on 3 November 2008. An error was subsequently identified. This notice is included in the online and print version to indicate that both have been corrected. [24 November 2008] Copyright © 2008 John Wiley & Sons, Ltd. [source]

Effect of N -Acetyl Cysteine against Aluminium-induced Cognitive Dysfunction and Oxidative Damage in Rats

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2009
Atish Prakash
Chronic aluminium exposure induces oxidative stress and increases amyloid beta levels in vivo. The role of oxidative stress has been well-suggested in these cognitive problems. Therefore, the present study was designed to explore the possible role of N -acetyl cysteine against aluminium mediating cognitive dysfunction and oxidative stress in rats. Aluminium chloride (100 mg/kg, p.o.) was given to rats daily for 6 weeks. N -acetyl cysteine (per se; 50 and 100 mg/kg, i.p.) pre-treatment was given 30 min. before aluminium daily for 6 weeks. On the third (21st day) and sixth week (42nd day) of the study, various behavioural tests (Morris water maze and elevated plus maze task paradigms) and locomotion (photoactometer) were done to evaluate cognitive tasks. The rats were killed on the 43rd day following the last behavioural test, and various biochemical tests were performed to assess the extent of oxidative damage. Chronic aluminium chloride administration resulted in poor retention of memory in Morris water maze, elevated plus maze task paradigms and caused marked oxidative damage. It also caused a significant increase in the acetylcholinesterase activity. Chronic administration of N -acetyl cysteine significantly improved memory retention in tasks, attenuated oxidative damage and acetylcholinesterase activity in aluminium-treated rats. The study suggests a neuroprotective effect of N -acetyl cysteine against aluminium-induced cognitive dysfunction and oxidative damage. [source]