Publications by authors named "Aarts H"

175 Publications

Mindfulness Reduces Reactivity to Food Cues: Underlying Mechanisms and Applications in Daily Life.

Curr Addict Rep 2017 28;4(2):151-157. Epub 2017 Apr 28.

Department of Psychology, Utrecht University, Heidelberglaan 1, 3854CS Utrecht, The Netherlands.

Purpose Of Review: Mindfulness-based interventions are becoming increasingly popular as a means to facilitate healthy eating. We suggest that the decentering component of mindfulness, which is the metacognitive insight that all experiences are impermanent, plays an especially important role in such interventions. To facilitate the application of decentering, we address its psychological mechanism to reduce reactivity to food cues, proposing that it makes thoughts and simulations in response to food cues less compelling. We discuss supporting evidence, applications, and challenges for future research.

Recent Findings: Experimental and correlational studies consistently find that the adoption of a decentering perspective reduces subjective cravings, physiological reactivity such as salivation, and unhealthy eating.

Summary: We suggest that the decentering perspective can be adopted in any situation to reduce reactivity to food cues. Considering people's high exposure to food temptations in daily life, this makes it a powerful tool to empower people to eat healthily.
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http://dx.doi.org/10.1007/s40429-017-0134-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5435775PMC
April 2017

Abnormal agency experiences in schizophrenia patients: Examining the role of psychotic symptoms and familial risk.

Psychiatry Res 2017 Apr 1;250:270-276. Epub 2016 Nov 1.

Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.

Experiencing self-agency over one's own action outcomes is essential for social functioning. Recent research revealed that patients with schizophrenia do not use implicitly available information about their action-outcomes (i.e., prime-based agency inference) to arrive at self-agency experiences. Here, we examined whether this is related to symptoms and/or familial risk to develop the disease. Fifty-four patients, 54 controls, and 19 unaffected (and unrelated) siblings performed an agency inference task, in which experienced agency was measured over action-outcomes that matched or mismatched outcome-primes that were presented before action performance. The Positive and Negative Syndrome Scale (PANSS) and Comprehensive Assessment of Symptoms and History (CASH) were administered to assess psychopathology. Impairments in prime-based inferences did not differ between patients with symptoms of over- and underattribution. However, patients with agency underattribution symptoms reported significantly lower overall self-agency experiences. Siblings displayed stronger prime-based agency inferences than patients, but weaker prime-based inferences than healthy controls. However, these differences were not statistically significant. Findings suggest that impairments in prime-based agency inferences may be a trait characteristic of schizophrenia. Moreover, this study may stimulate further research on the familial basis and the clinical relevance of impairments in implicit agency inferences.
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http://dx.doi.org/10.1016/j.psychres.2016.10.077DOI Listing
April 2017

Consumption Simulations Induce Salivation to Food Cues.

PLoS One 2016 7;11(11):e0165449. Epub 2016 Nov 7.

Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.

Salivation to food cues is typically explained in terms of mere stimulus-response links. However, food cues seem to especially increase salivation when food is attractive, suggesting a more complex psychological process. Adopting a grounded cognition perspective, we suggest that perceiving a food triggers simulations of consuming it, especially when attractive. These simulations then induce salivation, which effectively prepares the body for eating the food. In two experiments, we systematically examined the role of simulations on salivation to food cues. As stimuli, both experiments used an attractive, a neutral, and a sour food, as well as a non-food control object. In Experiment 1, participants were instructed to simulate eating every object they would be exposed to. We then exposed them to each object separately. Salivation was assessed by having participants spit their saliva into a cup after one minute of exposure. In Experiment 2, we instructed half of participants to simulate eating each object, and half to merely look at them, while measuring salivation as in Experiment 1. Afterwards, participants rated their simulations and desire to eat for each object separately. As predicted, foods increased salivation compared to the non-food control object, especially when they were attractive or sour (Exp. 1 and 2). Importantly, attractive and sour foods especially increased salivation when instructed to simulate (Exp. 2). These findings suggest that consumption simulations play an important role in inducing salivary responses to food cues. We discuss directions for future research as well as the role of simulations for other appetitive processes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0165449PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5098730PMC
September 2017

The implicit power motive predicts action selection.

Psychol Res 2017 May 23;81(3):560-570. Epub 2016 Mar 23.

Department of Psychology, Utrecht University, P.O. Box 126, 3584 CS, Utrecht, The Netherlands.

Previous research has indicated that implicit motives can reliably predict which behaviors people select or decide to perform. However, so far, the question of how these motives are able to predict this action selection process has received little attention. Based on ideomotor theory, we argue that implicit motives can predict action selection when an action has become associated with a motive-congruent (dis)incentive through repeated experiences with the action-outcome relationship. This idea was investigated by examining whether the implicit need for power (nPower) would come to predict action selection (i.e., choosing to press either of two buttons) when these actions had repeatedly resulted in motive-congruent (dis)incentives (i.e., submissive or dominant faces). Both Studies 1 and 2 indicated that participants became more likely to select the action predictive of the motive-congruent outcome as their history with the action-outcome relationship increased. Study 2 indicated that this effect stemmed from both an approach towards incentives and an avoidance of disincentives. These results indicate that implicit motives (particularly the power motive) can predict action selection as a result of learning which actions yield motive-congruent (dis)incentives. Our findings therefore offer a model of how implicit motives can come to predict which behaviors people select to perform.
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http://dx.doi.org/10.1007/s00426-016-0768-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5397432PMC
May 2017

Impaired frontal processing during agency inferences in schizophrenia.

Psychiatry Res Neuroimaging 2016 Feb 23;248:134-41. Epub 2015 Dec 23.

Department of Psychiatry of the Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands. Electronic address:

People generally experience themselves as the cause of outcomes following from their own actions. Such agency inferences occur fluently and are essential to social interaction. However, schizophrenia patients often experience difficulties in distinguishing their own actions from those of others. Building on recent research into the neural substrates underlying agency inferences in healthy individuals, the present study investigates how these inferences are represented on a neural level in patients with schizophrenia. Thirty-one schizophrenia patients and 31 healthy controls performed an agency inference task while functional magnetic resonance images were obtained. Participants were presented with a task wherein the relationship between their actions and the subsequent outcomes was ambiguous. They received instructions to cause specific outcomes to occur by pressing a key, but the task was designed to match or mismatch the color outcome with the participants' goal. Both groups experienced stronger agency when their goal matched (vs. mismatched) the outcome. However, region of interest analyses revealed that only controls showed the expected involvement of the medial prefrontal cortex and superior frontal gyrus, whereas in patients the agency experience was not related to brain activation. These findings are discussed in light of a hypofrontality model of schizophrenia.
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http://dx.doi.org/10.1016/j.pscychresns.2015.12.006DOI Listing
February 2016

Individual differences in action co-representation: not personal distress or subclinical psychotic experiences but sex composition modulates joint action performance.

Exp Brain Res 2016 Feb 2;234(2):499-510. Epub 2015 Nov 2.

Brain Center Rudolf Magnus, University Medical Center Utrecht, Huispostnummer A.01.126, PO Box 85500, 3508 GA, Utrecht, The Netherlands.

Successful social interaction requires the ability to integrate as well as distinguish own and others' actions. Normally, the integration and distinction of self and other are a well-balanced process, occurring without much effort or conscious attention. However, not everyone is blessed with the ability to balance self-other distinction and integration, resulting in personal distress in reaction to other people's emotions or even a loss of self [e.g., in (subclinical) psychosis]. Previous research has demonstrated that the integration and distinction of others' actions cause interference with one's own action performance (commonly assessed with a social Simon task). The present study had two goals. First, as previous studies on the social Simon effect employed relatively small samples (N < 50 per test), we aimed for a sample size that allowed us to test the robustness of the action interference effect. Second, we tested to what extent action interference reflects individual differences in traits related to self-other distinction (i.e., personal distress in reaction to other people's emotions and subclinical psychotic symptoms). Based on a questionnaire study among a large sample (N = 745), we selected a subsample (N = 130) of participants scoring low, average, or high on subclinical psychotic symptoms, or on personal distress. The selected participants performed a social Simon task. Results showed a robust social Simon effect, regardless of individual differences in personal distress or subclinical psychotic symptoms. However, exploratory analyses revealed that the sex composition of interaction pairs modulated social Simon effects. Possible explanations for these findings are discussed.
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http://dx.doi.org/10.1007/s00221-015-4475-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4731433PMC
February 2016

Attentional control and inferences of agency: Working memory load differentially modulates goal-based and prime-based agency experiences.

Conscious Cogn 2015 Dec 24;38:38-49. Epub 2015 Oct 24.

Department of Psychology, Utrecht University, Utrecht, The Netherlands.

Previous research indicates that people can infer self-agency, the experience of causing outcomes as a result of one's own actions, in situations where information about action-outcomes is pre-activated through goal-setting or priming. We argue that goal-based agency inferences rely on attentional control that processes information about matches and mismatches between intended and actual outcomes. Prime-based inferences follow an automatic cognitive accessibility process that relies on matches between primed and actual information about outcomes. We tested an improved task for a better examination of goal-based vs. primed-based agency inferences, and examined the moderating effect of working memory load on both types of inferences. Findings of four studies showed that goal-based, but not prime-based agency inferences dwindled under working memory load. These findings suggest that goal-based (vs. primed-based) agency inferences indeed rely on attentional control, thus rendering goal-based agency inferences especially prone to conditions that modulate goal-directed control processes.
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http://dx.doi.org/10.1016/j.concog.2015.10.002DOI Listing
December 2015

Put your plan into action: The influence of action plans on agency and responsibility.

J Pers Soc Psychol 2015 Jun;108(6):850-66

Department of Social and Cultural Psychology, Behavioural Science Institute, Radboud University Nijmegen.

While action plans and intentions have been considered to be important factors contributing to the personal sense of causation known as agency, the present research is the first to empirically investigate how action plans influence agency. Participants in multiple studies were required to plan or not to plan ahead their actions. Results consistently show that on trials in which participants were required to plan their actions, participants experienced reduced agency compared to trials in which participants were not required to plan their actions. These results were found for both explicit agency paradigms in which participants were asked for their experiences of causation (Studies 1 and 2), as well as in an implicit agency paradigm in which participants were asked to estimate the time between their actions and the consequences of their actions (Study 3). In addition, it was shown that the reduction in agency was smaller when plans and actions were temporally closer together (Study 4). In a final line of experiments we discovered that prior planning similarly reduced both the emotional experience of acting and feelings of responsibility in agents (Studies 5-7). However, the direction of this effect was reversed in observers, for whom cues related to planning by others increased attributions of responsibility toward those others (Study 8).
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http://dx.doi.org/10.1037/pspa0000024DOI Listing
June 2015

Variation in nitrogen use efficiencies on Dutch dairy farms.

J Sci Food Agric 2015 Dec 29;95(15):3055-8. Epub 2015 May 29.

Wageningen UR, Plant Research International, Wageningen, The Netherlands.

Background: On dairy farms, the input of nutrients including nitrogen is higher than the output in products such as milk and meat. This causes losses of nitrogen to the environment. One of the indicators for the losses of nitrogen is the nitrogen use efficiency. In the Dutch Minerals Policy Monitoring Program (LMM), many data on nutrients of a few hundred farms are collected which can be processed by the instrument Annual Nutrient Cycle Assessment (ANCA, in Dutch: Kringloopwijzer) in order to provide nitrogen use efficiencies.

Results: After dividing the dairy farms (available in the LMM program) according to soil type and in different classes for milk production ha(-1) , it is shown that considerable differences in nitrogen use efficiency exist between farms on the same soil type and with the same level of milk production ha(-1) .

Conclusion: This offers opportunities for improvement of the nitrogen use efficiency on many dairy farms. Benchmarking will be a useful first step in this process.
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http://dx.doi.org/10.1002/jsfa.7250DOI Listing
December 2015

First step in using molecular data for microbial food safety risk assessment; hazard identification of Escherichia coli O157:H7 by coupling genomic data with in vitro adherence to human epithelial cells.

Int J Food Microbiol 2015 Nov 10;213:130-8. Epub 2015 Apr 10.

National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, A. van Leeuwenhoeklaan 9, 3720 BA Bilthoven, The Netherlands.

The potential for using whole genome sequencing (WGS) data in microbiological risk assessment (MRA) has been discussed on several occasions since the beginning of this century. Still, the proposed heuristic approaches have never been applied in a practical framework. This is due to the non-trivial problem of mapping microbial information consisting of thousands of loci onto a probabilistic scale for risks. The paradigm change for MRA involves translation of multidimensional microbial genotypic information to much reduced (integrated) phenotypic information and onwards to a single measure of human risk (i.e. probability of illness). In this paper a first approach in methodology development is described for the application of WGS data in MRA; this is supported by a practical example. That is, combining genetic data (single nucleotide polymorphisms; SNPs) for Shiga toxin-producing Escherichia coli (STEC) O157 with phenotypic data (in vitro adherence to epithelial cells as a proxy for virulence) leads to hazard identification in a Genome Wide Association Study (GWAS). This application revealed practical implications when using SNP data for MRA. These can be summarized by considering the following main issues: optimum sample size for valid inference on population level, correction for population structure, quantification and calibration of results, reproducibility of the analysis, links with epidemiological data, anchoring and integration of results into a systems biology approach for the translation of molecular studies to human health risk. Future developments in genetic data analysis for MRA should aim at resolving the mapping problem of processing genetic sequences to come to a quantitative description of risk. The development of a clustering scheme focusing on biologically relevant information of the microbe involved would be a useful approach in molecular data reduction for risk assessment.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2015.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4613885PMC
November 2015

Abnormalities in the experience of self-agency in schizophrenia: A replication study.

Schizophr Res 2015 May 3;164(1-3):210-3. Epub 2015 Apr 3.

Department of Psychiatry of the Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.

People usually experience agency over their actions and subsequent outcomes. These agency inferences over action-outcomes are essential to social interaction, and occur when an actual outcome corresponds with either a specific goal (goal-based), and matches with action-outcome information that is subtly pre-activated in the situation at hand (prime-based). Recent research showed that schizophrenia patients exhibit goal-based inferences, but not prime-based inferences. Intrigued by these findings, and underscoring their potential role in explaining poor social functioning, we replicate patients' deficit in prime-based agency inferences. Additionally, we exclude the account that patients are unable to visually process and attend to primed information.
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http://dx.doi.org/10.1016/j.schres.2015.03.015DOI Listing
May 2015

Molecular hazard identification of non-O157 Shiga toxin-producing Escherichia coli (STEC).

PLoS One 2015 19;10(3):e0120353. Epub 2015 Mar 19.

National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Bilthoven, the Netherlands.

The complexity regarding Shiga toxin-producing Escherichia coli (STEC) in food safety enforcement as well as clinical care primarily relates to the current inability of an accurate risk assessment of individual strains due to the large variety in serotype and genetic content associated with (severe) disease. In order to classify the clinical and/or epidemic potential of a STEC isolate at an early stage it is crucial to identify virulence characteristics of putative pathogens from genomic information, which is referred to as 'predictive hazard identification'. This study aimed at identifying associations between virulence factors, phylogenetic groups, isolation sources and seropathotypes. Most non-O157 STEC in the Netherlands belong to phylogroup B1 and are characterized by the presence of ehxA, iha and stx2, but absence of eae. The large variability in the number of virulence factors present among serogroups and seropathotypes demonstrated that this was merely indicative for the virulence potential. While all the virulence gene associations have been worked out, it appeared that there is no specific pattern that would unambiguously enable hazard identification for an STEC strain. However, the strong correlations between virulence factors indicate that these arrays are not a random collection but are rather specific sets. Especially the presence of eae was strongly correlated to the presence of many of the other virulence genes, including all non-LEE encoded effectors. Different stx-subtypes were associated with different virulence profiles. The factors ehxA and ureC were significantly associated with HUS-associated strains (HAS) and not correlated to the presence of eae. This indicates their candidacy as important pathogenicity markers next to eae and stx2a.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0120353PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4366395PMC
December 2015

Viewpoint: effective stakeholder communication in agriculture: together we stand, divided we fall!

J Agric Sci 2014 Dec 1;152(Suppl 1):65-70. Epub 2014 May 1.

Institut de l'Elevage , Paris , France.

Substantial improvements of agricultural systems are necessary to meet the future requirements of humanity. However, current agricultural knowledge and information systems are generally not well suited to meet the necessary improvements in productivity and sustainability. For more effective application of research output, research producers and research consumers should not be considered as separate individuals in the knowledge chain but as collaborating partners creating synergy. The current paper investigates the relationships between scientists and stakeholders and identifies approaches to increase the effectiveness of their communication. On-farm research has proven to be an effective means of improving exploitation of research output at farm level because it connects all relevant partners in the process. Furthermore, pilot farms can act as an effective platform for communication and dissemination. Regional networks of pilot farms should be established and connected across regions.
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http://dx.doi.org/10.1017/S0021859614000276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4332277PMC
December 2014

Antibiotic resistance genes in food and gut (non-pathogenic) bacteria. Bad genes in good bugs.

Front Microbiol 2014 9;5:754. Epub 2015 Jan 9.

Department of Microbiology and Biochemistry of Dairy Products, Dairy Research Institute, Spanish National Research Council Villaviciosa, Asturias, Spain.

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http://dx.doi.org/10.3389/fmicb.2014.00754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4288317PMC
January 2015

Priming determinist beliefs diminishes implicit (but not explicit) components of self-agency.

Front Psychol 2014 17;5:1483. Epub 2014 Dec 17.

Department of Experimental Psychology, Ghent University Ghent, Belgium.

Weakening belief in the concept of free will yields pronounced effects upon social behavior, typically promoting selfish and aggressive over pro-social and helping tendencies. Belief manipulations have furthermore been shown to modulate basic and unconscious processes involved in motor control and self-regulation. Yet, to date, it remains unclear how high-level beliefs can impact such a wide range of behaviors. Here, we tested the hypothesis that priming disbelief in free will diminishes the sense of agency, i.e., the intrinsic sensation of being in control of one's own actions. To this end, we measured participants' implicit and explicit self-agency under both anti-free will and control conditions. Priming disbelief in free will reduced implicit but not explicit components of agency. These findings suggest that free will beliefs have a causal impact on the pre-reflective feeling of being in control of one's actions, and solidify previous proposals that implicit and explicit agency components tap into distinct facets of action awareness.
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http://dx.doi.org/10.3389/fpsyg.2014.01483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4268906PMC
January 2015

Cortical information flow during inferences of agency.

Front Hum Neurosci 2014 14;8:609. Epub 2014 Aug 14.

Department of Psychology, Utrecht University Utrecht, Netherlands.

Building on the recent finding that agency experiences do not merely rely on sensorimotor information but also on cognitive cues, this exploratory study uses electroencephalographic recordings to examine functional connectivity during agency inference processing in a setting where action and outcome are independent. Participants completed a computerized task in which they pressed a button followed by one of two color words (red or blue) and rated their experienced agency over producing the color. Before executing the action, a matching or mismatching color word was pre-activated by explicitly instructing participants to produce the color (goal condition) or by briefly presenting the color word (prime condition). In both conditions, experienced agency was higher in matching vs. mismatching trials. Furthermore, increased electroencephalography (EEG)-based connectivity strength was observed between parietal and frontal nodes and within the (pre)frontal cortex when color-outcomes matched with goals and participants reported high agency. This pattern of increased connectivity was not identified in trials where outcomes were pre-activated through primes. These results suggest that different connections are involved in the experience and in the loss of agency, as well as in inferences of agency resulting from different types of pre-activation. Moreover, the findings provide novel support for the involvement of a fronto-parietal network in agency inferences.
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http://dx.doi.org/10.3389/fnhum.2014.00609DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132368PMC
September 2014

An exploratory fMRI study into inferences of self-agency.

Soc Cogn Affect Neurosci 2015 May 27;10(5):708-12. Epub 2014 Aug 27.

Department of Social and Organizational Psychology, Utrecht University, Utrecht, the Netherlands and Department of Psychiatry of the Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands.

Building on the recent findings that the experience of self-agency over actions and corresponding outcomes can also rely on cognitive inferential processes, rather than motor prediction processes, this study aims to investigate the brain areas involved in agency inference processing in a setting where action and outcome are independent. Twenty-three right-handed subjects were scanned using functional MRI while performing an agency inference task, in which action outcomes matched or mismatched goals. The experience of self-agency was associated with increased activation in the inferior parietal lobule as well as the bilateral (medial) superior frontal cortex and medial prefrontal cortex. These findings provide new and exciting insights in the processing of inferential self-agency, providing a first look at the neural correlates of self-agency processing independent of motor-prediction processes.
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http://dx.doi.org/10.1093/scan/nsu106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420747PMC
May 2015

Exploiting the explosion of information associated with whole genome sequencing to tackle Shiga toxin-producing Escherichia coli (STEC) in global food production systems.

Int J Food Microbiol 2014 Sep 11;187:57-72. Epub 2014 Jul 11.

School of Biological Sciences, The University of Aberdeen, Aberdeen, Scotland, United Kingdom. Electronic address:

The rates of foodborne disease caused by gastrointestinal pathogens continue to be a concern in both the developed and developing worlds. The growing world population, the increasing complexity of agri-food networks and the wide range of foods now associated with STEC are potential drivers for increased risk of human disease. It is vital that new developments in technology, such as whole genome sequencing (WGS), are effectively utilized to help address the issues associated with these pathogenic microorganisms. This position paper, arising from an OECD funded workshop, provides a brief overview of next generation sequencing technologies and software. It then uses the agent-host-environment paradigm as a basis to investigate the potential benefits and pitfalls of WGS in the examination of (1) the evolution and virulence of STEC, (2) epidemiology from bedside diagnostics to investigations of outbreaks and sporadic cases and (3) food protection from routine analysis of foodstuffs to global food networks. A number of key recommendations are made that include: validation and standardization of acquisition, processing and storage of sequence data including the development of an open access "WGSNET"; building up of sequence databases from both prospective and retrospective isolates; development of a suite of open-access software specific for STEC accessible to non-bioinformaticians that promotes understanding of both the computational and biological aspects of the problems at hand; prioritization of research funding to both produce and integrate genotypic and phenotypic information suitable for risk assessment; training to develop a supply of individuals working in bioinformatics/software development; training for clinicians, epidemiologists, the food industry and other stakeholders to ensure uptake of the technology and finally review of progress of implementation of WGS. Currently the benefits of WGS are being slowly teased out by academic, government, and industry or private sector researchers around the world. The next phase will require a coordinated international approach to ensure that it's potential to contribute to the challenge of STEC disease can be realized in a cost effective and timely manner.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2014.07.002DOI Listing
September 2014

Distinct neural responses to conscious versus unconscious monetary reward cues.

Hum Brain Mapp 2014 Nov 2;35(11):5578-86. Epub 2014 Jul 2.

Department of Psychology, Utrecht University, Utrecht, The Netherlands; Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, The Netherlands.

Human reward pursuit is often assumed to involve conscious processing of reward information. However, recent research revealed that reward cues enhance cognitive performance even when perceived without awareness. Building on this discovery, the present functional MRI study tested two hypotheses using a rewarded mental-rotation task. First, we examined whether subliminal rewards engage the ventral striatum (VS), an area implicated in reward anticipation. Second, we examined differences in neural responses to supraliminal versus subliminal rewards. Results indicated that supraliminal, but not subliminal, high-value reward cues engaged brain areas involved in reward processing (VS) and task performance (supplementary motor area, motor cortex, and superior temporal gyrus). This pattern of findings is striking given that subliminal rewards improved performance to the same extent as supraliminal rewards. So, the neural substrates of conscious versus unconscious reward pursuit are vastly different-but despite their differences, conscious and unconscious reward pursuit may still produce the same behavioral outcomes.
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http://dx.doi.org/10.1002/hbm.22571DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4265283PMC
November 2014

Targeting impulsive processes of eating behavior via the internet. Effects on body weight.

Appetite 2014 Jul 24;78:102-9. Epub 2014 Mar 24.

Department of Psychology, Utrecht University, The Netherlands; Department of Social Psychology, University of Groningen, The Netherlands.

Because eating behavior can take on an impulsive nature many people experience difficulty with dieting to lose weight. Therefore, an experiment was conducted to test the effectiveness of two interventions targeting impulsive processes of eating behavior to facilitate weight loss: Implementation intentions to remind people about dieting versus a go/no-go task to change impulses toward palatable foods. Dieters performed an online training program (four times in 4 weeks) in which they were randomly assigned to a 2 (implementation intention condition: dieting versus control) × 2 (go/no-go task condition: food versus control) design. They formed either dieting implementation intentions (e.g., If I open the fridge I will think of dieting!) or control implementation intentions. Furthermore, they received either a go/no-go task in which behavioral stop signals were presented upon presentation of palatable foods (food go/no-go task), or upon control stimuli. Participants' weight was measured in the laboratory before and after the intervention. Strength of participants' dieting goal and their Body Mass Index (BMI; as a proxy for impulsiveness toward food) were examined as moderators. Results showed that both dieting implementation intentions and the food go/no-go task facilitated weight loss. Moreover, dieting implementation intentions facilitated weight loss particularly among people with a strong current dieting goal, whereas the food go/no-go task facilitated weight loss independent of this factor. Instead, the food go/no-go task, but not formation of dieting implementation intentions, was primarily effective among dieters with a relatively high BMI. These results provide the first preliminary evidence that interventions aimed at targeting impulsive eating-related processes via the internet can facilitate weight loss.
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http://dx.doi.org/10.1016/j.appet.2014.03.014DOI Listing
July 2014

A new perspective on human reward research: how consciously and unconsciously perceived reward information influences performance.

Cogn Affect Behav Neurosci 2014 Jun;14(2):493-508

Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106-9660, USA,

The question of how human performance can be improved through rewards is a recurrent topic of interest in psychology and neuroscience. Traditional, cognitive approaches to this topic have focused solely on consciously communicated rewards. Recently, a largely neuroscience-inspired perspective has emerged to examine the potential role of conscious awareness of reward information in effective reward pursuit. The present article reviews research employing a newly developed monetary-reward-priming paradigm that allows for a systematic investigation of this perspective. We analyze this research to identify similarities and differences in how consciously and unconsciously perceived rewards impact three distinct aspects relevant to performance: decision making, task preparation, and task execution. We further discuss whether conscious awareness, in modulating the effects of reward information, plays a role similar to its role in modulating the effects of other affective information. Implications of these insights for understanding the role of consciousness in modulating goal-directed behavior more generally are discussed.
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http://dx.doi.org/10.3758/s13415-013-0241-zDOI Listing
June 2014

Quantifying the sources of Salmonella on dressed carcasses of pigs based on serovar distribution.

Meat Sci 2014 Apr 12;96(4):1425-31. Epub 2013 Dec 12.

National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control (CIb), P.O. Box 1, 3720 BA Bilthoven, The Netherlands.

Salmonella serotyping data, qualitatively described by van Hoek et al. (2012), were used to quantify potential sources of Salmonella in a Dutch pig slaughterhouse. Statistical tests to compare per-day Salmonella prevalence and serotyping data from multiple points in the chain were used to find transmission pathways. A statistical model based on serotyping data was developed to attribute Salmonella on dressed carcasses to the most likely source. Approximately two-third of dressed carcasses carrying Salmonella on the medial surface had been contaminated by house flora. For carcasses carrying Salmonella on the distal surface, transient Salmonella from incoming pigs was a more important source. The relevance of the different sources of Salmonella varied within and between sampling days. Results were compared to those of another modeling approach, in which Salmonella concentration data from the same samples were used (Smid et al., 2012). They mostly agreed. The approach chosen by an individual slaughterhouse depends on the data that are collected.
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http://dx.doi.org/10.1016/j.meatsci.2013.12.002DOI Listing
April 2014

Non-essential genes form the hubs of genome scale protein function and environmental gene expression networks in Salmonella enterica serovar Typhimurium.

BMC Microbiol 2013 Dec 17;13:294. Epub 2013 Dec 17.

Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg, C, Denmark.

Background: Salmonella Typhimurium is an important pathogen of human and animals. It shows a broad growth range and survives in harsh conditions. The aim of this study was to analyze transcriptional responses to a number of growth and stress conditions as well as the relationship of metabolic pathways and/or cell functions at the genome-scale-level by network analysis, and further to explore whether highly connected genes (hubs) in these networks were essential for growth, stress adaptation and virulence.

Results: De novo generated as well as published transcriptional data for 425 selected genes under a number of growth and stress conditions were used to construct a bipartite network connecting culture conditions and significantly regulated genes (transcriptional network). Also, a genome scale network was constructed for strain LT2. The latter connected genes with metabolic pathways and cellular functions. Both networks were shown to belong to the family of scale-free networks characterized by the presence of highly connected nodes or hubs which are genes whose transcription is regulated when responding to many of the assayed culture conditions or genes encoding products involved in a high number of metabolic pathways and cell functions.The five genes with most connections in the transcriptional network (wraB, ygaU, uspA, cbpA and osmC) and in the genome scale network (ychN, siiF (STM4262), yajD, ybeB and dcoC) were selected for mutations, however mutagenesis of ygaU and ybeB proved unsuccessful. No difference between mutants and the wild type strain was observed during growth at unfavorable temperatures, pH values, NaCl concentrations and in the presence of H2O2. Eight mutants were evaluated for virulence in C57/BL6 mice and none differed from the wild type strain. Notably, however, deviations of phenotypes with respect to the wild type were observed when combinations of these genes were deleted.

Conclusion: Network analysis revealed the presence of hubs in both transcriptional and functional networks of S. Typhimurium. Hubs theoretically confer higher resistance to random mutation but a greater susceptibility to directed attacks, however, we found that genes that formed hubs were dispensable for growth, stress adaptation and virulence, suggesting that evolution favors non-essential genes as main connectors in cellular networks.
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http://dx.doi.org/10.1186/1471-2180-13-294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3878590PMC
December 2013

Stop signals decrease choices for palatable foods through decreased food evaluation.

Front Psychol 2013 26;4:875. Epub 2013 Nov 26.

Department of Psychology, Radboud University Nijmegen Nijmegen, Netherlands.

The present study explores whether presenting specific palatable foods in close temporal proximity of stop signals in a go/no-go task decreases subsequent evaluations of such foods among participants with a relatively high appetite. Furthermore, we tested whether any decreased evaluations could mediate subsequent food choice. Participants first received a go/no-go task in which palatable foods were consistently linked to go cues or no-go cues within participants. Next, evaluation of the palatable foods was measured as well as food choice. Replicating previous work, results show that among participants with a relatively high appetite palatable foods associated with no-go cues are less often chosen as snacks compared to when these foods are associated with go cues, whereas this manipulation did not affect participants with a relatively low appetite. Moreover, this effect was completely mediated by decreased evaluation of the palatable foods that had been associated with the no-go cues, whereas evaluation of the foods associated with go cues did not mediate this effect. Results further showed that the devaluation effect of foods associated with no-go cues was independent of the amount of pairings (4 vs. 12 vs. 24) with the no-go cues. The current findings suggest that decreased food evaluation is a mechanism that explains effects of stop signals on food choice.
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http://dx.doi.org/10.3389/fpsyg.2013.00875DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3840792PMC
December 2013

Comparing two psychological interventions in reducing impulsive processes of eating behaviour: effects on self-selected portion size.

Br J Health Psychol 2014 Nov 21;19(4):767-82. Epub 2013 Oct 21.

Department of Communication Science, VU University Amsterdam, The Netherlands.

Objective: Palatable food, such as sweets, contains properties that automatically trigger the impulse to consume it even when people have goals or intentions to refrain from consuming such food. We compared the effectiveness of two interventions in reducing the portion size of palatable food that people select for themselves. Specifically, the use of dieting implementation intentions that reduce behaviour towards palatable food via top-down implementation of a dieting goal was pitted against a stop-signal training that changes the impulse-evoking quality of palatable food from bottom-up.

Design: We compared the two interventions using a 2 × 2 factorial design.

Methods: Participants completed a stop-signal training in which they learned to withhold a behavioural response upon presentation of tempting sweets (vs. control condition) and formed implementation intentions to diet (vs. control condition). Selected portion size was measured in a sweet-shop-like environment (Experiment 1) and through a computerized snack dispenser (Experiment 2).

Results: Both interventions reduced the amount of sweets selected in the sweet shop environment (Experiment 1) and the snack dispenser (Experiment 2). On average, participants receiving an intervention selected 36% (Experiment 1) and 51% (Experiment 2) fewer sweets than control participants. In both studies, combining the interventions did not lead to additive effects: Employing one of the interventions appears to successfully eliminate instrumental behaviour towards tempting food, making the other intervention redundant.

Conclusions: Both interventions reduce self-selected portion size, which is considered a major contributor to the current obesity epidemic.

Statement Of Contribution: What is already known on this subject? Exposure to temptations, such as unhealthy palatable food, often frustrates people's attainment of long-term health goals. Current approaches to self-control suggest that this is partly because temptations automatically trigger impulsive or hedonic processes that override the influence of more deliberate processes on behaviour. This perspective has stimulated the development of new interventions - which have so far been studied in isolation - aimed at decreasing the influence of impulsive or hedonic processes to decrease unhealthy eating behaviour. What does this study add? Linking sweets to stop signals and diet-prime implementation intentions both reduce self-selected portion size. Combining the interventions does not lead to additive effects. Each intervention reduces self-selected portion size of sweets, making the other redundant.
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http://dx.doi.org/10.1111/bjhp.12075DOI Listing
November 2014

Adaptive control of human action: the role of outcome representations and reward signals.

Front Psychol 2013 9;4:602. Epub 2013 Sep 9.

Department of Psychology, Utrecht University Utrecht, Netherlands.

The present paper aims to advance the understanding of the control of human behavior by integrating two lines of literature that so far have led separate lives. First, one line of literature is concerned with the ideomotor principle of human behavior, according to which actions are represented in terms of their outcomes. The second line of literature mainly considers the role of reward signals in adaptive control. Here, we offer a combined perspective on how outcome representations and reward signals work together to modulate adaptive control processes. We propose that reward signals signify the value of outcome representations and facilitate the recruitment of control resources in situations where behavior needs to be maintained or adapted to attain the represented outcome. We discuss recent research demonstrating how adaptive control of goal-directed behavior may emerge when outcome representations are co-activated with positive reward signals.
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http://dx.doi.org/10.3389/fpsyg.2013.00602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3766794PMC
September 2013

The transcriptional heat shock response of Salmonella typhimurium shows hysteresis and heated cells show increased resistance to heat and acid stress.

PLoS One 2012 7;7(12):e51196. Epub 2012 Dec 7.

Institute of Food Research, Norwich, United Kingdom.

We investigated if the transcriptional response of Salmonella Typhimurium to temperature and acid variations was hysteretic, i.e. whether the transcriptional regulation caused by environmental stimuli showed memory and remained after the stimuli ceased. The transcriptional activity of non-replicating stationary phase cells of S. Typhimurium caused by the exposure to 45 °C and to pH 5 for 30 min was monitored by microarray hybridizations at the end of the treatment period as well as immediately and 30 minutes after conditions were set back to their initial values, 25 °C and pH 7. One hundred and two out of 120 up-regulated genes during the heat shock remained up-regulated 30 minutes after the temperature was set back to 25 °C, while only 86 out of 293 down regulated genes remained down regulated 30 minutes after the heat shock ceased. Thus, the majority of the induced genes exhibited hysteresis, i.e., they remained up-regulated after the environmental stress ceased. At 25 °C the transcriptional regulation of genes encoding for heat shock proteins was determined by the previous environment. Gene networks constructed with up-regulated genes were significantly more modular than those of down-regulated genes, implying that down-regulation was significantly less synchronized than up-regulation. The hysteretic transcriptional response to heat shock was accompanied by higher resistance to inactivation at 50 °C as well as cross-resistance to inactivation at pH 3; however, growth rates and lag times at 43 °C and at pH 4.5 were not affected. The exposure to pH 5 only caused up-regulation of 12 genes and this response was neither hysteretic nor accompanied of increased resistance to inactivation conditions. Cellular memory at the transcriptional level may represent a mechanism of adaptation to the environment and a deterministic source of variability in gene regulation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0051196PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3517412PMC
June 2013

Why most dieters fail but some succeed: a goal conflict model of eating behavior.

Psychol Rev 2013 Jan 10;120(1):110-38. Epub 2012 Dec 10.

Department of Psychology, Utrecht University, the Netherlands.

Theories of eating regulation often attribute overweight to a malfunction of homeostatic regulation of body weight. With the goal conflict model of eating, we present a new perspective that attributes the difficulty of chronic dieters (i.e., restrained eaters) in regulating their food intake to a conflict between 2 incompatible goals-namely, eating enjoyment and weight control. This model explains the findings of previous research and provides novel insights into the psychological mechanism responsible for both dietary failure and success. According to this model, although chronic dieters are motivated to pursue their weight control goal, they often fail in food-rich environments because they are surrounded by palatable food cues that strongly prime the goal of eating enjoyment. Due to the incompatibility of the eating enjoyment goal and the weight control goal, such increase in the activation of the eating enjoyment goal results in (a) an inhibition of the cognitive representation of the weight control goal and (b) preferential processing of palatable food stimuli. Both these processes interfere with the effective pursuit of the weight control goal and facilitate unhealthy eating. However, there is a minority of restrained eaters for whom, most likely due to past success in exerting self-control, tasty high-calorie food has become associated with weight control thoughts. For them, exposure to palatable food increases the accessibility of the weight control goal, enabling them to control their body weight in food-rich environments. Evidence for these proposed psychological mechanisms is provided, and implications for interventions are discussed.
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http://dx.doi.org/10.1037/a0030849DOI Listing
January 2013

Abnormalities in the establishment of feeling of self-agency in schizophrenia.

Schizophr Res 2013 Jan 22;143(1):50-4. Epub 2012 Nov 22.

Utrecht University, The Netherlands.

Background: People usually feel they cause their own actions and the consequences of those actions, i.e., they attribute behavior to the proper agent. Research suggests that there are two routes to the experience of self-agency: 1) an explicit route, where one has the intention to obtain a goal (if it occurs, I must have done it) and 2) an implicit route, where information about the goal is unconsciously available and increases the feeling of self-agency. Schizophrenia patients typically experience no behavioral control and exhibit difficulties in distinguishing one's own actions from those of others. The present study investigates differences in both routes to self-agency experiences between schizophrenia patients and controls.

Methods: Twenty-three schizophrenia patients and 23 controls performed a task where they performed an action (button press) and subsequently indicated whether or not they were the agent of the consequence of this action (the outcome) on a 9-point scale. The task can be manipulated to measure both the explicit and implicit route (by using priming) to the experience of self-agency.

Results: In the explicit condition (participants intended to produce a specific outcome, and this outcome matched their goal), both groups experienced enhanced self-agency. In the implicit condition (the outcome matched the primed outcome), healthy controls showed increased self-agency over the outcome, while patients did not. Potential differences in task motivation and attention did not explain these findings.

Conclusions: These findings provide new evidence for the idea that implicit processes leading to feelings of self-agency may be disturbed in schizophrenia.
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http://dx.doi.org/10.1016/j.schres.2012.10.024DOI Listing
January 2013

Erratum: Acquired antibiotic resistance genes: an overview.

Front Microbiol 2012 16;3:384. Epub 2012 Nov 16.

Department of Environmental and Occupational Health Sciences, School of Public Health Seattle, WA, USA.

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http://dx.doi.org/10.3389/fmicb.2012.00384DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3499791PMC
November 2012
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