Mechanisms underlying corruption of working memory in Parkinson's disease

Working memory (WM) impairments are reported to occur in patients with Parkinson's disease (PD). However, the mechanisms are unclear. Here, we investigate several putative factors that might drive poor performance, by examining the precision of recall, the order in which items are recalled and whether memories are corrupted by random guessing (attentional lapses). We used two separate tasks that examined the quality of WM recall under different loads and retention periods, as well as a traditional digit span test. Firstly, on a simple measure of WM recall, where patients were asked to reproduce the orientation of a centrally presented arrow, overall recall was not significantly impaired. However, there was some evidence for increased guessing (attentional lapses). On a new analogue version of the Corsi-span task, where participants had to reproduce on a touchscreen the exact spatial pattern of presented stimuli in the order and locations in which they appeared, there was a reduction in the precision of spatial WM at higher loads. This deficit was due to misremembering item order. At the highest load, there was reduced recall precision, whereas increased guessing was only observed at intermediate set sizes. Finally, PD patients had impaired backward, but not forward, digit spans. Overall, these results reveal the task- and load-dependent nature of WM deficits in PD. On simple low-load tasks, attentional lapses predominate, whereas at higher loads, in the spatial domain, the corruption of mnemonic information—both order item and precision—emerge as the main driver of impairment.     

Mental health of medical students: a cross-sectional study in Tehran

Medical students are subject to stress from sources related to medical training in addition to personal problems, resulting in significant mental distress. This study evaluates the scope of the problem in Tehran medical schools and sheds light on some of its associations. Students (604) of medicine from four medical schools in the city of Tehran responded to the Persian version of 28-item General Health Questionnaire (GHQ-28) in conjunction with a data collection sheet asking about age, sex, marital status, current training level, living place, grade point average in previous semester, and perceptions of their financial status. Of 602 students, 40.7% had mental distress (45.7% of female and 36.7% of male students). Distress was associated with being a woman (female to male odds ratio: 1.55) and very poor financial status (OR: 18.0).     

Assessment of apathy in neurological patients using the Apathy Motivation Index caregiver version

Apathy is a common, disabling neuropsychiatric syndrome that occurs across many brain disorders and may be associated with diminished motivation in behavioural, cognitive, emotional and social domains. Assessment is complicated by the variability of symptoms across apathy domains and self-report from patients, which can be misleading due to their lack of insight. Independent evaluation by clinicians also has limitations though if it has to be performed with limited time. Caregiver reports are a viable alternative, but current assessments for them either do not distinguish between different apathy domains or are interview-based and take long to administer. In this study, we developed a brief caregiver questionnaire version of the recently developed Apathy Motivation Index (AMI), which is a self-report tool. We confirmed three apathy factors in this new caregiver measure (AMI-CG) that were also present in the AMI: Behavioural Activation, Emotional Sensitivity and Social Motivation. Furthermore, we validated the scores against more extensive caregiver interviews using the established Lillle apathy rating scale as well as patient self-reports of apathy, measures of depression, anhedonia, cognition, activities of daily living and caregiver burden across four different neurological conditions: Parkinson's disease, Alzheimer's disease, subjective cognitive impairment and limbic encephalitis. The AMI-CG showed good internal reliability, external validity and diagnostic accuracy. It also uncovered cases of social apathy overlooked by traditional instruments. Crucially, patients who under-rated their apathy compared to informants were more likely to have difficulties performing everyday activities and to be a greater burden to caregivers. The findings provide evidence for a multidimensional conceptualization of apathy and an instrument for efficient detection of apathy based on caregiver reports for use in clinical practice.     

Attention,competition, and the parietal lobes: insights from Balint’s syndrome

Simultanagnosia (resulting from occipito-parietal damage) is a profound visual deficit, which impairs the ability to perceive multiple items in a visual display, while preserving the ability to recognise single objects. Here we demonstrate in a patient presenting with Balint’s syndrome that this deficit may result from an extreme form of competition between objects which makes it difficult for attention to be disengaged from an object once it has been selected.     

Conflict in object affordance revealed by grip force

Viewing objects can result in automatic, partial activation of motor plans associated with them-"object affordance". Here, we recorded grip force simultaneously from both hands in an object affordance task to investigate the effects of conflict between coactivated responses. Participants classified pictures of objects by squeezing force transducers with their left or right hand. Responses were faster on trials where the object afforded an action with the same hand that was required to make the response (congruent trials) compared to the opposite hand (incongruent trials). In addition, conflict between coactivated responses was reduced if it was experienced on the preceding trial, just like Gratton adaptation effects reported in "conflict" tasks (e.g., Eriksen flanker). This finding suggests that object affordance demonstrates conflict effects similar to those shown in other stimulus-response mapping tasks and thus could be integrated into the wider conceptual framework on overlearnt stimulus-response associations. Corrected erroneous responses occurred more frequently when there was conflict between the afforded response and the response required by the task, providing direct evidence that viewing an object activates motor plans appropriate for interacting with that object. Recording continuous grip force, as here, provides a sensitive way to measure coactivated responses in affordance tasks.     

Mothers' and fathers' childcare involvement with young children in rural families in Malaysia

There is a paucity of data on paternal involvement in childcare in traditional Muslim families in Asia. Using cultural‐ecological models of human development that focus on the developmental niche and hegemonic perspectives on masculinity, mothers' and fathers' levels of childcare involvement with infants were examined in 50 two‐parent, low‐income, rural Malay Muslim families residing in peninsular Malaysia. The major goals were to examine gender of parent and gender of child differences in involvement in childcare activities. Mothers and fathers were interviewed separately in their homes regarding the amount of time and levels of involvement in bedtime routines, physical care of, playing with, singing to, feeding, and soothing infants. Groupwise comparisons of parental perceptions revealed a marked gender‐differentiated pattern of involvement: Mothers perceived that they were significantly more involved in bedtime routines, physical care, feeding, playing, soothing, and singing to infants than did fathers. On average fathers estimated that they spent 18% as much time cleaning infants (0.63 versus 3.50 hours), 22% as much time feeding infants (0.76 versus 3.49), and 56% as much time playing with infants (2.77 versus 4.92 hours) relative to mothers. These patterns of involvement suggest that in traditional, rural Malay Muslim families, mothers are the primary caregivers to infants, and contrary to the father as play partner hypothesis, mothers engaged in more play with infants than did fathers. Despite divergent levels of involvement, mothers and fathers were equally as inclined to be involved with their male or female infants. Findings are interpreted in terms of traditional Muslim beliefs about gendered ideologies regarding childcare roles and levels of paternal involvement in groups of fathers in rural and urban Malaysia. The limitations, due in part to gathering data from single informants and the nature of the sample, and the implications of the findings for increasing paternal involvement are noted.     

Recall cues interfere with retrieval from visuospatial working memory

Visuospatial working memory allows us to hold multiple visual objects over short delays. It is typically tested by presenting an array of objects, then after a delay showing a ‘probe’ indicating which memory item to recall or reproduce by adjusting a target feature. However, recent studies demonstrate that information at the time of probe can disrupt recall. Here, in three experiments we test whether traditional memory probes, which contain features that compete with the feature to be recalled, may themselves interfere with performance. We asked participants to report the direction of one of the several coloured arrows in memory, based on its colour. First, we demonstrate that recall is better when the probe is initially just a coloured dot, rather than a coloured arrow which has to be adjusted to match orientation memory, consistent with interference from features of the probe itself. Second, this interference is present even when a mask follows the memory array, suggesting that the interference does not work by degrading immediate or iconic memory. Finally, when items are shown sequentially, the first and last items are invulnerable to probe interference. Our findings support recent theories of associative recall, in which probes reactivate features in WM, retrieving information by pattern completion.