Age-related changes in duration reproduction: involvement of working memory processes

The aim of the present research was to study age-related changes in duration reproduction by differentiating the working memory processes underlying this time estimation task. We compared performances of young and elderly adults in a duration reproduction task performed in simple and concurrent task conditions. Participants were also administered working memory tests to measure storage and central executive functions. Findings indicated a differential involvement of working memory storage and central executive functions in age-related differences in temporal tasks. The limited storage capacities explained age-related changes in the simple task of duration reproduction, and the dysfunctioning of central executive functions accounted for age-related changes in duration reproduction performed in a concurrent task condition, which involves greater attentional resources.     

Time-dependent effects of treadmill exercise on aversive memory and cyclooxygenase pathway function

Exercise induces brain function adaptations and improves learning and memory; however the time window of exercise effects has been poorly investigated. Studies demonstrate an important role for cyclooxygenase-2 (COX-2) pathway function in the mechanisms underlying memory formation. The aim of present work was to investigate the effects of treadmill exercise on aversive memory and COX-2, PGE(2) and E-prostanoid receptors contents in the rat hippocampus at different time points after exercise has ended. Adult male Wistar rats were assigned to non-exercised (sedentary) and exercised (running daily for 20min, for 2weeks) groups. The inhibitory avoidance task was used to assess aversive memory and the COX-2, PGE(2) and E-prostanoid receptors (EP1, EP2, EP3 and EP4) levels were determined 1h, 18h, 3days or 7days after the last training session of treadmill exercise. The step down latency in the inhibitory avoidance, COX-2 and EP4 receptors levels were acutely increased by exercise, with a significant positive correlation between aversive memory performance and COX-2 levels. Increased EP2 content decreased PGE(2) levels were observed 7days after the last running session. The treadmill exercise protocol facilitates inhibitory avoidance memory and induces time-dependent changes on COX-2 pathways function (COX-2, PGE(2) and EP receptors).     

The Influence of Two Cognitive-Linguistic Variables on Incidental Word Learning in 5-Year-Olds

The relation between incidental word learning and two cognitive-linguistic variables—phonological memory and phonological awareness—is not fully understood. Thirty-five typically developing, 5-year-old, preschool children participated in a study examining the association between phonological memory, phonological awareness, and incidental word learning. Children were exposed to target words in a read-aloud story that accompanied a wordless picture book. Target word comprehension was assessed before and after two readings of the story. Phonological awareness predicted incidental word learning but phonological memory did not. The influence of phonological awareness and phonological memory on word learning may be dependent on the demands of the word learning task.     

Locus of Control and Attitudes Toward Work and Retirement

Fifty-three older workers (M = 57.2) enrolled in a preretirement training program were administered a battery of measures designed to further evaluate the role that locus of control plays in determining attitudes toward work and retirement. Results suggested that perceived control related to work commitment. The extent of the relationship between perceived control and attitudes toward retirement, however, was mediated by sex, level of education, and self-rated health. Consistent with previous research, perceived control related to measures of adjustment.     

The role of stability in the dynamics of learning, memorizing, and forgetting new coordination patterns

According to a dynamic theory of learning, how a new memory is formed depends on the stability of the nearest preexisting memories. To predict retention after practice, the authors analyzed how 15 participants memorized 2 bimanual coordination patterns (45 degrees or 135 degrees relative phase). The authors assessed (a) how participants memorized the required patterns with learning and (b) how the associated memory layout evolved. Results showed that a practiced 45 degrees pattern near a very stable memory (0 degrees ) persisted, whereas a 135 degrees pattern near a less stable memory (180 degrees ) was forgotten. Those findings corroborate the proposition that retention of coordination patterns depends on the stability of the extant motor memories. The authors discuss that proposal in terms of the coevolution of accuracy and stability with learning to predict persistence of required or false memories.     

Post-training intrahippocampal inhibition of class I histone deacetylases enhances long-term object-location memory

Long-term memory formation involves covalent modification of the histone proteins that package DNA. Reducing histone acetylation by mutating histone acetyltransferases impairs long-term memory, and enhancing histone acetylation by inhibiting histone deacetylases (HDACs) improves long-term memory. Previous studies using HDAC inhibitors to enhance long-term memory have focused on the fear-conditioning task using broad-spectrum HDAC inhibitors. We have found that post-training intrahippocampal administration of the broad-spectrum HDAC inhibitor trichostatin A (TSA) or the class I HDAC-selective inhibitor MS275 enhances long-term object-location memory, supporting a role for class I HDACs in the enhancement of hippocampus-dependent memory induced by HDAC inhibition.     

Development of a metabolic equation for the NuStep recumbent stepper in older adults

The purpose of this study was to develop an accurate metabolic equation for estimating steady-state oxygen consumption (VO2) during submaximal NuStep exercise. Adults (N = 40; M age = 64.0 yr., SD = 6.5; M height = 170.1 cm, SD = 9.1; M weight = 85.7 kg, SD = 19.9) performed two randomized testing sessions. Each session consisted of six stages with combinations of four workloads (1, 3, 5, and 7) at 3 cadences (60, 80, and 100 steps/min.). Multiple regression analysis to predict steady-state VO2 from NuStep workload (W), NuStep steps/min., and subject body mass resulted in the following model (R2 = .73): Steady-state VO2 = 3.5 + 0.016 (W* steps/min.) + 0.092 (steps/min.) - 0.053 (weight). The standard error of the estimate and total error for the prediction of steady-state VO2 under all NuStep workload conditions were 2.3 mL/kg/min. and 2.4 mL/kg/ min., respectively. The standard error of the estimate and total error values are similar to those previously reported in the literature regarding the accuracy of metabolic equations for other exercise modalities. These findings support the use of the equation developed to predict steady-state VO2 for NuStep exercise in older adult clientele.     

Selective inhibition in children with attention-deficit hyperactivity disorder off and on stimulant medication

Selective inhibition requires discrimination between auditory signals and is assessed using a modification of the stop-signal task. Selective inhibition was assessed in a group of 59 clinic-referred, DSM-IV-diagnosed children with attention-deficit hyperactivity disorder (ADHD) and compared to that of a community sample of 59 children. Methylphenidate (MPH) effects on selective inhibition were assessed in a subset of the ADHD sample that participated in an acute, randomized, placebo-controlled, crossover trial with 3 fixed doses of MPH. Children with ADHD performed more poorly than controls on the majority of selective stop-signal task parameters: they exhibited more anticipatory (invalid) responses, with less accurate and more variable responses on the response execution task, as well as a slower selective inhibition process. MPH improved speed of both inhibition and response execution processes; it also reduced variability of response execution and decreased nonselective inhibition. On the one hand, findings are consistent with purported inhibition deficit in ADHD, but on the other hand, suggest that neither the impairment itself, nor MPH effects, were restricted to inhibition.     

Validity of specific motor skills in predicting table-tennis performance in novice players

An experiment assessed whether novice table-tennis players' ball-balancing and bouncing skills could predict their performances after a semester of being coached. A pretest-posttest design was used to test this hypothesis with 82 male and 77 female physical education students who initially performed the skills and subsequently participated in a round-robin tournament. Moderate negative but significant (p<.01) Spearman rank-order correlation coefficients were obtained between some of the ball control skills scores and overall ranking in the table-tennis tournament.     

Environmental enrichment modifies the PKA-dependence of hippocampal LTP and improves hippocampus-dependent memory

cAMP-dependent protein kinase (PKA) is critical for the expression of some forms of long-term potentiation (LTP) in area CA1 of the mouse hippocampus and for hippocampus-dependent memory. Exposure to spatially enriched environments can modify LTP and improve behavioral memory in rodents, but the molecular bases for the enhanced memory performance seen in enriched animals are undefined. We tested the hypothesis that exposure to a spatially enriched environment may alter the PKA dependence of hippocampal LTP. Hippocampal slices from enriched mice showed enhanced LTP following a single burst of 100-Hz stimulation in the Schaffer collateral pathway of area CA1. In slices from nonenriched mice, this single-burst form of LTP was less robust and was unaffected by Rp-cAMPS, an inhibitor of PKA. In contrast, the enhanced LTP in enriched mice was attenuated by Rp-cAMPS. Enriched slices expressed greater forskolin-induced, cAMP-dependent synaptic facilitation than did slices from nonenriched mice. Enriched mice showed improved memory for contextual fear conditioning, whereas memory for cued fear conditioning was unaffected following enrichment. Our data indicate that exposure of mice to spatial enrichment alters the PKA dependence of LTP and enhances one type of hippocampus-dependent memory. Environmental enrichment can transform the pharmacological profile of hippocampal LTP, possibly by altering the threshold for activity-dependent recruitment of the cAMP-PKA signaling pathway following electrical and chemical stimulation. We suggest that experience-dependent plasticity of the PKA dependence of hippocampal LTP may be important for regulating the efficacy of hippocampus-based memory.