Flanker performance in female college students with ADHD: a diffusion model analysis

Attention-deficit hyperactivity disorder (ADHD) is characterized by poor adaptation to environmental demands, which leads to various everyday life problems. The present study had four aims: (1) to compare performance in a flanker task in female college students with and without ADHD (N = 39) in a classical analyses of reaction time and error rate and studying the underlying processes using a diffusion model, (2) to compare the amount of focused attention, (3) to explore the adaptation of focused attention, and (4) to relate adaptation to psychological functioning. The study followed a 2-between (group: ADHD vs. control) × 2-within (flanker conflict: incongruent vs. congruent) × 2-within (conflict frequency: 20 vs. 80 %) design. Compared to a control group, the ADHD group displayed prolonged response times accompanied by fewer errors in a flanker task. Results from the diffusion model analyses revealed that the members of the ADHD group showed deficits in non-decisional processes (i.e., higher non-decision time) and leaned more toward accuracy than participants without ADHD (i.e., setting higher boundaries). The ADHD group showed a more focused attention and less adaptation to the task conditions which is related to psychological functioning. Deficient non-decisional processes and poor adaptation are in line with theories of ADHD and presumably typical for the ADHD population, although this has not been shown using a diffusion model. However, we assume that the cautious strategy of trading speed of for accuracy is specific to the subgroup of female college students with ADHD and might be interpreted as a compensation mechanism

Digit Ratio Predicts Sense of Direction in Women

The relative length of the second-to-fourth digits (2D:4D) has been linked with prenatal androgen in humans. The 2D:4D is sexually dimorphic, with lower values in males than females, and appears to correlate with diverse measures of behavior. However, the relationship between digit ratio and cognition, and spatial cognition in particular, has produced mixed results. In the present study, we hypothesized that spatial tasks separating cue conditions that either favored female or male strategies would examine this structure-function correlation with greater precision. Previous work suggests that males are better in the use of directional cues than females. In the present study, participants learned a target location in a virtual landscape environment, in conditions that contained either all directional (i.e., distant or compass bearing) cues, or all positional (i.e., local, small objects) cues. After a short delay, participants navigated back to the target location from a novel starting location. Males had higher accuracy in initial search direction than females in environments with all directional cues. Lower digit ratio was correlated with higher accuracy of initial search direction in females in environments with all directional cues. Mental rotation scores did not correlate with digit ratio in either males or females. These results demonstrate for the first time that a sex difference in the use of directional cues, i.e., the sense of direction, is associated with more male-like digit ratio.National Science Foundation (U.S.) (NSF ECCS-1028319)National Science Foundation (U.S.) (NSF Graduate Student Fellowship)Mary Elisabeth Rennie Endowment for Epilepsy Researc

Effects of the cannabinoid CB1 receptor antagonist rimonabant on distinct measures of impulsive behavior in rats

Rationale Pathological impulsivity is a prominent feature in several psychiatric disorders, but detailed understanding of the specific neuronal processes underlying impulsive behavior is as yet lacking. Objectives As recent findings have suggested involvement of the brain cannabinoid system in impulsivity, the present study aimed at further elucidating the role of cannabinoid CB1 receptor activation in distinct measures of impulsive behavior. Materials and methods The effects of the selective cannabinoid CB1 receptor antagonist, rimonabant (SR141716A) and agonist WIN55,212-2 were tested in various measures of impulsive behavior, namely, inhibitory control in a five-choice serial reaction time task (5-CSRTT), impulsive choice in a delayed reward paradigm, and response inhibition in a stop-signal paradigm. Results In the 5-CSRTT, SR141716A dose-dependently improved inhibitory control by decreasing the number of premature responses. Furthermore, SR141716A slightly improved attentional function, increased correct response latency, but did not affect other parameters. The CB1 receptor agonist WIN55,212-2 did not change inhibitory control in the 5-CSRTT and only increased response latencies and errors of omissions. Coadministration of WIN55,212-2 prevented the effects of SR141716A on inhibitory control in the 5-CSRTT. Impulsive choice and response inhibition were not affected by SR141716A at any dose, whereas WIN55,212-2 slightly impaired response inhibition but did not change impulsive choice. Conclusions The present data suggest that particularly the endocannabinoid system seems involved in some measures of impulsivity and provides further evidence for the existence of distinct forms of impulsivity that can be pharmacologically dissociated

EcoTILLING in Capsicum species: searching for new virus resistances

<p>Abstract</p> <p>Background</p> <p>The EcoTILLING technique allows polymorphisms in target genes of natural populations to be quickly analysed or identified and facilitates the screening of genebank collections for desired traits. We have developed an EcoTILLING platform to exploit <it>Capsicum </it>genetic resources. A perfect example of the utility of this EcoTILLING platform is its application in searching for new virus-resistant alleles in <it>Capsicum </it>genus. Mutations in translation initiation factors (eIF4E, eIF(iso)4E, eIF4G and eIF(iso)4G) break the cycle of several RNA viruses without affecting the plant life cycle, which makes these genes potential targets to screen for resistant germplasm.</p> <p>Results</p> <p>We developed and assayed a cDNA-based EcoTILLING platform with 233 cultivated accessions of the genus <it>Capsicum</it>. High variability in the coding sequences of the <it>eIF4E </it>and <it>eIF(iso)4E </it>genes was detected using the cDNA platform. After sequencing, 36 nucleotide changes were detected in the CDS of <it>eIF4E </it>and 26 in <it>eIF(iso)4E</it>. A total of 21 <it>eIF4E </it>haplotypes and 15 <it>eIF(iso)4E </it>haplotypes were identified. To evaluate the functional relevance of this variability, 31 possible eIF4E/eIF(iso)4E combinations were tested against <it>Potato virus Y</it>. The results showed that five new <it>eIF4E </it>variants (<it>pvr2¹⁰</it>, <it>pvr2¹¹</it>, <it>pvr2¹²</it>, <it>pvr2¹³</it>and <it>pvr2¹⁴</it>) were related to PVY-resistance responses.</p> <p>Conclusions</p> <p>EcoTILLING was optimised in different <it>Capsicum </it>species to detect allelic variants of target genes. This work is the first to use cDNA instead of genomic DNA in EcoTILLING. This approach avoids intronic sequence problems and reduces the number of reactions. A high level of polymorphism has been identified for initiation factors, showing the high genetic variability present in our collection and its potential use for other traits, such as genes related to biotic or abiotic stresses, quality or production. Moreover, the new <it>eIF4E </it>and <it>eIF(iso)4E </it>alleles are an excellent collection for searching for new resistance against other RNA viruses.</p

How Distinctive are ADHD and RD? Results of a Double Dissociation Study

The nature of the comorbidity between Attention-Deficit/Hyperactivity Disorder (ADHD) and Reading Disability (RD) was examined using a double dissociation design. Children were between 8 and 12 years of age and entered into four groups: ADHD only (n = 24), ADHD+RD (n = 29), RD only (n = 41) and normal controls (n = 26). In total, 120 children participated in the study; 38 girls and 82 boys. Both ADHD and RD were associated with impairments in inhibition and lexical decision, although inhibition and lexical decision were more severely impaired in RD than in ADHD. Visuospatial working memory deficits were specific to children with only ADHD. It is concluded that there was overlap on lexical decision and to a lesser extent on inhibition between ADHD and RD. In ADHD, impairments were dependent on IQ, which suggest that the overlap in lexical decision and inhibition is different in origin for ADHD and RD. The ADHD only group was specifically characterized by deficits in visuospatial working memory. Hence, no double dissociation between ADHD and RD was found on executive functioning and lexical decision

Effects of methylphenidate on attention in Wistar rats treated with the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4)

The aim of this study was to assess the effects of the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) on attention in rats as measured using the 5-choice-serial-reaction-time task (5CSRTT) and to investigate whether methylphenidate has effects on DSP4-treated rats. Methylphenidate is a noradrenaline and dopamine reuptake inhibitor and commonly used in the pharmacological treatment of individuals with attention deficit/hyperactivity disorder (ADHD). Wistar rats were trained in the 5CSRTT and treated with one of three doses of DSP4 or saline. Following the DSP4 treatment rats were injected with three doses of methylphenidate or saline and again tested in the 5CSRTT. The treatment with DSP4 caused a significant decline of performance in the number of correct responses and a decrease in response accuracy. A reduction in activity could also be observed. Whether or not the cognitive impairments are due to attention deficits or changes in explorative behaviour or activity remains to be investigated. The treatment with methylphenidate had no beneficial effect on the rats’ performance regardless of the DSP4 treatment. In the group without DSP4 treatment, methylphenidate led to a reduction in response accuracy and bidirectional effects in regard to parameters related to attention. These findings support the role of noradrenaline in modulating attention and call for further investigations concerning the effects of methylphenidate on attentional processes in rats

Study protocol of the iMPaCT project : A longitudinal cohort study assessing psychological determinants, sexual behaviour and chlamydia (re)infections in heterosexual STI clinic visitors

Acknowledgements We are grateful to the staff at the STI clinics of Amsterdam, Kennemerland, Hollands Noorden, Twente, who are involved in the recruitment and data collection of participants, and Marlous Ratten and Klazien Visser from Soapoli-online, who are involved in the coordination of laboratory testing of the home-based sampling kits at six-month follow-up. We also thank the staff at the STI department at the National Institute for Public Health and the Environment, especially Birgit van Benthem. Funding This project is funded by the Strategic Programme (SPR) of the National Institute for Public Health and the Environment (RIVM) (project number S/113004/01/IP). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Availability of data and materials The dataset (anonymised) generated during this study will be made available for interested parties on request.Peer reviewedPublisher PD