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.     

Work-Related Psychological Health Among Clergy Serving in The Presbyterian Church (USA): Testing the Idea of Balanced Affect

Drawing on the classic model of balanced affect, the Francis Burnout Inventory (FBI) conceptualises good work-related psychological health among clergy in terms of negative affect being balanced by positive affect. In a random sample of 744 clergy (539 clergymen and 205 clergywomen) serving in The Presbyterian Church (USA), negative affect was assessed by the Scale of Emotional Exhaustion in Ministry (SEEM) and positive affect was assessed by the Satisfaction in Ministry Scale (SIMS). At the same time, burnout was independently assessed using self-report measures of overall health and burnout, and by the extraversion and neuroticism scales of Eysenck’s dimensional model of personality. These independent measures of burnout indicated higher burnout among those who were emotionally exhausted and lower burnout among those who had high levels of satisfaction with their ministry. Crucially for proving the idea of balanced affect, there was a significant interaction between the effects of SEEM and SIMS scores on these independent measures of burnout, showing that the mitigating effects of positive affect on burnout increased with increasing levels of negative affect.     

Developmental differences in the neural correlates supporting semantics and syntax during sentence processing

School‐aged and adolescent children continue to demonstrate improvements in how they integrate and comprehend real‐time, auditory language over this developmental time period, which can have important implications for academic and social success. To better understand developmental changes in the neural processes engaged during language comprehension in this age group, we use electroencephalography to investigate how 8–9 year old, 12–13 year olds, and adults process semantics and syntax in naturally paced, auditory sentences. Participants listened to semantically and syntactically correct and incorrect sentences and were asked to complete an acceptability judgment task. When processing a semantic error, developmental differences were observed in theta, but not the N400, suggesting that the N400 may be too gross a measure to identify more subtle aspects of semantic development that occur in the school years. For the syntactic task, errors resulted in a larger P600 and greater beta decrease than correct sentences, but the amplitude and location of the P600 and amplitude of beta decreases differed as a function of age, suggesting specialization of syntactic skills is ongoing through adolescence. The current findings shed new light on the development of the neural oscillations supporting language comprehension and suggest that the neural substrates underlying semantic processing reach adult‐like levels at a younger age than those underlying syntactic processing.     

The effect of age of acquisition in visual word processing: further evidence for the semantic hypothesis

The authors investigated whether the meaning of visually presented words is activated faster for early-acquired words than for late-acquired words. They addressed the issue using the semantic Simon paradigm. In this paradigm, participants are instructed to decide whether a stimulus word is printed in uppercase or lowercase letters. However, they have to respond with a verbal label ("living" or "nonliving") that is either congruent with the meaning of the word (e.g., saying "living" to the stimulus DOG) or incongruent (e.g., saying "nonliving" to the stimulus dog). Results showed a significant congruency effect that was stronger for early-acquired words than for late-acquired words. The authors conclude that the age of acquisition is an important variable in the activation of the meaning of visually presented words.     

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.     

Cross-modal attentional entrainment: Insights from magicians

Recently, performance magic has become a source of insight into the processes underlying awareness. Magicians have highlighted a set of variables that can create moments of visual attentional suppression, which they call “off-beats.” One of these variables is akin to the phenomenon psychologists know as attentional entrainment. The current experiments, inspired by performance magic, explore the extent to which entrainment can occur across sensory modalities. Across two experiments using a difficult dot probe detection task, we find that the mere presence of an auditory rhythm can bias when visual attention is deployed, speeding responses to stimuli appearing in phase with the rhythm. However, the extent of this cross-modal influence is moderated by factors such as the speed of the entrainers and whether their frequency is increasing or decreasing. In Experiment 1, entrainment occurred for rhythms presented at .67 Hz, but not at 1.5 Hz. In Experiment 2, entrainment only occurred for rhythms that were slowing from 1.5 Hz to .67 Hz, not speeding. The results of these experiments challenge current models of temporal attention.     

Global Zimbabweans: Diaspora Engagement and Disengagement

Since 2000, migration from crisis-ridden Zimbabwe has led to almost one million people leaving the country. The majority migrate to neighbouring South Africa and Botswana, and most of the research on the Zimbabwean diaspora to date has focused on South Africa and the UK. However, the Zimbabwean diaspora is now truly global in its distribution. This paper argues that more attention should therefore be paid to Zimbabweans in other jurisdictions in the Global South and North. Zimbabweans began migrating to Canada in increasing numbers after 2000, most as refugees but also as immigrants and students. Based on a survey of the Zimbabwean diaspora in Canada, this paper focuses on their migration history, demographic characteristics and backward linkages with Zimbabwe. Given the interest in diaspora engagement in the global migration and development literature, it is important to understand the nature of these linkages in order to assess the potential for diaspora involvement in Zimbabwean development. The paper argues that under current economic and political conditions in Zimbabwe, this potential remains weak.