Modulatory influence of dopamine receptors on consolidation of object recognition memory

The role of dopamine receptors in regulating the formation of recognition memory remains poorly understood. Here we show the effects of systemic administration of dopamine receptor agonists and antagonists on the formation of memory for novel object recognition in rats. In Experiment I, rats received an intraperitoneal (i.p.) injection of vehicle, the selective D1 receptor agonist SKF38393 (1.0 and 5.0mg/kg), or the D2 receptor agonist quinpirole (1.0 and 5.0mg/kg) immediately after training. In Experiment II, rats received an injection of vehicle, the dopamine receptor antagonist SCH23390 (0.1 and 0.05 mg/kg), or the D2 receptor antagonist raclopride (0.5 and 0.1mg/kg) before training, followed by an injection of vehicle or the nonselective dopamine receptor agonist apomorphine (0.05 mg/kg) immediately after training. SKF38393 at 5mg/kg produced an enhancement of novel object recognition memory measured at both 24 and 72 h after training, whereas the dose of 10mg/kg impaired 24-h retention. Posttraining administration of quinpirole did not affect 24-h retention. Apomorphine enhanced memory in rats given pretraining raclopride, suggesting that the effect was mediated by selective activation of D1 receptors. The results indicate that activation of D1 receptors can enhance recognition memory consolidation. Importantly, pharmacological activation of D1 receptors enhanced novel object recognition memory even under conditions in which control rats showed significant retention.     

Verbal mediating responses: effects on generalization of say-do correspondence and noncorrespondence

We analyzed the effects of verbal mediating responses on the acquisition and generalization of say-do correspondence and noncorrespondence. Participants were assigned to groups in which either reinforcers (feedback and tokens) were arranged for say-do correspondence and noncorrespondence, or no reinforcers were programmed. Participants in these groups were further subdivided into groups in which they were required to repeat what was said previously, were required to repeat random numbers, or no verbalizations were required. When correspondence was reinforced, repetition of what was said produced greater acquisition and generalization of correspondence. When noncorrespondence was reinforced, repetition of numbers facilitated acquisition and generalization of noncorrespondence. Verbal mediating responses interacted with contingencies of reinforcement in determining acquisition and generalization of correspondence and noncorrespondence.     

Human variable ratio performance

The generality of the mathematical principles of reinforcement (MPR) was tested with humans. In Experiment 1A, participants’ mouse clicks were reinforced according to a series of variable-ratio (VR) values. In one condition, a situated task was used (searching for treasure on a map presented via a PC monitor); in the other, abstract version of the task, participants clicked on a white screen. Under the “map” condition, response rates increased with increasing ratio value before decreasing with further ratio increases; under the “no-map” condition, response rates decreased linearly from a peak at the smallest ratio. In Experiment 1B, the pattern of responding was confirmed under the “map” conditions using a different set of ratio values. In Experiment 2, reinforcer magnitude was manipulated using the “map” context. Response rates did not differ significantly when large rather than small cash reinforcers were delivered according to a VR 30 but were significantly higher when large rather than small cash reinforcers were delivered according to a VR 120. Together these experiments offer qualified support for extending MPR to the behavior of human participants.     

Integrated memory for objects, places, and temporal order: evidence for episodic-like memory in mice

Human episodic memory refers to the recollection of an unique past experience in terms of what happened, and where and when it happened. Factoring out the issue of conscious recollection, episodic memory, even at the behavioral level, has been difficult to demonstrate in non-human mammals. Although, it was previously shown that rodents can associate what and when or what and where information given on unique trials, it proved to be difficult to demonstrate memory for what, where, and when simultaneously in mammals, without using extensive training procedures, which might induce semantic rather than episodic memory recall. Towards the goal of an animal model of human episodic memory we designed an three-trial object exploration task in which different versions of the novelty-preference paradigm were combined to subsume (a) object recognition memory, (b) the memory for locations in which objects were explored, and (c) the temporal order memory for object presented at distinct time points. We found that mice spent more time exploring two "old familiar" objects relative to two "recent familiar" objects, reflecting memory for what and when and concomitantly directed more exploration at a spatially displaced "old familiar" object relative to a stationary "old familiar" object, reflecting memory for what and where. These results suggest that during a single test trial the mice were able to (a) recognize previously explored objects, (b) remember the location in which particular objects were previously encountered, and (c) to discriminate the relative recency in which different objects were presented. According to the currently discussed behavioral criteria for episodic-like memory in animals, our results suggest that mice are capable to form such higher order memories.     

Performance of chronotypes on memory tests during the morning and the evening shifts

Memory consists of several phases or processes that can be influenced by many factors, including the individual's circadian rhythm and the time of day at which tests are performed. The present objective was to evaluate the performance on memory tests of different chronotypes during the morning and the evening shifts. Subjects (21 men and 26 women, between the ages of 20 and 35 yr.) were evaluated for memory and metamemory differences in the morning and in the afternoon, using a battery of neuropsychological tests composed of the Word List with Emotional Content, Visual Memory, Scale-Semantic Memory, Digit Span, Word-Pairs Associated, Verbal Fluency Test, and Metamemory questionnaire. In the evening shift, there was a statistical difference among chronotypes on the Word List with Neutral Content and on the Verbal Fluency Test. In the morning, there were no statistically significant differences; however, the morning-type subjects had higher scores on the metamemory tests (p<.01), while the evening-type subjects had higher scores in the afternoon (p<.01). In spite of their perception, on Word-Pairs Associated and Word List with Emotional Content, the subjects, independently of their chronotype, showed better performance by the evening than by the morning shift. These results highlight the importance of controlling the shift of day and chronotype in studies with the objective of exploration of human performance.     

Is time limit at the minimum swimming velocity of VO2 max influenced by stroking parameters?

The aim of this study was to observe the relationship between time limit at the minimum velocity that elicits maximal oxygen consumption (TLim-v VO2 max) and stroke rate, stroke length, and stroke index. 13 men and 10 women, highly trained swimmers, performed an intermittent incremental test for v VO2 max assessment and an all-out swim to estimate TLim-v VO2 max. The mean +/- SD TLim-v VO2 max, v VO2 max, stroke rate, stroke length, and stroke index values were 233.36 +/- 53.92 sec., 1.40 +/- .06 meter/sec., 35.58 +/- 2.89 cycles/min., 2.39 +/- .22 meter/cycle, and 3.36 +/- .41 meter2/(cycle x sec.), respectively. The correlation between TLim-v VO2 max and stroke rate was -.51 (p < .01), and values for TLim-v VO2 max with stroke length (r = .52, p < .01) and stroke index (r = .45, p < .05). These results seem to suggest that technical skill is a key factor in typical efforts requiring prolonged aerobic power.     

COVID-19 Vaccination Acceptance: A Case of Interplay Between Political and Health Dimensions

Vaccines are essential for the eradication of diseases. Yet for many reasons, individuals do not embrace them completely. In the COVID-19 pandemic and with the possibility of the Brazilian population's immunization against the disease, both political and health-related dimensions might have had a role in individual COVID-19 vaccination acceptance. In two studies (n = 974), we tested the hypothesis that participants' vaccination acceptance is related to their past vote in the 2018 Brazilian presidential election (being or not being a Jair Bolsonaro voter) and their different levels of perceived vulnerability to disease (PVD). We further tested whether Bolsonaro's opposition or ambiguous messages towards vaccination (vs. control) increased vaccination rejection among those who have (vs. have not) voted for him and who are low (vs. high) in PVD. Results show that Bolsonaro (vs. non-Bolsonaro) voters accepted less vaccination, with higher rejection rates when participants expressed low (vs. high) PVD. Also, when primed either with Bolsonaro's opposed or ambiguous messages towards COVID-19 vaccination, such participants accepted less vaccines (vs. participants primed with neutral information). These findings are the first to show that the COVID-19 vaccine acceptance is related to their past vote and leadership influence but also different levels of perceived vulnerability to disease.     

Measures of infant self-regulation during the first year of life: A systematic review

This study aimed to systematically review the measures used to assess infant self-regulation during the first 12 months of life. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement protocol. From 235 selected papers, 79 provided information on behavioural and physiological measures to assess infant self-regulation during the first 12 months of life. Thirty-six behavioural (30 observational and 6 parent-report) and five physiological different measures were identified. Studies with a longitudinal design, comprising larger samples, and aiming to assess infant self-regulation later in infancy, mostly used behavioural measures than physiological measures. Studies comprising lower samples and aiming to assess infant self-regulation earlier in infancy, mostly used observational than parent-reported measures. Studies targeting younger infants used physiological measures and studies targeting older infants used behavioural measures, with observational measures used with younger infants and parental-reported measures used with older infants during the first year of life. When measuring self-regulation is important to consider infant's age, to fit the measurement procedures with the self-regulation development level.     

Undernutrition during suckling and latent learning ability of rehabilitated adult male rats

The present report investigates the effects of early undernutrition on the latent learning ability of rehabilitated adult male rats in a simple maze task. Rats were undernourished during suckling by feeding their dams an 8% casein diet. Well-nourished dams received a 25% casein diet during the same period. Rats were weaned at 21 days of age and nutritionally rehabilitated until they became adults, when behavioral task was conducted. Under a nonappetitive condition, rats were exposed either to an open field or to a maze apparatus. They were thereafter deprived of water and tested in the maze apparatus. Both well-nourished and undernourished rats that had been previously exposed to the maze performed better than those exposed to the open field. Nutritional treatment had no effect on performance of either the latent learning or of the open-field groups. These results suggest that rehabilitated adult rats are able to learn about the environment when no immediate reinforcement is involved. The discrepancy between our findings and results reported by others may be due to differences in task complexity and/or perhaps to the fact that nutritional rehabilitation also plays a role in reversing some of the deleterious effects of early undernutrition on learning ability of rats.     

Measurement invariance of the Utrecht Work Engagement Scale for Students: A study across secondary school pupils and university students

School engagement is a multidimensional construct characterized by vigour, dedication, and absorption towards academic work that is related to school achievement. This study aimed to examine the measurement invariance of a school engagement measure – the Utrecht Work Engagement Scale-Students (UWES-S) – across secondary school pupils and university students. Two samples of secondary school pupils (n = 251) and university students (n = 229) were used. The results supported the original three-factor structure (vigour, dedication and absorption) of the UWES-S instead of a two- or a one-factor structure in both samples. Evidence for the metric and scalar invariance of the measure across secondary school pupils and university students was also found. The university sample had higher scores in vigour and absorption but not in dedication. These findings demonstrate that the UWES-S can be used for developmental studies where school engagement and its relation with other variables needs to be compared across distinct educational levels.