Sleep deprivation effects on object discrimination task in zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>)

The zebrafish is an ideal vertebrate model for neurobehavioral studies with translational relevance to humans. Many aspects of sleep have been studied, but we still do not understand how and why sleep deprivation alters behavioral and physiological processes. A number of hypotheses suggest its role in memory consolidation. In this respect, the aim of this study was to analyze the effects of sleep deprivation on memory in zebrafish (Danio rerio), using an object discrimination paradigm. Four treatments were tested: control, partial sleep deprivation, total sleep deprivation by light pulses, and total sleep deprivation by extended light. The control group explored the new object more than the known object, indicating clear discrimination. The partially sleep-deprived group explored the new object more than the other object in the discrimination phase, suggesting a certain degree of discriminative performance. By contrast, both total sleep deprivation groups equally explored all objects, regardless of their novelty. It seems that only one night of sleep deprivation is enough to affect discriminative response in zebrafish, indicating its negative impact on cognitive processes. We suggest that this study could be a useful screening tool for cognitive dysfunction and a better understanding of the effect of sleep-wake cycles on cognition.     

Development of an evaluation scale for sitting and standing from the ground for children with Duchenne muscular dystrophy

The authors developed an evaluation scale for sit-stand from the ground for children with Duchenne muscular dystrophy (DMD) and tested its reliability. The construction occurred in stages: (a) the characterization of the movement in healthy children, (b) the characterization of the movement in children with DMD, (c) the elaboration of the 1st version of the scale and the manual, (d) the evaluation by experts and readjustments, and (e) the analysis of inter- and intraexaminer reliability and correlation with the Vignos Scale, age, and time for the execution of the activity. The scale comprehended 3 phases for sitting and 5 for the standing. A very good repeatability of the measures of sitting and standing (ICC = 0.89 and 0.84, respectively) and excellent reproducibility (ICC = 0.93 and 0.92, respectively) was demonstrated. The Kappa coefficient for the 8 phases in the interexaminer analysis varied from 0.77 to 1.00 (excellent reliability), and in the intraexaminer analysis varied from 0.80 to 1.00 (excellent reliability). Good correlation was found between the variables on the Vignos Scale (age: r = 0.58; stand: r = 0.56). The scale is a reliability instrument that allows evaluation of the activity of sitting and standing in children with DMD.     

A Deliberative Approach to Causation

Fundamental physics makes no clear use of causal notions; it uses laws that operate in relevant respects in both temporal directions and that relate whole systems across times. But by relating causation to evidence, we can explain how causation fits in to a physical picture of the world and explain its temporal asymmetry. This paper takes up a deliberative approach to causation, according to which causal relations correspond to the evidential relations we need when we decide on one thing in order to achieve another. Tamsin's taking her umbrella is a cause of her staying dry, for example, if and only if her deciding to take her umbrella for the sake of staying dry is adequate grounds for believing she'll stay dry. This correspondence explains why causation matters: knowledge of causal structure helps us make decisions that are evidence of outcomes we seek. The account also explains why we can control the future and not the past, and why causes come before their effects. When agents properly deliberate, their decisions can never count as evidence for any outcomes they may seek in the past. From this it follows that causal relations don't run backwards. This deliberative asymmetry is itself traced back to asymmetries of evidence and entropy, providing a new way of deriving causal asymmetry from temporally symmetric laws.     

The impact of attention load on the use of statistical information and coarticulation as speech segmentation cues

In two artificial language learning experiments, we investigated the impact of attention load on segmenting speech through two sublexical cues: transitional probabilities (TPs) and coarticulation. In Experiment 1, we observed that coarticulation processing was resilient to high attention load, whereas TP computation was penalized in a graded manner. In Experiment 2, we showed that encouraging participants to actively search for “word” candidates enhanced overall performance but was not sufficient to preclude the impairment of statistically driven segmentation by attention load. As long as attentional resources were depleted, independently of their intention to find these “words,” participants segmented only TP words with the highest TPs, not TP words with lower TPs. Attention load thus has a graded and differential impact on the relative weighting of the cues in speech segmentation, even when only sublexical cues are available in the signal.     

Is there still a cognitive cost of being a twin in the UK?

ObjectiveTo investigate whether twins still perform below singletons in cognitive ability tests and in national educational attainment examinations in a recent UK cohort of 11-year-olds.DesignPopulation-based cohort study, using a validated method of twin extraction.SettingEnglish state schools.Participants178,599 pupils (mean age 11 years) attending English state schools in 2004, representing 93% of local educational authorities.Main outcome measuresVerbal, quantitative and nonverbal reasoning measured by the Cognitive Abilities Test — Third Edition (CAT3), and educational attainment in English, maths and science from Key Stage 2 national curriculum tests.ResultsTwin-singleton differences in cognitive ability were of negligible effect size. Mean performance of twins was 1% of a SD below singletons on general cognitive ability, 3% lower on verbal reasoning, and less than 1% of a SD lower on quantitative and nonverbal reasoning, with and without adjustment for sex. Almost identical proportions of twins and singletons attained the expected standards of educational performance in English (80.4% versus 80.5%, respectively), maths (77.4% versus 77.3%), and science (90.1% versus 88.8%). There were no differences in rates of twins and singletons achieving higher or lower performance levels.ConclusionThe cognitive cost of being a twin reported in previous cohorts of UK children no longer exists in a large, contemporary and population-representative sample.     

Learning orthography in adulthood: A magnetoencephalographic study

Previous work demonstrated that there were differences between literate and comparable illiterate adult subjects. These differences were found in the performance on several tests and on patterns of activation on PET and fMRI. In the present study subjects that learned to read and to write in adulthood (being previously completely illiterate) were compared to controls, that is subjects that learned at school at the proper age. Magnetoencephalography was done while subjects were reading words. Results showed that, although the reading performance was the same in both groups while performing the task, the pattern of source distribution was different between groups. There were more late sources in right temporo‐parietal areas of late literates compared to controls and more late sources in left inferior frontal cortex in control subjects. It is concluded that learning to read in adulthood is a process supported by different brain structures from the ones used when learning occurs at the proper age. This may suggest that the same task can be similarly performed by relying on diverse functional brain anatomic networks.