Caffeine modulates attention network function

The present work investigated the effects of caffeine (0 mg, 100 mg, 200 mg, 400 mg) on a flanker task designed to test Posner’s three visual attention network functions: alerting, orienting, and executive control [Posner, M. I. (2004). Cognitive neuroscience of attention. New York, NY: Guilford Press]. In a placebo-controlled, double-blind study using a repeated-measures design, we found that the effects of caffeine on visual attention vary as a function of dose and the attention network under examination. Caffeine improved alerting and executive control function in a dose–response manner, asymptoting at 200 mg; this effect is congruent with caffeine’s adenosine-mediated effects on dopamine-rich areas of brain, and the involvement of these areas in alerting and the executive control of visual attention. Higher doses of caffeine also led to a marginally less efficient allocation of visual attention towards cued regions during task performance (i.e., orienting). Taken together, results of this study demonstrate that caffeine has differential effects on visual attention networks as a function of dose, and such effects have implications for hypothesized interactions of caffeine, adenosine and dopamine in brain areas mediating visual attention.     

Role of motor processes in extrinsically encoding mental transformations

Previous research has shown that imagined perspective rotations elicit spatial and low-level cortical motor areas of the brain when participants rely on knowledge of their physical body, or body percept (Wraga, Flynn, Boyle, & Evans, 2010). The current study used functional magnetic resonance imaging (fMRI) to investigate whether recruitment of the body percept would activate low-level cortical motor areas of the brain within other classes of mental transformations. Participants performed imagined object and perspective rotations of three-dimensional Shephard-Metzler (1971) stimuli. For each task, participants used button presses serving as virtual pointers to locate a prescribed portion of the stimuli with respect to their "right" and "left." We found low-level cortical motor activation (M1) for both mental transformations; however, the degree to which such activation related to participants' performance differed, as well as the recruitment of additional nonmotoric strategies. The results are discussed in terms of recent hypotheses regarding the role of the body percept in extrinsically encoded mental transformations.     

Acute caffeine consumption enhances the executive control of visual attention in habitual consumers

Recent work suggests that a dose of 200–400 mg caffeine can enhance both vigilance and the executive control of visual attention in individuals with low caffeine consumption profiles. The present study seeks to determine whether individuals with relatively high caffeine consumption profiles would show similar advantages. To this end, we examined the effects of four caffeine doses (0 mg, 100 mg, 200 mg, 400 mg) on low- and high-level visual attention in individuals with high consumption profiles (n = 36), in a double-blind study using a repeated measures design. Results from the Attention Network Test indicated that caffeine enhanced both vigilance and the executive control of visual attention, but only at the highest administered dose (400 mg). We demonstrate that in habitual consumers high doses of caffeine can produce beneficial changes in visual attention. These results carry implications for the theorized interactions between caffeine, adenosine and dopamine in brain regions mediating visual attention.     

Gene knockout of insulin-regulated aminopeptidase: Loss of the specific binding site for angiotensin IV and age-related deficit in spatial memory

The AT₄ ligands, angiotensin IV and LVV-hemorphin 7, elicit robust effects on facilitating memory by binding to a specific site in the brain historically termed the angiotensin AT₄ receptor. The identification of the AT₄ receptor as insulin-regulated aminopeptidase (IRAP) is controversial, with other proteins speculated to be the target(s) of these peptides. In this study we have utilized IRAP knockout mice to investigate IRAP in the brain. We demonstrate that the high-affinity binding site for angiotensin IV is absent in IRAP knockout mice brain sections in parallel with the loss of IRAP immunostaining, providing irrefutable proof that IRAP is the specific high-affinity binding site for AT₄ ligands. However, our characterization of the behavioural phenotype of the IRAP knockout mice revealed a totally unexpected finding. In contrast to the acute effects of IRAP inhibitors in enhancing memory, deletion of the IRAP gene resulted in mice with an accelerated, age-related decline in spatial memory that was only detected in the Y maze paradigm. Moreover, no alterations in behaviour of the IRAP knockout mice were observed that could assist in elucidating the endogenous substrate(s). Our results highlight the importance of analysing the behavioural phenotype of knockout mice across different ages and in distinct memory paradigms.     

Trajectories of Parenting Processes and Adolescent Substance Use: Reciprocal Effects

Drawing on transactional theories of child development, we assessed bidirectional links between trajectories of adolescent substance use and parenting processes from early through mid adolescence. Hierarchical generalized models estimated trajectories for 3,317 adolescents from the National Longitudinal Survey of Youth 1997, exploring both between- and within-individual effects. Between individuals, adolescents reporting more regular family activities and greater father and mother knowledge of friends and teachers experienced lower levels of substance use through mid adolescence. Similarly, adolescents with more frequent substance use reported lower family activities, father knowledge, and mother knowledge, though these differences dissipated over time. More conservative within-individual differences indicated a prospective protective effect of family activities, with increases in adolescent participation in family activities predicting later declines in substance use. Results support the central importance of engagement in regular family activities, and suggest the need for further exploration of transactional processes between parents and children in the development of risk behaviors.     

Repetition and dual coding in procedural multimedia presentations

Students learned toy assembly sequences presented in picture, text, or one of three multimedia formats, and completed order verification, recall, and object assembly tasks. Experiment 1 compared repetitious (i.e. dual format presentations each conveying similar information) with complementary (i.e. dual format presentations each conveying different information) multimedia presentations. Repetitious presentations appear to provide learning benefits as a function of their inherent redundancy; complementary presentations provide benefits as a result of users actively integrating picture and text elements into a cohesive mental model. Experiment 2 compared repetitious with interleaved (i.e. assembly steps presented in alternating picture‐text formats) multimedia presentations. Again, multimedia presentations led to overall learning advantages relative to single‐format presentations, with an emphasis on both repetition and integrative working memory processes. Object assembly performance consistently demonstrated the utility of picture learning, with or without accompanying text. Results are considered relative to classic and contemporary learning theory, and inform educational design. Copyright © 2007 John Wiley & Sons, Ltd.     

Malingering as a categorical or dimensional construct: the latent structure of feigned psychopathology as measured by the SIRS and MMPI-2

The 6 nonoverlapping primary scales of the Structured Interview of Reported Symptoms (SIRS) were subjected to taxometric analysis in a group of 1,211 criminal and civil examinees in order to investigate the latent structure of feigned psychopathology. Both taxometric procedures used in this study, mean above minus below a cut (MAMBAC) and maximum covariance (MAXCOV), produced dimensional results. A subgroup of participants (n = 711) with valid Minnesota Multiphasic Personality Inventory-2 (MMPI-2) protocols were included in a second round of analyses in which the 6 nonoverlapping primary scales of the SIRS and the Infrequency (F), Infrequency-Psychopathology (Fp), and Dissimulation (Ds) scales of the MMPI-2 served as indicators. Again, the results were more consistent with dimensional latent structure than with taxonic latent structure. On the basis of these findings, it is concluded that feigned psychopathology forms a dimension (levels of fabrication or exaggeration) rather than a taxon (malingering-honest dichotomy) and that malingering is a quantitative distinction rather than a qualitative one. The theoretical and clinical practice implications of these findings are discussed.     

Psychiatric Disorders in Clinical Genetics I: Addressing Family Histories of Psychiatric Illness

This is the first article of a two-part professional development series addressing genetic counseling for personal and family histories of psychiatric disorders. It is based on an Educational Breakout Session presented by the Psychiatric Special Interest Group of the National Society of Genetic Counselors at the 2006 Annual Education Conference. This article examines issues that arise in addressing family histories of psychiatric illness, while the second article in the series considers the generation and provision of individualized recurrence risks for psychiatric disorders. In this article we discuss the importance of managing uncertainty for affected individuals and their close family members who have been referred to genetics for a number of different indications. We then use four simulated cases to make recommendations about the scope and timing of discussions related to the psychiatric family history.     

Testing a self-determination theory intervention for motivating tobacco cessation: supporting autonomy and competence in a clinical trial.

A longitudinal randomized trial tested the self-determination theory (SDT) intervention and process model of health behavior change for tobacco cessation (N = 1006). Adult smokers were recruited for a study of smokers' health and were assigned to intensive treatment or community care. Participants were relatively poor and undereducated. Intervention patients perceived greater autonomy support and reported greater autonomous and competence motivations than did control patients. They also reported greater medication use and significantly greater abstinence. Structural equation modeling analyses confirmed the SDT process model in which perceived autonomy support led to increases in autonomous and competence motivations, which in turn led to greater cessation. The causal role of autonomy support in the internalization of autonomous motivation, perceived competence, and smoking cessation was supported.