Dissociable roles of the mPFC-to-VTA Pathway in the control of Impulsive Action and Risk-Related Decision-Making in Roman High- And Low-Avoidance Rats.

BACKGROUND: Impulsive action and risk-related decision-making (RDM) are associated with various psychiatric disorders including drug abuse. Both behavioral traits have also been linked to reduced frontocortical activity and alterations in dopamine function in the ventral tegmental area (VTA). However, despite direct projections from the medial prefrontal cortex (mPFC) to the VTA, the specific role of the mPFC-to-VTA pathway in controlling impulsive action and RDM remains unexplored. METHODS: We used Positron Emission Tomography with [18F]-Fluorodeoxyglucose to evaluate brain metabolic activity in Roman High- (RHA) and Low-avoidance (RLA) rats, which exhibit innate differences in impulsive action and RDM. Notably, we used a viral-based double dissociation chemogenetic strategy to isolate, for the first time, the role of the mPFC-to-VTA pathway in controlling these behaviors. We selectively activated the mPFC-to-VTA pathway in RHA rats and inhibited it in RLA rats, assessing the effects on impulsive action and RDM in the rat gambling task. RESULTS: Our results showed that RHA rats displayed higher impulsive action, less optimal decision-making, and lower cortical activity than RLA rats at baseline. Chemogenetic activation of the mPFC-to-VTA pathway reduced impulsive action in RHA rats, whereas chemogenetic inhibition had the opposite effect in RLA rats. However, these manipulations did not affect RDM. Thus, by specifically targeting the mPFC-to-VTA pathway in a phenotype-dependent way, we were reverted innate patterns of impulsive action, but not RDM. CONCLUSION: Our findings suggest a dissociable role of the mPFC-to-VTA pathway in impulsive action and RDM, highlighting its potential as a target for investigating impulsivity-related disorders.

Associations between Sleep Disorders and Impulsive-Compulsive Behaviors in Parkinson's Disease: A Prospective Cohort Study.

OBJECTIVE: To examine the associations of excessive daytime sleepiness (EDS) and probable rapid eye movement sleep behavior disorder (pRBD), respectively, with impulsive-compulsive behaviors (ICBs) over a 5-year follow-up in patients with early Parkinson's disease (PD). METHODS: The Parkinson's Progression Markers Initiative is a multicenter cohort study based on an ongoing and open-ended registry. Longitudinal associations of sleep disorders with ICB over 5-year follow-up visits were estimated using generalized linear mixed-effects models among PD participants. RESULTS: A total of 825 PD participants were enrolled at baseline. The study sample had a median baseline age of 63.1 (interquartile range: 55.6-69.3) years and comprised 496 (61.5%) men. Among them, 201 (24.9%) had ICB at baseline. In the generalized mixed-effects models, EDS (odds ratio [OR] = 1.09, 95% confidence interval [CI] 1.05, 1.12) and RBD (OR = 1.07, 95% CI 1.03, 1.12) were substantially associated with higher odds of developing ICB over time in PD patients, after multivariate adjustment including age, gender, family history, GDS score, STAI-Y score, MDS-UPDRS part III score, LEDD, and disease duration. Consistent results were observed when stratifying by age at baseline, gender, and PD family history. CONCLUSIONS: The study findings suggest a longitudinal association between EDS and pRBD with an increased risk of developing ICB in patients with PD. The findings emphasize the significance of evaluating and addressing sleep disorders in PD patients as a potential approach to managing ICB.

Triangulation of Hard X-Ray Sources in an X-Class Solar Flare with ASO-S/HXI and Solar Orbiter/STIX.

HXI on ASO-S and STIX onboard Solar Orbiter are the first simultaneously operating solar hard X-ray imaging spectrometers. ASO-S's low Earth orbit and Solar Orbiter's periodic displacement from the Sun-Earth line enables multi-viewpoint solar hard X-ray spectroscopic imaging analysis for the first time. Here, we demonstrate the potential of this new capability by reporting the first results of 3D triangulation of hard X-ray sources in the SOL2023-12-31T21:55 X5 flare. HXI and STIX observed the flare near the east limb with an observer separation angle of 18°. We triangulated the brightest regions within each source, which enabled us to characterise the large-scale hard X-ray geometry of the flare. The footpoints were found to be in the chromosphere within uncertainty, as expected, while the thermal looptop source was centred at an altitude of 15.1 ± 1 Mm. Given the footpoint separation, this implies a more elongated magnetic-loop structure than predicted by a semi-circular model. These results show the strong diagnostic power of joint HXI and STIX observations for understanding the 3D geometry of solar flares. We conclude by discussing the next steps required to fully exploit their potential.

Time-restricted feeding can increase food-related impulsivity: a randomized controlled trial.

OBJECTIVES: Although an increasing number of studies show that time-restricted feeding may improve metabolic health, studies examining the behavioral effects of this eating pattern are limited. This study examined the effect of time-restricted feeding on impulsivity in adults. METHODS: Thirty adults aged 25-41 years participated in this randomized controlled trial. The intervention group followed time-restricted feeding for 4 weeks and there was no energy restriction in the intervention group (n = 15) or control group (n = 15). Impulsivity was assessed before and after the intervention with the Barratt Impulsiveness Scale and the Go/NoGo task. RESULTS: The compliance rate (the percentage of days when participants had a feeding time of ≤ 8 hours/day) of the intervention group to the time-restricted feeding pattern was 92.38 ± 4.24%. The Barratt Impulsiveness Scale-11 total score of the intervention group increased from 55.53 ± 6.37 to 59.47 ± 7.67 (p = 0.02). During the Go/NoGo task, an indicator of inhibitory control, the reaction time to food and non-food stimuli was significantly shortened in the intervention group (respectively; p = 0.009, p = 0.01). In the control group, no significant change was detected in impulsivity determined by the BIS-11 or Go/NoGo task. DISCUSSION: This study showed that although time-restricted feeding may reduce body weight, it can lead to increased impulsivity and impaired inhibitory control.Trial registration: ClinicalTrials.gov identifier: NCT04960969.

Brain structural alterations associated with impulsiveness in male violent patients with schizophrenia.

BACKGROUND: Violence in schizophrenia (SCZ) is a phenomenon associated with neurobiological factors. However, the neural mechanisms of violence in patients with SCZ are not yet sufficiently understood. Thus, this study aimed to explore the structural changes associated with the high risk of violence and its association with impulsiveness in patients with SCZ to reveal the possible neurobiological basis. METHOD: The voxel-based morphometry approach and whole-brain analyses were used to measure the alteration of gray matter volume (GMV) for 45 schizophrenia patients with violence (VSC), 45 schizophrenia patients without violence (NSC), and 53 healthy controls (HC). Correlation analyses were used to examine the association of impulsiveness and brain regions associated with violence. RESULTS: The results demonstrated reduced GMV in the right insula within the VSC group compared with the NSC group, and decreased GMV in the right temporal pole and left orbital part of superior frontal gyrus only in the VSC group compared to the HC group. Spearman correlation analyses further revealed a positive correlation between impulsiveness and GMV of the left superior temporal gyrus, bilateral insula and left medial orbital part of the superior frontal gyrus in the VSC group. CONCLUSION: Our findings have provided further evidence for structural alterations in patients with SCZ who had engaged in severe violence, as well as the relationship between the specific brain alterations and impulsiveness. This work provides neural biomarkers and improves our insight into the neural underpinnings of violence in patients with SCZ.

A comprehensive measure assessing different types of problematic use of the internet among Chinese adolescents: The Assessment of Criteria for Specific Internet-use Disorders (ACSID-11).

BACKGROUND: Problematic use of the internet (PUI) is prevalent, particularly among adolescents and young adults. Given the limited measures to assess specific types of PUI, which encompasses a broad spectrum of activities such as online gaming, social media use, pornography use, shopping, gambling, and web-streaming, Muller et al. (2022) developed the Assessment of Criteria for Specific Internet-use Disorders (ACSID-11) to comprehensively assess different types of PUI (i.e., gaming, shopping, social media use, gambling, and pornography use). The present study aimed to validate the Chinese ACSID-11 among adolescents incorporating cross-cultural adaptations. METHODS: Using forward-backward translation method, a culturally adapted version of the ACSID-11 was prepared. Then, a cross-sectional online survey was administered between September 8 and September 26, 2023. Adolescents, using a convenience sample (N = 11,492; mean age = 16.42 years [SD ± 0.91]; 59.1% male), were recruited from six schools to complete the translated ACSID-11, Internet Gaming Disorder Scale-Short Form (IGDS9-SF), Bergen Social Media Addiction Scale (BSMAS), and Smartphone Application Based Addiction Scale (SABAS) via an online platform. Pearson correlation coefficients assessed convergent/discriminant validity. Factor structure and measurement invariance were examined through confirmatory factor analysis (CFA) and multi-group CFA. Cronbach's alpha and McDonald's omega tested internal consistency. RESULTS: Associations between the ACSID-11 components and other scales supported convergent validity (i.e., ACSID-11 gaming scale with IGDS9-SF [0.37 ≤ r ≤ 0.41]; social networks use scale with BSMAS [0.24 ≤ r ≤ 0.31]) and discriminant validity (i.e., online gambling scale with BSMAS [0.16 ≤ r ≤ 0.19] and with SABAS [0.11 ≤ r ≤ 0.13]). A four-factor solution indicated good fit with comparative fit index (CFI) ranging from 0.982 to 0.958. The ACSID-11 was measurement invariant across sexes (∆CFI = -0.001 to 0.000) and different levels of related addictive behaviors (∆CFI = -0.001 to 0.000). Both Cronbach's alpha and McDonald's omega (0.63 to 0.97) were acceptable for both frequency and intensity of responses. CONCLUSIONS: The ACSID-11 is an appropriate scale to assess different kinds of PUI among Chinese adolescents and students. Psychometric assessment of the measure in other cultures and among clinical samples is recommended.

Active and passive waiting in impulsive choice: Effects of fixed-interval and fixed-time delays.

Behavioral interventions to improve self-control, preference for a larger-later (LL) reward over a smaller-sooner (SS) reward, involve experience with delayed rewards. Whether they involve timing processes remains controversial. In rats, there have been inconsistent results on whether timing processes may be involved in intervention-induced improvements in self-control. Interventions that improved self-control with corresponding timing improvements used fixed-interval (FI) delays, whereas interventions that failed to find corresponding timing improvements used fixed-time (FT) delays. The FI schedule includes a response contingency (active waiting), whereas the FT schedule delivers reward automatically (passive waiting). The present study compared the effects of FI and FT schedules in interventions and impulsive choice tasks to evaluate effects on self-control and timing behavior. The impulsive choice task evaluated preference for an SS option (one pellet after 10-, 15-, 20-, 25-, and 30-s delays) versus an LL option (two pellets after a 30-s delay). The intervention task included forced-choice SS (one pellet after 10 s) and LL (two pellets after 30 s) sessions under FI or FT schedules. FI schedules produced greater sensitivity to SS delay in the impulsive choice task. Both FI and FT interventions increased LL choices. Following choice testing, temporal bisection and peak interval tasks revealed better timing precision for rats with an FI delay experience. Overall, the FI choice contingency was associated with improved temporal attention and timing precision.

Exercise Recovers Weight Gain, but Not Increased Impulsive Choice, Caused by a High-Fat Diet.

A high-fat diet has negative effects on physical, neurological, and behavioral outcomes. One consistent finding is that a diet high in fat increases impulsive choice behavior-behavior that is linked to a wide range of other negative health behaviors. While the mechanism for this increase in impulsive choice is not well understood, exercise, with its well-known and many benefits, may serve as an effective and accessible way to combat increased impulsive choice associated with a high-fat diet. The goal of this work was to test this possibility. Rats were divided into four groups in a two-by-two factorial design: exercise and control diet, sedentary and control diet, exercise and high-fat diet, sedentary and high-fat diet. Rats in the exercise groups engaged in 30-min of forced, moderate intensity wheel-running exercise five days per week. Rats in the high-fat diet groups ate a diet high in fat. Impulsive choice was measured using a delay discounting task. Exercise prevented weight gain associated with the high-fat diet. Exercise also preserved relative motivation for food reinforcement. However, exercise did not prevent increases in impulsive choice observed for rats that consumed a high-fat diet relative to the rats that consumed the control diet. This work rules out several possible mechanisms by which a high-fat diet may increase impulsive choice behavior. It makes clear that exercise alone may not stave off increases in impulsive choice caused by a high-fat diet. Future work is necessary to uncover the underlying mechanism for this effect and discover interventions, perhaps ones that combine both physically and cognitively demanding activities, to improve health and behavior as it relates to decision making processes.

Laboratory method to induce state boredom increases impulsive choice in people who use cocaine and controls.

Background: Impulsive choice is associated with both cocaine use and relapse. Little is known about the influence of transient states on impulsive choice in people who use cocaine (PWUC).Objective: This study investigated the direct effects of induced boredom on impulsive choice (i.e., temporal discounting) in PWUC relative to well-matched community controls.Methods: Forty-one PWUC (≥1× cocaine use in past 3 months; 7 females) and 38 demographically matched controls (5 females) underwent two experimental conditions in counterbalanced order. Temporal discounting was assessed immediately after a standardized boredom induction task (peg-turning) and a self-selected video watched for the same duration (non-boredom). Subjective mood state and perceived task characteristics were assessed at baseline, during experimental manipulations, and after the choice task.Results: PWUC and controls were well matched on sex, age, and socioeconomic status. Groups were also similar in reported use of drugs other than cocaine, except for recent cigarette and alcohol use (PWUC > controls). As expected, peg-turning increased boredom in the sample overall, with higher boredom reported during peg-turning than the video (p < .001, η2p = .20). Participants overall exhibited greater impulsive choice after boredom than non-boredom (p = .028, η2p = .07), with no preferential effects in PWUC (p > .05, BF01 = 2.9).Conclusion: Experimentally induced boredom increased state impulsivity irrespective of cocaine use status - in PWUC and carefully matched controls - suggesting a broad link between boredom and impulsive choice. This is the first study to show that transient boredom directly increases impulsive choice. Data support a viable laboratory method to further parse the effects of boredom on impulsive choice.

Cocaine self-administration behavior is associated with subcortical and cortical morphometry measures in individuals with cocaine use disorder.

Background: Individual differences in gray-matter morphometry in the limbic system and frontal cortex have been linked to clinical features of cocaine use disorder (CUD). Self-administration paradigms can provide more direct measurements of the relationship between the regulation of cocaine use and gray-matter morphometry when compared to self-report assessments.Objectives: Our goal was to investigate associations with self-administration behavior in subcortical and cortical brain regions. We hypothesized the number of cocaine infusions self-administered would be correlated with gray-matter volumes (GMVs) in the striatum, amygdala, and hippocampus. Due to scarcity in human studies, we did not hypothesize subcortical directionality. In the frontal cortex, we hypothesized thickness would be negatively correlated with self-administered cocaine.Methods: We conducted an analysis of cocaine self-administration and structural MRI data from 33 (nFemales = 10) individuals with moderate-to-severe CUD. Self-administration lasted 60-minutes and cocaine (8, 16, or 32 mg/70 kg) was delivered on an FR1 schedule (5-minute lockout). Subcortical and cortical regression analyses were performed that included combined bilateral regions and age, experimental variables and use history as confounders.Results: Self-administered cocaine infusions were positively associated with caudal GMV (b = 0.18, p = 0.030) and negatively with putamenal GMV (b = -0.10, p = 0.041). In the cortical model, infusions were positively associated with insular thickness (b = 0.39, p = 0.008) and women appeared to self-administer cocaine more frequently (b = 0.23, p = 0.019).Conclusions: Brain morphometry features in the striatum and insula may contribute to cocaine consumption in CUD. These differences in morphometry may reflect consequences of prolonged use, predisposed vulnerability, or other possibilities.Clinical Trial Numbers: NCT01978431; NCT03471182.

Understanding the Co-occurrence of Gambling Disorder and Problematic Pornography Use: Exploring Sociodemographic and Clinical Factors.

The co-occurrence between gambling disorder (GD) and problematic pornography use (PPU) has not yet been explored. Therefore, the present study compared (a) sociodemographic variables, (b) GD-related factors, (c) substance use, (d) psychopathology, (e) personality features, (f) impulsivity, and (g) emotion regulation between individuals with GD (GD group) and those with co-occurring GD and PPU (GD+PPU group). The sample consisted of 359 treatment-seeking individuals with GD: n = 332 individuals had GD only (GD group) and n = 37 individuals had GD and co-occurring PPU (GD+PPU group). GD severity, impulsivity, psychopathology, personality, emotion regulation, and other sociodemographic and clinical variables were assessed. No between-group differences in sociodemographic measures were observed. The GD+PPU group demonstrated greater GD severity and a higher likelihood of substance use compared to those without PPU. Furthermore, the presence of PPU was associated with worse psychopathology, higher impulsivity (except for lack of premeditation and positive urgency), more difficulties in emotion regulation (except for non-acceptance of emotions and limited access to emotions), and a personality profile characterized by lower levels of self-directedness and cooperativeness. The co-occurrence of GD and PPU seems associated with a more dysfunctional clinical profile.

Matched Stochastic Resonance Enhanced Underwater Passive Sonar Detection under Non-Gaussian Impulsive Background Noise.

Remote passive sonar detection with low-frequency band spectral lines has attracted much attention, while complex low-frequency non-Gaussian impulsive noisy environments would strongly affect the detection performance. This is a challenging problem in weak signal detection, especially for the high false alarm rate caused by heavy-tailed impulsive noise. In this paper, a novel matched stochastic resonance (MSR)-based weak signal detection model is established, and two MSR-based detectors named MSR-PED and MSR-PSNR are proposed based on a theoretical analysis of the MSR output response. Comprehensive detection performance analyses in both Gasussian and non-Gaussian impulsive noise conditions are presented, which revealed the superior performance of our proposed detector under non-Gasussian impulsive noise. Numerical analysis and application verification have revealed the superior detection performance with the proposed MSR-PSNR detector compared with energy-based detection methods, which can break through the high false alarm rate problem caused by heavy-tailed impulsive noise. For a typical non-Gasussian impulsive noise assumption with α=1.5, the proposed MSR-PED and MSR-PSNR can achieve approximately 16 dB and 22 dB improvements, respectively, in the detection performance compared to the classical PED method. For stronger, non-Gaussian impulsive noise conditions corresponding to α=1, the improvement in detection performance can be more significant. Our proposed MSR-PSNR methods can overcome the challenging problem of a high false alarm rate caused by heavy-tailed impulsive noise. This work can lay a solid foundation for breaking through the challenges of underwater passive sonar detection under non-Gaussian impulsive background noise, and can provide important guidance for future research work.

Validation of the German long and short versions of the UPPS-P Impulsive Behavior Scale.

OBJECTIVE: The UPPS-P Impulsive Behavior Scale is a widely used self-report measure of impulsivity, but there is currently no validated German version that includes the Positive Urgency scale. METHODS: We combined existing German translations of UPPS scales and included the Positive Urgency dimension to validate the UPPS-P in a sample of 399 participants. In addition, we developed a revised short version of the UPPS-P (SUPPS-P) with 20 items and conducted a confirmatory factor analysis (CFA) to verify the structure in an independent validation sample with 349 participants. To determine evidence of convergent and discriminant validity, we used measures of impulsivity, depression, anxiety, stress, problematic alcohol and substance use. RESULTS: CFA of the five factorial structure of the UPPS-P demonstrated acceptable fits and evidence of validity and reliability for the subscales. Psychometric characteristics of the SUPPS-P using the original item configuration were not satisfactory. As a result, we developed a revised German version of the SUPPS-P and confirmed the five-factor structure using a CFA in the validation sample. For the revised version, model fits and evidence of validity and internal consistencies were good. Associations with other constructs were as expected. For example, whereas Sensation Seeking was associated moderately with problematic alcohol use, lacking associations of Lack of Premeditation to internalizing symptoms showed evidence of discriminant validity. DISCUSSION: The German translations of both UPPS-P and SUPPS-P are valid tools for measuring impulsive behaviors. They are well-suited for exploring the associations between different facets of impulsivity and psychopathological phenomena.

Hooked on technology: examining the co-occurrence of nomophobia and impulsive sensation seeking among nursing students.

BACKGROUND: Nomophobia, the crippling fear of being disconnected from mobile devices, is a burgeoning global concern. Given the critical nature of the profession of nursing students, understanding nomophobia's prevalence and potential impacts on patient care and professional conductors becomes even more crucial. AIM: This study explores the relationship between nomophobia and impulsive sensation-seeking among nursing students in Egypt. DESIGN AND METHODS: A multicenter cross-sectional survey was conducted with 1626 nursing students randomly selected from three universities across Egypt. TOOLS: The Arabic versions of the Nomophobia and Impulsive Sensation Seeking Questionnaires were employed to gather data. RESULTS: Our findings revealed that 40.3% of the surveyed nursing students exhibited severe nomophobia, indicating a substantial dependence on their mobile devices. Notably, this high prevalence was accompanied by a strong tendency towards impulsive sensation-seeking behaviors. Furthermore, a stepwise regression analysis identified several significant predictors of nomophobia (p < 0.001). Impulsive sensation-seeking, year of study, average daily smartphone usage, and age emerged as key factors, explaining 27.5% of the variability in nomophobia scores. CONCLUSION: The prevalence of nomophobia among Egyptian nursing students is undeniable, highlighting their substantial reliance on mobile devices. A significant association with impulsive sensation-seeking behavior further compounds this dependence. Factors such as impulsive sensation seeking, year of study, average daily smartphone usage, and age were identified as significant predictors of nomophobia. Recognizing these factors as key predictors of nomophobia is crucial for designing effective interventions and psychotherapies. Prioritizing such interventions can promote future nurses' well-being and ensure they deliver the highest quality care to their patients.

Cut-and-paste for impulsive gravitational waves with Λ: the mathematical analysis.

Impulsive gravitational waves are theoretical models of short but violent bursts of gravitational radiation. They are commonly described by two distinct spacetime metrics, one of local Lipschitz regularity and the other one even distributional. These two metrics are thought to be 'physically equivalent' since they can be formally related by a 'discontinuous coordinate transformation'. In this paper we provide a mathematical analysis of this issue for the entire class of nonexpanding impulsive gravitational waves propagating in a background spacetime of constant curvature. We devise a natural geometric regularisation procedure to show that the notorious change of variables arises as the distributional limit of a family of smooth coordinate transformations. In other words, we establish that both spacetimes arise as distributional limits of a smooth sandwich wave taken in different coordinate systems which are diffeomorphically related.

NIDM: network impulsive dynamics on multiplex biological network for disease-gene prediction.

The prediction of genes related to diseases is important to the study of the diseases due to high cost and time consumption of biological experiments. Network propagation is a popular strategy for disease-gene prediction. However, existing methods focus on the stable solution of dynamics while ignoring the useful information hidden in the dynamical process, and it is still a challenge to make use of multiple types of physical/functional relationships between proteins/genes to effectively predict disease-related genes. Therefore, we proposed a framework of network impulsive dynamics on multiplex biological network (NIDM) to predict disease-related genes, along with four variants of NIDM models and four kinds of impulsive dynamical signatures (IDSs). NIDM is to identify disease-related genes by mining the dynamical responses of nodes to impulsive signals being exerted at specific nodes. By a series of experimental evaluations in various types of biological networks, we confirmed the advantage of multiplex network and the important roles of functional associations in disease-gene prediction, demonstrated superior performance of NIDM compared with four types of network-based algorithms and then gave the effective recommendations of NIDM models and IDS signatures. To facilitate the prioritization and analysis of (candidate) genes associated to specific diseases, we developed a user-friendly web server, which provides three kinds of filtering patterns for genes, network visualization, enrichment analysis and a wealth of external links (http://bioinformatics.csu.edu.cn/DGP/NID.jsp). NIDM is a protocol for disease-gene prediction integrating different types of biological networks, which may become a very useful computational tool for the study of disease-related genes.

Dual-systems models of the genetic architecture of impulsive personality traits: neurogenetic evidence of distinct but related factors.

BACKGROUND: Dual-systems models, positing an interaction between two distinct and competing systems (i.e. top-down self-control, and bottom-up reward- or emotion-based drive), provide a parsimonious framework for investigating the interplay between cortical and subcortical brain regions relevant to impulsive personality traits (IPTs) and their associations with psychopathology. Despite recent developments in multivariate analysis of genome-wide association studies (GWAS), molecular genetic investigations of these models have not been conducted. METHODS: Using IPT GWAS, we conducted confirmatory genomic structural equation models (GenomicSEM) to empirically evaluate dual-systems models of the genetic architecture of IPTs. Genetic correlations between dual-systems factors and relevant cortical and subcortical neuroimaging phenotypes (regional/structural volume, cortical surface area, cortical thickness) were estimated and compared. RESULTS: GenomicSEM dual-systems models underscored important sources of shared and unique genetic variance between top-down and bottom-up constructs. Specifically, a dual-systems genomic model consisting of sensation seeking and lack of self-control factors demonstrated distinct but related sources of genetic influences (rg = 0.60). Genetic correlation analyses provided evidence of differential associations between dual-systems factors and cortical neuroimaging phenotypes (e.g. lack of self-control negatively associated with cortical thickness, sensation seeking positively associated with cortical surface area). No significant associations were observed with subcortical phenotypes. CONCLUSIONS: Dual-systems models of the genetic architecture of IPTs tested were consistent with study hypotheses, but associations with relevant neuroimaging phenotypes were mixed (e.g. no associations with subcortical volumes). Findings demonstrate the utility of dual-systems models for studying IPT genetic influences, but also highlight potential limitations as a framework for interpreting IPTs as endophenotypes for psychopathology.

Separating Vibrational Coherences in Ground/Excited Electronic States of Solvent/Solute Following Non-Resonant/Resonant Impulsive Excitation.

In a quest to track down the origin of coherent vibrational motions observed in femtosecond pump-probe transients, whether they arise from ground/excited electronic state of solute or are contributed by the solvent, we demonstrate a method for extricating vibrations under resonant and non-resonant impulsive excitations using a diatomic solute in condensed phase (iodine in carbon tetrachloride) with aid of spectral dispersion of the chirped broadband probe. Most importantly, we show how a sum over intensities for a select region of detection wavelengths and Fourier transform of data over select temporal window untwine contributions from vibrational modes of different origins. Thus, in a single pump-probe experiment, vibrational features specific to solute as well as solvent are disentangled that are otherwise spectrally overlapping and are non-separable in conventional (spontaneous/stimulated) Raman spectroscopy employing narrowband excitation. We envision wide-ranging applications of this method to unveil vibrational features in complex molecular systems.

Effects of the estrous cycle on impulsive choice and interval timing in female rats.

Research in humans and animals shows differences in impulsive choice, which is a failure to wait for larger, delayed rewards, when comparing males and females. It is possible that fluctuations in sex hormones (estradiol and progesterone) across the reproductive cycle contribute to sex differences in impulsive choice. The current study delivered an impulsive choice task with peak interval trials to female rats while estrous cycles, the rodent reproductive cycle, were tracked over the course of the task. Female rats were more sensitive to changes in delay in the proestrus phase of the estrous cycle and made more larger-later choices when in estrus, particularly when the delay to the smaller reward was short. Estradiol increases dramatically during proestrus while progesterone peaks during estrus, suggesting that estradiol and progesterone may affect impulsive choice through mechanisms such as delay discounting, delay aversion, and/or timing processes. Analyses of timing of the choice task delays showed inconsistent effects of the estrous cycle across delays, suggesting that reward-timing interactions may have complicated how hormone fluctuations affected interval timing. Further research is needed to determine the mechanism underlying increased larger-later choices during the estrus phase, increased delay sensitivity during the proestrus phase, and variability in interval timing across delays and estrous cycle stages.

Blood python (Python brongersmai) strike kinematics and forces are robust to variations in substrate geometry.

Snake strikes are some of the most rapid accelerations in terrestrial vertebrates. Generating rapid body accelerations requires high ground reaction forces, but on flat surfaces snakes must rely on static friction to prevent slip. We hypothesize that snakes may be able to take advantage of structures in the environment to prevent their body from slipping, potentially allowing them to generate faster and more forceful strikes. To test this hypothesis, we captured high-speed video and forces from defensive strikes of juvenile blood pythons (Python brongersmai) on a platform that was either open on all sides or with two adjacent walls opposite the direction of the strike. Contrary to our predictions, snakes maintained high performance on open platforms by imparting rearward momentum to the posterior body and tail. This compensatory behavior increases robustness to changes in their strike conditions and could allow them to exploit variable environments.