Cerebral autoregulation index at high altitude assessed by thigh-cuff and transfer function analysis techniques.

NEW FINDINGS: What is the central question of this study? Whether cerebral autoregulation (CA) is impaired at high altitude and associated with acute mountain sickness remains controversial. We sought to compare two of the most common methods to assess dynamic CA in subjects who ascended to 3424 m and acclimatized. What is the main finding and its importance? We found that CA was reduced at 3424 m when assessed by the classic thigh-cuff inflation-deflation technique, but not when evaluated by transfer function analysis. These findings suggest that the cerebral vasculature of healthy individuals may become less able to buffer a large, abrupt drop in arterial blood pressure, while still maintaining the ability to regulate slow rhythmical oscillations, during periods of moderate hypoxaemia. ABSTRACT: The occurrence and implications of changes in cerebral autoregulation (CA) at high altitude are controversial and confounded by differences in methods used to assess CA. To compare two of the most common methods of dynamic CA assessment, we studied 11 young, healthy sea-level residents (six females and five males; 20.5 ± 2.3 years old) as they ascended to 3424 m and acclimatized over 13 days. A common autoregulation index (ARI) was calculated from the following: (i) transfer function analysis (TFA ARI) of resting oscillations in arterial blood pressure (ABP; finger plethysmography) and middle cerebral artery blood velocity (MCAv; transcranial Doppler); and (ii) MCAv responses following large, abrupt reductions in ABP using the classic thigh-cuff technique (Cuff ARI). Symptoms of acute mountain sickness (AMS) were monitored using the Lake Louise AMS Questionnaire. Cuff ARI scores decreased (P = 0.021) as subjects ascended from low (4.7 ± 1.5) to high altitude (3.2 ± 1.6) and did not change after 13 days of acclimatization (2.9 ± 1.3). The TFA ARI scores were not affected by ascent or acclimatization to 3424 m. Neither Cuff nor TFA ARI scores were correlated with AMS symptoms. These findings suggest that the cerebral vasculature of healthy individuals may become less able to buffer large step changes in ABP, while still maintaining the ability to regulate slow rhythmical oscillations, during periods of moderate hypoxaemia. Given the inherent differences in the autoregulatory stimulus between methods, multiple assessment techniques may be needed to clarify the implications of changes in cerebrovascular regulation at high altitude.

Understanding ideational fluency as a survival process.

BACKGROUND: When students generate ideas, important inter-individual variance exists both in the quantity and the quality of ideas they are able to produce (e.g., perfectionists who have few highly creative ideas or mass producers who produce a lot of uncreative ideas). In educational psychology research on creativity, the relation between the quantity and quality of ideas has not been well understood, limiting progress in this area. AIMS: We conceptualized Ideational Fluency as a phenomenon that requires participants to 'survive' to produce more ideas, and where dropping out of the ideational process was analogous to 'dying'. Using this novel paradigm, we aimed to test the relations among Fluency (as a dependent variable); and creative Expertise, Originality and self-reported Personality attributes (as independent variables). SAMPLE AND METHOD: Participants were drawn from three groups: those with demonstrated expertise in stage or screen acting (n = 104); undergraduates being trained in the same domain (n = 100), and adults with no acting training or experience (n = 92). Participants responded to the Alternate Uses Task; Non-parametric and semi-parametric survival models were fit to their Ideational Fluency; and average and maximum Originality scores, as well as self-reported Personality attributes, were used as covariates. RESULTS: Across all participants, the Ideational Fluency survival function showed an S-shape, but the Expertise grouping interacted with that pattern. The survival rate of professional actors decreased more rapidly during the first few ideas, but after the 5th idea, professional actors displayed a clear advantage in survival rate. Participants who were less original on average but who showed a high maximum Originality, as well as those participants who reported more Assertiveness and less Industriousness, also survived further into the Ideational process. CONCLUSIONS: Contrary to our hypothesis, professional actors' advantage in Fluency did not manifest in the survival model until after the 5th idea generated. A quantity-quality trade-off was observed with average Originality being associated with shorter survival, but that trade-off was not observed with maximum Originality, which was associated with longer survival.

Measuring flexibility: A text-mining approach.

In creativity research, ideational flexibility, the ability to generate ideas by shifting between concepts, has long been the focus of investigation. However, psychometric work to develop measurement procedures for flexibility has generally lagged behind other creativity-relevant constructs such as fluency and originality. Here, we build from extant research to theoretically posit, and then empirically validate, a text-mining based method for measuring flexibility in verbal divergent thinking (DT) responses. The empirical validation of this method is accomplished in two studies. In the first study, we use the verbal form of the Torrance Test of Creative Thinking (TTCT) to demonstrate that our novel flexibility scoring method strongly and positively correlates with traditionally used TTCT flexibility scores. In the second study, we conduct a confirmatory factor analysis using the Alternate Uses Task to show reliability and construct validity of our text-mining based flexibility scoring. In addition, we also examine the relationship between personality facets and flexibility of ideas to provide criterion validity of our scoring methodology. Given the psychometric evidence presented here and the practicality of automated scores, we recommend adopting this new method which provides a less labor-intensive and less costly objective measurement of flexibility.