The Temporal Nature of the Acute Stress Response and its Impact on Explicit Learning

Acute stress is commonly experienced by many throughout their lives. Given the demanding lifestyle of many career paths, it\u27s important to gauge the influence of these stressors upon cognitive performance. The present dissertation focus\u27 upon explicit learning in attempts to explore one avenue of the stress-cognition relationship. The Trier Social Stress Test (TSST) was used as a lab stressor for Experiments 1 and 2, in which participants are asked to give a speech and complete a difficult math task in front of 2 evaluators trained to monitor non-verbal behavior. Experiment 1 investigates the dynamic stress response during the minutes following stress, and how changes in the physiological response influence cognitive task performance. Stress was measured cardiovascularly, hormonally and as a self-reported appraisal of the situation. Findings from Experiment 1 revealed a time point 55 min following stress in which participants\u27 task performance was enhanced compared to a non-stressed comparison condition. These results suggest explicit task performance can be facilitated given a sufficient length of time following stress. Experiment 2 was designed in attempts to replicate the delayed RB task enhancement following the TSST, and given suggestions from the extant literature, explore if this task enhancement is attributed to enhanced working memory (WM). WM was assessed using an n-back task. Results confirmed the delayed RB task enhancement 55 min after stress, however no effect was present for n-back task performance. Experiment 3 was designed to understand if the RB task enhancement extended for a number of hours following stress. Additionally, cold-pressor stress was used to assess if the delayed task enhancement was stressor specific. In this task, participants were asked to submerge their hand in ice-water for up to 3 min. Results revealed a marginal task enhancement following a similar delay as Experiments 1 & 2, however the enhanced task performance did not remain hours later. Taken together the present experiments suggest a time frame following a delay from stress in which explicit learning and more specifically RB category learning is enhanced, however it doesn\u27t seem as if this effect is due to the impact of stress on WM

Unsupervised Category Learning with Integral-Dimension Stimuli

Despite the recent surge in research on unsupervised category learning, the majority of studies have focused on unconstrained tasks in which no instructions are provided about the underlying category structure. Relatively little research has focused on constrained tasks in which the goal is to learn pre-defined stimulus clusters in the absence of feedback. The few studies that have addressed this issue have focused almost exclusively on stimuli for which it is relatively easy to attend selectively to the component dimensions (i.e., separable dimensions). In the present study, we investigated the ability of participants to learn categories constructed from stimuli for which it is difficult, if not impossible, to attend selectively to the component dimensions (i.e., integral dimensions). The experiments demonstrate that individuals are capable of learning categories constructed from the integral dimensions of brightness and saturation, but this ability is generally limited to category structures requiring selective attention to brightness. As might be expected with integral dimensions, participants were often able to integrate brightness and saturation information in the absence of feedback – an ability not observed in previous studies with separable dimensions. Even so, there was a bias to weight brightness more heavily than saturation in the categorization process, suggesting a weak form of selective attention to brightness. These data present an important challenge for the development of models of unsupervised category learning

Is Pressure Stressful? The Impact of Pressure on the Stress Response and Category Learning

We examine the basic question of whether pressure is stressful. We propose that when examining the role of stress or pressure in cognitive performance it is important to consider the type of pressure, the stress response, and the aspect of cognition assessed. In Experiment 1, outcome pressure was not experienced as stressful but did lead to impaired performance on a rule-based (RB) category learning task and not a more procedural information-integration (II) task. In Experiment 2, the addition of monitoring pressure resulted in a modest stress response to combined pressure and impairment on both tasks. Across experiments, higher stress appraisals were associated with decreased performance on the RB, but not the II, task. In turn, higher stress-reactivity (heart rate) was associated with enhanced performance on the II, but not the RB, task. This work represents an initial step towards integrating the stress-cognition and pressure-cognition literatures and suggests that integrating these fields may require consideration of the type of pressure, the stress-response, and the cognitive system mediating performance

Is Pressure Stressful? The Impact of Pressure on the Stress Response and Category Learning

We examine the basic question of whether pressure is stressful. We propose that when examining the role of stress or pressure in cognitive performance it is important to consider the type of pressure, the stress response, and the aspect of cognition assessed. In Experiment 1, outcome pressure was not experienced as stressful but did lead to impaired performance on a rule-based (RB) category learning task and not a more procedural information-integration (II) task. In Experiment 2, the addition of monitoring pressure resulted in a modest stress response to combined pressure and impairment on both tasks. Across experiments, higher stress appraisals were associated with decreased performance on the RB, but not the II, task. In turn, higher stress-reactivity (heart rate) was associated with enhanced performance on the II, but not the RB, task. This work represents an initial step towards integrating the stress-cognition and pressure-cognition literatures and suggests that integrating these fields may require consideration of the type of pressure, the stress-response, and the cognitive system mediating performance

Nanosheet formation by an anionic surfactant-like peptide and modulation of self-assembly through ionic complexation

The surfactant-like peptide (Ala)6-(Asp) (A6D) is shown to self-assemble into ultrathin (3 nm thick) nanosheets in aqueous solution above a critical aggregation concentration. A combination of circular dichroism and FTIR spectroscopy and X-ray diffraction shows that the nanosheets comprise interdigitated bilayers of the peptide with β-sheet conformation. The self-assembly can be modulated by addition of hexamethylenediamine which is expected to interact with the anionic C terminus (and C-terminal D residue) of the peptide. Multiple ordered nanostructures can be accessed depending on the amount of added diamine. Nanosheet and bicontinuous network structures were observed using cryogenic-TEM and small-angle X-ray scattering. Addition of hexamethylenediamine at a sufficiently large molar ratio leads to disruption of the ordered nanostructure and the formation of a solution of A6D–diamine molecular complexes with highly charged end groups. The multiple acid-functionalized nanostructures that are accessible in this system are expected to have many applications in the fabrication of new nanomaterials

Neural correlates of abnormal sensory discrimination in laryngeal dystonia

AbstractAberrant sensory processing plays a fundamental role in the pathophysiology of dystonia; however, its underpinning neural mechanisms in relation to dystonia phenotype and genotype remain unclear. We examined temporal and spatial discrimination thresholds in patients with isolated laryngeal form of dystonia (LD), who exhibited different clinical phenotypes (adductor vs. abductor forms) and potentially different genotypes (sporadic vs. familial forms). We correlated our behavioral findings with the brain gray matter volume and functional activity during resting and symptomatic speech production. We found that temporal but not spatial discrimination was significantly altered across all forms of LD, with higher frequency of abnormalities seen in familial than sporadic patients. Common neural correlates of abnormal temporal discrimination across all forms were found with structural and functional changes in the middle frontal and primary somatosensory cortices. In addition, patients with familial LD had greater cerebellar involvement in processing of altered temporal discrimination, whereas sporadic LD patients had greater recruitment of the putamen and sensorimotor cortex. Based on the clinical phenotype, adductor form-specific correlations between abnormal discrimination and brain changes were found in the frontal cortex, whereas abductor form-specific correlations were observed in the cerebellum and putamen. Our behavioral and neuroimaging findings outline the relationship of abnormal sensory discrimination with the phenotype and genotype of isolated LD, suggesting the presence of potentially divergent pathophysiological pathways underlying different manifestations of this disorder

Pregnant women’s awareness, knowledge and beliefs about pelvic floor muscles: a cross-sectional survey

Introduction and hypothesis: Pregnant women benefit from completing pelvic floor muscle exercises (PFMEs). The aims of the study were to evaluate pregnant women’s levels of awareness, knowledge, and beliefs about the pelvic floor muscles (PFMs) and PFMEs. Methods: A cross-sectional survey was conducted. Respondents were pregnant women over the age of 18 years who attended antenatal clinics in Western Australia (WA). Questionnaire items measured awareness and knowledge about PFMs, confidence and beliefs about engaging in PFMEs, and attendance at antenatal education (ANE) classes. Chi-squared tests examined potential associations between questionnaire items and respondent characteristics. Results: Mean gestation of respondents (n = 633 out of 850; 74% response rate) was 28.7 (+7.8) weeks and 50% were giving birth for the first time. Although 76% of respondents knew that PFMs can prevent urinary incontinence, only 27% knew that they prevented faecal incontinence and 41% thought it was normal to leak urine when pregnant. Only n = 72 (11%) were practicing PFMEs. Respondents who had attended ANE (28%) were significantly more knowledgeable about pelvic floor function (p < .001) and significantly less likely to believe that leaking urine during pregnancy was normal (p = 0.02), compared with those who had not attended ANE. Respondents who did not speak English at home (18%) were significantly less knowledgeable about PFMs and PFMEs, and significantly less likely to have attended, or planned to attend, ANE classes. Conclusion: Pregnant women require more health education regarding PFMs. Education should be provided using diverse modes, especially for women from migrant backgrounds and women who do not plan to attend formal ANE classes

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected