Obstructive Sleep Apnea Alters Sleep Stage Transition Dynamics

Enhanced characterization of sleep architecture, compared with routine polysomnographic metrics such as stage percentages and sleep efficiency, may improve the predictive phenotyping of fragmented sleep. One approach involves using stage transition analysis to characterize sleep continuity.We analyzed hypnograms from Sleep Heart Health Study (SHHS) participants using the following stage designations: wake after sleep onset (WASO), non-rapid eye movement (NREM) sleep, and REM sleep. We show that individual patient hypnograms contain insufficient number of bouts to adequately describe the transition kinetics, necessitating pooling of data. We compared a control group of individuals free of medications, obstructive sleep apnea (OSA), medical co-morbidities, or sleepiness (n = 374) with mild (n = 496) or severe OSA (n = 338). WASO, REM sleep, and NREM sleep bout durations exhibited multi-exponential temporal dynamics. The presence of OSA accelerated the "decay" rate of NREM and REM sleep bouts, resulting in instability manifesting as shorter bouts and increased number of stage transitions. For WASO bouts, previously attributed to a power law process, a multi-exponential decay described the data well. Simulations demonstrated that a multi-exponential process can mimic a power law distribution.OSA alters sleep architecture dynamics by decreasing the temporal stability of NREM and REM sleep bouts. Multi-exponential fitting is superior to routine mono-exponential fitting, and may thus provide improved predictive metrics of sleep continuity. However, because a single night of sleep contains insufficient transitions to characterize these dynamics, extended monitoring of sleep, probably at home, would be necessary for individualized clinical application

Are Better Workers Also Better Humans? On Pharmacological Cognitive Enhancement in the Workplace and Conflicting Societal Domains

The article investigates the sociocultural implications of the changing modern workplace and of pharmacological cognitive enhancement (PCE) as a potential adaptive tool from the viewpoint of social niche construction. We will attempt to elucidate some of the sociocultural and technological trends that drive and influence the characteristics of this specific niche, and especially to identify the kind of capabilities and adaptations that are being promoted, and to ascertain the capabilities and potentialities that might become diminished as a result. In this context, we will examine what PCE is, and how and why it might be desirable as a tool for adaptation within the workplace. As human beings are, or at least should be allowed to be, more than merely productive, able-bodied and able-minded workers, we will further examine how adaptation to the workplace niche could result in problems in other domains of modern societal life that require the same or other cognitive capabilities. In this context we will also focus on the concept of responsibility and how it pertains to PCE and the modern workplace niche. This will shed some light on the kind of trends related to workplace niche construction, PCE and capability promotion that we can expect in the future, and on the contexts in which this might be either beneficial or detrimental to the individual as a well-rounded human being, and to other members of society

How the Emotional Content of Discourse Affects Language Comprehension

Emotion effects on cognition have often been reported. However, only few studies investigated emotional effects on subsequent language processing, and in most cases these effects were induced by non-linguistic stimuli such as films, faces, or pictures. Here, we investigated how a paragraph of positive, negative, or neutral emotional valence affects the processing of a subsequent emotionally neutral sentence, which contained either semantic, syntactic, or no violation, respectively, by means of event-related brain potentials (ERPs). Behavioral data revealed strong effects of emotion; error rates and reaction times increased significantly in sentences preceded by a positive paragraph relative to negative and neutral ones. In ERPs, the N400 to semantic violations was not affected by emotion. In the syntactic experiment, however, clear emotion effects were observed on ERPs. The left anterior negativity (LAN) to syntactic violations, which was not visible in the neutral condition, was present in the negative and positive conditions. This is interpreted as reflecting modulatory effects of prior emotions on syntactic processing, which is discussed in the light of three alternative or complementary explanations based on emotion-induced cognitive styles, working memory, and arousal models. The present effects of emotion on the LAN are especially remarkable considering that syntactic processing has often been regarded as encapsulated and autonomous

Modafinil improves rapid shifts of attention

Rationale: The majority of studies investigating the cognitive effects of modafinil, a wake-promoting compound, demonstrate some improvements in attention. The potential of the drug to selectively benefit distinct components of attention has yet to be fully explored in healthy adults. Objective: The present study was conducted to investigate modafinil's effect on specific cognitive tasks that tax components of attention switching. One required the rapid switching of attention between stimuli, and another contained an embedded working memory component on top of the attentional shift requirements. Additionally, prospective memory was examined, which requires the interruption of an ongoing activity to retrieve and act upon a previously formed intention. Materials and methods: Healthy non-smoking volunteers, matched on age, intelligence, and baseline cognitive ability, received either a capsule that contained 200 mg modafinil or placebo. Subjective measures of mood and physiological response were taken throughout the experimental session, and the tasks were completed between 2 and 3 h post-dosing. Results: Two hundred milligrams modafinil improved accuracy without a reaction time trade-off, in both conditions of the attention-shifting task, but only when resources were most challenged. In contrast, the drug afforded no improvement in prospective remembering or in the ongoing task that was interrupted. Conclusion: Modafinil appears to promote rapid switching of attention in conditions that are most demanding, whilst it offers no benefits in a task that requires unpredictable and infrequent disengagement of attention from an ongoing task in order to act upon an alternative task