For Whom (and When) the Time Bell Tolls: Chronotypes and the Synchrony Effect.

Circadian rhythms are powerful timekeepers that drive physiological and intellectual functioning throughout the day. These rhythms vary across individuals, with morning chronotypes rising and peaking early in the day and evening chronotypes showing a later rise in arousal, with peaks in the afternoon or evening. Chronotype also varies with age from childhood to adolescence to old age. As a result of these differences, the time of day at which people are best at attending, learning, solving analytical problems, making complex decisions, and even behaving ethically varies. Across studies of attention and memory and a range of allied areas, including academic achievement, judgment and decision-making, and neuropsychological assessment, optimal outcomes are found when performance times align with peaks in circadian arousal, a finding known as the synchrony effect. The benefits of performing in synchrony with one's chronotype (and the costs of not doing so) are most robust for individuals with strong morning or evening chronotypes and for tasks that require effortful, analytical processing or the suppression of distracting information. Failure to take the synchrony effect into consideration may be a factor in issues ranging from replication difficulties to school timing to assessing intellectual disabilities and apparent cognitive decline in aging.

Seeing is Disliking: Evidence of Bias Against Individuals with Autism Spectrum Disorder in Traditional Job Interviews.

Job interviews are an integral component of the hiring process in most fields. Our research examines job interview performance of those with autism spectrum disorder (ASD) compared to neurotypical (NT) individuals. ASD and NT individuals were taped engaging in mock job interviews. Candidates were rated on a variety of dimensions by respondents who either watched the interview videos or read the interview transcripts and were naïve to the neurodiversity of the interviewees. NT candidates outperformed ASD candidates in the video condition, but in the absence of visual and social cues (transcript condition), individuals with ASD outperformed NT candidates. Our findings suggest that social style significantly influences hiring decisions in traditional job interviews and may bias evaluators against otherwise qualified candidates.

Caffeine dosing in premature neonates: impact of birth weight on a pharmacokinetic simulation study.

BACKGROUND: The optimal caffeine dosing in extremely premature neonates remains elusive. This study aimed to evaluate the impact of birth weight on caffeine pharmacokinetics and various dosing regimens. METHODS: In this pharmacokinetic simulation study, we generated the body weights (0-49 days of postnatal age [PNA]) of neonates <28 weeks gestational age with different birth weights (550, 750, and 1050 g). Their pharmacokinetic parameters were determined based on published pharmacokinetic models. Then, we simulated and compared the caffeine base concentration-time profiles of standard versus off-label caffeine citrate dose regimens. RESULTS: The half-life decreased and the weight-adjusted clearance increased more significantly in neonates with lower birth weights, resulting in lower caffeine plasma concentrations. The neonate with the lowest birth weight did not achieve a threshold trough concentration of 15 mg/L after receiving the standard dose (5 mg/kg/day), while the higher-birth-weights (≥750 g) had trough concentrations below the threshold around the second week of life. Higher caffeine doses (10 mg/kg/day) resulted in peak concentrations of <36 mg/L by 10-14 days of PNA while maintaining trough concentrations above 15 mg/L throughout the 49 days PNA. CONCLUSION: Higher-than-standard caffeine dosing may be needed for extremely premature neonates, especially for those with lower birth weights. IMPACT: Extremely premature neonates with a lower birth weight may require a higher weight-based caffeine dosing due to their higher weight-adjusted clearance and shorter half-lives. Not only do these extremely premature neonates have a higher risk of developing bronchopulmonary dysplasia due to their structurally underdeveloped lungs, but the low birth weight-related underdosing may further contribute to the reduced caffeine effectiveness. Higher-than-standard caffeine citrate dosing (e.g., 10 mg/kg/day maintenance dose) may be needed to further prevent bronchopulmonary dysplasia.

A comparison of the college experience for students with and without disabilities.

Students with intellectual and developmental disabilities (IDD) have joined the ranks of college students in pursuit of personal independence, community integration, and employment. To achieve these aims, there is a need for a strong understanding of the college experience for students with IDD, including identification of the academic, social, and personal challenges they face as well as the supports that are available to address those challenges. This research provides preliminary insights into the college experience for students with IDD by comparing the perceptions, attitudes, and activities of students with IDD to those of students without disabilities and students with mild learning disabilities (MLD). Our data suggest a number of similarities in the college experience for students with and without disabilities such as similar influences from family and teachers with respect to attending college. In addition, some surprising advantages expressed by students with IDD were found, such as reporting greater ease in developing close friendships than students with MLD. Considerations and discussion on the ways in which students with IDD benefit from the additional supports and services provided to them are also discussed.

The best of both worlds: emotional cues improve prospective memory execution and reduce repetition errors.

Prospective memory (PM) errors are commonly investigated as failures to execute an intended task (e.g., taking medication), and some studies suggest that emotional PM cues significantly reduce such failures. In Experiment 1, we extended these findings and additionally explored whether improved PM performance with emotional cues comes at the expense of performance on the ongoing task. Our results indicated that both younger and older adults are more likely to respond to emotional than to neutral PM cues, but the emotional cues did not differentially disrupt the performance on the ongoing task for either age group. Because older adults are also prone to mistakenly repeating a completed PM task, in Experiment 2 we further examined whether emotional PM cues increased repetition errors for older adults. Despite equivalent opportunity for repetition errors across cue type, older adults committed significantly fewer repetition errors with emotional than with neutral cues. Thus, these experiments demonstrated that older adults can effectively use emotional cues to help them initiate actions and to minimize repetition errors.

The impact of emotion on prospective memory and monitoring: no pain, big gain.

The emotionally enhanced memory effect is robust across studies of retrospective memory, with heightened recall for items with emotional content (e.g., words like "murder") relative to neutral items (e.g., words like "envelope"). Only a handful of studies have examined the influence of emotion on prospective memory (PM), with mixed results. In some cases emotion enhances PM, and in others it impairs PM. Interpretation of these findings is clouded by methodological differences across studies and by the fact that, to date, no study has examined the impact of emotion on PM monitoring. In our study, we assessed PM performance when PM targets were neutral, negative, and positive, and also investigated monitoring across these different PM target types. Participants showed heightened PM performance for positive and negative relative to neutral targets, yet there was no evidence of additional monitoring for emotional targets. In fact, measures of monitoring were significantly reduced when the PM targets were emotional rather than neutral. Our findings suggest that it is possible to boost PM performance in a focal task using emotional cues, and that the use of emotional cues reduces the need for monitoring.

Diverse contexts of zoonotic transmission of simian foamy viruses in Asia.

In Asia, contact between persons and nonhuman primates is widespread in multiple occupational and nonoccupational contexts. Simian foamy viruses (SFVs) are retroviruses that are prevalent in all species of nonhuman primates. To determine SFV prevalence in humans, we tested 305 persons who lived or worked around nonhuman primates in several South and Southeast Asian countries; 8 (2.6%) were confirmed SFV positive by Western blot and, for some, by PCR. The interspecies interactions that likely resulted in virus transmission were diverse; 5 macaque taxa were implicated as a potential source of infection. Phylogenetic analysis showed that SFV from 3 infected persons was similar to that from the nonhuman primate populations with which the infected persons reported contact. Thus, SFV infections are likely to be prevalent among persons who live or work near nonhuman primates in Asia.

A premature termination codon mutation at the C terminus of foamy virus Gag downregulates the levels of spliced pol mRNA.

Foamy viruses (FV) comprise a subfamily of retroviruses. Orthoretroviruses, such as human immunodeficiency virus type 1, synthesize Gag and Pol from unspliced genomic RNA. However, FV Pol is expressed from a spliced mRNA independently of Gag. FV pol splicing uses a 3' splice site located at the 3' end of gag, resulting in a shared exon between gag and pol. Previously, our laboratory showed that C-terminal Gag premature termination codon (PTC) mutations in the 3' shared exon led to greatly decreased levels of Pol protein (C. R. Stenbak and M. L. Linial, J. Virol. 78:9423-9430, 2004). To further characterize these mutants, we quantitated the levels of unspliced gag and spliced pol mRNAs using a real-time PCR assay. In some of the PTC mutants, the levels of spliced pol mRNA were reduced as much as 30-fold, whereas levels of unspliced gag RNA were not affected. Substitutions of a missense codon in place of a PTC restored normal levels of spliced pol mRNA. Disrupting Upf proteins involved in nonsense-mediated mRNA decay (NMD) did not affect Pol protein expression. Introduction of an exonic splicing enhancer downstream of the PTC mutation restored pol splicing to the wild-type level. Taken together, our results show that the PTC mutation itself is responsible for decreased levels of pol mRNA but that mechanisms other than NMD might be involved in downregulating Pol expression. The results also suggest that normal pol splicing utilizes a suboptimal splice site seen for other spliced mRNAs in most retroviruses, in that introduced exonic enhancer elements can increase splicing efficiency.

Sensitive assays for simian foamy viruses reveal a high prevalence of infection in commensal, free-ranging Asian monkeys.

Foamy viruses (FV) are retroviruses that naturally infect many hosts, including most nonhuman primates (NHPs). Zoonotic infection by primate FV has been documented in people in Asia who reported contact with free-ranging macaques. FV transmission in Asia is a concern, given abundant human-NHP contact, particularly at monkey temples and in urban settings. We have developed three assays capable of detecting the presence of FV in Asian NHP species that are commensal with humans: enzyme-linked immunosorbent assay (ELISA), Western blot assays using recombinant viral Gag protein, and an indicator cell line that can detect macaque FV. The recombinant ELISA correlates very well with the presence of FV sequences detected by PCR. We have used these assays to demonstrate both that FV is highly prevalent among free-ranging NHPs and that seroconversion occurs at a young age in these animals. These assays should also prove useful for large-scale analysis of the prevalence of FV infections in human populations in Asia that are commensal with free-ranging NHPs.

Implicit memory, age, and time of day: paradoxical priming effects.

Memory retrieval can occur by at least two routes: a deliberate one, as when one attempts to retrieve an event or fact, and an unintentional one, as when one's behavior is triggered by the past without one's knowledge or awareness. We assessed the efficacy of these retrieval systems as a function of circadian arousal and time of day. Evening-type younger adults and morning-type older adults were tested at either peak (morning for old; evening for young) or off-peak times on implicit and explicit stem completion (Experiment 1) or on implicit category generation (Experiment 2). Results for explicit stem-cued recall replicated better performance for each age group at its peak time. In stark contrast, implicit performance was better at off-peak than at peak times of day, raising the possibility that the processes that serve explicit and implicit retrieval are on different circadian schedules, and highlighting the need to consider individual differences in circadian arousal when assessing either memory system.

Aging, source memory, and emotion.

In 2 experiments we assessed younger and older adults' ability to remember contextual information about an event. Each experiment examined memory for 3 different types of contextual information: (a) perceptual information (e.g., location of an item); (b) conceptual, nonemotional information (e.g., quality of an item); and (c) conceptual, emotional information (e.g., safety of an item). Consistent with a large literature on aging and source memory, younger adults outperformed older adults when the contextual information was perceptual in nature and when it was conceptual, but not emotional. Age differences in source memory were eliminated, however, when participants recalled emotional source information. These findings suggest that emotional information differentially engages older adults, possibly evoking enhanced elaborations and associations. The data are also consistent with a growing literature, suggesting that emotional processing remains stable with age (e.g., Carstensen & Turk-Charles, 1994, 1998; Isaacowitz, Charles, & Carstensen, 2000).

Importance of basic residues in binding of rous sarcoma virus nucleocapsid to the RNA packaging signal.

In the context of the Rous sarcoma virus Gag polyprotein, only the nucleocapsid (NC) domain is required to mediate the specificity of genomic RNA packaging. We have previously showed that the Saccharomyces cerevisiae three-hybrid system provides a rapid genetic assay to analyze the RNA and protein components of the avian retroviral RNA-Gag interactions necessary for specific encapsidation. In this study, using both site-directed mutagenesis and in vivo random screening in the yeast three-hybrid binding assay, we have examined the amino acids in NC required for genomic RNA binding. We found that we could delete either of the two Cys-His boxes without greatly abrogating either RNA binding or packaging, although the two Cys-His boxes are likely to be required for efficient viral assembly and release. In contrast, substitutions for the Zn-coordinating residues within the boxes did prevent RNA binding, suggesting changes in the overall conformation of the protein. In the basic region between the two Cys-His boxes, three positively charged residues, as well as basic residues flanking the two boxes, were necessary for both binding and packaging. Our results suggest that the stretches of positively charged residues within NC that need to be in a proper conformation appear to be responsible for selective recognition and binding to the packaging signal (Psi)-containing RNAs.

Age, time of testing, and proactive interference.

A four-list version of a release from proactive interference paradigm was used to assess the degree to which older and younger adults tested at optimal and nonoptimal times of day are vulnerable to interference effects in memory, effects that may increase at nonoptimal times. Morning type older adults and Evening type younger adults were tested either early in the morning or late in the afternoon. Standard buildup and release effects were shown for all age groups except for older adults tested in the afternoon; they failed to show release. Recall and intrusion data suggested that older adults are more vulnerable to proactive interference than younger adults and that for older adults at least, interference effects are heightened at nonoptimal times of day. The data are discussed in terms of an inhibitory model of control over the contents of working memory (Hasher, Zacks, & May, 1999).

Truth and character: sources that older adults can remember.

Are age differences in source memory inevitable? The two experiments reported here examined the hypothesis that the type of source information being tested mediates the magnitude of age differences in source memory. In these studies, participants listened to statements made by two different speakers. We compared younger and older adults' source memory in a traditional perceptual source task (memory for voice) and in two affective, conceptually based source tasks (truth of the statements, character of a person in a photo). In both studies, the perceptual and conceptual source information were conveyed in the same manner, as one speaker was associated with one type of information (e.g., female voice speaks truth). Age differences were robust for decisions regarding who said each statement but were negligible or truth or character decisions. These findings are provocative because they suggest that the type of information can influence age-related patterns of performance for source-conveyed information.