What drives sleep-dependent memory consolidation: Greater gain or less loss?

When memory is tested after a delay, performance is typically better if the retention interval includes sleep. However, it is unclear what accounts for this well-established effect. It is possible that sleep enhances the retrieval of information, but it is also possible that sleep protects against memory loss that normally occurs during waking activity. We developed a new research approach to investigate these possibilities. Participants learned a list of paired-associate items and were tested on the items after a 12-h interval that included waking or sleep. We analyzed the number of items gained versus the number of items lost across time. The sleep condition showed more items gained and fewer items lost than did the wake condition. Furthermore, the difference between the conditions (favoring sleep) in lost items was greater than the difference in gain, suggesting that loss prevention may primarily account for the effect of sleep on declarative memory consolidation. This finding may serve as an empirical constraint on theories of memory consolidation.     

Book Review

Previous efforts to demonstrate the coping benefits of Muslim beliefs have yielded ambiguous outcomes. With a sample of 200 Pakistani adults, this project used the Islamic Positive Religious Coping and Identification (IPRCI) subscale within the Psychological Measure of Islamic Religiousness (PMIR) to examine relationships with the experience and behaviour of Ramadan. Preliminary confirmatory factor analyses revealed a need to focus on a Positive Islamic Coping factor within the IPRCI. Positive Islamic Coping correlated directly with Positive Ramadan Experience and Ramadan Behaviour and inversely with Negative Ramadan Experience. Along with other PMIR variables assessing Muslim commitments more generally, Positive Islamic Coping helped mediate relationships between Ramadan Experience and Ramadan Behaviour. Punishing Allah Reappraisal from the PMIR displayed only minimal evidence that it recorded a maladaptive form of religious coping. These data confirmed Positive Islamic Coping as an operationalisation of adaptive Muslim coping and illustrated the importance of examining measures that are relevant within a religious tradition.     

Emerging roles of epigenetic mechanisms in the enduring effects of early-life stress and experience on learning and memory

Epigenetic mechanisms are involved in programming gene expression throughout development. In addition, they are key contributors to the processes by which early-life experience fine-tunes the expression levels of key neuronal genes, governing learning and memory throughout life. Here we describe the long-lasting, bi-directional effects of early-life experience on learning and memory. We discuss how enriched postnatal experience enduringly augments spatial learning, and how chronic early-life stress results in persistent and progressive deficits in the structure and function of hippocampal neurons. The existing and emerging roles of epigenetic mechanisms in these fundamental neuroplasticity phenomena are illustrated.     

Enduring deficits in contextual and auditory fear conditioning after adolescent, not adult, social instability stress in male rats

Adolescence is a time of developmental changes and reorganization in the brain and stress systems, thus, adolescents may be more vulnerable than adults to the effects of chronic mild stressors. Most studies, however, have not directly compared stress experienced in adolescence to the same stress experience in adulthood. In the present study, adolescent (n=46) and adult (n=48) male rats underwent 16 days of social instability stress (daily 1h isolation and change of cage partners) or were non-stress controls. Rats were then tested on the strength of acquired contextual and cued fear conditioning, as well as extinction learning, beginning either the day after the stress procedure or 3 weeks later. No difference was found among the groups during the Training Phase of conditioning. Irrespective of the time between the social stress experience and fear conditioning, rats stressed in adolescence had decreased context and cue memory, and cue generalization compared to control rats, as measured by the percentage of time spent freezing in tests. Social instability stress in adulthood had no effect on any measure of fear conditioning. The results support the hypothesis that adolescence is a time of heightened vulnerability to stressors.     

The psychological impact of facial changes in scleroderma

The physical disabilities associated with scleroderma are well known but the psychological impact of the condition has received less attention. Few studies have examined appearance related issues, most notably of the face. The aim of this study is to evaluate the psychological impact of facial, aesthetic and functional changes in scleroderma. One hundred seventy-one patients with a clinical diagnosis of scleroderma were recruited into the study. Digital photographs were objectively graded into groups based on severity of disfigurement as judged by an observer. Facial movement was recorded using a modified House-Brackmann Grading Scale. Psychological evaluation comprised the Derriford Appearance Scale short-form (DAS), the Noticeability and Worry score and the Hospital Anxiety and Depression Scale (HADS). Severity of disfigurement predicted decreased mouth opening, the extent to which participants judged their appearance as noticeable to others, and the level of appearance-related concern as measured by the DAS24. There was an inverse relationship with age. Facial changes were ranked as the most worrying aspect of the condition. This study shows facial disfigurement impacts on patient with scleroderma independent of functional changes related to systemic disease. The major difficulty is with the perceived noticeably of the condition to other people and the resulting self-consciousness in social encounters.     

Cognitive abilities explaining age-related changes in time perception of short and long durations

The current study investigated how the development of cognitive abilities explains the age-related changes in temporal judgment over short and long duration ranges from 0.5 to 30 s. Children (5- and 9-year-olds) as well as adults were given a temporal bisection task with four different duration ranges: a duration range shorter than 1 s, two duration ranges longer than 3 s (4-8 s and >15 s), and an intermediate duration range (1.25-2.5 s). Their cognitive abilities were also assessed using a series of neuropsychological tests. The results showed that temporal sensitivity improved with age for each duration range but that this improvement occurred earlier for the short durations than for the long durations. Furthermore, the results revealed that the age-related improvement in time sensitivity for the durations shorter than 1 s was explained by the development of short-term memory span, whereas that for long durations was explained by the development of attention/executive functions. To summarize, the development of the abilities required to process long durations seems to be explained mainly by the development of attentional resources.