Suchergebnisse

Dendrite morphology, a neuron's anatomical fingerprint, is a neuroscientist's asset in unveiling organizational principles in the brain. However, the genetic program encoding the morphological identity of a single dendrite remains a mystery. In order to obtain a formal understanding of dendritic branching, we studied distributions of morphological parameters in a group of four individually identifiable neurons of the fly visual system. We found that parameters relating to the branching topology were similar throughout all cells. Only parameters relating to the area covered by the dendrite were cell type specific. With these areas, artificial dendrites were grown based on optimization principles minimizing the amount of wiring and maximizing synaptic democracy. Although the same branching rule was used for all cells, this yielded dendritic structures virtually indistinguishable from their real counterparts. From these principles we derived a fully-automated model-based neuron reconstruction procedure validating the artificial branching rule. In conclusion, we suggest that the genetic program implementing neuronal branching could be constant in all cells whereas the one responsible for the dendrite spanning field should be cell specific.

This research was financially supported by grants from the Spanish Ministry of Science, Innovation, and Universities and the Andalusian Government (Fondos FEDER): doctoral research grant ES-2016-078667 to NA, A-CTS-111-UGR18 and PGC2018-093786-B-I00 to MB, and PSI2015-65502-C2-2-P to CG-A. ; While scientific interest in understanding the grit trait has grown exponentially in recent years, one important gap in the grit literature relates to its biological and neural substrate. In the present study, we adopted a hypotheses-driven approach in a large sample of young adults (N = 120) with diverse educational backgrounds and work experiences in order to investigate the electrophysiological correlates of grit both during rest and while performing a learning task. Additionally, we selected a measure of impulsiveness to better understand the neural similarities and differences between grit and related self-control constructs. Based on previous work that implicated the prefrontal cortex in grit, we hypothesized that high grit participants would have lower frontal theta/beta ratio (a broadly used index that reflects prefrontally-mediated top–down processes, which might indicate better control over subcortical information). Furthermore, we expected the perseverance of effort facet of grit to be linked to higher complexity during task engagement because previous research has shown complexity indexes (entropy and fractal dimension) to be linked to effort while performing cognitive tasks. Our results revealed that although there were no differences at rest as a function of grit, the participants with high grit and high consistency of interest scores exhibited lower frontal theta/beta ratios during the learning task. This pattern suggests that individual differences in gritmight bemore evident when top-down control processes are at work. Furthermore, there was a positive association between perseverance of effort and entropy at task, which might indicate more effort and engagement in the task. Finally, no association was found between the neural indexes (frontal theta/beta ratio, entropy, or fractal dimension) and impulsiveness, neither impulsiveness mediated between grit and brain measures. Finally, when controlling for impulsiveness and demographic variables (gender, age, education, and work experience) the effects at the facet level remained statistically significant. While there is still a long way to fully understand the neural mechanisms of grit, the present work constitutes a step toward unveiling the electrophysiological prints of grit. ; Spanish Ministry of Science, Innovation, and Universities and the Andalusian Government (Fondos FEDER) ES-2016-078667 A-CTS-111-UGR18 PGC2018-093786-B-I00 PSI2015-65502-C2-2-P

This study extends previous work that has shown that perceived threats to the security of employees' jobs can have deleterious effects on their health. The study examined (a) whether intrinsic work characteristics are better predictors of perceived job security than extrinsic work characteristics and (b) whether job security contributes to the prediction of employee health independent of intrinsic and extrinsic characteristics of their jobs. Participants in the study were 104 employees from the central personnel office of a large state agency. Job security was found to be related to both intri nsic and extrinsic work factors, although more closely related to intrinsic factors. Perceptions of job security contributed unique (and significant) variance to the prediction of employee health, suggesting that job security is central to the physical and psychological well-being of employees. Implications for understanding the impact of job security on workers' lives are discussed.

13 12 ; S ; [EN] A study has been made of the effect of chronic exercise on myocardial electrophysiological heterogeneity and stability, as well as of the role of cholinergic neurons in these changes. Determinations in hearts from untrained and trained rabbits on a treadmill were performed. The hearts were isolated and perfused. A pacing electrode and a recording multielectrode were located in the left ventricle. The parameters determined during induced VF, before and after atropine (1 mu M), were: fibrillatory cycle length (VV), ventricular functional refractory period (FRPVF), normalized energy (NE) of the fibrillatory signal and its coefficient of variation (CV), and electrical ventricular activation complexity, as an approach to myocardial heterogeneity and stability. The VV interval was longer in the trained group than in the control group both prior to atropine (78 +/- 10 vs. 68 +/- 10 ms) and after atropine (76 +/- 8 vs. 67 +/- 10 ms). Likewise, FRPVF was longer in the trained group than in the control group both prior to and after atropine (53 +/- 8 vs. 42 +/- 7 ms and 50 +/- 6 vs. 40 +/- 6 ms, respectively), and atropine did not modify FRPVF. The CV of FRPVF was lower in the trained group than in the control group prior to atropine (12.5 +/- 1.5% vs. 15.1 +/- 3.8%) and, decreased after atropine (15.1 +/- 3.8% vs. 12.2 +/- 2.4%) in the control group. The trained group showed higher NE values before (0.40 +/- 0.04 vs. 0.36 +/- 0.05) and after atropine (0.37 +/- 0.04 vs. 0.34 +/- 0.06; p = 0.08). Training decreased the CV of NE both before (23.3 +/- 2% vs. 25.2 +/- 4%; p = 0.08) and after parasympathetic blockade (22.6 +/- 1% vs. 26.1 +/- 5%). Cholinergic blockade did not modify these parameters within the control and trained groups. Activation complexity was lower in the trained than in the control animals before atropine (34 +/- 8 vs. 41 +/- 5), and increased after atropine in the control group (41 +/- 5 vs. 48 +/- 9, respectively). Thus, training decreases the intrinsic heterogeneity of the myocardium, ...

AbstractObservational learning is an important mechanism for cognitive and social development. However, the neurophysiological mechanisms underlying observational learning in children are not well understood. In this study, we used a probabilistic reward‐based observational learning paradigm to compare behavioral and electrophysiological markers of individual and observational reinforcement learning in 8‐ to 10‐year‐old children. Specifically, we manipulated the amount of observable information as well as children's similarity in age to the observed person (same‐aged child vs. adult) to examine the effects of similarity in age on the integration of observed information in children. We show that the feedback‐related negativity (FRN) during individual reinforcement learning reflects the valence of outcomes of own actions. Furthermore, we found that the feedback‐related negativity during observational reinforcement learning (oFRN) showed a similar distinction between outcome valences of observed actions. This suggests that the oFRN can serve as a measure of observational learning in middle childhood. Moreover, during observational learning children profited from the additional social information and imitated the choices of their own peers more than those of adults, indicating that children have a tendency to conform more with similar others (e.g. their own peers) compared to dissimilar others (adults). Taken together, our results show that children can benefit from integrating observable information and that oFRN may serve as a measure of observational learning in children.

Previous research on job satisfaction in government employees has not distinguished professionals from other high status groups such as managers. Professionals and blue-collar workers employed in a state government in the U.S. (N = 252) were compared in order to learn more about the quality of the professional work experience. Data on job satisfaction, task characteristics, and aspirations for intrinsic fulfillment through work were collected via a questionnaire. Results suggested that there was no difference between the two groups in job satisfaction. However, professionals rated their jobs as significantly lower in skill variety, task identity, task significance, autonomy, and knowledge of results. Professionals also believed that their jobs should provide less intrinsic fulfillment than did the blue-collar workers. It was speculated that professionals employed in government maintain minimal levels of job satisfaction despite less fulfilling jobs by reducing their aspirations for fulfillment in work.

The need for transitioning towards low-carbon energy systems, and the recent boom in available data, allows for a constant re-evaluation of global electricity sector decarbonization progress, and its underlying theoretical assumptions. Arguably, the existing decarbonization literature and institutional support frameworks focus on top-down supply side mechanisms, where policies, goals, access to financing, and technology innovation are suggested as the main drivers. Here, we synthesize eleven global datasets that range from electricity decarbonization progress, to quality of governance, to international fossil fuel subsidies, and environmental policies, amongst several others, and use methods from data mining to explore the factors that may be fostering or hindering decarbonization progress. This exercise allows us to present numerous hypotheses worth exploring in future research. Some of these hypotheses suggest that policies might be ineffective when misaligned with country specific motivators and inherent characteristics, that even in the absence of policy there are particular inherent characteristics that foster decarbonization progress (e.g., relatively high local energy prices, foreign energy import dependency and the absence of a large extractive resource base), and that the interaction of country-specific enabling environments, inherent characteristics, and motivations is what determines decarbonization progress, rather than stand-alone support mechanisms. We present the hypothesis that existing support mechanisms for decarbonization may be relying too much on blanket strategies (e.g., policies, targets), and that there is a need for support mechanisms that encompass a wider diversity of country-specific underlying conditions. All code and data in this analysis is available upon request.