Adaptive disengagement buffers self-esteem from negative social feedback.

PubMed

Leitner, Jordan B; Hehman, Eric; Deegan, Matthew P; Jones, James M

2014-11-01

The degree to which self-esteem hinges on feedback in a domain is known as a contingency of self-worth, or engagement. Although previous research has conceptualized engagement as stable, it would be advantageous for individuals to dynamically regulate engagement. The current research examined whether the tendency to disengage from negative feedback accounts for variability in self-esteem. We created the Adaptive Disengagement Scale (ADS) to capture individual differences in the tendency to disengage self-esteem from negative outcomes. Results demonstrated that the ADS is reliable and valid (Studies 1 and 2). Furthermore, in response to negative social feedback, higher scores on the ADS predicted greater state self-esteem (Study 3), and this relationship was mediated by disengagement (Study 4). These findings demonstrate that adaptive disengagement protects self-esteem from negative outcomes and that the ADS is a valid measure of individual differences in the implementation of this process. © 2014 by the Society for Personality and Social Psychology, Inc.

Comparing the effects of positive and negative feedback in information-integration category learning.

PubMed

Freedberg, Michael; Glass, Brian; Filoteo, J Vincent; Hazeltine, Eliot; Maddox, W Todd

2017-01-01

Categorical learning is dependent on feedback. Here, we compare how positive and negative feedback affect information-integration (II) category learning. Ashby and O'Brien (2007) demonstrated that both positive and negative feedback are required to solve II category problems when feedback was not guaranteed on each trial, and reported no differences between positive-only and negative-only feedback in terms of their effectiveness. We followed up on these findings and conducted 3 experiments in which participants completed 2,400 II categorization trials across three days under 1 of 3 conditions: positive feedback only (PFB), negative feedback only (NFB), or both types of feedback (CP; control partial). An adaptive algorithm controlled the amount of feedback given to each group so that feedback was nearly equated. Using different feedback control procedures, Experiments 1 and 2 demonstrated that participants in the NFB and CP group were able to engage II learning strategies, whereas the PFB group was not. Additionally, the NFB group was able to achieve significantly higher accuracy than the PFB group by Day 3. Experiment 3 revealed that these differences remained even when we equated the information received on feedback trials. Thus, negative feedback appears significantly more effective for learning II category structures. This suggests that the human implicit learning system may be capable of learning in the absence of positive feedback.

Effects of Oxytocin and Vasopressin on Preferential Brain Responses to Negative Social Feedback.

PubMed

Gozzi, Marta; Dashow, Erica M; Thurm, Audrey; Swedo, Susan E; Zink, Caroline F

2017-06-01

Receiving negative social feedback can be detrimental to emotional, cognitive, and physical well-being, and fear of negative social feedback is a prominent feature of mental illnesses that involve social anxiety. A large body of evidence has implicated the neuropeptides oxytocin and vasopressin in the modulation of human neural activity underlying social cognition, including negative emotion processing; however, the influence of oxytocin and vasopressin on neural activity elicited during negative social evaluation remains unknown. Here 21 healthy men underwent functional magnetic resonance imaging in a double-blind, placebo-controlled, crossover design to determine how intranasally administered oxytocin and vasopressin modulated neural activity when receiving negative feedback on task performance from a study investigator. We found that under placebo, a preferential response to negative social feedback compared with positive social feedback was evoked in brain regions putatively involved in theory of mind (temporoparietal junction), pain processing (anterior insula and supplementary motor area), and identification of emotionally important visual cues in social perception (right fusiform). These activations weakened with oxytocin and vasopressin administration such that neural responses to receiving negative social feedback were not significantly greater than positive social feedback. Our results show effects of both oxytocin and vasopressin on the brain network involved in negative social feedback, informing the possible use of a pharmacological approach targeting these regions in multiple disorders with impairments in social information processing.

Dissociation between active and observational learning from positive and negative feedback in Parkinsonism.

PubMed

Kobza, Stefan; Ferrea, Stefano; Schnitzler, Alfons; Pollok, Bettina; Südmeyer, Martin; Bellebaum, Christian

2012-01-01

Feedback to both actively performed and observed behaviour allows adaptation of future actions. Positive feedback leads to increased activity of dopamine neurons in the substantia nigra, whereas dopamine neuron activity is decreased following negative feedback. Dopamine level reduction in unmedicated Parkinson's Disease patients has been shown to lead to a negative learning bias, i.e. enhanced learning from negative feedback. Recent findings suggest that the neural mechanisms of active and observational learning from feedback might differ, with the striatum playing a less prominent role in observational learning. Therefore, it was hypothesized that unmedicated Parkinson's Disease patients would show a negative learning bias only in active but not in observational learning. In a between-group design, 19 Parkinson's Disease patients and 40 healthy controls engaged in either an active or an observational probabilistic feedback-learning task. For both tasks, transfer phases aimed to assess the bias to learn better from positive or negative feedback. As expected, actively learning patients showed a negative learning bias, whereas controls learned better from positive feedback. In contrast, no difference between patients and controls emerged for observational learning, with both groups showing better learning from positive feedback. These findings add to neural models of reinforcement-learning by suggesting that dopamine-modulated input to the striatum plays a minor role in observational learning from feedback. Future research will have to elucidate the specific neural underpinnings of observational learning.

Developmental and Gender Related Differences in Response Switches after Nonrepresentative Negative Feedback

ERIC Educational Resources Information Center

Jansen, Brenda R. J.; van Duijvenvoorde, Anna C. K.; Huizenga, Hilde M.

2014-01-01

In many decision making tasks negative feedback is probabilistic and, as a consequence, may be given when the decision is actually correct. This feedback can be referred to as nonrepresentative negative feedback. In the current study, we investigated developmental and gender related differences in such switching after nonrepresentative negative…

Dissociation between Active and Observational Learning from Positive and Negative Feedback in Parkinsonism

PubMed Central

Kobza, Stefan; Ferrea, Stefano; Schnitzler, Alfons; Pollok, Bettina

2012-01-01

Feedback to both actively performed and observed behaviour allows adaptation of future actions. Positive feedback leads to increased activity of dopamine neurons in the substantia nigra, whereas dopamine neuron activity is decreased following negative feedback. Dopamine level reduction in unmedicated Parkinson’s Disease patients has been shown to lead to a negative learning bias, i.e. enhanced learning from negative feedback. Recent findings suggest that the neural mechanisms of active and observational learning from feedback might differ, with the striatum playing a less prominent role in observational learning. Therefore, it was hypothesized that unmedicated Parkinson’s Disease patients would show a negative learning bias only in active but not in observational learning. In a between-group design, 19 Parkinson’s Disease patients and 40 healthy controls engaged in either an active or an observational probabilistic feedback-learning task. For both tasks, transfer phases aimed to assess the bias to learn better from positive or negative feedback. As expected, actively learning patients showed a negative learning bias, whereas controls learned better from positive feedback. In contrast, no difference between patients and controls emerged for observational learning, with both groups showing better learning from positive feedback. These findings add to neural models of reinforcement-learning by suggesting that dopamine-modulated input to the striatum plays a minor role in observational learning from feedback. Future research will have to elucidate the specific neural underpinnings of observational learning. PMID:23185586

Adult Age Differences in Learning from Positive and Negative Probabilistic Feedback

PubMed Central

Simon, Jessica R.; Howard, James H.; Howard, Darlene V.

2010-01-01

Objective Past research has investigated age differences in frontal-based decision making, but few studies have focused on the behavioral effects of striatal-based changes in healthy aging. Feedback learning has been found to vary with dopamine levels; increases in dopamine facilitate learning from positive feedback, whereas decreases facilitate learning from negative feedback. Given previous evidence of striatal dopamine depletion in healthy aging, we investigated behavioral differences between college-aged and healthy old adults using a feedback learning task that is sensitive to both frontal and striatal processes. Method Seventeen college-aged (M = 18.9 years) and 24 healthy, older adults (M = 70.3 years) completed the Probabilistic selection task, in which participants are trained on probabilistic stimulus-outcome information and then tested to determine whether they learned more from positive or negative feedback. Results As a group, the old adults learned equally well from positive and negative feedback, whereas the college-aged group learned more from positive than negative feedback, F(1, 39) = 4.10, p < .05, reffect = .3. However, these group differences were not due to the older individuals being more balanced learners. Most individuals of both ages were balanced learners, but while all of the remaining young learners had a positive bias, the remaining older learners were split between those with positive and negative learning biases (χ2(2) = 6.12, p<.047). Conclusions These behavioral results are consistent with the dopamine theory of striatal aging, and suggest there might be adult age differences in the kinds of information people use when faced with a current choice. PMID:20604627

Control your anger! The neural basis of aggression regulation in response to negative social feedback

PubMed Central

van Duijvenvoorde, Anna C. K.; Bakermans-Kranenburg, Marian J.; Crone, Eveline A.

2016-01-01

Abstract Negative social feedback often generates aggressive feelings and behavior. Prior studies have investigated the neural basis of negative social feedback, but the underlying neural mechanisms of aggression regulation following negative social feedback remain largely undiscovered. In the current study, participants viewed pictures of peers with feedback (positive, neutral or negative) to the participant’s personal profile. Next, participants responded to the peer feedback by pressing a button, thereby producing a loud noise toward the peer, as an index of aggression. Behavioral analyses showed that negative feedback led to more aggression (longer noise blasts). Conjunction neuroimaging analyses revealed that both positive and negative feedback were associated with increased activity in the medial prefrontal cortex (PFC) and bilateral insula. In addition, more activation in the right dorsal lateral PFC (dlPFC) during negative feedback vs neutral feedback was associated with shorter noise blasts in response to negative social feedback, suggesting a potential role of dlPFC in aggression regulation, or top-down control over affective impulsive actions. This study demonstrates a role of the dlPFC in the regulation of aggressive social behavior. PMID:26755768

Reduced sensitivity to neutral feedback versus negative feedback in subjects with mild depression: Evidence from event-related potentials study.

PubMed

Li, Peng; Song, Xinxin; Wang, Jing; Zhou, Xiaoran; Li, Jiayi; Lin, Fengtong; Hu, Zhonghua; Zhang, Xinxin; Cui, Hewei; Wang, Wenmiao; Li, Hong; Cong, Fengyu; Roberson, Debi

2015-11-01

Many previous event-related potential (ERP) studies have linked the feedback related negativity (FRN) component with medial frontal cortex processing and associated this component with depression. Few if any studies have investigated the processing of neutral feedback in mildly depressive subjects in the normal population. Two experiments compared brain responses to neutral feedback with behavioral performance in mildly depressed subjects who scored highly on the Beck Depression Inventory (high BDI) and a control group with lower BDI scores (low BDI). In the first study, the FRN component was recorded when neutral, negative or positive feedback was pseudo-randomly delivered to the two groups in a time estimation task. In the second study, real feedback was provided to the two groups in the same task in order to measure their actual accuracy of performance. The results of experiment one (Exp. 1) revealed that a larger FRN effect was elicited by neutral feedback than by negative feedback in the low BDI group, but no significant difference was found between neutral condition and negative condition in the High BDI group. The present findings demonstrated that depressive tendencies influence the processing of neutral feedback in medial frontal cortex. The FRN effect may work as a helpful index for investigating cognitive bias in depression in future studies. Copyright © 2015 Elsevier Inc. All rights reserved.

Stereotype threat engenders neural attentional bias toward negative feedback to undermine performance.

PubMed

Forbes, Chad E; Leitner, Jordan B

2014-10-01

Stereotype threat, a situational pressure individuals experience when they fear confirming a negative group stereotype, engenders a cascade of physiological stress responses, negative appraisals, and performance monitoring processes that tax working memory resources necessary for optimal performance. Less is known, however, about how stereotype threat biases attentional processing in response to performance feedback, and how such attentional biases may undermine performance. Women received feedback on math problems in stereotype threatening compared to stereotype-neutral contexts while continuous EEG activity was recorded. Findings revealed that stereotype threatened women elicited larger midline P100 ERPs, increased phase locking between anterior cingulate cortex and dorsolateral prefrontal cortex (two regions integral for attentional processes), and increased power in left fusiform gyrus in response to negative feedback compared to positive feedback and women in stereotype-neutral contexts. Increased power in left fusiform gyrus in response to negative feedback predicted underperformance on the math task among stereotype threatened women only. Women in stereotype-neutral contexts exhibited the opposite trend. Findings suggest that in stereotype threatening contexts, neural networks integral for attention and working memory are biased toward negative, stereotype confirming feedback at very early speeds of information processing. This bias, in turn, plays a role in undermining performance. Copyright © 2014 Elsevier B.V. All rights reserved.

Negative plant-soil feedback predicts tree-species relative abundance in a tropical forest.

PubMed

Mangan, Scott A; Schnitzer, Stefan A; Herre, Edward A; Mack, Keenan M L; Valencia, Mariana C; Sanchez, Evelyn I; Bever, James D

2010-08-05

The accumulation of species-specific enemies around adults is hypothesized to maintain plant diversity by limiting the recruitment of conspecific seedlings relative to heterospecific seedlings. Although previous studies in forested ecosystems have documented patterns consistent with the process of negative feedback, these studies are unable to address which classes of enemies (for example, pathogens, invertebrates, mammals) exhibit species-specific effects strong enough to generate negative feedback, and whether negative feedback at the level of the individual tree is sufficient to influence community-wide forest composition. Here we use fully reciprocal shade-house and field experiments to test whether the performance of conspecific tree seedlings (relative to heterospecific seedlings) is reduced when grown in the presence of enemies associated with adult trees. Both experiments provide strong evidence for negative plant-soil feedback mediated by soil biota. In contrast, above-ground enemies (mammals, foliar herbivores and foliar pathogens) contributed little to negative feedback observed in the field. In both experiments, we found that tree species that showed stronger negative feedback were less common as adults in the forest community, indicating that susceptibility to soil biota may determine species relative abundance in these tropical forests. Finally, our simulation models confirm that the strength of local negative feedback that we measured is sufficient to produce the observed community-wide patterns in tree-species relative abundance. Our findings indicate that plant-soil feedback is an important mechanism that can maintain species diversity and explain patterns of tree-species relative abundance in tropical forests.

Interlocked positive and negative feedback network motifs regulate β-catenin activity in the adherens junction pathway

PubMed Central

Klinke, David J.; Horvath, Nicholas; Cuppett, Vanessa; Wu, Yueting; Deng, Wentao; Kanj, Rania

2015-01-01

The integrity of epithelial tissue architecture is maintained through adherens junctions that are created through extracellular homotypic protein–protein interactions between cadherin molecules. Cadherins also provide an intracellular scaffold for the formation of a multiprotein complex that contains signaling proteins, including β-catenin. Environmental factors and controlled tissue reorganization disrupt adherens junctions by cleaving the extracellular binding domain and initiating a series of transcriptional events that aim to restore tissue homeostasis. However, it remains unclear how alterations in cell adhesion coordinate transcriptional events, including those mediated by β-catenin in this pathway. Here were used quantitative single-cell and population-level in vitro assays to quantify the endogenous pathway dynamics after the proteolytic disruption of the adherens junctions. Using prior knowledge of isolated elements of the overall network, we interpreted these data using in silico model-based inference to identify the topology of the regulatory network. Collectively the data suggest that the regulatory network contains interlocked network motifs consisting of a positive feedback loop, which is used to restore the integrity of adherens junctions, and a negative feedback loop, which is used to limit β-catenin–induced gene expression. PMID:26224311

Negative Feedback Enables Fast and Flexible Collective Decision-Making in Ants

PubMed Central

Grüter, Christoph; Schürch, Roger; Czaczkes, Tomer J.; Taylor, Keeley; Durance, Thomas; Jones, Sam M.; Ratnieks, Francis L. W.

2012-01-01

Positive feedback plays a major role in the emergence of many collective animal behaviours. In many ants pheromone trails recruit and direct nestmate foragers to food sources. The strong positive feedback caused by trail pheromones allows fast collective responses but can compromise flexibility. Previous laboratory experiments have shown that when the environment changes, colonies are often unable to reallocate their foragers to a more rewarding food source. Here we show both experimentally, using colonies of Lasius niger, and with an agent-based simulation model, that negative feedback caused by crowding at feeding sites allows ant colonies to maintain foraging flexibility even with strong recruitment to food sources. In a constant environment, negative feedback prevents the frequently found bias towards one feeder (symmetry breaking) and leads to equal distribution of foragers. In a changing environment, negative feedback allows a colony to quickly reallocate the majority of its foragers to a superior food patch that becomes available when foraging at an inferior patch is already well underway. The model confirms these experimental findings and shows that the ability of colonies to switch to a superior food source does not require the decay of trail pheromones. Our results help to resolve inconsistencies between collective foraging patterns seen in laboratory studies and observations in the wild, and show that the simultaneous action of negative and positive feedback is important for efficient foraging in mass-recruiting insect colonies. PMID:22984518

Interrogative pressure in simulated forensic interviews: the effects of negative feedback.

PubMed

McGroarty, Allan; Baxter, James S

2007-08-01

Much experimental research on interrogative pressure has concentrated on the effects of leading questions, and the role of feedback in influencing responses in the absence of leading questions has been neglected by comparison. This study assessed the effect of negative feedback and the presence of a second interviewer on interviewee responding in simulated forensic interviews. Participants viewed a videotape of a crime, answered questions about the clip and were requestioned after receiving feedback. Compared with neutral feedback, negative feedback resulted in more response changes, higher reported state anxiety and higher ratings of interview difficulty. These results are consistent with Gudjonsson and Clark's (1986) model of interrogative suggestibility. The presence and involvement of a second interviewer did not significantly affect interviewee responding, although trait anxiety scores were elevated when a second interviewer was present. The theoretical and applied implications of these findings are considered.

[Study of negative feedback between wild-type BRAF or RAFV600E and Mps1 in melanoma].

PubMed

Zhang, Ling; He, Chanting; Bi, Yanghui; Liu, Feng; Cui, Heyang; Wang, Juan; Song, Bin; Shi, Ruyi; Yang, Bin; Wang, Fang; Jia, Zhiwu; Zhao, Zhenxiang; Liu, Jing

2015-04-01

To study the effect of Mps1 on BRAFWT/MEK/ERK pathway in the presence of wild type BRAF or BRAFV600E in melanoma. Melanoma cells harboring BRAFWT genotype were transfected either with pBabe-puro-GST-BRAF-WT and/or pBabe-puro-GFP-Mps1-WT or pBabe-puro-GST-BRAFV600E and/or pBabe-puro-GFP-Mps1-WT, followed by Western blot to detect Mps1 and p-ERK expression. The melanoma cells harboring BRAFWT and BRAFV600E genotype were infected with pSUPER-Mps1 retrovirus to knockdown the endogenous Mps1 protein, followed by Western blot to detect Mps1 and p-ERK expression. Meanwhile, melanoma cells harboring BRAFV600E genotype were infected with pBabe-puro-GFP-Mps1 and Western blot was performed to detect Mps1 and p-ERK expression. In melanoma cells harboring BRAFWT genotype and transfected with pBabe-puro-GST-BRAF-WT and pBabe-puro-GFP-Mps1-WT, phospho-ERK levels were notably reduced as compared to either negative control or empty vector. However, cells transfected with pBabe-puro-GST-BRAFV600E and pBabe-puro-GFP-Mps1-WT, phospho-ERK levels did not change significantly compared with either negative control or empty vector. Knockout of Mps1 in BRAF wild-type cell lines led to an increased ERK activity. However, there was no significant change of ERK activity in BRAFV600E cell lines in the absence of Mps1. The expression of p-ERK in BRAFV600E mutant cell lines infected with pBabe-puro-GFP-Mps1-WT did not show any significant difference from either negative control or empty vector. Based on these findings, it suggests that there exists an auto-regulatory negative feedback loop between the Mps1 kinase and BRAFWT/ERK signaling. Oncogenic BRAFV600E abrogates the regulatory negative feedback loop of Mps1 on the MAPK pathway.

Evaluating the negative or valuing the positive? Neural mechanisms supporting feedback-based learning across development.

PubMed

van Duijvenvoorde, Anna C K; Zanolie, Kiki; Rombouts, Serge A R B; Raijmakers, Maartje E J; Crone, Eveline A

2008-09-17

How children learn from positive and negative performance feedback lies at the foundation of successful learning and is therefore of great importance for educational practice. In this study, we used functional magnetic resonance imaging (fMRI) to examine the neural developmental changes related to feedback-based learning when performing a rule search and application task. Behavioral results from three age groups (8-9, 11-13, and 18-25 years of age) demonstrated that, compared with adults, 8- to 9-year-old children performed disproportionally more inaccurately after receiving negative feedback relative to positive feedback. Additionally, imaging data pointed toward a qualitative difference in how children and adults use performance feedback. That is, dorsolateral prefrontal cortex and superior parietal cortex were more active after negative feedback for adults, but after positive feedback for children (8-9 years of age). For 11- to 13-year-olds, these regions did not show differential feedback sensitivity, suggesting that the transition occurs around this age. Pre-supplementary motor area/anterior cingulate cortex, in contrast, was more active after negative feedback in both 11- to 13-year-olds and adults, but not 8- to 9-year-olds. Together, the current data show that cognitive control areas are differentially engaged during feedback-based learning across development. Adults engage these regions after signals of response adjustment (i.e., negative feedback). Young children engage these regions after signals of response continuation (i.e., positive feedback). The neural activation patterns found in 11- to 13-year-olds indicate a transition around this age toward an increased influence of negative feedback on performance adjustment. This is the first developmental fMRI study to compare qualitative changes in brain activation during feedback learning across distinct stages of development.

Application of simple negative feedback model for avalanche photodetectors investigation

NASA Astrophysics Data System (ADS)

Kushpil, V. V.

2009-10-01

A simple negative feedback model based on Miller's formula is used to investigate the properties of Avalanche Photodetectors (APDs). The proposed method can be applied to study classical APD as well as new type of devices, which are operating in the Internal Negative Feedback (INF) regime. The method shows a good sensitivity to technological APD parameters making it possible to use it as a tool to analyse various APD parameters. It also allows better understanding of the APD operation conditions. The simulations and experimental data analysis for different types of APDs are presented.

Negative feedback from maternal signals reduces false alarms by collectively signalling offspring.

PubMed

Hamel, Jennifer A; Cocroft, Reginald B

2012-09-22

Within animal groups, individuals can learn of a predator's approach by attending to the behaviour of others. This use of social information increases an individual's perceptual range, but can also lead to the propagation of false alarms. Error copying is especially likely in species that signal collectively, because the coordination required for collective displays relies heavily on social information. Recent evidence suggests that collective behaviour in animals is, in part, regulated by negative feedback. Negative feedback may reduce false alarms by collectively signalling animals, but this possibility has not yet been tested. We tested the hypothesis that negative feedback increases the accuracy of collective signalling by reducing the production of false alarms. In the treehopper Umbonia crassicornis, clustered offspring produce collective signals during predator attacks, advertising the predator's location to the defending mother. Mothers signal after evicting the predator, and we show that this maternal communication reduces false alarms by offspring. We suggest that maternal signals elevate offspring signalling thresholds. This is, to our knowledge, the first study to show that negative feedback can reduce false alarms by collectively behaving groups.

Beyond Symmetry Breaking: Competition and Negative Feedback in GTPase regulation

PubMed Central

Wu, Chi-Fang; Lew, Daniel J.

2013-01-01

Summary Cortical domains are often specified by the local accumulation of active GTPases. Such domains can arise through spontaneous symmetry breaking, suggesting that GTPase accumulation occurs via positive feedback. Here, we focus on recent advances in fungal and plant cell models, where new work suggests that polarity-controlling GTPases develop only one “front” because GTPase clusters engage in a winner-takes-all competition. However, in some circumstances two or more GTPase domains can co-exist, and the basis for the switch from competition to coexistence remains an open question. Polarity GTPases can undergo oscillatory clustering and dispersal, suggesting that these systems contain negative feedback. Negative feedback may prevent polarity clusters from spreading too far, regulate the balance between competition and co-existence, and provide directional flexibility for cells tracking gradients. PMID:23731999

Reciprocal, Longitudinal Associations among Adolescents' Negative Feedback-Seeking, Depressive Symptoms, and Peer Relations

ERIC Educational Resources Information Center

Borelli, Jessica L.; Prinstein, Mitchell J.

2006-01-01

This study examined reciprocal associations among adolescents' negative feedback-seeking, depressive symptoms, perceptions of friendship quality, and peer-reported social preference over an 11-month period. A total of 478 adolescents in grades 6-8 completed measures of negative feedback-seeking, depressive symptoms, friendship quality,…

Positive and negative feedback learning and associated dopamine and serotonin transporter binding after methamphetamine.

PubMed

Stolyarova, Alexandra; O'Dell, Steve J; Marshall, John F; Izquierdo, Alicia

2014-09-01

Learning from mistakes and prospectively adjusting behavior in response to reward feedback is an important facet of performance monitoring. Dopamine (DA) pathways play an important role in feedback learning and a growing literature has also emerged on the importance of serotonin (5HT) in reward learning, particularly during punishment or reward omission (negative feedback). Cognitive impairments resulting from psychostimulant exposure may arise from altered patterns in feedback learning, which in turn may be modulated by DA and 5HT transmission. We analyzed long-term, off-drug changes in learning from positive and negative feedback and associated striatal DA transporter (DAT) and frontocortical 5HT transporter (SERT) binding in rats pretreated with methamphetamine (mAMPH). Specifically, we assessed the reversal phase of pairwise visual discrimination learning in rats receiving single dose- (mAMPHsingle) vs. escalating-dose exposure (mAMPHescal). Using fine-grained trial-by-trial analyses, we found increased sensitivity to and reliance on positive feedback in mAMPH-pretreated animals, with the mAMPHsingle group showing more pronounced use of this type of feedback. In contrast, overall negative feedback sensitivity was not altered following any mAMPH treatment. In addition to validating the enduring effects of mAMPH on early reversal learning, we found more consecutive error commissions before the first correct response in mAMPH-pretreated rats. This behavioral rigidity was negatively correlated with subregional frontocortical SERT whereas positive feedback sensitivity negatively correlated with striatal DAT binding. These results provide new evidence for the overlapping, yet dissociable roles of DA and 5HT systems in overcoming perseveration and in learning new reward rules. Copyright © 2014 Elsevier B.V. All rights reserved.

Learning from negative feedback in patients with major depressive disorder is attenuated by SSRI antidepressants

PubMed Central

Herzallah, Mohammad M.; Moustafa, Ahmed A.; Natsheh, Joman Y.; Abdellatif, Salam M.; Taha, Mohamad B.; Tayem, Yasin I.; Sehwail, Mahmud A.; Amleh, Ivona; Petrides, Georgios; Myers, Catherine E.; Gluck, Mark A.

2013-01-01

One barrier to interpreting past studies of cognition and major depressive disorder (MDD) has been the failure in many studies to adequately dissociate the effects of MDD from the potential cognitive side effects of selective serotonin reuptake inhibitors (SSRIs) use. To better understand how remediation of depressive symptoms affects cognitive function in MDD, we evaluated three groups of subjects: medication-naïve patients with MDD, medicated patients with MDD receiving the SSRI paroxetine, and healthy control (HC) subjects. All were administered a category-learning task that allows for dissociation between learning from positive feedback (reward) vs. learning from negative feedback (punishment). Healthy subjects learned significantly better from positive feedback than medication-naïve and medicated MDD groups, whose learning accuracy did not differ significantly. In contrast, medicated patients with MDD learned significantly less from negative feedback than medication-naïve patients with MDD and healthy subjects, whose learning accuracy was comparable. A comparison of subject’s relative sensitivity to positive vs. negative feedback showed that both the medicated MDD and HC groups conform to Kahneman and Tversky’s (1979) Prospect Theory, which expects losses (negative feedback) to loom psychologically slightly larger than gains (positive feedback). However, medicated MDD and HC profiles are not similar, which indicates that the state of medicated MDD is not “normal” when compared to HC, but rather balanced with less learning from both positive and negative feedback. On the other hand, medication-naïve patients with MDD violate Prospect Theory by having significantly exaggerated learning from negative feedback. This suggests that SSRI antidepressants impair learning from negative feedback, while having negligible effect on learning from positive feedback. Overall, these findings shed light on the importance of dissociating the cognitive consequences of

Learning from negative feedback in patients with major depressive disorder is attenuated by SSRI antidepressants.

PubMed

Herzallah, Mohammad M; Moustafa, Ahmed A; Natsheh, Joman Y; Abdellatif, Salam M; Taha, Mohamad B; Tayem, Yasin I; Sehwail, Mahmud A; Amleh, Ivona; Petrides, Georgios; Myers, Catherine E; Gluck, Mark A

2013-01-01

One barrier to interpreting past studies of cognition and major depressive disorder (MDD) has been the failure in many studies to adequately dissociate the effects of MDD from the potential cognitive side effects of selective serotonin reuptake inhibitors (SSRIs) use. To better understand how remediation of depressive symptoms affects cognitive function in MDD, we evaluated three groups of subjects: medication-naïve patients with MDD, medicated patients with MDD receiving the SSRI paroxetine, and healthy control (HC) subjects. All were administered a category-learning task that allows for dissociation between learning from positive feedback (reward) vs. learning from negative feedback (punishment). Healthy subjects learned significantly better from positive feedback than medication-naïve and medicated MDD groups, whose learning accuracy did not differ significantly. In contrast, medicated patients with MDD learned significantly less from negative feedback than medication-naïve patients with MDD and healthy subjects, whose learning accuracy was comparable. A comparison of subject's relative sensitivity to positive vs. negative feedback showed that both the medicated MDD and HC groups conform to Kahneman and Tversky's (1979) Prospect Theory, which expects losses (negative feedback) to loom psychologically slightly larger than gains (positive feedback). However, medicated MDD and HC profiles are not similar, which indicates that the state of medicated MDD is not "normal" when compared to HC, but rather balanced with less learning from both positive and negative feedback. On the other hand, medication-naïve patients with MDD violate Prospect Theory by having significantly exaggerated learning from negative feedback. This suggests that SSRI antidepressants impair learning from negative feedback, while having negligible effect on learning from positive feedback. Overall, these findings shed light on the importance of dissociating the cognitive consequences of MDD

Relationship between Counseling Students' Childhood Memories and Current Negative Self-Evaluations When Receiving Corrective Feedback

ERIC Educational Resources Information Center

Stroud, Daniel; Olguin, David; Marley, Scott

2016-01-01

This article entails a study focused on the relationship between counseling students' negative childhood memories of receiving corrective feedback and current negative self-evaluations when receiving similar feedback in counselor education programs. Participants (N = 186) completed the Corrective Feedback Instrument-Revised (CFI-R; Hulse-Killacky…

A theory of circular organization and negative feedback: defining life in a cybernetic context.

PubMed

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

A Theory of Circular Organization and Negative Feedback: Defining Life in a Cybernetic Context

NASA Astrophysics Data System (ADS)

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

Punishment sensitivity modulates the processing of negative feedback but not error-induced learning.

PubMed

Unger, Kerstin; Heintz, Sonja; Kray, Jutta

2012-01-01

Accumulating evidence suggests that individual differences in punishment and reward sensitivity are associated with functional alterations in neural systems underlying error and feedback processing. In particular, individuals highly sensitive to punishment have been found to be characterized by larger mediofrontal error signals as reflected in the error negativity/error-related negativity (Ne/ERN) and the feedback-related negativity (FRN). By contrast, reward sensitivity has been shown to relate to the error positivity (Pe). Given that Ne/ERN, FRN, and Pe have been functionally linked to flexible behavioral adaptation, the aim of the present research was to examine how these electrophysiological reflections of error and feedback processing vary as a function of punishment and reward sensitivity during reinforcement learning. We applied a probabilistic learning task that involved three different conditions of feedback validity (100%, 80%, and 50%). In contrast to prior studies using response competition tasks, we did not find reliable correlations between punishment sensitivity and the Ne/ERN. Instead, higher punishment sensitivity predicted larger FRN amplitudes, irrespective of feedback validity. Moreover, higher reward sensitivity was associated with a larger Pe. However, only reward sensitivity was related to better overall learning performance and higher post-error accuracy, whereas highly punishment sensitive participants showed impaired learning performance, suggesting that larger negative feedback-related error signals were not beneficial for learning or even reflected maladaptive information processing in these individuals. Thus, although our findings indicate that individual differences in reward and punishment sensitivity are related to electrophysiological correlates of error and feedback processing, we found less evidence for influences of these personality characteristics on the relation between performance monitoring and feedback-based learning.

A PI3-kinase-mediated negative feedback regulates neuronal excitability.

PubMed

Howlett, Eric; Lin, Curtis Chun-Jen; Lavery, William; Stern, Michael

2008-11-01

Use-dependent downregulation of neuronal activity (negative feedback) can act as a homeostatic mechanism to maintain neuronal activity at a particular specified value. Disruption of this negative feedback might lead to neurological pathologies, such as epilepsy, but the precise mechanisms by which this feedback can occur remain incompletely understood. At one glutamatergic synapse, the Drosophila neuromuscular junction, a mutation in the group II metabotropic glutamate receptor gene (DmGluRA) increased motor neuron excitability by disrupting an autocrine, glutamate-mediated negative feedback. We show that DmGluRA mutations increase neuronal excitability by preventing PI3 kinase (PI3K) activation and consequently hyperactivating the transcription factor Foxo. Furthermore, glutamate application increases levels of phospho-Akt, a product of PI3K signaling, within motor nerve terminals in a DmGluRA-dependent manner. Finally, we show that PI3K increases both axon diameter and synapse number via the Tor/S6 kinase pathway, but not Foxo. In humans, PI3K and group II mGluRs are implicated in epilepsy, neurofibromatosis, autism, schizophrenia, and other neurological disorders; however, neither the link between group II mGluRs and PI3K, nor the role of PI3K-dependent regulation of Foxo in the control of neuronal excitability, had been previously reported. Our work suggests that some of the deficits in these neurological disorders might result from disruption of glutamate-mediated homeostasis of neuronal excitability.

Using negative emotional feedback to modify risky behavior of young moped riders.

PubMed

Megías, Alberto; Cortes, Abilio; Maldonado, Antonio; Cándido, Antonio

2017-05-19

The aim of this research was to investigate whether the use of messages with negative emotional content is effective in promoting safe behavior of moped riders and how exactly these messages modulate rider behavior. Participants received negative feedback when performing risky behaviors using a computer task. The effectiveness of this treatment was subsequently tested in a riding simulator. The results demonstrated how riders receiving negative feedback had a lower number of traffic accidents than a control group. The reduction in accidents was accompanied by a set of changes in the riding behavior. We observed a lower average speed and greater respect for speed limits. Furthermore, analysis of the steering wheel variance, throttle variance, and average braking force provided evidence for a more even and homogenous riding style. This greater abidance of traffic regulations and friendlier riding style could explain some of the causes behind the reduction in accidents. The use of negative emotional feedback in driving schools or advanced rider assistance systems could enhance riding performance, making riders aware of unsafe practices and helping them to establish more accurate riding habits. Moreover, the combination of riding simulators and feedback-for example, in the training of novice riders and traffic offenders-could be an efficient tool to improve their hazard perception skills and promote safer behaviors.

Why do some therapists not deal with outcome monitoring feedback? A feasibility study on the effect of regulatory focus and person-organization fit on attitude and outcome.

PubMed

de Jong, Kim; de Goede, Marije

2015-01-01

Despite research on its effectiveness, many therapists still have negative attitudes toward using outcome monitoring feedback. The current study aims to investigate how the perceived match between values of an individual and those of the organization (Person-Organization fit; PO fit), and motivation to prevent failure or to achieve success (regulatory focus) are related to therapists' attitude, attitude changes over time, and outcomes. Therapists (n = 20) filled out a feedback attitude questionnaire at two points in time: before the start of outcome monitoring, and after six months. In addition, they completed measures on PO fit and regulatory focus. PO fit was predictive of outcomes, when feedback was provided, but did not predict therapists' attitude. Therapists with a strong prevention focus (prevent failures), had a more positive attitude toward feedback, but achieved slower symptom reduction in their at risk cases. A strong promotion focus (achieve success) was not predictive of attitude, but did result in faster symptom reduction in at risk patients when feedback was provided. Therapists motivational approach to work and the perceived match with the organization they work for, can influence both their attitude toward outcome monitoring and their outcomes.

Regulated recovery of pulsatile growth hormone secretion from negative feedback: a preclinical investigation

PubMed Central

Bowers, Cyril Y.

2011-01-01

Although stimulatory (feedforward) and inhibitory (feedback) dynamics jointly control neurohormone secretion, the factors that supervise feedback restraint are poorly understood. To parse the regulation of growth hormone (GH) escape from negative feedback, 25 healthy men and women were studied eight times each during an experimental GH feedback clamp. The clamp comprised combined bolus infusion of GH or saline and continuous stimulation by saline GH-releasing hormone (GHRH), GHRP-2, or both peptides after randomly ordered supplementation with placebo (both sexes) vs. E2 (estrogen; women) and T (testosterone; men). Endpoints were GH pulsatility and entropy (a model-free measure of feedback quenching). Gender determined recovery of pulsatile GH secretion from negative feedback in all four secretagog regimens (0.003 ≤ P ≤ 0.017 for women>men). Peptidyl secretagog controlled the mass, number, and duration of feedback-inhibited GH secretory bursts (each, P < 0.001). E2/T administration potentiated both pulsatile (P = 0.006) and entropic (P < 0.001) modes of GH recovery. IGF-I positively predicted the escape of GH secretory burst number and mode (P = 0.022), whereas body mass index negatively forecast GH secretory burst number and mass (P = 0.005). The composite of gender, body mass index, E2, IGF-I, and peptidyl secretagog strongly regulates the escape of pulsatile and entropic GH secretion from autonegative feedback. The ensemble factors identified in this preclinical investigation enlarge the dynamic model of GH control in humans. PMID:21795635

Modelling and analysis of gene regulatory network using feedback control theory

NASA Astrophysics Data System (ADS)

El-Samad, H.; Khammash, M.

2010-01-01

Molecular pathways are a part of a remarkable hierarchy of regulatory networks that operate at all levels of organisation. These regulatory networks are responsible for much of the biological complexity within the cell. The dynamic character of these pathways and the prevalence of feedback regulation strategies in their operation make them amenable to systematic mathematical analysis using the same tools that have been used with success in analysing and designing engineering control systems. In this article, we aim at establishing this strong connection through various examples where the behaviour exhibited by gene networks is explained in terms of their underlying control strategies. We complement our analysis by a survey of mathematical techniques commonly used to model gene regulatory networks and analyse their dynamic behaviour.

A negative feedback signal that is triggered by peril curbs honey bee recruitment.

PubMed

Nieh, James C

2010-02-23

Decision making in superorganisms such as honey bee colonies often uses self-organizing behaviors, feedback loops that allow the colony to gather information from multiple individuals and achieve reliable and agile solutions. Honey bees use positive feedback from the waggle dance to allocate colony foraging effort. However, the use of negative feedback signals by superorganisms is poorly understood. I show that conspecific attacks at a food source lead to the production of stop signals, communication that was known to reduce waggle dancing and recruitment but lacked a clear natural trigger. Signalers preferentially targeted nestmates visiting the same food source, on the basis of its odor. During aggressive food competition, attack victims increased signal production by 43 fold. Foragers that attacked competitors or experienced no aggression did not alter signal production. Biting ambush predators also attack foragers at flowers. Simulated biting of foragers or exposure to bee alarm pheromone also elicited signaling (88-fold and 14-fold increases, respectively). This provides the first clear evidence of a negative feedback signal elicited by foraging peril to counteract the positive feedback of the waggle dance. As in intra- and intercellular communication, negative feedback may play an important, though currently underappreciated, role in self-organizing behaviors within superorganisms. Copyright 2010 Elsevier Ltd. All rights reserved.

Analytical study of robustness of a negative feedback oscillator by multiparameter sensitivity

PubMed Central

2014-01-01

Background One of the distinctive features of biological oscillators such as circadian clocks and cell cycles is robustness which is the ability to resume reliable operation in the face of different types of perturbations. In the previous study, we proposed multiparameter sensitivity (MPS) as an intelligible measure for robustness to fluctuations in kinetic parameters. Analytical solutions directly connect the mechanisms and kinetic parameters to dynamic properties such as period, amplitude and their associated MPSs. Although negative feedback loops are known as common structures to biological oscillators, the analytical solutions have not been presented for a general model of negative feedback oscillators. Results We present the analytical expressions for the period, amplitude and their associated MPSs for a general model of negative feedback oscillators. The analytical solutions are validated by comparing them with numerical solutions. The analytical solutions explicitly show how the dynamic properties depend on the kinetic parameters. The ratio of a threshold to the amplitude has a strong impact on the period MPS. As the ratio approaches to one, the MPS increases, indicating that the period becomes more sensitive to changes in kinetic parameters. We present the first mathematical proof that the distributed time-delay mechanism contributes to making the oscillation period robust to parameter fluctuations. The MPS decreases with an increase in the feedback loop length (i.e., the number of molecular species constituting the feedback loop). Conclusions Since a general model of negative feedback oscillators was employed, the results shown in this paper are expected to be true for many of biological oscillators. This study strongly supports that the hypothesis that phosphorylations of clock proteins contribute to the robustness of circadian rhythms. The analytical solutions give synthetic biologists some clues to design gene oscillators with robust and desired period

Effect of Temperature on Synthetic Positive and Negative Feedback Gene Networks

NASA Astrophysics Data System (ADS)

Charlebois, Daniel A.; Marshall, Sylvia; Balazsi, Gabor

Synthetic biological systems are built and tested under well controlled laboratory conditions. How altering the environment, such as the ambient temperature affects their function is not well understood. To address this question for synthetic gene networks with positive and negative feedback, we used mathematical modeling coupled with experiments in the budding yeast Saccharomyces cerevisiae. We found that cellular growth rates and gene expression dose responses change significantly at temperatures above and below the physiological optimum for yeast. Gene expression distributions for the negative feedback-based circuit changed from unimodal to bimodal at high temperature, while the bifurcation point of the positive feedback circuit shifted up with temperature. These results demonstrate that synthetic gene network function is context-dependent. Temperature effects should thus be tested and incorporated into their design and validation for real-world applications. NSERC Postdoctoral Fellowship (Grant No. PDF-453977-2014).

False feedback and beliefs influence name recall in younger and older adults.

PubMed

Strickland-Hughes, Carla M; West, Robin Lea; Smith, Kimberly A; Ebner, Natalie C

2017-09-01

Feedback is an important self-regulatory process that affects task effort and subsequent performance. Benefits of positive feedback for list recall have been explored in research on goals and feedback, but the effect of negative feedback on memory has rarely been studied. The current research extends knowledge of memory and feedback effects by investigating face-name association memory and by examining the potential mediation of feedback effects, in younger and older adults, through self-evaluative beliefs. Beliefs were assessed before and after name recognition and name recall testing. Repeated presentation of false positive feedback was compared to false negative feedback and a no feedback condition. Results showed that memory self-efficacy declined over time for participants in the negative and no feedback conditions but was sustained for those receiving positive feedback. Furthermore, participants who received negative feedback felt older after testing than before testing. For name recall, the positive feedback group outperformed the negative feedback and no feedback groups combined, with no age interactions. The observed feedback-related effects on memory were fully mediated by changes in memory self-efficacy. These findings advance our understanding of how beliefs are related to feedback in memory and inform future studies examining the importance of self-regulation in memory.

Positive And Negative Feedback Loops Coupled By Common Transcription Activator And Repressor

NASA Astrophysics Data System (ADS)

Sielewiesiuk, Jan; Łopaciuk, Agata

2015-03-01

Dynamical systems consisting of two interlocked loops with negative and positive feedback have been studied using the linear analysis of stability and numerical solutions. Conditions for saddle-node bifurcation were formulated in a general form. Conditions for Hopf bifurcations were found in a few symmetrical cases. Auto-oscillations, when they exist, are generated by the negative feedback repressive loop. This loop determines the frequency and amplitude of oscillations. The positive feedback loop of activation slightly modifies the oscillations. Oscillations are possible when the difference between Hilll's coefficients of the repression and activation is sufficiently high. The highly cooperative activation loop with a fast turnover slows down or even makes the oscillations impossible. The system under consideration can constitute a component of epigenetic or enzymatic regulation network.

A HIF-LIMD1 negative feedback mechanism mitigates the pro-tumorigenic effects of hypoxia.

PubMed

Foxler, Daniel E; Bridge, Katherine S; Foster, John G; Grevitt, Paul; Curry, Sean; Shah, Kunal M; Davidson, Kathryn M; Nagano, Ai; Gadaleta, Emanuela; Rhys, Hefin I; Kennedy, Paul T; Hermida, Miguel A; Chang, Ting-Yu; Shaw, Peter E; Reynolds, Louise E; McKay, Tristan R; Wang, Hsei-Wei; Ribeiro, Paulo S; Plevin, Michael J; Lagos, Dimitris; Lemoine, Nicholas R; Rajan, Prabhakar; Graham, Trevor A; Chelala, Claude; Hodivala-Dilke, Kairbaan M; Spendlove, Ian; Sharp, Tyson V

2018-06-21

The adaptive cellular response to low oxygen tensions is mediated by the hypoxia-inducible factors (HIFs), a family of heterodimeric transcription factors composed of HIF-α and HIF-β subunits. Prolonged HIF expression is a key contributor to cellular transformation, tumorigenesis and metastasis. As such, HIF degradation under hypoxic conditions is an essential homeostatic and tumour-suppressive mechanism. LIMD1 complexes with PHD2 and VHL in physiological oxygen levels (normoxia) to facilitate proteasomal degradation of the HIF-α subunit. Here, we identify LIMD1 as a HIF-1 target gene, which mediates a previously uncharacterised, negative regulatory feedback mechanism for hypoxic HIF-α degradation by modulating PHD2-LIMD1-VHL complex formation. Hypoxic induction of LIMD1 expression results in increased HIF-α protein degradation, inhibiting HIF-1 target gene expression, tumour growth and vascularisation. Furthermore, we report that copy number variation at the LIMD1 locus occurs in 47.1% of lung adenocarcinoma patients, correlates with enhanced expression of a HIF target gene signature and is a negative prognostic indicator. Taken together, our data open a new field of research into the aetiology, diagnosis and prognosis of LIMD1 -negative lung cancers. © 2018 The Authors. Published under the terms of the CC BY 4.0 license.

Feedback, the various tasks of the doctor, and the feedforward alternative.

PubMed

Kluger, Avraham N; Van Dijk, Dina

2010-12-01

This study aims to alert users of feedback to its dangers, explain some of its complexities and offer the feedforward alternative. We review the damage that feedback may cause to both motivation and performance. We provide an initial solution to the puzzle of the feedback sign (positive versus negative) using the concepts of promotion focus and prevention focus. We discuss additional open questions pertaining to feedback sign and consider implications for health care systems. Feedback that threatens the self is likely to debilitate recipients and, on average, positive and negative feedback are similar in their effects on performance. Positive feedback contributes to motivation and performance under promotion focus, but the same is true for negative feedback under prevention focus. We offer an alternative to feedback--the feedforward interview--and describe a brief protocol and suggestions on how it might be used in medical education. Feedback is a double-edged sword; its effective application includes careful consideration of regulatory focus and of threats to the self. Feedforward may be a good substitute for feedback in many settings. © Blackwell Publishing Ltd 2010.

How time delay and network design shape response patterns in biochemical negative feedback systems.

PubMed

Börsch, Anastasiya; Schaber, Jörg

2016-08-24

Negative feedback in combination with time delay can bring about both sustained oscillations and adaptive behaviour in cellular networks. Here, we study which design features of systems with delayed negative feedback shape characteristic response patterns with special emphasis on the role of time delay. To this end, we analyse generic two-dimensional delay differential equations describing the dynamics of biochemical signal-response networks. We investigate the influence of several design features on the stability of the model equilibrium, i.e., presence of auto-inhibition and/or mass conservation and the kind and/or strength of the delayed negative feedback. We show that auto-inhibition and mass conservation have a stabilizing effect, whereas increasing abruptness and decreasing feedback threshold have a de-stabilizing effect on the model equilibrium. Moreover, applying our theoretical analysis to the mammalian p53 system we show that an auto-inhibitory feedback can decouple period and amplitude of an oscillatory response, whereas the delayed feedback can not. Our theoretical framework provides insight into how time delay and design features of biochemical networks act together to elicit specific characteristic response patterns. Such insight is useful for constructing synthetic networks and controlling their behaviour in response to external stimulation.

Age, sex and individual differences in punishment sensitivity: factors influencing the feedback-related negativity.

PubMed

Santesso, Diane L; Dzyundzyak, Angela; Segalowitz, Sidney J

2011-11-01

The anterior cingulate cortex (ACC) is central to evaluating performance outcomes and has been linked to individual differences in affective responses to feedback. We used electrophysiological source localization to examine the feedback-related negativity (FRN) and related ACC activity during a gambling task in relation to punishment and reward sensitivity among 16- to 17-year-old adolescents (n=20) and 18- to 29-year-old adults (n=30). The FRN was larger for monetary loss compared to win feedback and larger for high relative to low monetary value feedback, with no age differences in the FRN for win or loss feedback. Self-reported sensitivity to punishment accounted for unique variance (over sex and sensitivity to reward) in FRNs, with higher scores relating to larger FRNs and increased rostral ACC activity. These results support the ACC role in experiencing negative performance feedback, especially for individuals highly sensitive to punishment. Copyright © 2011 Society for Psychophysiological Research.

Feeling Better About Self After Receiving Negative Feedback: When the Sense That Ability Can Be Improved Is Activated.

PubMed

Hu, Xinyi; Chen, Yinghe; Tian, Baowei

2016-01-01

Past studies suggest that managers and educators often consider negative feedback as a motivator for individuals to think about their shortcomings and improve their work, but delivering negative feedback does not always achieve desired results. The present study, based on incremental theory, employed an intervention method to activate the belief that a particular ability could be improved after negative feedback. Three experiments tested the intervention effect on negative self-relevant emotion. Study 1 indicated conveying suggestions for improving ability reduced negative self-relevant emotion after negative feedback. Study 2 tested whether activating the sense of possible improvement in the ability could reduce negative self-relevant emotion. Results indicated activating the belief that ability could be improved reduced negative self-relevant emotion after failure, but delivering emotion management information alone did not yield the same effect. Study 3 extended the results by affirming the effort participants made in doing the test, and found the affirmation reduced negative self-relevant emotion. Collectively, the findings indicated focusing on the belief that the ability could be improved in the future can reduce negative self-relevant emotion after negative feedback.

Managing Written and Oral Negative Feedback in a Synchronous Online Teaching Situation

ERIC Educational Resources Information Center

Guichon, Nicolas; Betrancourt, Mireille; Prie, Yannick

2012-01-01

This case study focuses on the feedback that is provided by tutors to learners in the course of synchronous online teaching. More specifically, we study how trainee tutors used the affordances of Visu, an experimental web videoconferencing system, to provide negative feedback. Visu features classical functionalities such as video and chat, and it…

Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition.

PubMed

Maron, John L; Laney Smith, Alyssa; Ortega, Yvette K; Pearson, Dean E; Callaway, Ragan M

2016-08-01

Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their effects in isolation. We sampled soil from two intermountain grassland communities where we also measured the relative abundance of plant species. In greenhouse experiments, we quantified the direction and magnitude of plant-soil feedbacks for 10 target species that spanned a range of abundances in the field. In soil from both sites, plant-soil feedbacks were mostly negative, with more abundant species suffering greater negative feedbacks than rare species. In contrast, the average response to competition for each species was unrelated with its abundance in the field. We also determined how competitive response varied among our target species when plants competed in live vs. sterile soil. Interspecific competition reduced plant size, but the strength of this negative effect was unchanged by plant-soil feedbacks. Finally, when plants competed interspecifically, we asked how conspecific-trained, heterospecific-trained, and sterile soil influenced the competitive responses of our target species and how this varied depending on whether target species were abundant or rare in the field. Here, we found that both abundant and rare species were not as harmed by competition when they grew in heterospecific-trained soil compared to when they grew in conspecific-cultured soil. Abundant species were also not as harmed by competition when growing in sterile vs. conspecific-trained soil, but this was not the case for rare species. Our results suggest that abundant plants accrue species-specific soil pathogens to a greater extent than rare species. Thus, negative feedbacks may be critical for preventing abundant species from

The Role of Implicit Negative Feedback in SLA: Models and Recasts in Japanese and Spanish.

ERIC Educational Resources Information Center

Long, Michael; Inagaki, Shunji; Ortega, Lourdes

1998-01-01

Two experiments were conducted to assess relative utility of models and recasts in second-language (L2) Japanese and Spanish. Using pretest, posttest, control group design, each study provided evidence of adults' ability to learn from implicit negative feedback; in one case, support for notion that reactive implicit negative feedback can be more…

The Effects of a Local Negative Feedback Function between Choice and Relative Reinforcer Rate

PubMed Central

Davison, Michael; Elliffe, Douglas; Marr, M. Jackson

2010-01-01

Four pigeons were trained on two-key concurrent variable-interval schedules with no changeover delay. In Phase 1, relative reinforcers on the two alternatives were varied over five conditions from .1 to .9. In Phases 2 and 3, we instituted a molar feedback function between relative choice in an interreinforcer interval and the probability of reinforcers on the two keys ending the next interreinforcer interval. The feedback function was linear, and was negatively sloped so that more extreme choice in an interreinforcer interval made it more likely that a reinforcer would be available on the other key at the end of the next interval. The slope of the feedback function was −1 in Phase 2 and −3 in Phase 3. We varied relative reinforcers in each of these phases by changing the intercept of the feedback function. Little effect of the feedback functions was discernible at the local (interreinforcer interval) level, but choice measured at an extended level across sessions was strongly and significantly decreased by increasing the negative slope of the feedback function. PMID:21451748

Fear of negative evaluation modulates electrocortical and behavioral responses when anticipating social evaluative feedback

PubMed Central

Van der Molen, Melle J. W.; Poppelaars, Eefje S.; Van Hartingsveldt, Caroline T. A.; Harrewijn, Anita; Gunther Moor, Bregtje; Westenberg, P. Michiel

2014-01-01

Cognitive models posit that the fear of negative evaluation (FNE) is a hallmark feature of social anxiety. As such, individuals with high FNE may show biased information processing when faced with social evaluation. The aim of the current study was to examine the neural underpinnings of anticipating and processing social-evaluative feedback, and its correlates with FNE. We used a social judgment paradigm in which female participants (N = 31) were asked to indicate whether they believed to be socially accepted or rejected by their peers. Anticipatory attention was indexed by the stimulus preceding negativity (SPN), while the feedback-related negativity and P3 were used to index the processing of social-evaluative feedback. Results provided evidence of an optimism bias in social peer evaluation, as participants more often predicted to be socially accepted than rejected. Participants with high levels of FNE needed more time to provide their judgments about the social-evaluative outcome. While anticipating social-evaluative feedback, SPN amplitudes were larger for anticipated social acceptance than for social rejection feedback. Interestingly, the SPN during anticipated social acceptance was larger in participants with high levels of FNE. None of the feedback-related brain potentials correlated with the FNE. Together, the results provided evidence of biased information processing in individuals with high levels of FNE when anticipating (rather than processing) social-evaluative feedback. The delayed response times in high FNE individuals were interpreted to reflect augmented vigilance imposed by the upcoming social-evaluative threat. Possibly, the SPN constitutes a neural marker of this vigilance in females with higher FNE levels, particularly when anticipating social acceptance feedback. PMID:24478667

Fear of negative evaluation modulates electrocortical and behavioral responses when anticipating social evaluative feedback.

PubMed

Van der Molen, Melle J W; Poppelaars, Eefje S; Van Hartingsveldt, Caroline T A; Harrewijn, Anita; Gunther Moor, Bregtje; Westenberg, P Michiel

2013-01-01

Cognitive models posit that the fear of negative evaluation (FNE) is a hallmark feature of social anxiety. As such, individuals with high FNE may show biased information processing when faced with social evaluation. The aim of the current study was to examine the neural underpinnings of anticipating and processing social-evaluative feedback, and its correlates with FNE. We used a social judgment paradigm in which female participants (N = 31) were asked to indicate whether they believed to be socially accepted or rejected by their peers. Anticipatory attention was indexed by the stimulus preceding negativity (SPN), while the feedback-related negativity and P3 were used to index the processing of social-evaluative feedback. Results provided evidence of an optimism bias in social peer evaluation, as participants more often predicted to be socially accepted than rejected. Participants with high levels of FNE needed more time to provide their judgments about the social-evaluative outcome. While anticipating social-evaluative feedback, SPN amplitudes were larger for anticipated social acceptance than for social rejection feedback. Interestingly, the SPN during anticipated social acceptance was larger in participants with high levels of FNE. None of the feedback-related brain potentials correlated with the FNE. Together, the results provided evidence of biased information processing in individuals with high levels of FNE when anticipating (rather than processing) social-evaluative feedback. The delayed response times in high FNE individuals were interpreted to reflect augmented vigilance imposed by the upcoming social-evaluative threat. Possibly, the SPN constitutes a neural marker of this vigilance in females with higher FNE levels, particularly when anticipating social acceptance feedback.

Negative feedback in ants: crowding results in less trail pheromone deposition

PubMed Central

Czaczkes, Tomer J.; Grüter, Christoph; Ratnieks, Francis L. W.

2013-01-01

Crowding in human transport networks reduces efficiency. Efficiency can be increased by appropriate control mechanisms, which are often imposed externally. Ant colonies also have distribution networks to feeding sites outside the nest and can experience crowding. However, ants do not have external controllers or leaders. Here, we report a self-organized negative feedback mechanism, based on local information, which downregulates the production of recruitment signals in crowded parts of a network by Lasius niger ants. We controlled crowding by manipulating trail width and the number of ants on a trail, and observed a 5.6-fold reduction in the number of ants depositing trail pheromone from least to most crowded conditions. We also simulated crowding by placing glass beads covered in nest-mate cuticular hydrocarbons on the trail. After 10 bead encounters over 20 cm, forager ants were 45 per cent less likely to deposit pheromone. The mechanism of negative feedback reported here is unusual in that it acts by downregulating the production of a positive feedback signal, rather than by direct inhibition or the production of an inhibitory signal. PMID:23365196

Positive and negative feedback regulatory loops of thiol-oxidative stress response mediated by an unstable isoform of sigmaR in actinomycetes.

PubMed

Kim, Min-Sik; Hahn, Mi-Young; Cho, Yoobok; Cho, Sang-Nae; Roe, Jung-Hye

2009-09-01

Alternate sigma factors provide an effective way of diversifying bacterial gene expression in response to environmental changes. In Streptomyces coelicolor where more than 65 sigma factors are predicted, sigma(R) is the major regulator for response to thiol-oxidative stresses. sigma(R) becomes available when its bound anti-sigma factor RsrA is oxidized at sensitive cysteine thiols to form disulphide bonds. sigma(R) regulon includes genes for itself and multiple thiol-reducing systems, which constitute positive and negative feedback loops respectively. We found that the positive amplification loop involves an isoform of sigma(R) (sigma(R')) with an N-terminal extension of 55 amino acids, produced from an upstream start codon. A major difference between constitutive sigma(R) and inducible sigma(R') is that the latter is markedly unstable (t(1/2) approximately 10 min) compared with the former (> 70 min). The rapid turnover of sigma(R') is partly due to induced ClpP1/P2 proteases from the sigma(R) regulon. This represents a novel way of elaborating positive and negative feedback loops in a control circuit. Similar phenomenon may occur in other actinomycetes that harbour multiple start codons in the sigR homologous gene. We observed that sigH gene, the sigR orthologue in Mycobacterium smegmatis, produces an unstable larger isoform of sigma(H) upon induction by thiol-oxidative stress.

Prospect theory does not describe the feedback-related negativity value function.

PubMed

Sambrook, Thomas D; Roser, Matthew; Goslin, Jeremy

2012-12-01

Humans handle uncertainty poorly. Prospect theory accounts for this with a value function in which possible losses are overweighted compared to possible gains, and the marginal utility of rewards decreases with size. fMRI studies have explored the neural basis of this value function. A separate body of research claims that prediction errors are calculated by midbrain dopamine neurons. We investigated whether the prospect theoretic effects shown in behavioral and fMRI studies were present in midbrain prediction error coding by using the feedback-related negativity, an ERP component believed to reflect midbrain prediction errors. Participants' stated satisfaction with outcomes followed prospect theory but their feedback-related negativity did not, instead showing no effect of marginal utility and greater sensitivity to potential gains than losses. Copyright © 2012 Society for Psychophysiological Research.

Study of positive and negative feedback sensitivity in psychosis using the Wisconsin Card Sorting Test.

PubMed

Farreny, Aida; Del Rey-Mejías, Ángel; Escartin, Gemma; Usall, Judith; Tous, Núria; Haro, Josep Maria; Ochoa, Susana

2016-07-01

Schizophrenia involves marked motivational and learning deficits that may reflect abnormalities in reward processing. The purpose of this study was to examine positive and negative feedback sensitivity in schizophrenia using computational modeling derived from the Wisconsin Card Sorting Test (WCST). We also aimed to explore feedback sensitivity in a sample with bipolar disorder. Eighty-three individuals with schizophrenia and 27 with bipolar disorder were included. Demographic, clinical and cognitive outcomes, together with the WCST, were considered in both samples. Computational modeling was performed using the R syntax to calculate 3 parameters based on trial-by-trial execution on the WCST: reward sensitivity (R), punishment sensitivity (P), and choice consistency (D). The associations between outcome variables and the parameters were investigated. Positive and negative sensitivity showed deficits, but P parameter was clearly diminished in schizophrenia. Cognitive variables, age, and symptoms were associated with R, P, and D parameters in schizophrenia. The sample with bipolar disorder would show cognitive deficits and feedback abnormalities to a lesser extent than individuals with schizophrenia. Negative feedback sensitivity demonstrated greater deficit in both samples. Idiosyncratic cognitive requirements in the WCST might introduce confusion when supposing model-free reinforcement learning. Negative symptoms of schizophrenia were related to lower feedback sensitivity and less goal-directed patterns of choice. Copyright © 2016 Elsevier Inc. All rights reserved.

Modeling gene regulatory network motifs using statecharts

PubMed Central

2012-01-01

Background Gene regulatory networks are widely used by biologists to describe the interactions among genes, proteins and other components at the intra-cellular level. Recently, a great effort has been devoted to give gene regulatory networks a formal semantics based on existing computational frameworks. For this purpose, we consider Statecharts, which are a modular, hierarchical and executable formal model widely used to represent software systems. We use Statecharts for modeling small and recurring patterns of interactions in gene regulatory networks, called motifs. Results We present an improved method for modeling gene regulatory network motifs using Statecharts and we describe the successful modeling of several motifs, including those which could not be modeled or whose models could not be distinguished using the method of a previous proposal. We model motifs in an easy and intuitive way by taking advantage of the visual features of Statecharts. Our modeling approach is able to simulate some interesting temporal properties of gene regulatory network motifs: the delay in the activation and the deactivation of the "output" gene in the coherent type-1 feedforward loop, the pulse in the incoherent type-1 feedforward loop, the bistability nature of double positive and double negative feedback loops, the oscillatory behavior of the negative feedback loop, and the "lock-in" effect of positive autoregulation. Conclusions We present a Statecharts-based approach for the modeling of gene regulatory network motifs in biological systems. The basic motifs used to build more complex networks (that is, simple regulation, reciprocal regulation, feedback loop, feedforward loop, and autoregulation) can be faithfully described and their temporal dynamics can be analyzed. PMID:22536967

Mode Selection Rules for a Two-Delay System with Positive and Negative Feedback Loops

NASA Astrophysics Data System (ADS)

Takahashi, Kin'ya; Kobayashi, Taizo

2018-04-01

The mode selection rules for a two-delay system, which has negative feedback with a short delay time t1 and positive feedback with a long delay time t2, are studied numerically and theoretically. We find two types of mode selection rules depending on the strength of the negative feedback. When the strength of the negative feedback |α1| (α1 < 0) is sufficiently small compared with that of the positive feedback α2 (> 0), 2m + 1-th harmonic oscillation is well sustained in a neighborhood of t1/t2 = even/odd, i.e., relevant condition. In a neighborhood of the irrelevant condition given by t1/t2 = odd/even or t1/t2 = odd/odd, higher harmonic oscillations are observed. However, if |α1| is slightly less than α2, a different mode selection rule works, where the condition t1/t2 = odd/even is relevant and the conditions t1/t2 = odd/odd and t1/t2 = even/odd are irrelevant. These mode selection rules are different from the mode selection rule of the normal two-delay system with two positive feedback loops, where t1/t2 = odd/odd is relevant and the others are irrelevant. The two types of mode selection rules are induced by individually different mechanisms controlling the Hopf bifurcation, i.e., the Hopf bifurcation controlled by the "boosted bifurcation process" and by the "anomalous bifurcation process", which occur for |α1| below and above the threshold value αth, respectively.

Telling good from bad news: ADHD differentially affects processing of positive and negative feedback during guessing.

PubMed

van Meel, Catharina S; Oosterlaan, Jaap; Heslenfeld, Dirk J; Sergeant, Joseph A

2005-01-01

Neuroimaging studies on ADHD suggest abnormalities in brain regions associated with decision-making and reward processing such as the anterior cingulate cortex (ACC) and orbitofrontal cortex. Recently, event-related potential (ERP) studies demonstrated that the ACC is involved in processing feedback signals during guessing and gambling. The resulting negative deflection, the 'feedback-related negativity' (FRN) has been interpreted as reflecting an error in reward prediction. In the present study, ERPs elicited by positive and negative feedback were recorded in children with ADHD and normal controls during guessing. 'Correct' and 'incorrect' guesses resulted in respectively monetary gains and losses. The FRN amplitude to losses was more pronounced in the ADHD group than in normal controls. Positive and negative feedback differentially affected long latency components in the ERP waveforms of normal controls, but not ADHD children. These later deflections might be related to further emotional or strategic processing. The present findings suggest an enhanced sensitivity to unfavourable outcomes in children with ADHD, probably due to abnormalities in mesolimbic reward circuits. In addition, further processing, such as affective evaluation and the assessment of future consequences of the feedback signal seems to be altered in ADHD. These results may further help understanding the neural basis of decision-making deficits in ADHD.

Genome-Wide Negative Feedback Drives Transgenerational DNA Methylation Dynamics in Arabidopsis

PubMed Central

Kassam, Mohamed; Duvernois-Berthet, Evelyne; Cortijo, Sandra; Takashima, Kazuya; Saze, Hidetoshi; Toyoda, Atsushi; Fujiyama, Asao; Colot, Vincent; Kakutani, Tetsuji

2015-01-01

Epigenetic variations of phenotypes, especially those associated with DNA methylation, are often inherited over multiple generations in plants. The active and inactive chromatin states are heritable and can be maintained or even be amplified by positive feedback in a transgenerational manner. However, mechanisms controlling the transgenerational DNA methylation dynamics are largely unknown. As an approach to understand the transgenerational dynamics, we examined long-term effect of impaired DNA methylation in Arabidopsis mutants of the chromatin remodeler gene DDM1 (Decrease in DNA Methylation 1) through whole genome DNA methylation sequencing. The ddm1 mutation induces a drastic decrease in DNA methylation of transposable elements (TEs) and repeats in the initial generation, while also inducing ectopic DNA methylation at hundreds of loci. Unexpectedly, this ectopic methylation can only be seen after repeated self-pollination. The ectopic cytosine methylation is found primarily in the non-CG context and starts from 3’ regions within transcription units and spreads upstream. Remarkably, when chromosomes with reduced DNA methylation were introduced from a ddm1 mutant into a DDM1 wild-type background, the ddm1-derived chromosomes also induced analogous de novo accumulation of DNA methylation in trans. These results lead us to propose a model to explain the transgenerational DNA methylation redistribution by genome-wide negative feedback. The global negative feedback, together with local positive feedback, would ensure robust and balanced differentiation of chromatin states within the genome. PMID:25902052

Feedback-related negativity in children with two subtypes of attention deficit hyperactivity disorder.

PubMed

Gong, Jingbo; Yuan, Jiajin; Wang, Suhong; Shi, Lijuan; Cui, Xilong; Luo, Xuerong

2014-01-01

The current model of ADHD suggests abnormal reward and punishment sensitivity, although differences in ADHD subgroups are unclear. This study aimed to investigate the effect of feedback valence (reward or punishment) and punishment magnitude (small or large) on Feedback-Related Negativity (FRN) and Late Positive Potential (LPP) in two subtypes of ADHD (ADHD-C and ADHD-I) compared to typically developing children (TD) during a children's gambling task. Children with ADHD-C (n = 16), children with ADHD-I (n = 15) and typically developing children (n = 15) performed a children's gambling task under three feedback conditions: large losses, small losses and gains. FRN and LPP components in brain potentials were recorded and analyzed. In TD children and children with ADHD-C, large loss feedback evoked more negative FRN amplitudes than small loss feedback, suggesting that brain sensitivity to the punishment and its magnitude is not impaired in children with ADHD-C. In contrast to these two groups, the FRN effect was absent in children with ADHD-I. The LPP amplitudes were larger in children with ADHD-C in comparison with those with ADHD-I, regardless of feedback valence and magnitude. Children with ADHD-C exhibit intact brain sensitivity to punishment similar to TD children. In contrast, children with ADHD-I are significantly impaired in neural sensitivity to the feedback stimuli and in particular, to punishment, compared to TD and ADHD-C children. Thus, FRN, rather than LPP, is a reliable index of the difference in reward and punishment sensitivity across different ADHD-subcategories.

The price of soliciting and receiving negative feedback: self-verification theory as a vulnerability to depression theory.

PubMed

Joiner, T E

1995-05-01

The hypothesis that people who seek and receive negative feedback are vulnerable to increases in depressed symptoms was tested among 100 undergraduates and their roommates. Students and roommates completed questionnaires on their views of each other and on their own levels of negative feedback seeking, depressed and anxious symptoms, negative and positive affect, and self-esteem. Three weeks later, students and roommates completed the same questionnaires. Results were, in general, consistent with prediction. Students who reported an interest in their roommates' negative feedback and who lived with a roommate who viewed them negatively were at heightened risk for increases in depressed symptoms. These results could not be explained in terms of the variables' relations to trait self-esteem. The symptom specificity of the effect was moderately supported. Implications for work on interpersonal vulnerability to depression are discussed.

[On efficiency of biomanagement with negative feedback from patient's EEG in correction of functional disorders, caused by stress].

PubMed

Fedotchev, A I

2010-01-01

The perspective approach to non-pharmacological correction of the stress induced functional disorders in humans, based on the double negative feedback from patient's EEG was validated and experimentally tested. The approach implies a simultaneous use of narrow frequency EEG-oscillators, characteristic for each patient and recorded in real time span, in two independent contours of negative feedback--traditional contour of adaptive biomanagement and additional contour of resonance stimulation. In the last the signals of negative feedback from individual narrow frequency EEG oscillators are not recognized by the subject, but serve for an automatic modulation of the parameters of the sensory impact. Was shown that due to combination of active (conscious perception) and passive (automatic modulation) use of signals of negative feedback from narrow frequency EEG components of the patient, opens a possibility of considerable increase of efficiency of the procedures of EEG biomanagement.

A Simple Negative Interaction in the Positive Transcriptional Feedback of a Single Gene Is Sufficient to Produce Reliable Oscillations

PubMed Central

Miró-Bueno, Jesús M.; Rodríguez-Patón, Alfonso

2011-01-01

Negative and positive transcriptional feedback loops are present in natural and synthetic genetic oscillators. A single gene with negative transcriptional feedback needs a time delay and sufficiently strong nonlinearity in the transmission of the feedback signal in order to produce biochemical rhythms. A single gene with only positive transcriptional feedback does not produce oscillations. Here, we demonstrate that this single-gene network in conjunction with a simple negative interaction can also easily produce rhythms. We examine a model comprised of two well-differentiated parts. The first is a positive feedback created by a protein that binds to the promoter of its own gene and activates the transcription. The second is a negative interaction in which a repressor molecule prevents this protein from binding to its promoter. A stochastic study shows that the system is robust to noise. A deterministic study identifies that the dynamics of the oscillator are mainly driven by two types of biomolecules: the protein, and the complex formed by the repressor and this protein. The main conclusion of this paper is that a simple and usual negative interaction, such as degradation, sequestration or inhibition, acting on the positive transcriptional feedback of a single gene is a sufficient condition to produce reliable oscillations. One gene is enough and the positive transcriptional feedback signal does not need to activate a second repressor gene. This means that at the genetic level an explicit negative feedback loop is not necessary. The model needs neither cooperative binding reactions nor the formation of protein multimers. Therefore, our findings could help to clarify the design principles of cellular clocks and constitute a new efficient tool for engineering synthetic genetic oscillators. PMID:22205920

Risk-Taking and the Feedback Negativity Response to Loss among At-Risk Adolescents

PubMed Central

Crowley, Michael J.; Wu, Jia; Crutcher, Clifford; Bailey, Christopher A.; Lejuez, C.W.; Mayes, Linda C.

2009-01-01

Event-related brain potentials were examined in 32 adolescents (50% female) from a high-risk sample, who were exposed to cocaine and other drugs prenatally. Adolescents were selected for extreme high- or low-risk behavior on the Balloon Analog Risk Task, a measure of real-world risk-taking propensity. The feedback error-related negativity (fERN), an event-related potential (ERP) that occurs when an expected reward does not occur, was examined in a game in which choices lead to monetary gains and losses with feedback delayed 1 or 2 s. The fERN was clearly visible in the fronto-central scalp region in this adolescent sample. Feedback type, feedback delay, risk status, and sex were all associated with fERN variability. Monetary feedback also elicited a P300-like component, moderated by delay and sex. Delaying reward feedback may provide a means for studying complementary functioning of dopamine and norepinephrine systems. PMID:19372694

A Framework for Engineering Stress Resilient Plants Using Genetic Feedback Control and Regulatory Network Rewiring.

PubMed

Foo, Mathias; Gherman, Iulia; Zhang, Peijun; Bates, Declan G; Denby, Katherine J

2018-05-23

Crop disease leads to significant waste worldwide, both pre- and postharvest, with subsequent economic and sustainability consequences. Disease outcome is determined both by the plants' response to the pathogen and by the ability of the pathogen to suppress defense responses and manipulate the plant to enhance colonization. The defense response of a plant is characterized by significant transcriptional reprogramming mediated by underlying gene regulatory networks, and components of these networks are often targeted by attacking pathogens. Here, using gene expression data from Botrytis cinerea-infected Arabidopsis plants, we develop a systematic approach for mitigating the effects of pathogen-induced network perturbations, using the tools of synthetic biology. We employ network inference and system identification techniques to build an accurate model of an Arabidopsis defense subnetwork that contains key genes determining susceptibility of the plant to the pathogen attack. Once validated against time-series data, we use this model to design and test perturbation mitigation strategies based on the use of genetic feedback control. We show how a synthetic feedback controller can be designed to attenuate the effect of external perturbations on the transcription factor CHE in our subnetwork. We investigate and compare two approaches for implementing such a controller biologically-direct implementation of the genetic feedback controller, and rewiring the regulatory regions of multiple genes-to achieve the network motif required to implement the controller. Our results highlight the potential of combining feedback control theory with synthetic biology for engineering plants with enhanced resilience to environmental stress.

Impaired coupling of local and global functional feedbacks underlies abnormal synchronization and negative symptoms of schizophrenia.

PubMed

Noh, Kyungchul; Shin, Kyung Soon; Shin, Dongkwan; Hwang, Jae Yeon; Kim, June Sic; Jang, Joon Hwan; Chung, Chun Kee; Kwon, Jun Soo; Cho, Kwang-Hyun

2013-04-10

Abnormal synchronization of brain oscillations is found to be associated with various core symptoms of schizophrenia. However, the underlying mechanism of this association remains yet to be elucidated. In this study, we found that coupled local and global feedback (CLGF) circuits in the cortical functional network are related to the abnormal synchronization and also correlated to the negative symptom of schizophrenia. Analysis of the magnetoencephalography data obtained from patients with chronic schizophrenia during rest revealed an increase in beta band synchronization and a reduction in gamma band power compared to healthy controls. Using a feedback identification method based on non-causal impulse responses, we constructed functional feedback networks and found that CLGF circuits were significantly reduced in schizophrenia. From computational analysis on the basis of the Wilson-Cowan model, we unraveled that the CLGF circuits are critically involved in the abnormal synchronization and the dynamical switching between beta and gamma bands power in schizophrenia. Moreover, we found that the abundance of CLGF circuits was negatively correlated with the development of negative symptoms of schizophrenia, suggesting that the negative symptom is closely related to the impairment of this circuit. Our study implicates that patients with schizophrenia might have the impaired coupling of inter- and intra-regional functional feedbacks and that the CLGF circuit might serve as a critical bridge between abnormal synchronization and the negative symptoms of schizophrenia.

Feedback Valence Affects Auditory Perceptual Learning Independently of Feedback Probability

PubMed Central

Amitay, Sygal; Moore, David R.; Molloy, Katharine; Halliday, Lorna F.

2015-01-01

Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they were doing equally well, while 10% positive or 90% negative feedback informed them they were doing equally badly. In all conditions the feedback was random in relation to the listeners’ responses (because the task was to discriminate three identical tones), yet both the valence (negative vs. positive) and the probability of feedback (10% vs. 90%) affected learning. Feedback that informed listeners they were doing badly resulted in better post-training performance than feedback that informed them they were doing well, independent of valence. In addition, positive feedback during training resulted in better post-training performance than negative feedback, but only positive feedback indicating listeners were doing badly on the task resulted in learning. As we have previously speculated, feedback that better reflected the difficulty of the task was more effective in driving learning than feedback that suggested performance was better than it should have been given perceived task difficulty. But contrary to expectations, positive feedback was more effective than negative feedback in driving learning. Feedback thus had two separable effects on learning: feedback valence affected motivation on a subjectively difficult task, and learning occurred only when feedback probability reflected the subjective difficulty. To optimize learning, training programs need to take into consideration both feedback valence and probability. PMID:25946173

Removal of Negative Feedback Enhances WCST Performance for Individuals with ASD

ERIC Educational Resources Information Center

Broadbent, Jaclyn; Stokes, Mark A.

2013-01-01

Negative feedback was explored as a potential mechanism that may exacerbate perseverative behaviours in individuals with Asperger's syndrome (AS). The current study compared 50 individuals with AS and 50 typically developing (TD) individuals for their abilities to successfully complete the Wisconsin Card Sorting Task (WCST) in the presence or…

Are Success and Failure Experiences Equally Motivational? An Investigation of Regulatory Focus and Feedback

ERIC Educational Resources Information Center

Shu, Tse-Mei; Lam, Shui-fong

2011-01-01

The present study extended regulatory focus theory (Idson & Higgins, 2000) to an educational setting and attempted to identify individuals with high motivation after both success and failure feedback. College students in Hong Kong (N = 180) participated in an experiment with a 2 promotion focus (high vs. low) x 2 prevention focus (high vs.…

Feedback enhances the positive effects and reduces the negative effects of multiple-choice testing.

PubMed

Butler, Andrew C; Roediger, Henry L

2008-04-01

Multiple-choice tests are used frequently in higher education without much consideration of the impact this form of assessment has on learning. Multiple-choice testing enhances retention of the material tested (the testing effect); however, unlike other tests, multiple-choice can also be detrimental because it exposes students to misinformation in the form of lures. The selection of lures can lead students to acquire false knowledge (Roediger & Marsh, 2005). The present research investigated whether feedback could be used to boost the positive effects and reduce the negative effects of multiple-choice testing. Subjects studied passages and then received a multiple-choice test with immediate feedback, delayed feedback, or no feedback. In comparison with the no-feedback condition, both immediate and delayed feedback increased the proportion of correct responses and reduced the proportion of intrusions (i.e., lure responses from the initial multiple-choice test) on a delayed cued recall test. Educators should provide feedback when using multiple-choice tests.

The Context Matters: Outcome Probability and Expectation Mismatch Modulate the Feedback Negativity When Self-Evaluation of Response Correctness Is Possible

PubMed Central

Leue, Anja; Cano Rodilla, Carmen; Beauducel, André

2015-01-01

Individuals typically evaluate whether their performance and the obtained feedback match. Previous research has shown that feedback negativity (FN) depends on outcome probability and feedback valence. It is, however, less clear to what extent previous effects of outcome probability on FN depend on self-evaluations of response correctness. Therefore, we investigated the effects of outcome probability on FN amplitude in a simple go/no-go task that allowed for the self-evaluation of response correctness. We also investigated effects of performance incompatibility and feedback valence. In a sample of N = 22 participants, outcome probability was manipulated by means of precues, feedback valence by means of monetary feedback, and performance incompatibility by means of feedback that induced a match versus mismatch with individuals' performance. We found that the 100% outcome probability condition induced a more negative FN following no-loss than the 50% outcome probability condition. The FN following loss was more negative in the 50% compared to the 100% outcome probability condition. Performance-incompatible loss resulted in a more negative FN than performance-compatible loss. Our results indicate that the self-evaluation of the correctness of responses should be taken into account when the effects of outcome probability and expectation mismatch on FN are investigated. PMID:26783525

The Context Matters: Outcome Probability and Expectation Mismatch Modulate the Feedback Negativity When Self-Evaluation of Response Correctness Is Possible.

PubMed

Leue, Anja; Cano Rodilla, Carmen; Beauducel, André

2015-01-01

Individuals typically evaluate whether their performance and the obtained feedback match. Previous research has shown that feedback negativity (FN) depends on outcome probability and feedback valence. It is, however, less clear to what extent previous effects of outcome probability on FN depend on self-evaluations of response correctness. Therefore, we investigated the effects of outcome probability on FN amplitude in a simple go/no-go task that allowed for the self-evaluation of response correctness. We also investigated effects of performance incompatibility and feedback valence. In a sample of N = 22 participants, outcome probability was manipulated by means of precues, feedback valence by means of monetary feedback, and performance incompatibility by means of feedback that induced a match versus mismatch with individuals' performance. We found that the 100% outcome probability condition induced a more negative FN following no-loss than the 50% outcome probability condition. The FN following loss was more negative in the 50% compared to the 100% outcome probability condition. Performance-incompatible loss resulted in a more negative FN than performance-compatible loss. Our results indicate that the self-evaluation of the correctness of responses should be taken into account when the effects of outcome probability and expectation mismatch on FN are investigated.

Leader-member exchange and member performance: a new look at individual-level negative feedback-seeking behavior and team-level empowerment climate.

PubMed

Chen, Ziguang; Lam, Wing; Zhong, Jian An

2007-01-01

From a basis in social exchange theory, the authors investigated whether, and how, negative feedback-seeking behavior and a team empowerment climate affect the relationship between leader-member exchange (LMX) and member performance. Results showed that subordinates' negative feedback-seeking behavior mediated the relationship between LMX and both objective and subjective in-role performance. In addition, the level of a team's empowerment climate was positively related to subordinates' own sense of empowerment, which in turn negatively moderated the effects of LMX on negative feedback-seeking behavior. 2007 APA, all rights reserved

Changes in Intrinsic Motivation as a Function of Negative Feedback and Threats.

ERIC Educational Resources Information Center

Deci, Edward L.; Cascio, Wayne F.

Recent studies have demonstrated that external rewards can affect intrinsic motivation to perform an activity. Money tends to decrease intrinsic motivation, whereas positive verbal reinforcements tend to increase intrinsic motivation. This paper presents evidence that negative feedback and threats of punishment also decrease intrinsic motivation.…

Reward Expectation Modulates Feedback-Related Negativity and EEG Spectra

PubMed Central

Cohen, Michael X; Elger, Christian E.; Ranganath, Charan

2007-01-01

The ability to evaluate outcomes of previous decisions is critical to adaptive decision-making. The feedback-related negativity (FRN) is an event-related potential (ERP) modulation that distinguishes losses from wins, but little is known about the effects of outcome probability on these ERP responses. Further, little is known about the frequency characteristics of feedback processing, for example, event-related oscillations and phase synchronizations. Here, we report an EEG experiment designed to address these issues. Subjects engaged in a probabilistic reinforcement learning task in which we manipulated, across blocks, the probability of winning and losing to each of two possible decision options. Behaviorally, all subjects quickly adapted their decision-making to maximize rewards. ERP analyses revealed that the probability of reward modulated neural responses to wins, but not to losses. This was seen both across blocks as well as within blocks, as learning progressed. Frequency decomposition via complex wavelets revealed that EEG responses to losses, compared to wins, were associated with enhanced power and phase coherence in the theta frequency band. As in the ERP analyses, power and phase coherence values following wins but not losses were modulated by reward probability. Some findings between ERP and frequency analyses diverged, suggesting that these analytic approaches provide complementary insights into neural processing. These findings suggest that the neural mechanisms of feedback processing may differ between wins and losses. PMID:17257860

The Positive Impact of Negative Feedback

DTIC Science & Technology

2011-03-01

8 Feedback Moderation...and Feedback Usefulness ..................................................................................29 Figure 8 . Moderation Plot of...discrepancies may play a motivational role in 8 leadership development, and Atwater et al. (1998) asserted that others-self agreement may be

Acute Stress Modulates Feedback Processing in Men and Women: Differential Effects on the Feedback-Related Negativity and Theta and Beta Power

PubMed Central

Banis, Stella; Geerligs, Linda; Lorist, Monicque M.

2014-01-01

Sex-specific prevalence rates in mental and physical disorders may be partly explained by sex differences in physiological stress responses. Neural networks that might be involved are those underlying feedback processing. Aim of the present EEG study was to investigate whether acute stress alters feedback processing, and whether stress effects differ between men and women. Male and female participants performed a gambling task, in a control and a stress condition. Stress was induced by exposing participants to a noise stressor. Brain activity was analyzed using both event-related potential and time-frequency analyses, measuring the feedback-related negativity (FRN) and feedback-related changes in theta and beta oscillatory power, respectively. While the FRN and feedback-related theta power were similarly affected by stress induction in both sexes, feedback-related beta power depended on the combination of stress induction condition and sex. FRN amplitude and theta power increases were smaller in the stress relative to the control condition in both sexes, demonstrating that acute noise stress impairs performance monitoring irrespective of sex. However, in the stress but not in the control condition, early lower beta-band power increases were larger for men than women, indicating that stress effects on feedback processing are partly sex-dependent. Our findings suggest that sex-specific effects on feedback processing may comprise a factor underlying sex-specific stress responses. PMID:24755943

Feedback-related negativity codes outcome valence, but not outcome expectancy, during reversal learning.

PubMed

von Borries, A K L; Verkes, R J; Bulten, B H; Cools, R; de Bruijn, E R A

2013-12-01

Optimal behavior depends on the ability to assess the predictive value of events and to adjust behavior accordingly. Outcome processing can be studied by using its electrophysiological signatures--that is, the feedback-related negativity (FRN) and the P300. A prominent reinforcement-learning model predicts an FRN on negative prediction errors, as well as implying a role for the FRN in learning and the adaptation of behavior. However, these predictions have recently been challenged. Notably, studies so far have used tasks in which the outcomes have been contingent on the response. In these paradigms, the need to adapt behavioral responses is present only for negative, not for positive feedback. The goal of the present study was to investigate the effects of positive as well as negative violations of expectancy on FRN amplitudes, without the usual confound of behavioral adjustments. A reversal-learning task was employed in which outcome value and outcome expectancy were orthogonalized; that is, both positive and negative outcomes were equally unexpected. The results revealed a double dissociation, with effects of valence but not expectancy on the FRN and, conversely, effects of expectancy but not valence on the P300. While FRN amplitudes were largest for negative-outcome trials, irrespective of outcome expectancy, P300 amplitudes were largest for unexpected-outcome trials, irrespective of outcome valence. These FRN effects were interpreted to reflect an evaluation along a good-bad dimension, rather than reflecting a negative prediction error or a role in behavioral adaptation. By contrast, the P300 reflects the updating of information relevant for behavior in a changing context.

Depression and selection of positive and negative social feedback: motivated preference or cognitive balance?

PubMed

Alloy, L B; Lipman, A J

1992-05-01

In this commentary we examine Swann, Wenzlaff, Krull, and Pelham's (1992) findings with respect to each of 5 central propositions in self-verification theory. We conclude that although the data are consistent with self-verification theory, none of the 5 components of the theory have been demonstrated convincingly as yet. Specifically, we argue that depressed subjects' selection of social feedback appears to be balanced or evenhanded rather than biased toward negative feedback and that there is little evidence to indicate that depressives actively seek negative appraisals. Furthermore, we suggest that the studies are silent with respect to the motivational postulates of self-verification theory and that a variety of competing cognitive and motivational models can explain Swann et al.'s findings as well as self-verification theory.

Self-verification and social anxiety: preference for negative social feedback and low social self-esteem.

PubMed

Valentiner, David P; Skowronski, John J; McGrath, Patrick B; Smith, Sarah A; Renner, Kerry A

2011-10-01

A self-verification model of social anxiety views negative social self-esteem as a core feature of social anxiety. This core feature is proposed to be maintained through self-verification processes, such as by leading individuals with negative social self-esteem to prefer negative social feedback. This model is tested in two studies. In Study 1, questionnaires were administered to a college sample (N = 317). In Study 2, questionnaires were administered to anxiety disordered patients (N = 62) before and after treatment. Study 1 developed measures of preference for negative social feedback and social self-esteem, and provided evidence of their incremental validity in a college sample. Study 2 found that these two variables are not strongly related to fears of evaluation, are relatively unaffected by a treatment that targets such fears, and predict residual social anxiety following treatment. Overall, these studies provide preliminary evidence for a self-verification model of social anxiety.

Blocked versus randomized presentation modes differentially modulate feedback-related negativity and P3b amplitudes

PubMed Central

Pfabigan, Daniela M.; Zeiler, Michael; Lamm, Claus; Sailer, Uta

2014-01-01

Objective Electrophysiological studies on feedback processing typically use a wide range of feedback stimuli which might not always be comparable. The current study investigated whether two indicators of feedback processing – feedback-related negativity (FRN) and P3b – differ for feedback stimuli with explicit (facial expressions) or assigned valence information (symbols). In addition, we assessed whether presenting feedback in either a trial-by-trial or a block-wise fashion affected these ERPs. Methods EEG was recorded in three experiments while participants performed a time estimation task and received two different types of performance feedback. Results Only P3b amplitudes varied consistently in response to feedback type for both presentation types. Moreover, the blocked feedback type presentation yielded more distinct FRN peaks, higher effect sizes, and a significant relation between FRN amplitudes and behavioral task performance measures. Conclusion Both stimulus type and presentation mode may provoke systematic changes in feedback-related ERPs. The current findings point at important potential confounds that need to be controlled for when designing FRN or P3b studies. Significance Studies investigating P3b amplitudes using mixed types of stimuli have to be interpreted with caution. Furthermore, we suggest implementing a blocked presentation format when presenting different feedback types within the same experiment. PMID:24144779

Negative feedback regulation of wild-type p53 biosynthesis.

PubMed Central

Mosner, J; Mummenbrauer, T; Bauer, C; Sczakiel, G; Grosse, F; Deppert, W

1995-01-01

When growth-arrested mouse fibroblasts re-entered the cell-cycle, the rise in tumour suppressor p53 mRNA level markedly preceded the rise in expression of the p53 protein. Furthermore, gamma-irradiation of such cells led to a rapid increase in p53 protein biosynthesis even in the presence of the transcription inhibitor actinomycin D. Both findings strongly suggest that p53 biosynthesis in these cells is regulated at the translational level. We present evidence for an autoregulatory control of p53 expression by a negative feed-back loop: p53 mRNA has a predicted tendency to form a stable stem-loop structure that involves the 5'-untranslated region (5'-UTR) plus some 280 nucleotides of the coding sequence. p53 binds tightly to the 5'-UTR region and inhibits the translation of its own mRNA, most likely mediated by the p53-intrinsic RNA re-annealing activity. The inhibition of p53 biosynthesis requires wild-type p53, as it is not observed with MethA mutant p53, p53-catalysed translational inhibition is selective; it might be restricted to p53 mRNA and a few other mRNAs that are able to form extensive stem-loop structures. Release from negative feed-back regulation of p53 biosynthesis, e.g. after damage-induced nuclear transport of p53, might provide a means for rapidly increasing p53 protein levels when p53 is required to act as a cell-cycle checkpoint determinant after DNA damage. Images PMID:7556087

The Human Ventromedial Frontal Lobe Is Critical for Learning from Negative Feedback

ERIC Educational Resources Information Center

Wheeler, Elizabeth Z.; Fellows, Lesley K.

2008-01-01

Are positive and negative feedback weighed in a common balance in the brain, or do they influence behaviour through distinct neural mechanisms? Recent neuroeconomic studies in both human and non-human primates indicate that the ventromedial frontal lobe carries information about both losses and gains, suggesting that this region may encode value…

Attention training through gaze-contingent feedback: Effects on reappraisal and negative emotions.

PubMed

Sanchez, Alvaro; Everaert, Jonas; Koster, Ernst H W

2016-10-01

Reappraisal is central to emotion regulation but its mechanisms are unclear. This study tested the theoretical prediction that emotional attention bias is linked to reappraisal of negative emotion-eliciting stimuli and subsequent emotional responding using a novel attentional control training. Thirty-six undergraduates were randomly assigned to either the control or the attention training condition and were provided with different task instructions while they performed an interpretation task. Whereas control participants freely created interpretations, participants in the training condition were instructed to allocate attention toward positive words to efficiently create positive interpretations (i.e., recruiting attentional control) while they were provided with gaze-contingent feedback on their viewing behavior. Transfer to attention bias and reappraisal success was evaluated using a dot-probe task and an emotion regulation task which were administered before and after the training. The training condition was effective at increasing attentional control and resulted in beneficial effects on the transfer tasks. Analyses supported a serial indirect effect with larger attentional control acquisition in the training condition leading to negative attention bias reduction, in turn predicting greater reappraisal success which reduced negative emotions. Our results indicate that attentional mechanisms influence the use of reappraisal strategies and its impact on negative emotions. The novel attention training highlights the importance of tailored feedback to train attentional control. The findings provide an important step toward personalized delivery of attention training. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Clustering and negative feedback by endocytosis in planar cell polarity signaling is modulated by ubiquitinylation of prickle.

PubMed

Cho, Bomsoo; Pierre-Louis, Gandhy; Sagner, Andreas; Eaton, Suzanne; Axelrod, Jeffrey D

2015-05-01

The core components of the planar cell polarity (PCP) signaling system, including both transmembrane and peripheral membrane associated proteins, form asymmetric complexes that bridge apical intercellular junctions. While these can assemble in either orientation, coordinated cell polarization requires the enrichment of complexes of a given orientation at specific junctions. This might occur by both positive and negative feedback between oppositely oriented complexes, and requires the peripheral membrane associated PCP components. However, the molecular mechanisms underlying feedback are not understood. We find that the E3 ubiquitin ligase complex Cullin1(Cul1)/SkpA/Supernumerary limbs(Slimb) regulates the stability of one of the peripheral membrane components, Prickle (Pk). Excess Pk disrupts PCP feedback and prevents asymmetry. We show that Pk participates in negative feedback by mediating internalization of PCP complexes containing the transmembrane components Van Gogh (Vang) and Flamingo (Fmi), and that internalization is activated by oppositely oriented complexes within clusters. Pk also participates in positive feedback through an unknown mechanism promoting clustering. Our results therefore identify a molecular mechanism underlying generation of asymmetry in PCP signaling.

Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

NASA Technical Reports Server (NTRS)

Farr, William H.

2009-01-01

Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

Dynamics of GnRH Neuron Ionotropic GABA and Glutamate Synaptic Receptors Are Unchanged during Estrogen Positive and Negative Feedback in Female Mice.

PubMed

Liu, Xinhuai; Porteous, Robert; Herbison, Allan E

2017-01-01

Inputs from GABAergic and glutamatergic neurons are suspected to play an important role in regulating the activity of the gonadotropin-releasing hormone (GnRH) neurons. The GnRH neurons exhibit marked plasticity to control the ovarian cycle with circulating estradiol concentrations having profound "feedback" effects on their activity. This includes "negative feedback" responsible for suppressing GnRH neuron activity and "positive feedback" that occurs at mid-cycle to activate the GnRH neurons to generate the preovulatory luteinizing hormone surge. In the present study, we employed brain slice electrophysiology to question whether synaptic ionotropic GABA and glutamate receptor signaling at the GnRH neuron changed at times of negative and positive feedback. We used a well characterized estradiol (E)-treated ovariectomized (OVX) mouse model to replicate negative and positive feedback. Miniature and spontaneous postsynaptic currents (mPSCs and sPSCs) attributable to GABA A and glutamatergic receptor signaling were recorded from GnRH neurons obtained from intact diestrous, OVX, OVX + E (negative feedback), and OVX + E+E (positive feedback) female mice. Approximately 90% of GnRH neurons exhibited spontaneous GABA A -mPSCs in all groups but no significant differences in the frequency or kinetics of mPSCs were found at the times of negative or positive feedback. Approximately 50% of GnRH neurons exhibited spontaneous glutamate mPSCs but again no differences were detected. The same was true for spontaneous PSCs in all cases. These observations indicate that the kinetics of ionotropic GABA and glutamate receptor synaptic transmission to GnRH neurons remain stable across the different estrogen feedback states.

The strength of negative plant-soil feedback increases from the intraspecific to the interspecific and the functional group level.

PubMed

Bukowski, Alexandra R; Schittko, Conrad; Petermann, Jana S

2018-02-01

One of the processes that may play a key role in plant species coexistence and ecosystem functioning is plant-soil feedback, the effect of plants on associated soil communities and the resulting feedback on plant performance. Plant-soil feedback at the interspecific level (comparing growth on own soil with growth on soil from different species) has been studied extensively, while plant-soil feedback at the intraspecific level (comparing growth on own soil with growth on soil from different accessions within a species) has only recently gained attention. Very few studies have investigated the direction and strength of feedback among different taxonomic levels, and initial results have been inconclusive, discussing phylogeny, and morphology as possible determinants. To test our hypotheses that the strength of negative feedback on plant performance increases with increasing taxonomic level and that this relationship is explained by morphological similarities, we conducted a greenhouse experiment using species assigned to three taxonomic levels (intraspecific, interspecific, and functional group level). We measured certain fitness-related aboveground traits and used them along literature-derived traits to determine the influence of morphological similarities on the strength and direction of the feedback. We found that the average strength of negative feedback increased from the intraspecific over the interspecific to the functional group level. However, individual accessions and species differed in the direction and strength of the feedback. None of our results could be explained by morphological dissimilarities or individual traits. Synthesis . Our results indicate that negative plant-soil feedback is stronger if the involved plants belong to more distantly related species. We conclude that the taxonomic level is an important factor in the maintenance of plant coexistence with plant-soil feedback as a potential stabilizing mechanism and should be addressed explicitly

Network Modeling Reveals Prevalent Negative Regulatory Relationships between Signaling Sectors in Arabidopsis Immune Signaling

PubMed Central

Sato, Masanao; Tsuda, Kenichi; Wang, Lin; Coller, John; Watanabe, Yuichiro; Glazebrook, Jane; Katagiri, Fumiaki

2010-01-01

Biological signaling processes may be mediated by complex networks in which network components and network sectors interact with each other in complex ways. Studies of complex networks benefit from approaches in which the roles of individual components are considered in the context of the network. The plant immune signaling network, which controls inducible responses to pathogen attack, is such a complex network. We studied the Arabidopsis immune signaling network upon challenge with a strain of the bacterial pathogen Pseudomonas syringae expressing the effector protein AvrRpt2 (Pto DC3000 AvrRpt2). This bacterial strain feeds multiple inputs into the signaling network, allowing many parts of the network to be activated at once. mRNA profiles for 571 immune response genes of 22 Arabidopsis immunity mutants and wild type were collected 6 hours after inoculation with Pto DC3000 AvrRpt2. The mRNA profiles were analyzed as detailed descriptions of changes in the network state resulting from the genetic perturbations. Regulatory relationships among the genes corresponding to the mutations were inferred by recursively applying a non-linear dimensionality reduction procedure to the mRNA profile data. The resulting static network model accurately predicted 23 of 25 regulatory relationships reported in the literature, suggesting that predictions of novel regulatory relationships are also accurate. The network model revealed two striking features: (i) the components of the network are highly interconnected; and (ii) negative regulatory relationships are common between signaling sectors. Complex regulatory relationships, including a novel negative regulatory relationship between the early microbe-associated molecular pattern-triggered signaling sectors and the salicylic acid sector, were further validated. We propose that prevalent negative regulatory relationships among the signaling sectors make the plant immune signaling network a “sector-switching” network, which

Negative emotions and behaviour: The role of regulatory emotional self-efficacy.

PubMed

Mesurado, Belén; Vidal, Elisabeth Malonda; Mestre, Anna Llorca

2018-04-01

The objective of this study is to test a longitudinal model that analyses the direct effect of negative emotions (anger, depression and anxiety, wave 1) on prosocial and aggressive behaviour (wave 2) in adolescents. And the indirect effect of negative emotions (wave 1) on prosocial and aggressive behaviour (wave 2) through regulatory emotional self-efficacy. Data was obtained from 417 adolescents in a two-wave longitudinal study (225 girls, M age = 14.70 years) from schools located in Valencia, Spain. SEM was employed to explore longitudinal models. The results showed that anger had a direct relationship with prosocial behaviour and aggression, measured two years later. However, the depression and anxiety states did not predict prosociality and aggressiveness. The mediation role of regulatory emotional self-efficacy between negative emotion and behaviours was only partially confirmed. Finally, only the perception of self-efficacy in expressing positive affect is related to prosociality and aggressiveness. Copyright © 2018 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

MEK-Dependent Negative Feedback Underlies BCR-ABL-Mediated Oncogene Addiction

PubMed Central

Asmussen, Jennifer; Lasater, Elisabeth A.; Tajon, Cheryl; Oses-Prieto, Juan; Jun, Young-wook; Taylor, Barry S.; Burlingame, Alma; Craik, Charles S.; Shah, Neil P.

2014-01-01

The clinical experience with BCR-ABL tyrosine kinase inhibitors (TKIs) for the treatment of chronic myeloid leukemia (CML) provides compelling evidence for oncogene addiction. Yet, the molecular basis of oncogene addiction remains elusive. Through unbiased quantitative phosphoproteomic analyses of CML cells transiently exposed to BCR-ABL TKI, we identified persistent downregulation of growth factor receptor (GF-R) signaling pathways. We then established and validated a tissue-relevant isogenic model of BCR-ABL-mediated addiction, and found evidence for myeloid GF-R signaling pathway rewiring that profoundly and persistently dampens physiologic pathway activation. We demonstrate that eventual restoration of ligand-mediated GF-R pathway activation is insufficient to fully rescue cells from a competing apoptotic fate. In contrast to previous work with BRAFV600E in melanoma cells, feedback inhibition following BCR-ABL TKI treatment is markedly prolonged, extending beyond the time required to initiate apoptosis. Mechanistically, BCR-ABL-mediated oncogene addiction is facilitated by persistent high levels of MEK-dependent negative feedback. PMID:24362263

Better Bet-Hedging with coupled positive and negative feedback loops

NASA Astrophysics Data System (ADS)

Narula, Jatin; Igoshin, Oleg

2011-03-01

Bacteria use the phenotypic heterogeneity associated with bistable switches to distribute the risk of activating stress response strategies like sporulation and persistence. However bistable switches offer little control over the timing of phenotype switching and first passage times (FPT) for individual cells are found to be exponentially distributed. We show that a genetic circuit consisting of interlinked positive and negative feedback loops allows cells to control the timing of phenotypic switching. Using a mathematical model we find that in this system a stable high expression state and stable low expression limit cycle coexist and the FPT distribution for stochastic transitions between them shows multiple peaks at regular intervals. A multimodal FPT distribution allows cells to detect the persistence of stress and control the rate of phenotype transition of the population. We further show that extracellular signals from cell-cell communication that change the strength of the feedback loops can modulate the FPT distribution and allow cells even greater control in a bet-hedging strategy.

Examination of a perceived cost model of employees' negative feedback-seeking behavior.

PubMed

Lu, Kuo-Ming; Pan, Su-Ying; Cheng, Jen-Wei

2011-01-01

The present study extends the feedback-seeking behavior literature by investigating how supervisor-related antecedents (i.e., supervisors' expert power, reflected appraisals of supervisors, and supervisors' emotional intelligence) influence subordinates' negative feedback-seeking behavior (NFSB) through different cost/value perceptions (i.e., expectancy value, self-presentation cost, and ego cost). Using data collected from 216 supervisor-subordinate dyads from various industries in Taiwan, we employ structural equation modeling analysis to test our hypotheses. The results show that expectancy value mediates the relationship between supervisor expert power and subordinates' NFSB. Moreover, self-presentation cost mediates the relationship between reflected appraisals of supervisors' and subordinates' NFSB. Theoretical and practical implications of this study are also discussed.

Blocked versus randomized presentation modes differentially modulate feedback-related negativity and P3b amplitudes.

PubMed

Pfabigan, Daniela M; Zeiler, Michael; Lamm, Claus; Sailer, Uta

2014-04-01

Electrophysiological studies on feedback processing typically use a wide range of feedback stimuli which might not always be comparable. The current study investigated whether two indicators of feedback processing - feedback-related negativity (FRN) and P3b - differ for feedback stimuli with explicit (facial expressions) or assigned valence information (symbols). In addition, we assessed whether presenting feedback in either a trial-by-trial or a block-wise fashion affected these ERPs. EEG was recorded in three experiments while participants performed a time estimation task and received two different types of performance feedback. Only P3b amplitudes varied consistently in response to feedback type for both presentation types. Moreover, the blocked feedback type presentation yielded more distinct FRN peaks, higher effect sizes, and a significant relation between FRN amplitudes and behavioral task performance measures. Both stimulus type and presentation mode may provoke systematic changes in feedback-related ERPs. The current findings point at important potential confounds that need to be controlled for when designing FRN or P3b studies. Studies investigating P3b amplitudes using mixed types of stimuli have to be interpreted with caution. Furthermore, we suggest implementing a blocked presentation format when presenting different feedback types within the same experiment. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

A noninvasive measure of negative-feedback strength, approximate entropy, unmasks strong diurnal variations in the regularity of LH secretion.

PubMed

Liu, Peter Y; Iranmanesh, Ali; Keenan, Daniel M; Pincus, Steven M; Veldhuis, Johannes D

2007-11-01

The secretion of anterior-pituitary hormones is subject to negative feedback. Whether negative feedback evolves dynamically over 24 h is not known. Conventional experimental paradigms to test this concept may induce artifacts due to nonphysiological feedback. These limitations might be overcome by a noninvasive methodology to quantify negative feedback continuously over 24 h without disrupting the axis. The present study exploits a recently validated model-free regularity statistic, approximate entropy (ApEn), which monitors feedback changes with high sensitivity and specificity (both >90%; Pincus SM, Hartman ML, Roelfsema F, Thorner MO, Veldhuis JD. Am J Physiol Endocrinol Metab 273: E948-E957, 1999). A time-incremented moving window of ApEn was applied to LH time series obtained by intensive (10-min) blood sampling for four consecutive days (577 successive measurements) in each of eight healthy men. Analyses unveiled marked 24-h variations in ApEn with daily maxima (lowest feedback) at 1100 +/- 1.7 h (mean +/- SE) and minima (highest feedback) at 0430 +/- 1.9 h. The mean difference between maximal and minimal 24-h LH ApEn was 0.348 +/- 0.018, which differed by P < 0.001 from all three of randomly shuffled versions of the same LH time series, simulated pulsatile data and assay noise. Analyses artificially limited to 24-h rather than 96-h data yielded reproducibility coefficients of 3.7-9.0% for ApEn maxima and minima. In conclusion, a feedback-sensitive regularity statistic unmasks strong and consistent 24-h rhythmicity of the orderliness of unperturbed pituitary-hormone secretion. These outcomes suggest that ApEn may have general utility in probing dynamic mechanisms mediating feedback in other endocrine systems.

Feedback-related negativity is enhanced in adolescence during a gambling task with and without probabilistic reinforcement learning.

PubMed

Martínez-Velázquez, Eduardo S; Ramos-Loyo, Julieta; González-Garrido, Andrés A; Sequeira, Henrique

2015-01-21

Feedback-related negativity (FRN) is a negative deflection that appears around 250 ms after the gain or loss of feedback to chosen alternatives in a gambling task in frontocentral regions following outcomes. Few studies have reported FRN enhancement in adolescents compared with adults in a gambling task without probabilistic reinforcement learning, despite the fact that learning from positive or negative consequences is crucial for decision-making during adolescence. Therefore, the aim of the present research was to identify differences in FRN amplitude and latency between adolescents and adults on a gambling task with favorable and unfavorable probabilistic reinforcement learning conditions, in addition to a nonlearning condition with monetary gains and losses. Higher rate scores of high-magnitude choices during the final 30 trials compared with the first 30 trials were observed during the favorable condition, whereas lower rates were observed during the unfavorable condition in both groups. Higher FRN amplitude in all conditions and longer latency in the nonlearning condition were observed in adolescents compared with adults and in relation to losses. Results indicate that both the adolescents and the adults improved their performance in relation to positive and negative feedback. However, the FRN findings suggest an increased sensitivity to external feedback to losses in adolescents compared with adults, irrespective of the presence or absence of probabilistic reinforcement learning. These results reflect processing differences on the neural monitoring system and provide new perspectives on the dynamic development of an adolescent's brain.

Glucocorticoid and cytokine crosstalk: Feedback, feedforward, and co-regulatory interactions determine repression or resistance

PubMed Central

Shah, Suharsh; Altonsy, Mohammed O.; Gerber, Antony N.

2017-01-01

Inflammatory signals induce feedback and feedforward systems that provide temporal control. Although glucocorticoids can repress inflammatory gene expression, glucocorticoid receptor recruitment increases expression of negative feedback and feedforward regulators, including the phosphatase, DUSP1, the ubiquitin-modifying enzyme, TNFAIP3, or the mRNA-destabilizing protein, ZFP36. Moreover, glucocorticoid receptor cooperativity with factors, including nuclear factor-κB (NF-κB), may enhance regulator expression to promote repression. Conversely, MAPKs, which are inhibited by glucocorticoids, provide feedforward control to limit expression of the transcription factor IRF1, and the chemokine, CXCL10. We propose that modulation of feedback and feedforward control can determine repression or resistance of inflammatory gene expression toglucocorticoid. PMID:28283576

Don't judge me: Psychophysiological evidence of gender differences to social evaluative feedback.

PubMed

Vanderhasselt, Marie-Anne; De Raedt, Rudi; Nasso, Selene; Puttevils, Louise; Mueller, Sven C

2018-05-01

Human beings have a basic need for esteemed social connections, and receiving negative self-evaluative feedback induces emotional distress. The aim of the current study is to measure eye movements (a physiological marker of attention allocation) and pupillary responses (a physiological marker of cognitive and emotional processing) as online and objective indices of participants' reaction to positive/negative social evaluations from the same or opposite sex. Following the paradigm, subjective mood ratings and heart rate variability (HRV) - as an objective index of regulatory effort- were measured. Results demonstrate clear gender-specific results in all measures. Eye-movements demonstrate that male participants respond more with other-focused attention (and specifically to male participants), whereas women respond more with self-focused attention following negative social evaluative feedback. Pupillary responses show that social evaluative feedback is specifically eliciting cognitive/affective processes in male participants to regulate emotional responses when provided by the opposite gender. Finally, following the paradigm, female (as compared to male) participants were more subjectively reactive to the paradigm (i.e., self-reports), and were less able to engage contextual- and goal related regulatory control of emotional responses (reduced HRV). Although the current study focused on psychiatrically healthy young adults, results may contribute to our understanding of sex differences in internalizing mental problems, such as rumination. Copyright © 2018 Elsevier B.V. All rights reserved.

Response to "The Iris Hypothesis: A Negative or Positive Cloud Feedback?"

NASA Technical Reports Server (NTRS)

Chou, Ming-Dah; Lindzen, Richard S.; Hou, Arthur Y.; Lau, William K. M. (Technical Monitor)

2001-01-01

Based on radiance measurements of Japan's Geostationary Meteorological Satellite, Lindzen et al. found that the high-level cloud cover averaged over the tropical western Pacific decreases with increasing sea surface temperature. They further found that the response of high-level clouds to the sea surface temperature had an effect of reducing the magnitude of climate change, which is referred as a negative climate feedback. Lin et al. reassessed the results found by Lindzen et al. by analyzing the radiation and clouds derived from the Tropical Rainfall Measuring Mission Clouds and the Earth's Radiant Energy System measurements. They found a weak positive feedback between high-level clouds and the surface temperature. We have found that the approach taken by Lin et al. to estimating the albedo and the outgoing longwave radiation is incorrect and that the inferred climate sensitivity is unreliable.

Feedback regulation in a stem cell model with acute myeloid leukaemia.

PubMed

Jiao, Jianfeng; Luo, Min; Wang, Ruiqi

2018-04-24

The haematopoietic lineages with leukaemia lineages are considered in this paper. In particular, we mainly consider that haematopoietic lineages are tightly controlled by negative feedback inhibition of end-product. Actually, leukemia has been found 100 years ago. Up to now, the exact mechanism is still unknown, and many factors are thought to be associated with the pathogenesis of leukemia. Nevertheless, it is very necessary to continue the profound study of the pathogenesis of leukemia. Here, we propose a new mathematical model which include some negative feedback inhibition from the terminally differentiated cells of haematopoietic lineages to the haematopoietic stem cells and haematopoietic progenitor cells in order to describe the regulatory mechanisms mentioned above by a set of ordinary differential equations. Afterwards, we carried out detailed dynamical bifurcation analysis of the model, and obtained some meaningful results. In this work, we mainly perform the analysis of the mathematic model by bifurcation theory and numerical simulations. We have not only incorporated some new negative feedback mechanisms to the existing model, but also constructed our own model by using the modeling method of stem cell theory with probability method. Through a series of qualitative analysis and numerical simulations, we obtain that the weak negative feedback for differentiation probability is conducive to the cure of leukemia. However, with the strengthening of negative feedback, leukemia will be more difficult to be cured, and even induce death. In contrast, strong negative feedback for differentiation rate of progenitor cells can promote healthy haematopoiesis and suppress leukaemia. These results demonstrate that healthy progenitor cells are bestowed a competitive advantage over leukaemia stem cells. Weak g 1 , g 2 , and h 1 enable the system stays in the healthy state. However, strong h 2 can promote healthy haematopoiesis and suppress leukaemia.

Global attractivity of non-autonomous Lotka-Volterra competition system without instantaneous negative feedback

NASA Astrophysics Data System (ADS)

Tang, X. H.; Zou, Xingfu

We consider a non-autonomous Lotka-Volterra competition system with distributed delays but without instantaneous negative feedbacks (i.e., pure delay systems). We establish some 3/2-type and M-matrix-type criteria for global attractivity of the positive equilibrium of the system, which generalise and improve the existing ones.

Quantifying the Negative Feedback of Vegetation to Greenhouse Warming: A Modeling Approach

NASA Technical Reports Server (NTRS)

Bounous, L.; Hall, F. G.; Sellers, P. J.; Kumar, A.; Collatz, G. J.; Tucker, C. J.; Imhoff, M. L.

2010-01-01

Several climate models indicate that in a 2 x CO2 environment, temperature and precipitation would increase and runoff would increase faster than precipitation. These models, however, did not allow the vegetation to increase its leaf density as a response to the physiological effects of increased CO2 and consequent changes in climate. Other assessments included these interactions but did not account for the vegetation down-regulation to reduce plant's photosynthetic activity and as such resulted in a weak vegetation negative response. When we combine these interactions in climate simulations with 2 x CO2, the associated increase in precipitation contributes primarily to increase evapotranspiration rather than surface runoff, consistent with observations, and results in an additional cooling effect not fully accounted for in previous simulations with elevated CO2. By accelerating the water cycle, this feedback slows but does not alleviate the projected warming, reducing the land surface warming by 0.6 C. Compared to previous studies, these results imply that long term negative feedback from CO2-induced increases in vegetation density could reduce temperature following a stabilization of CO2 concentration.

Neural correlates of preparatory and regulatory control over positive and negative emotion.

PubMed

Seo, Dongju; Olman, Cheryl A; Haut, Kristen M; Sinha, Rajita; MacDonald, Angus W; Patrick, Christopher J

2014-04-01

This study used functional magnetic resonance imaging to investigate brain activation during preparatory and regulatory control while participants (N = 24) were instructed either to simply view or decrease their emotional response to, pleasant, neutral or unpleasant pictures. A main effect of emotional valence on brain activity was found in the right precentral gyrus, with greater activation during positive than negative emotion regulation. A main effect of regulation phase was evident in the bilateral anterior prefrontal cortex (PFC), precuneus, posterior cingulate cortex, right putamen and temporal and occipital lobes, with greater activity in these regions during preparatory than regulatory control. A valence X regulation interaction was evident in regions of ventromedial PFC and anterior cingulate cortex, reflecting greater activation while regulating negative than positive emotion, but only during active emotion regulation (not preparation). Conjunction analyses revealed common brain regions involved in differing types of emotion regulation including selected areas of left lateral PFC, inferior parietal lobe, temporal lobe, right cerebellum and bilateral dorsomedial PFC. The right lateral PFC was additionally activated during the modulation of both positive and negative valence. Findings demonstrate significant modulation of brain activity during both preparation for, and active regulation of positive and negative emotional states.

Glucocorticoid and cytokine crosstalk: Feedback, feedforward, and co-regulatory interactions determine repression or resistance.

PubMed

Newton, Robert; Shah, Suharsh; Altonsy, Mohammed O; Gerber, Antony N

2017-04-28

Inflammatory signals induce feedback and feedforward systems that provide temporal control. Although glucocorticoids can repress inflammatory gene expression, glucocorticoid receptor recruitment increases expression of negative feedback and feedforward regulators, including the phosphatase, DUSP1, the ubiquitin-modifying enzyme, TNFAIP3, or the mRNA-destabilizing protein, ZFP36. Moreover, glucocorticoid receptor cooperativity with factors, including nuclear factor-κB (NF-κB), may enhance regulator expression to promote repression. Conversely, MAPKs, which are inhibited by glucocorticoids, provide feedforward control to limit expression of the transcription factor IRF1, and the chemokine, CXCL10. We propose that modulation of feedback and feedforward control can determine repression or resistance of inflammatory gene expression toglucocorticoid. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Can we bet on negative emissions to achieve the 2°C target even under strong carbon cycle feedbacks?

NASA Astrophysics Data System (ADS)

Tanaka, K.; Yamagata, Y.; Yokohata, T.; Emori, S.; Hanaoka, T.

2015-12-01

Negative emission technologies such as Bioenergy with Carbon dioxide Capture and Storage (BioCCS) play an ever more crucial role in meeting the 2°C stabilization target. However, such technologies are currently at their infancy and their future penetrations may fall short of the scale required to stabilize the warming. Furthermore, the overshoot in the mid-century prior to a full realization of negative emissions would give rise to a risk because such a temporal but excessive warming above 2°C might amplify itself by strengthening climate-carbon cycle feedbacks. It has not been extensively assessed yet how carbon cycle feedbacks might play out during the overshoot in the context of negative emissions. This study explores how 2°C stabilization pathways, in particular those which undergo overshoot, can be influenced by carbon cycle feedbacks and asks their climatic and economic consequences. We compute 2°C stabilization emissions scenarios under a cost-effectiveness principle, in which the total abatement costs are minimized such that the global warming is capped at 2°C. We employ a reduced-complexity model, the Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate model (ACC2), which comprises a box model of the global carbon cycle, simple parameterizations of the atmospheric chemistry, and a land-ocean energy balance model. The total abatement costs are estimated from the marginal abatement cost functions for CO2, CH4, N2O, and BC.Our preliminary results show that, if carbon cycle feedbacks turn out to be stronger than what is known today, it would incur substantial abatement costs to keep up with the 2°C stabilization goal. Our results also suggest that it would be less expensive in the long run to plan for a 2°C stabilization pathway by considering strong carbon cycle feedbacks because it would cost more if we correct the emission pathway in the mid-century to adjust for unexpectedly large carbon cycle feedbacks during overshoot. Furthermore, our

A Negative-Feedback Loop between the Detoxification/Antioxidant Response Factor SKN-1 and Its Repressor WDR-23 Matches Organism Needs with Environmental Conditions

PubMed Central

Leung, Chi K.; Wang, Ying; Deonarine, Andrew; Tang, Lanlan; Prasse, Stephanie

2013-01-01

Negative-feedback loops between transcription factors and repressors in responses to xenobiotics, oxidants, heat, hypoxia, DNA damage, and infection have been described. Although common, the function of feedback is largely unstudied. Here, we define a negative-feedback loop between the Caenorhabditis elegans detoxification/antioxidant response factor SKN-1/Nrf and its repressor wdr-23 and investigate its function in vivo. Although SKN-1 promotes stress resistance and longevity, we find that tight regulation by WDR-23 is essential for growth and reproduction. By disabling SKN-1 transactivation of wdr-23, we reveal that feedback is required to set the balance between growth/reproduction and stress resistance/longevity. We also find that feedback is required to set the sensitivity of a core SKN-1 target gene to an electrophile. Interestingly, the effect of feedback on target gene induction is greatly reduced when the stress response is strongly activated, presumably to ensure maximum activation of cytoprotective genes during potentially fatal conditions. Our work provides a framework for understanding the function of negative feedback in inducible stress responses and demonstrates that manipulation of feedback alone can shift the balance of competing animal processes toward cell protection, health, and longevity. PMID:23836880

Risky decision making from childhood through adulthood: Contributions of learning and sensitivity to negative feedback.

PubMed

Humphreys, Kathryn L; Telzer, Eva H; Flannery, Jessica; Goff, Bonnie; Gabard-Durnam, Laurel; Gee, Dylan G; Lee, Steve S; Tottenham, Nim

2016-02-01

Decision making in the context of risk is a complex and dynamic process that changes across development. Here, we assessed the influence of sensitivity to negative feedback (e.g., loss) and learning on age-related changes in risky decision making, both of which show unique developmental trajectories. In the present study, we examined risky decision making in 216 individuals, ranging in age from 3-26 years, using the balloon emotional learning task (BELT), a computerized task in which participants pump up a series of virtual balloons to earn points, but risk balloon explosion on each trial, which results in no points. It is important to note that there were 3 balloon conditions, signified by different balloon colors, ranging from quick- to slow-to-explode, and participants could learn the color-condition pairings through task experience. Overall, we found age-related increases in pumps made and points earned. However, in the quick-to-explode condition, there was a nonlinear adolescent peak for points earned. Follow-up analyses indicated that this adolescent phenotype occurred at the developmental intersection of linear age-related increases in learning and decreases in sensitivity to negative feedback. Adolescence was marked by intermediate values on both these processes. These findings show that a combination of linearly changing processes can result in nonlinear changes in risky decision making, the adolescent-specific nature of which is associated with developmental improvements in learning and reduced sensitivity to negative feedback. (c) 2016 APA, all rights reserved).

Depression-related difficulties disengaging from negative faces are associated with sustained attention to negative feedback during social evaluation and predict stress recovery

PubMed Central

Romero, Nuria; De Raedt, Rudi

2017-01-01

The present study aimed to clarify: 1) the presence of depression-related attention bias related to a social stressor, 2) its association with depression-related attention biases as measured under standard conditions, and 3) their association with impaired stress recovery in depression. A sample of 39 participants reporting a broad range of depression levels completed a standard eye-tracking paradigm in which they had to engage/disengage their gaze with/from emotional faces. Participants then underwent a stress induction (i.e., giving a speech), in which their eye movements to false emotional feedback were measured, and stress reactivity and recovery were assessed. Depression level was associated with longer times to engage/disengage attention with/from negative faces under standard conditions and with sustained attention to negative feedback during the speech. These depression-related biases were associated and mediated the association between depression level and self-reported stress recovery, predicting lower recovery from stress after giving the speech. PMID:28362826

Mean field analysis of a spatial stochastic model of a gene regulatory network.

PubMed

Sturrock, M; Murray, P J; Matzavinos, A; Chaplain, M A J

2015-10-01

A gene regulatory network may be defined as a collection of DNA segments which interact with each other indirectly through their RNA and protein products. Such a network is said to contain a negative feedback loop if its products inhibit gene transcription, and a positive feedback loop if a gene product promotes its own production. Negative feedback loops can create oscillations in mRNA and protein levels while positive feedback loops are primarily responsible for signal amplification. It is often the case in real biological systems that both negative and positive feedback loops operate in parameter regimes that result in low copy numbers of gene products. In this paper we investigate the spatio-temporal dynamics of a single feedback loop in a eukaryotic cell. We first develop a simplified spatial stochastic model of a canonical feedback system (either positive or negative). Using a Gillespie's algorithm, we compute sample trajectories and analyse their corresponding statistics. We then derive a system of equations that describe the spatio-temporal evolution of the stochastic means. Subsequently, we examine the spatially homogeneous case and compare the results of numerical simulations with the spatially explicit case. Finally, using a combination of steady-state analysis and data clustering techniques, we explore model behaviour across a subregion of the parameter space that is difficult to access experimentally and compare the parameter landscape of our spatio-temporal and spatially-homogeneous models.

The Effect of Positive and Negative Feedback on Risk-Taking across Different Contexts.

PubMed

Losecaat Vermeer, Annabel B; Sanfey, Alan G

2015-01-01

Preferences for risky choices have often been shown to be unstable and context-dependent. Though people generally avoid gambles with mixed outcomes, a phenomenon often attributed to loss aversion, contextual factors can impact this dramatically. For example, people typically prefer risky options after a financial loss, while generally choosing safer options after a monetary gain. However, it is unclear what exactly contributes to these preference shifts as a function of prior outcomes, as these gain/loss outcomes are usually confounded with participant performance, and therefore it is unclear whether these effects are driven purely by the monetary gains or losses, or rather by success or failure at the actual task. Here, we experimentally separated the effects of monetary gains/losses from performance success/failure prior to a standard risky choice. Participants performed a task in which they experienced contextual effects: 1) monetary gain or loss based directly on performance, 2) monetary gain or loss that was randomly awarded and was, crucially, independent from performance, and 3) success or failure feedback based on performance, but without any monetary incentive. Immediately following these positive/negative contexts, participants were presented with a gain-loss gamble that they had to decide to either play or pass. We found that risk preferences for identical sets of gambles were biased by positive and negative contexts containing monetary gains and losses, but not by contexts containing performance feedback. This data suggests that the observed framing effects are driven by aversion for monetary losses and not simply by the positive or negative valence of the context, or by potential moods resulting from positive or negative contexts. These results highlight the specific context dependence of risk preferences.

Early Detection of Online Auction Opportunistic Sellers through the Use of Negative-Positive Feedback

ERIC Educational Resources Information Center

Reinert, Gregory J.

2010-01-01

Apparently fraud is a growth industry. The monetary losses from Internet fraud have increased every year since first officially reported by the Internet Crime Complaint Center (IC3) in 2000. Prior research studies and third-party reports of fraud show rates substantially higher than eBay's reported negative feedback rate of less than 1%. The…

Negative plant soil feedback explaining ring formation in clonal plants.

PubMed

Cartenì, Fabrizio; Marasco, Addolorata; Bonanomi, Giuliano; Mazzoleni, Stefano; Rietkerk, Max; Giannino, Francesco

2012-11-21

Ring shaped patches of clonal plants have been reported in different environments, but the mechanisms underlying such pattern formation are still poorly explained. Water depletion in the inner tussocks zone has been proposed as a possible cause, although ring patterns have been also observed in ecosystems without limiting water conditions. In this work, a spatially explicit model is presented in order to investigate the role of negative plant-soil feedback as an additional explanation for ring formation. The model describes the dynamics of the plant biomass in the presence of toxicity produced by the decomposition of accumulated litter in the soil. Our model qualitatively reproduces the emergence of ring patterns of a single clonal plant species during colonisation of a bare substrate. The model admits two homogeneous stationary solutions representing bare soil and uniform vegetation cover which depend only on the ratio between the biomass death and growth rates. Moreover, differently from other plant spatial patterns models, but in agreement with real field observations of vegetation dynamics, we demonstrated that the pattern dynamics always lead to spatially homogeneous vegetation covers without creation of stable Turing patterns. Analytical results show that ring formation is a function of two main components, the plant specific susceptibility to toxic compounds released in the soil by the accumulated litter and the decay rate of these same compounds, depending on environmental conditions. These components act at the same time and their respective intensities can give rise to the different ring structures observed in nature, ranging from slight reductions of biomass in patch centres, to the appearance of marked rings with bare inner zones, as well as the occurrence of ephemeral waves of plant cover. Our results highlight the potential role of plant-soil negative feedback depending on decomposition processes for the development of transient vegetation patterns

Inhibin may be involved in negative feedback in the prairie dog (Cynomys ludovicianus).

PubMed

Foreman, Darhl

2007-02-01

The changes in inhibin immunostaining in the gonads during the annual reproductive cycle of both sexes of the prairie dog are described. No inhibin immunostaining was found in primary or secondary follicles of the ovary. Theca and granulosa cells of preovulatory Graafian follicles found in January and February stained for inhibin. Corpora lutea of both pregnant and non-pregnant females stain more densely for inhibin than follicles. Inhibin staining is present in luteal cells for at least 4 months during regression, longer than detectable progesterone is secreted. Sertoli cells in the testes do not have inhibin immunostaining during recrudescence. These cells show light immunostain for inhibin during peak spermatogenic activity in January and February but stain more deeply during early regression of the testis. Stain is gradually lost in the next 4-5 months as the tubules close. Leydig cells and germ cells do not stain for inhibin at any stage of the annual cycle but interstitial cells and tunic cells stain during the breeding phase. The presence of immunochemical staining for inhibin in prairie dog gonads during regression suggests that inhibin is part of a negative feedback complex that includes progesterone in the female and testosterone or another androgen in the male. Negative feedback during regression may also cause gonadal inactivity.

A minimal mathematical model combining several regulatory cycles from the budding yeast cell cycle.

PubMed

Sriram, K; Bernot, G; Képès, F

2007-11-01

A novel topology of regulatory networks abstracted from the budding yeast cell cycle is studied by constructing a simple nonlinear model. A ternary positive feedback loop with only positive regulations is constructed with elements that activates the subsequent element in a clockwise fashion. A ternary negative feedback loop with only negative regulations is constructed with the elements that inhibit the subsequent element in an anticlockwise fashion. Positive feedback loop exhibits bistability, whereas the negative feedback loop exhibits limit cycle oscillations. The novelty of the topology is that the corresponding elements in these two homogeneous feedback loops are linked by the binary positive feedback loops with only positive regulations. This results in the emergence of mixed feedback loops in the network that displays complex behaviour like the coexistence of multiple steady states, relaxation oscillations and chaos. Importantly, the arrangement of the feedback loops brings in the notion of checkpoint in the model. The model also exhibits domino-like behaviour, where the limit cycle oscillations take place in a stepwise fashion. As the aforementioned topology is abstracted from the budding yeast cell cycle, the events that govern the cell cycle are considered for the present study. In budding yeast, the sequential activation of the transcription factors, cyclins and their inhibitors form mixed feedback loops. The transcription factors that involve in the positive regulation in a clockwise orientation generates ternary positive feedback loop, while the cyclins and their inhibitors that involve in the negative regulation in an anticlockwise orientation generates ternary negative feedback loop. The mutual regulation between the corresponding elements in the transcription factors and the cyclins and their inhibitors generates binary positive feedback loops. The bifurcation diagram constructed for the whole system can be related to the different events of the

Using Feedback to Promote Physical Activity: The Role of the Feedback Sign

PubMed Central

Kramer, Jan-Niklas

2017-01-01

Background Providing feedback is a technique to promote health behavior that is emphasized by behavior change theories. However, these theories make contradicting predictions regarding the effect of the feedback sign—that is, whether the feedback signals success or failure. Thus, it is unclear whether positive or negative feedback leads to more favorable behavior change in a health behavior intervention. Objective The aim of this study was to examine the effect of the feedback sign in a health behavior change intervention. Methods Data from participants (N=1623) of a 6-month physical activity intervention was used. Participants received a feedback email at the beginning of each month. Feedback was either positive or negative depending on the participants’ physical activity in the previous month. In an exploratory analysis, change in monthly step count averages was used to evaluate the feedback effect. Results The feedback sign did not predict the change in monthly step count averages over the course of the intervention (b=−84.28, P=.28). Descriptive differences between positive and negative feedback can be explained by regression to the mean. Conclusions The feedback sign might not influence the effect of monthly feedback emails sent out to participants of a large-scale physical activity intervention. However, randomized studies are needed to further support this conclusion. Limitations as well as opportunities for future research are discussed. PMID:28576757

Repression of enhancer II activity by a negative regulatory element in the hepatitis B virus genome.

PubMed Central

Lo, W Y; Ting, L P

1994-01-01

Enhancer II of human hepatitis B virus has dual functions in vivo. Located at nucleotides (nt) 1646 to 1741, it can stimulate the surface and X promoters from a downstream position. Moreover, the same sequence can also function as upstream regulatory element that activates the core promoter in a position- and orientation-dependent manner. In this study, we report the identification and characterization of a negative regulatory element (NRE) upstream of enhancer II (nt 1613 to 1636) which can repress both the enhancer and upstream stimulatory function of the enhancer II sequence in differentiated liver cells. This NRE has marginal inhibitory effect by itself but a strong repressive function in the presence of a functional enhancer II. Mutational analysis reveals that sequence from nt 1616 to 1621 is required for repression of enhancer activity by the NRE. Gel shift analysis reveals that this negative regulatory region can be recognized by a specific protein factor(s) present at the 0.4 M NaCl fraction of HepG2 nuclear extracts. The discovery of the NRE indicates that HBV gene transcription is controlled by combined effects of both positive and negative regulation. It also provides a unique system with which to study the mechanism of negative regulation of gene expression. Images PMID:8107237

The magnitude and colour of noise in genetic negative feedback systems.

PubMed

Voliotis, Margaritis; Bowsher, Clive G

2012-08-01

The comparative ability of transcriptional and small RNA-mediated negative feedback to control fluctuations or 'noise' in gene expression remains unexplored. Both autoregulatory mechanisms usually suppress the average (mean) of the protein level and its variability across cells. The variance of the number of proteins per molecule of mean expression is also typically reduced compared with the unregulated system, but is almost never below the value of one. This relative variance often substantially exceeds a recently obtained, theoretical lower limit for biochemical feedback systems. Adding the transcriptional or small RNA-mediated control has different effects. Transcriptional autorepression robustly reduces both the relative variance and persistence (lifetime) of fluctuations. Both benefits combine to reduce noise in downstream gene expression. Autorepression via small RNA can achieve more extreme noise reduction and typically has less effect on the mean expression level. However, it is often more costly to implement and is more sensitive to rate parameters. Theoretical lower limits on the relative variance are known to decrease slowly as a measure of the cost per molecule of mean expression increases. However, the proportional increase in cost to achieve substantial noise suppression can be different away from the optimal frontier-for transcriptional autorepression, it is frequently negligible.

The magnitude and colour of noise in genetic negative feedback systems

PubMed Central

Voliotis, Margaritis; Bowsher, Clive G.

2012-01-01

The comparative ability of transcriptional and small RNA-mediated negative feedback to control fluctuations or ‘noise’ in gene expression remains unexplored. Both autoregulatory mechanisms usually suppress the average (mean) of the protein level and its variability across cells. The variance of the number of proteins per molecule of mean expression is also typically reduced compared with the unregulated system, but is almost never below the value of one. This relative variance often substantially exceeds a recently obtained, theoretical lower limit for biochemical feedback systems. Adding the transcriptional or small RNA-mediated control has different effects. Transcriptional autorepression robustly reduces both the relative variance and persistence (lifetime) of fluctuations. Both benefits combine to reduce noise in downstream gene expression. Autorepression via small RNA can achieve more extreme noise reduction and typically has less effect on the mean expression level. However, it is often more costly to implement and is more sensitive to rate parameters. Theoretical lower limits on the relative variance are known to decrease slowly as a measure of the cost per molecule of mean expression increases. However, the proportional increase in cost to achieve substantial noise suppression can be different away from the optimal frontier—for transcriptional autorepression, it is frequently negligible. PMID:22581772

Blowin' in the Wind: Both "Negative" and "Positive" Feedback in an Obscured High-z Quasar

NASA Astrophysics Data System (ADS)

Cresci, G.; Mainieri, V.; Brusa, M.; Marconi, A.; Perna, M.; Mannucci, F.; Piconcelli, E.; Maiolino, R.; Feruglio, C.; Fiore, F.; Bongiorno, A.; Lanzuisi, G.; Merloni, A.; Schramm, M.; Silverman, J. D.; Civano, F.

2015-01-01

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, preventing massive galaxies to overgrow and producing the red colors of ellipticals. On the other hand, some models are also requiring "positive" active galactic nucleus feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively driven winds are available. Here we present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z = 1.59 QSO detected in the XMM-COSMOS survey, in which we clearly resolve a fast (1500 km s-1) and extended (up to 13 kpc from the black hole) outflow in the [O III] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U-band flux from Hubble Space Telescope/Advanced Camera for Surveys imaging enable to map the current star formation in the host galaxy: both tracers independently show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy ("negative feedback"), but also triggering star formation by outflow induced pressure at the edges ("positive feedback"). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.

Neural correlates of experienced moral emotion: an fMRI investigation of emotion in response to prejudice feedback.

PubMed

Fourie, Melike M; Thomas, Kevin G F; Amodio, David M; Warton, Christopher M R; Meintjes, Ernesta M

2014-01-01

Guilt, shame, and embarrassment are quintessential moral emotions with important regulatory functions for the individual and society. Moral emotions are, however, difficult to study with neuroimaging methods because their elicitation is more intricate than that of basic emotions. Here, using functional MRI (fMRI), we employed a novel social prejudice paradigm to examine specific brain regions associated with real-time moral emotion, focusing on guilt and related moral-negative emotions. The paradigm induced intense moral-negative emotion (primarily guilt) in 22 low-prejudice individuals through preprogrammed feedback indicating implicit prejudice against Black and disabled people. fMRI data indicated that this experience of moral-negative emotion was associated with increased activity in anterior paralimbic structures, including the anterior cingulate cortex (ACC) and anterior insula, in addition to areas associated with mentalizing, including the dorsomedial prefrontal cortex, posterior cingulate cortex, and precuneus. Of significance was prominent conflict-related activity in the supragenual ACC, which is consistent with theories proposing an association between acute guilt and behavioral inhibition. Finally, a significant negative association between self-reported guilt and neural activity in the pregenual ACC suggested a role of self-regulatory processes in response to moral-negative affect. These findings are consistent with the multifaceted self-regulatory functions of moral-negative emotions in social behavior.

Alternative Polyadenylation Allows Differential Negative Feedback of Human miRNA miR-579 on Its Host Gene ZFR

PubMed Central

Hinske, Ludwig Christian; Galante, Pedro A. F.; Limbeck, Elisabeth; Möhnle, Patrick; Parmigiani, Raphael B.; Ohno-Machado, Lucila; Camargo, Anamaria A.; Kreth, Simone

2015-01-01

About half of the known miRNA genes are located within protein-coding host genes, and are thus subject to co-transcription. Accumulating data indicate that this coupling may be an intrinsic mechanism to directly regulate the host gene’s expression, constituting a negative feedback loop. Inevitably, the cell requires a yet largely unknown repertoire of methods to regulate this control mechanism. We propose APA as one possible mechanism by which negative feedback of intronic miRNA on their host genes might be regulated. Using in-silico analyses, we found that host genes that contain seed matching sites for their intronic miRNAs yield longer 32UTRs with more polyadenylation sites. Additionally, the distribution of polyadenylation signals differed significantly between these host genes and host genes of miRNAs that do not contain potential miRNA binding sites. We then transferred these in-silico results to a biological example and investigated the relationship between ZFR and its intronic miRNA miR-579 in a U87 cell line model. We found that ZFR is targeted by its intronic miRNA miR-579 and that alternative polyadenylation allows differential targeting. We additionally used bioinformatics analyses and RNA-Seq to evaluate a potential cross-talk between intronic miRNAs and alternative polyadenylation. CPSF2, a gene previously associated with alternative polyadenylation signal recognition, might be linked to intronic miRNA negative feedback by altering polyadenylation signal utilization. PMID:25799583

Relaxation oscillations and hierarchy of feedbacks in MAPK signaling

NASA Astrophysics Data System (ADS)

Kochańczyk, Marek; Kocieniewski, Paweł; Kozłowska, Emilia; Jaruszewicz-Błońska, Joanna; Sparta, Breanne; Pargett, Michael; Albeck, John G.; Hlavacek, William S.; Lipniacki, Tomasz

2017-01-01

We formulated a computational model for a MAPK signaling cascade downstream of the EGF receptor to investigate how interlinked positive and negative feedback loops process EGF signals into ERK pulses of constant amplitude but dose-dependent duration and frequency. A positive feedback loop involving RAS and SOS, which leads to bistability and allows for switch-like responses to inputs, is nested within a negative feedback loop that encompasses RAS and RAF, MEK, and ERK that inhibits SOS via phosphorylation. This negative feedback, operating on a longer time scale, changes switch-like behavior into oscillations having a period of 1 hour or longer. Two auxiliary negative feedback loops, from ERK to MEK and RAF, placed downstream of the positive feedback, shape the temporal ERK activity profile but are dispensable for oscillations. Thus, the positive feedback introduces a hierarchy among negative feedback loops, such that the effect of a negative feedback depends on its position with respect to the positive feedback loop. Furthermore, a combination of the fast positive feedback involving slow-diffusing membrane components with slower negative feedbacks involving faster diffusing cytoplasmic components leads to local excitation/global inhibition dynamics, which allows the MAPK cascade to transmit paracrine EGF signals into spatially non-uniform ERK activity pulses.

Blowin' in the wind: both `negative' and `positive' feedback in an outflowing quasar at z~1.6

NASA Astrophysics Data System (ADS)

Cresci, Giovanni

2015-02-01

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation, preventing massive galaxies to over-grow and producing the red colors of ellipticals. On the other hand, some models are also requiring `positive' AGN feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively-driven winds are available. We present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z=1.59 QSO, in which we clearly resolve a fast (1500 km/s) and extended (up to 13 kpc from the black hole) outflow in the [OIII] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U band flux show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy (`negative feedback'), but also triggering star formation by outflow induced pressure at the edges (`positive feedback'). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.

Development of a low noise induction magnetic sensor using magnetic flux negative feedback in the time domain.

PubMed

Wang, X G; Shang, X L; Lin, J

2016-05-01

Time-domain electromagnetic system can implement great depth detection. As for the electromagnetic system, the receiver utilized an air coil sensor, and the matching mode of the sensor employed the resistance matching method. By using the resistance matching method, the vibration of the coil in the time domain can be effectively controlled. However, the noise of the sensor, especially the noise at the resonance frequency, will be increased as well. In this paper, a novel design of a low noise induction coil sensor is proposed, and the experimental data and noise characteristics are provided. The sensor is designed based on the principle that the amplified voltage will be converted to current under the influence of the feedback resistance of the coil. The feedback loop around the induction coil exerts a magnetic field and sends the negative feedback signal to the sensor. The paper analyses the influence of the closed magnetic feedback loop on both the bandwidth and the noise of the sensor. The signal-to-noise ratio is improved dramatically.

Fetal programming: excess prenatal testosterone reduces postnatal luteinizing hormone, but not follicle-stimulating hormone responsiveness, to estradiol negative feedback in the female.

PubMed

Sarma, Hirendra N; Manikkam, Mohan; Herkimer, Carol; Dell'Orco, James; Welch, Kathleen B; Foster, Douglas L; Padmanabhan, Vasantha

2005-10-01

Exposure of female sheep fetuses to excess testosterone (T) during early to midgestation produces postnatal hypergonadotropism manifest as a selective increase in LH. This hypergonadotropism may result from reduced sensitivity to estradiol (E2) negative feedback and/or increased pituitary sensitivity to GnRH. We tested the hypothesis that excess T before birth reduces responsiveness of LH and FSH to E2 negative feedback after birth. Pregnant ewes were treated with T propionate (100 mg/kg in cotton seed oil) or vehicle twice weekly from d 30-90 gestation. Responsiveness to E2 negative feedback was assessed at 12 and 24 wk of age in the ovary-intact female offspring. Our experimental strategy was first to arrest follicular growth and reduce endogenous E2 by administering the GnRH antagonist (GnRH-A), Nal-Glu (50 microg/kg sc every 12 h for 72 h), and then provide a fixed amount of exogenous E2 via an implant. Blood samples were obtained every 20 min at 12 wk and every 10 min at 24 wk before treatment, during and after GnRH-A treatment both before and after E2 implant. GnRH-A ablated LH pulsatility, reduced FSH by approximately 25%, and E2 production diminished to near detection limit of assay at both ages in both groups. Prenatal T treatment produced a precocious and selective reduction in responsiveness of LH but not FSH to E2 negative feedback, which was manifest mainly at the level of LH/GnRH pulse frequency. Collectively, these findings support the hypothesis that prenatal exposure to excess T decreases postnatal responsiveness to E2 inhibitory feedback of LH/GnRH secretion to contribute to the development of hypergonadotropism.

Interrogation of inhibitor of nuclear factor κB α/nuclear factor κB (IκBα/NF-κB) negative feedback loop dynamics: from single cells to live animals in vivo.

PubMed

Moss, Britney L; Elhammali, Adnan; Fowlkes, Tiffanie; Gross, Shimon; Vinjamoori, Anant; Contag, Christopher H; Piwnica-Worms, David

2012-09-07

Full understanding of the biological significance of negative feedback processes requires interrogation at multiple scales as follows: in single cells, cell populations, and live animals in vivo. The transcriptionally coupled IκBα/NF-κB negative feedback loop, a pivotal regulatory node of innate immunity and inflammation, represents a model system for multiscalar reporters. Using a κB(5)→IκBα-FLuc bioluminescent reporter, we rigorously evaluated the dynamics of ΙκBα degradation and subsequent NF-κB transcriptional activity in response to diverse modes of TNFα stimulation. Modulating TNFα concentration or pulse duration yielded complex, reproducible, and differential ΙκBα dynamics in both cell populations and live single cells. Tremendous heterogeneity in the transcriptional amplitudes of individual responding cells was observed, which was greater than the heterogeneity in the transcriptional kinetics of responsive cells. Furthermore, administration of various TNFα doses in vivo generated ΙκBα dynamic profiles in the liver resembling those observed in single cells and populations of cells stimulated with TNFα pulses. This suggested that dose modulation of circulating TNFα was perceived by hepatocytes in vivo as pulses of increasing duration. Thus, a robust bioluminescent reporter strategy enabled rigorous quantitation of NF-κB/ΙκBα dynamics in both live single cells and cell populations and furthermore, revealed reproducible behaviors that informed interpretation of in vivo studies.

Cell shape and negative links in regulatory motifs together control spatial information flow in signaling networks.

PubMed

Neves, Susana R; Tsokas, Panayiotis; Sarkar, Anamika; Grace, Elizabeth A; Rangamani, Padmini; Taubenfeld, Stephen M; Alberini, Cristina M; Schaff, James C; Blitzer, Robert D; Moraru, Ion I; Iyengar, Ravi

2008-05-16

The role of cell size and shape in controlling local intracellular signaling reactions, and how this spatial information originates and is propagated, is not well understood. We have used partial differential equations to model the flow of spatial information from the beta-adrenergic receptor to MAPK1,2 through the cAMP/PKA/B-Raf/MAPK1,2 network in neurons using real geometries. The numerical simulations indicated that cell shape controls the dynamics of local biochemical activity of signal-modulated negative regulators, such as phosphodiesterases and protein phosphatases within regulatory loops to determine the size of microdomains of activated signaling components. The model prediction that negative regulators control the flow of spatial information to downstream components was verified experimentally in rat hippocampal slices. These results suggest a mechanism by which cellular geometry, the presence of regulatory loops with negative regulators, and key reaction rates all together control spatial information transfer and microdomain characteristics within cells.

Influences of State and Trait Affect on Behavior, Feedback-Related Negativity, and P3b in the Ultimatum Game

PubMed Central

Riepl, Korbinian; Mussel, Patrick; Osinsky, Roman; Hewig, Johannes

2016-01-01

The present study investigates how different emotions can alter social bargaining behavior. An important paradigm to study social bargaining is the Ultimatum Game. There, a proposer gets a pot of money and has to offer part of it to a responder. If the responder accepts, both players get the money as proposed by the proposer. If he rejects, none of the players gets anything. Rational choice models would predict that responders accept all offers above 0. However, evidence shows that responders typically reject a large proportion of all unfair offers. We analyzed participants’ behavior when they played the Ultimatum Game as responders and simultaneously collected electroencephalogram data in order to quantify the feedback-related negativity and P3b components. We induced state affect (momentarily emotions unrelated to the task) via short movie clips and measured trait affect (longer-lasting emotional dispositions) via questionnaires. State happiness led to increased acceptance rates of very unfair offers. Regarding neurophysiology, we found that unfair offers elicited larger feedback-related negativity amplitudes than fair offers. Additionally, an interaction of state and trait affect occurred: high trait negative affect (subsuming a variety of aversive mood states) led to increased feedback-related negativity amplitudes when participants were in an angry mood, but not if they currently experienced fear or happiness. We discuss that increased rumination might be responsible for this result, which might not occur, however, when people experience happiness or fear. Apart from that, we found that fair offers elicited larger P3b components than unfair offers, which might reflect increased pleasure in response to fair offers. Moreover, high trait negative affect was associated with decreased P3b amplitudes, potentially reflecting decreased motivation to engage in activities. We discuss implications of our results in the light of theories and research on depression and

Influences of State and Trait Affect on Behavior, Feedback-Related Negativity, and P3b in the Ultimatum Game.

PubMed

Riepl, Korbinian; Mussel, Patrick; Osinsky, Roman; Hewig, Johannes

2016-01-01

The present study investigates how different emotions can alter social bargaining behavior. An important paradigm to study social bargaining is the Ultimatum Game. There, a proposer gets a pot of money and has to offer part of it to a responder. If the responder accepts, both players get the money as proposed by the proposer. If he rejects, none of the players gets anything. Rational choice models would predict that responders accept all offers above 0. However, evidence shows that responders typically reject a large proportion of all unfair offers. We analyzed participants' behavior when they played the Ultimatum Game as responders and simultaneously collected electroencephalogram data in order to quantify the feedback-related negativity and P3b components. We induced state affect (momentarily emotions unrelated to the task) via short movie clips and measured trait affect (longer-lasting emotional dispositions) via questionnaires. State happiness led to increased acceptance rates of very unfair offers. Regarding neurophysiology, we found that unfair offers elicited larger feedback-related negativity amplitudes than fair offers. Additionally, an interaction of state and trait affect occurred: high trait negative affect (subsuming a variety of aversive mood states) led to increased feedback-related negativity amplitudes when participants were in an angry mood, but not if they currently experienced fear or happiness. We discuss that increased rumination might be responsible for this result, which might not occur, however, when people experience happiness or fear. Apart from that, we found that fair offers elicited larger P3b components than unfair offers, which might reflect increased pleasure in response to fair offers. Moreover, high trait negative affect was associated with decreased P3b amplitudes, potentially reflecting decreased motivation to engage in activities. We discuss implications of our results in the light of theories and research on depression and

Impact of time delays on oscillatory dynamics of interlinked positive and negative feedback loops

NASA Astrophysics Data System (ADS)

Huang, Bo; Tian, Xinyu; Liu, Feng; Wang, Wei

2016-11-01

Interlinking a positive feedback loop (PFL) with a negative feedback loop (NFL) constitutes a typical motif in genetic networks, performing various functions in cell signaling. How time delay in feedback regulation affects the dynamics of such systems still remains unclear. Here, we investigate three systems of interlinked PFL and NFL with time delays: a synthetic genetic oscillator, a three-node circuit, and a simplified single-node model. The stability of steady states and the routes to oscillation in the single-node model are analyzed in detail. The amplitude and period of oscillations vary with a pointwise periodicity over a range of time delay. Larger-amplitude oscillations can be induced when the PFL has an appropriately long delay, in comparison with the PFL with no delay or short delay; this conclusion holds true for all the three systems. We unravel the underlying mechanism for the above effects via analytical derivation under a limiting condition. We also develop a stochastic algorithm for simulating a single reaction with two delays and show that robust oscillations can be maintained by the PFL with a properly long delay in the single-node system. This work presents an effective method for constructing robust large-amplitude oscillators and interprets why similar circuit architectures are engaged in timekeeping systems such as circadian clocks.

Coordination of the Arc Regulatory System and Pheromone-Mediated Positive Feedback in Controlling the Vibrio fischeri lux Operon

PubMed Central

Septer, Alecia N.; Stabb, Eric V.

2012-01-01

Bacterial pheromone signaling is often governed both by environmentally responsive regulators and by positive feedback. This regulatory combination has the potential to coordinate a group response among distinct subpopulations that perceive key environmental stimuli differently. We have explored the interplay between an environmentally responsive regulator and pheromone-mediated positive feedback in intercellular signaling by Vibrio fischeri ES114, a bioluminescent bacterium that colonizes the squid Euprymna scolopes. Bioluminescence in ES114 is controlled in part by N-(3-oxohexanoyl)-L-homoserine lactone (3OC6), a pheromone produced by LuxI that together with LuxR activates transcription of the luxICDABEG operon, initiating a positive feedback loop and inducing luminescence. The lux operon is also regulated by environmentally responsive regulators, including the redox-responsive ArcA/ArcB system, which directly represses lux in culture. Here we show that inactivating arcA leads to increased 3OC6 accumulation to initiate positive feedback. In the absence of positive feedback, arcA-mediated control of luminescence was only ∼2-fold, but luxI-dependent positive feedback contributed more than 100 fold to the net induction of luminescence in the arcA mutant. Consistent with this overriding importance of positive feedback, 3OC6 produced by the arcA mutant induced luminescence in nearby wild-type cells, overcoming their ArcA repression of lux. Similarly, we found that artificially inducing ArcA could effectively repress luminescence before, but not after, positive feedback was initiated. Finally, we show that 3OC6 produced by a subpopulation of symbiotic cells can induce luminescence in other cells co-colonizing the host. Our results suggest that even transient loss of ArcA-mediated regulation in a sub-population of cells can induce luminescence in a wider community. Moreover, they indicate that 3OC6 can communicate information about both cell density and the state of

Look who's judging-Feedback source modulates brain activation to performance feedback in social anxiety.

PubMed

Peterburs, Jutta; Sandrock, Carolin; Miltner, Wolfgang H R; Straube, Thomas

2016-06-01

It is as yet unknown if behavioral and neural correlates of performance monitoring in socially anxious individuals are affected by whether feedback is provided by a person or a computer. This fMRI study investigated modulation of feedback processing by feedback source (person vs. computer) in participants with high (HSA) (N=16) and low social anxiety (LSA) (N=16). Subjects performed a choice task in which they were informed that they would receive positive or negative feedback from a person or the computer. Subjective ratings indicated increased arousal and anxiety in HSA versus LSA, most pronounced for social and negative feedback. FMRI analyses yielded hyperactivation in ventral medial prefrontal cortex (vmPFC)/anterior cingulate cortex (ACC) and insula for social relative to computer feedback, and in mPFC/ventral ACC for positive relative to negative feedback in HSA as compared to LSA. These activation patterns are consistent with increased interoception and self-referential processing in social anxiety, especially during processing of positive feedback. Increased ACC activation in HSA to positive feedback may link to unexpectedness of (social) praise as posited in social anxiety disorder (SAD) psychopathology. Activation in rostral ACC showed a reversed pattern, with decreased activation to positive feedback in HSA, possibly indicating altered action values depending on feedback source and valence. The present findings corroborate a crucial role of mPFC for performance monitoring in social anxiety. Copyright © 2016 Elsevier Inc. All rights reserved.

Negative feedback via RSK modulates Erk-dependent progression from naïve pluripotency.

PubMed

Nett, Isabelle Re; Mulas, Carla; Gatto, Laurent; Lilley, Kathryn S; Smith, Austin

2018-06-12

Mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signalling is implicated in initiation of embryonic stem (ES) cell differentiation. The pathway is subject to complex feedback regulation. Here, we examined the ERK-responsive phosphoproteome in ES cells and identified the negative regulator RSK1 as a prominent target. We used CRISPR/Cas9 to create combinatorial mutations in RSK family genes. Genotypes that included homozygous null mutations in Rps6ka1, encoding RSK1, resulted in elevated ERK phosphorylation. These RSK-depleted ES cells exhibit altered kinetics of transition into differentiation, with accelerated downregulation of naïve pluripotency factors, precocious expression of transitional epiblast markers and early onset of lineage specification. We further show that chemical inhibition of RSK increases ERK phosphorylation and expedites ES cell transition without compromising multilineage potential. These findings demonstrate that the ERK activation profile influences the dynamics of pluripotency progression and highlight the role of signalling feedback in temporal control of cell state transitions. © 2018 The Authors. Published under the terms of the CC BY 4.0 license.

Negative Feedback Mediated by Fast Inhibitory Autapse Enhances Neuronal Oscillations Near a Hopf Bifurcation Point

NASA Astrophysics Data System (ADS)

Jia, Bing

One-parameter and two-parameter bifurcations of the Morris-Lecar (ML) neuron model with and without the fast inhibitory autapse, which is a synapse from a neuron onto itself, are investigated. The ML neuron model without autapse manifests an inverse Hopf bifurcation point from firing to a depolarized resting state with high level of membrane potential, with increasing depolarization current. When a fast inhibitory autapse is introduced, a negative feedback or inhibitory current is applied to the ML model. With increasing conductance of the autapse to middle level, the depolarized resting state near the inverse Hopf bifurcation point can change to oscillation and the parameter region of the oscillation becomes wide, which can be well interpreted by the dynamic responses of the depolarized resting state to the inhibitory current stimulus mediated by the autapse. The enlargement of the parameter region of the oscillation induced by the negative feedback presents a novel viewpoint different from the traditional one that inhibitory synapse often suppresses the neuronal oscillation activities. Furthermore, complex nonlinear dynamics such as the coexisting behaviors and codimension-2 bifurcations including the Bautin and cusp bifurcations are acquired. The relationship between the bifurcations and the depolarization block, a physiological concept that indicates a neuron can enter resting state when receiving the depolarization current, is discussed.

Feedback is the breakfast of champions: the significance of self-controlled formal feedback for autonomous task engagement.

PubMed

Meng, Liang; Yang, Zijing

2018-01-03

With the aim of examining the positive effect of the formal feedback mechanism itself beyond its informational aspect, we engaged participants in the stopwatch task and recorded their electroencephalogram throughout the experiment. This task requires a button press to stop the watch within a given time interval, the completion of which is simultaneously accompanied by adequate information on task performance. In the self-controlled feedback mode, participants could freely choose whether to request formal feedback after completing the task. In another mode, additional feedback was not provided. The 'non-choice' cue was found to elicit a more negative cue-elicited feedback negativity compared with 'choice', suggesting that the opportunity to solicit formal feedback was perceived as more desirable. In addition, a more enhanced stimulus-preceding negativity was observed prior to the task initiation cue in the self-controlled feedback condition, indicating that participants paid more sustained anticipatory attention during task preparation. Taken together, these electrophysiological results suggested an inherent reward within the formal feedback mechanism itself and the significance of self-controlled formal feedback for autonomous task engagement.

Using high-level construal and perceptions of changeability to promote self-change over self-protection motives in response to negative feedback.

PubMed

Belding, Jennifer N; Naufel, Karen Z; Fujita, Kentaro

2015-06-01

Diagnostic negative information presents people with a motivational dilemma. Although negative feedback can provide useful information with which to guide future self-improvement efforts, it also presents short-term affective costs. We propose that construal level, jointly with the perceived changeability of the feedback domain, determines whether people choose to accept or dismiss such information. Whereas low-level construal promotes short-term self-protection motivation (promoting dismissal), high-level construal promotes long-term self-change motivation (promoting acceptance)--to the extent that change is perceived as possible. Four studies support this hypothesis and examine underlying cognitive and motivational mechanisms. The present work may provide an integrative theoretical framework for understanding when people will be open to and accept negative diagnostic information, and has important practical implications for promoting self-change efforts. © 2015 by the Society for Personality and Social Psychology, Inc.

Negative feedback regulation of Homer 1a on norepinephrine-dependent cardiac hypertrophy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiarello, Carmelina; Bortoloso, Elena; Carpi, Andrea

2013-07-15

Homers are scaffolding proteins that modulate diverse cell functions being able to assemble signalling complexes. In this study, the presence, sub-cellular distribution and function of Homer 1 was investigated. Homer 1a and Homer 1b/c are constitutively expressed in cardiac muscle of both mouse and rat and in HL-1 cells, a cardiac cell line. As judged by confocal immunofluorescence microscopy, Homer 1a displays sarcomeric and peri-nuclear localization. In cardiomyocytes and cultured HL-1 cells, the hypertrophic agonist norepinephrine (NE) induces α{sub 1}-adrenergic specific Homer 1a over-expression, with a two-to-three-fold increase within 1 h, and no up-regulation of Homer 1b/c, as judged bymore » Western blot and qPCR. In HL-1 cells, plasmid-driven over-expression of Homer 1a partially antagonizes activation of ERK phosphorylation and ANF up-regulation, two well-established, early markers of hypertrophy. At the morphometric level, NE-induced increase of cell size is likewise and partially counteracted by exogenous Homer 1a. Under the same experimental conditions, Homer 1b/c does not have any effect on ANF up-regulation nor on cell hypertrophy. Thus, Homer 1a up-regulation is associated to early stages of cardiac hypertrophy and appears to play a negative feedback regulation on molecular transducers of hypertrophy. -- Highlights: • Homer 1a is constitutively expressed in cardiac tissue. • In HL-1 cells, norepinephrine activates signaling pathways leading to hypertrophy. • Homer 1a up-regulation is an early event of norepinephrine-induced hypertrophy. • Homer 1a plays a negative feedback regulation modulating pathological hypertrophy. • Over-expression of Homer 1a per se does not induce hypertrophy.« less

Elevated atmospheric CO2 negatively impacts photosynthesis through radiative forcing and physiology-mediated climate feedback

NASA Astrophysics Data System (ADS)

Zhu, Peng; Zhuang, Qianlai; Ciais, Philippe; Welp, Lisa; Li, Wenyu; Xin, Qinchuan

2017-02-01

Increasing atmospheric CO2 affects photosynthesis involving directly increasing leaf carboxylation rates, stomatal closure, and climatic effects. The direct effects are generally thought to be positive leading to increased photosynthesis, while its climatic effects can be regionally positive or negative. These effects are usually considered to be independent from each other, but they are in fact coupled through interactions between land surface exchanges of gases and heat and the physical climate system. In particular, stomatal closure reduces evapotranspiration and increases sensible heat emissions from ecosystems, leading to decreased atmospheric moisture and precipitation and local warming. We use a coupled earth system model to attribute the influence of the increase in CO2 on gross primary productivity (GPP) during the period of 1930-2011. In our model, CO2 radiative effects cause climate change that has only a negligible effect on global GPP (a reduction of 0.9 ± 2% during the last 80 years) because of opposite responses between tropical and northern biomes. On the other hand, CO2 physiological effects on GPP are both positive, by increased carboxylation rates and water use efficiency (7.1 ± 0.48% increase), and negative, by vegetation-climate feedback reducing precipitation, as a consequence of decreased transpiration and increased sensible heat in areas without water limitation (2.7 ± 1.76% reduction).When considering the coupled atmosphere-vegetation system, negative climate feedback on photosynthesis and plant growth due to the current level of CO2 opposes 29-38% of the gains from direct fertilization effects.

Negative feedback regulation of TGF-beta signaling by the SnoN oncoprotein.

PubMed

Stroschein, S L; Wang, W; Zhou, S; Zhou, Q; Luo, K

1999-10-22

Smad proteins mediate transforming growth factor-beta (TGF-beta) signaling to regulate cell growth and differentiation. The SnoN oncoprotein was found to interact with Smad2 and Smad4 and to repress their abilities to activate transcription through recruitment of the transcriptional corepressor N-CoR. Immediately after TGF-beta stimulation, SnoN is rapidly degraded by the nuclear accumulation of Smad3, allowing the activation of TGF-beta target genes. By 2 hours, TGF-beta induces a marked increase in SnoN expression, resulting in termination of Smad-mediated transactivation. Thus, SnoN maintains the repressed state of TGF-beta-responsive genes in the absence of ligand and participates in negative feedback regulation of TGF-beta signaling.

Grassland establishment under varying resource availability: a test of positive and negative feedback.

PubMed

Baer, Sara G; Blair, John M

2008-07-01

The traditional logic of carbon (C) and nitrogen (N) interactions in ecosystems predicts further increases or decreases in productivity (positive feedback) in response to high and low fertility in the soil, respectively; but the potential for development of feedback in ecosystems recovering from disturbance is less well understood. Furthermore, this logic has been challenged in grassland ecosystems where frequent fires or grazing may reduce the contribution of aboveground litter inputs to soil organic matter pools and nutrient supply for plant growth, relative to forest ecosystems. Further, if increases in plant productivity increase soil C content more than soil N content, negative feedback may result from increased microbial demand for N making less available for plant growth. We used a field experiment to test for feedback in an establishing grassland by comparing aboveground net primary productivity (ANPP) and belowground pools and fluxes of C and N in soil with enriched, ambient, and reduced N availability. For eight years annual N enrichment increased ANPP, root N, and root tissue quality, but root C:N ratios remained well above the threshold for net mineralization of N. There was no evidence that N enrichment increased root biomass, soil C or N accrual rates, or storage of C in total, microbial, or mineralizable pools within this time frame. However, the net nitrogen mineralization potential (NMP) rate was greater following eight years of N enrichment, and we attributed this to N saturation of the microbial biomass. Grassland developing under experimentally imposed N limitation through C addition to the soil exhibited ANPP, root biomass and quality, and net NMP rate similar to the ambient soil. Similarity in productivity and roots in the reduced and ambient N treatments was attributed to the potentially high nitrogen-use efficiency (NUE) of the dominant C4 grasses, and increasing cover of legumes over time in the C-amended soil. Thus, in a developing

Negative Feedback Control of Pituitary Thyroid-stimulating Hormone Synthesis and Secretion by Thyroid Hormones during Metamorphosis in Xenopus laevis

EPA Science Inventory

A basic understanding of the endocrinology of the hypothalamic-pituitary-thyroid (HPT) axis of anuran larvae is necessary for predicting the consequences of HPT perturbation by thyroid-disrupting chemicals (TDCs) on the whole organism. This project examined negative feedback con...

Feedback in Action--The Mechanism of the Iris.

ERIC Educational Resources Information Center

Pingnet, B.; And Others

1988-01-01

Describes two demonstration experiments. Outlines a demonstration of the general principle of positive and negative feedback and the influence of time delays in feedback circuits. Elucidates the principle of negative feedback with a model of the iris of the eye. Emphasizes the importance of feedback in biological systems. (CW)

A negative feedback mechanism for the long-term stabilization of the earth's surface temperature

NASA Technical Reports Server (NTRS)

Walker, J. C. G.; Hays, P. B.; Kasting, J. F.

1981-01-01

It is suggested that the partial pressure of carbon dioxide in the atmosphere is buffered, over geological time scales, by a negative feedback mechanism, in which the rate of weathering of silicate minerals (followed by deposition of carbonate minerals) depends on surface temperature, which in turn depends on the carbon dioxide partial pressure through the greenhouse effect. Although the quantitative details of this mechanism are speculative, it appears able to partially stabilize the earth's surface temperature against the steady increase of solar luminosity, believed to have occurred since the origin of the solar system.

Stochasticity and bifurcations in a reduced model with interlinked positive and negative feedback loops of CREB1 and CREB2 stimulated by 5-HT.

PubMed

Hao, Lijie; Yang, Zhuoqin; Bi, Yuanhong

2016-04-01

The cyclic AMP (cAMP)-response element-binding protein (CREB) family of transcription factors is crucial in regulating gene expression required for long-term memory (LTM) formation. Upon exposure of sensory neurons to the neurotransmitter serotonin (5-HT), CREB1 is activated via activation of the protein kinase A (PKA) intracellular signaling pathways, and CREB2 as a transcriptional repressor is relieved possibly via phosphorylation of CREB2 by mitogen-activated protein kinase (MAPK). Song et al. [18] proposed a minimal model with only interlinked positive and negative feedback loops of transcriptional regulation by the activator CREB1 and the repressor CREB2. Without considering feedbacks between the CREB proteins, Pettigrew et al. [8] developed a computational model characterizing complex dynamics of biochemical pathways downstream of 5-HT receptors. In this work, to describe more simply the biochemical pathways and gene regulation underlying 5-HT-induced LTM, we add the important extracellular sensitizing stimulus 5-HT as well as the product Ap-uch into the Song's minimal model. We also strive to examine dynamical properties of the gene regulatory network under the changing concentration of the stimulus, [5-HT], cooperating with the varying positive feedback strength in inducing a high state of CREB1 for the establishment of long-term memory. Different dynamics including monostability, bistability and multistability due to coexistence of stable steady states and oscillations is investigated by means of codimension-2 bifurcation analysis. At the different positive feedback strengths, comparative analysis of deterministic and stochastic dynamics reveals that codimension-1 bifurcation with respect to [5-HT] as the parameter can predict diverse stochastic behaviors resulted from the finite number of molecules, and the number of CREB1 molecules more and more preferentially resides near the high steady state with increasing [5-HT], which contributes to long

Negative feedback regulation of ABA biosynthesis in peanut (Arachis hypogaea): a transcription factor complex inhibits AhNCED1 expression during water stress

PubMed Central

Liu, Shuai; Li, Meijuan; Su, Liangchen; Ge, Kui; Li, Limei; Li, Xiaoyun; Liu, Xu; Li, Ling

2016-01-01

Abscisic acid (ABA), a key plant stress-signaling hormone, is produced in response to drought and counteracts the effects of this stress. The accumulation of ABA is controlled by the enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). In Arabidopsis, NCED3 is regulated by a positive feedback mechanism by ABA. In this study in peanut (Arachis hypogaea), we demonstrate that ABA biosynthesis is also controlled by negative feedback regulation, mediated by the inhibitory effect on AhNCED1 transcription of a protein complex between transcription factors AhNAC2 and AhAREB1. AhNCED1 was significantly down-regulated after PEG treatment for 10 h, at which time ABA content reached a peak. A ChIP-qPCR assay confirmed AhAREB1 and AhNAC2 binding to the AhNCED1 promoter in response to ABA. Moreover, the interaction between AhAREB1 and AhNAC2, and a transient expression assay showed that the protein complex could negatively regulate the expression of AhNCED1. The results also demonstrated that AhAREB1 was the key factor in AhNCED1 feedback regulation, while AhNAC2 played a subsidiary role. ABA reduced the rate of AhAREB1 degradation and enhanced both the synthesis and degradation rate of the AhNAC2 protein. In summary, the AhAREB1/AhNAC2 protein complex functions as a negative feedback regulator of drought-induced ABA biosynthesis in peanut. PMID:27892506

Negative feedback adjustment challenges reconstruction study from tree rings: A study case of response of Populus euphratica to river discontinuous flow and ecological water conveyance.

PubMed

Ling, Hongbo; Zhang, Pei; Guo, Bin; Xu, Hailiang; Ye, Mao; Deng, Xiaoya

2017-01-01

Drought stress changes the relationship between the growth of tree rings and variations in ambient temperature. However, it is not clear how the growth of trees changes in response to drought of varying intensities, especially in arid areas. Therefore, Tree rings were studied for 6years in Populus euphratica to assess the impacts of abrupt changes in environment on tree rings using the theories and methods in dendrohydrology, ecology and phytophysiology. The width of tree rings increased by 8.7% after ecological water conveyance downstream of Tarim River compared to that when the river water had been cut off. However, during intermediate drought, as the depth of the groundwater increases, the downward trend in the tree rings was reversed because of changes in the physiology of the tree. Therefore, the growth of tree rings shows a negative feedback to intermediate drought stress, an observation that challenges the homogenization theory of tree ring reconstruction based on the traditional methods. Owing to the time lag, the cumulative effect and the negative feedback between the growth of tree rings and drought stress, the reconstruction of past environment by studying the patterns of tree rings is often inaccurate. Our research sets out to verify the hypothesis that intermediate drought stress results in a negative feedback adjustment and thus to answers two scientific questions: (1) How does the negative feedback adjustment promote the growth of tree rings as a result of intermediate drought stress? (2) How does the negative feedback adjustment lower the accuracy with which the past is reconstructed based on tree rings? This research not only enriches the connotations of intermediate disturbance hypothesis and reconstruction theory of tree rings, but also provides a scientific basis for the conservation of desert riparian forests worldwide. Copyright © 2016 Elsevier B.V. All rights reserved.

Children's reasoning about evaluative feedback.

PubMed

Heyman, Gail D; Fu, Genyue; Sweet, Monica A; Lee, Kang

2009-11-01

Children's reasoning about the willingness of peers to convey accurate positive and negative performance feedback to others was investigated among a total of 179 6- to 11-year-olds from the USA and China. In Study 1, which was conducted in the USA only, participants responded that peers would be more likely to provide positive feedback than negative feedback, and this tendency was strongest among the younger children. In Study 2, the expectation that peers would preferentially disclose positive feedback was replicated among children from the USA, and was also seen among younger but not older children from China. Participants in all groups took the relationship between communication partners into account when predicting whether peers would express evaluative feedback. Results of open-ended responses suggested cross-cultural differences, including a greater emphasis by Chinese children on the implications of evaluative feedback for future performance, and reference by some older Chinese children to the possibility that positive feedback might make the recipient 'too proud'.

A CRY-BIC negative-feedback circuitry regulating blue light sensitivity of Arabidopsis.

PubMed

Wang, Xu; Wang, Qin; Han, Yun-Jeong; Liu, Qing; Gu, Lianfeng; Yang, Zhaohe; Su, Jun; Liu, Bobin; Zuo, Zecheng; He, Wenjin; Wang, Jian; Liu, Bin; Matsui, Minami; Kim, Jeong-Il; Oka, Yoshito; Lin, Chentao

2017-11-01

Cryptochromes are blue light receptors that regulate various light responses in plants. Arabidopsis cryptochrome 1 (CRY1) and cryptochrome 2 (CRY2) mediate blue light inhibition of hypocotyl elongation and long-day (LD) promotion of floral initiation. It has been reported recently that two negative regulators of Arabidopsis cryptochromes, Blue light Inhibitors of Cryptochromes 1 and 2 (BIC1 and BIC2), inhibit cryptochrome function by blocking blue light-dependent cryptochrome dimerization. However, it remained unclear how cryptochromes regulate the BIC gene activity. Here we show that cryptochromes mediate light activation of transcription of the BIC genes, by suppressing the activity of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), resulting in activation of the transcription activator ELONGATED HYPOCOTYL 5 (HY5) that is associated with chromatins of the BIC promoters. These results demonstrate a CRY-BIC negative-feedback circuitry that regulates the activity of each other. Surprisingly, phytochromes also mediate light activation of BIC transcription, suggesting a novel photoreceptor co-action mechanism to sustain blue light sensitivity of plants under the broad spectra of solar radiation in nature. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

When to throw the switch: The adaptiveness of modifying emotion regulation strategies based on affective and physiological feedback.

PubMed

Birk, Jeffrey L; Bonanno, George A

2016-08-01

Particular emotion regulation (ER) strategies are beneficial in certain contexts, but little is known about the adaptiveness of switching strategies after implementing an initial strategy. Research and theory on regulatory flexibility suggest that people switch strategies dynamically and that internal states provide feedback indicating when switches are appropriate. Frequent switching may predict positive outcomes among people who respond to this feedback. We investigated whether internal feedback (particularly corrugator activity, heart rate, or subjective negative intensity) guides people to switch to an optimal (i.e., distraction) but not nonoptimal (i.e., reappraisal) strategy for regulating strong emotion. We also tested whether switching frequency and responsiveness to internal feedback (RIF) together predict well-being. While attempting to regulate emotion elicited by unpleasant pictures, participants could switch to an optimal (Study 1; reappraisal-to-distraction order; N = 90) or nonoptimal (Study 2; distraction-to-reappraisal order; N = 95) strategy for high-arousal emotion. A RIF score for each emotion measure indexed the relative strength of emotion during the initial phase for trials on which participants later switched strategies. As hypothesized, negative intensity, corrugator activity, and the magnitude of heart rate deceleration during this early phase were higher on switch than maintain trials in Study 1 only. Critically, in Study 1 only, greater switching frequency predicted higher and lower life satisfaction for participants with high and low corrugator RIF, respectively, even after controlling for reappraisal success. Individual differences in RIF may contribute to subjective well-being provided that the direction of strategy switching aligns well with regulatory preferences for high emotion. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Tree range expansion may be enhanced by escape from negative plant-soil feedbacks.

PubMed

McCarthy-Neumann, Sarah; Ibáñez, Inés

2012-12-01

Many plant species are expected to shift their distributional ranges in response to global warming. As they arrive at new sites, migrant plant species may be released from their natural soil pathogens and/or deprived of key symbiotic organisms. Under such scenarios plant-soil feedbacks (PSF) will likely have an impact on plant species' ability to establish in new areas. In this study we evaluated the role that PSF may play on the migratory potential of dominant temperate tree species at the northern limit of their distributional range in the Great Lakes region of North America. To test their ability to expand their current range, we assessed seedling establishment, i.e., survival, of local and potential migrant tree species in a field transplant experiment. To test for the presence and strength of PSF, we also assessed seedling survival during establishment in a greenhouse experiment, where the potential migrant species were grown in soils collected within and beyond their distributional ranges. The combination of experiments provided us with a comprehensive understanding of the role of PSF in seedling establishment in new areas. In the field, we found that survival for most migrant species was similar to those of the local community, ensuring that these species could establish in areas beyond their current range. In the greenhouse, we found that the majority of species experienced strong negative conspecific feedbacks mediated by soil biota, but these responses occurred for most species only in low light conditions. Lastly, our combined results indicate that migrant tree species can colonize and may even have enhanced short-term recruitment beyond their ranges due to a lack of conspecific adults (and the resulting negative PSF from these adults).

Generalized Anxiety Disorder and Social Anxiety Disorder, but Not Panic Anxiety Disorder, Are Associated with Higher Sensitivity to Learning from Negative Feedback: Behavioral and Computational Investigation

PubMed Central

Khdour, Hussain Y.; Abushalbaq, Oday M.; Mughrabi, Ibrahim T.; Imam, Aya F.; Gluck, Mark A.; Herzallah, Mohammad M.; Moustafa, Ahmed A.

2016-01-01

Anxiety disorders, including generalized anxiety disorder (GAD), social anxiety disorder (SAD), and panic anxiety disorder (PAD), are a group of common psychiatric conditions. They are characterized by excessive worrying, uneasiness, and fear of future events, such that they affect social and occupational functioning. Anxiety disorders can alter behavior and cognition as well, yet little is known about the particular domains they affect. In this study, we tested the cognitive correlates of medication-free patients with GAD, SAD, and PAD, along with matched healthy participants using a probabilistic category-learning task that allows the dissociation between positive and negative feedback learning. We also fitted all participants' data to a Q-learning model and various actor-critic models that examine learning rate parameters from positive and negative feedback to investigate effects of valence vs. action on performance. SAD and GAD patients were more sensitive to negative feedback than either PAD patients or healthy participants. PAD, SAD, and GAD patients did not differ in positive-feedback learning compared to healthy participants. We found that Q-learning models provide the simplest fit of the data in comparison to other models. However, computational analysis revealed that groups did not differ in terms of learning rate or exploration values. These findings argue that (a) not all anxiety spectrum disorders share similar cognitive correlates, but are rather different in ways that do not link them to the hallmark of anxiety (higher sensitivity to negative feedback); and (b) perception of negative consequences is the core feature of GAD and SAD, but not PAD. Further research is needed to examine the similarities and differences between anxiety spectrum disorders in other cognitive domains and potential implementation of behavioral therapy to remediate cognitive deficits. PMID:27445719

Generalized Anxiety Disorder and Social Anxiety Disorder, but Not Panic Anxiety Disorder, Are Associated with Higher Sensitivity to Learning from Negative Feedback: Behavioral and Computational Investigation.

PubMed

Khdour, Hussain Y; Abushalbaq, Oday M; Mughrabi, Ibrahim T; Imam, Aya F; Gluck, Mark A; Herzallah, Mohammad M; Moustafa, Ahmed A

2016-01-01

Anxiety disorders, including generalized anxiety disorder (GAD), social anxiety disorder (SAD), and panic anxiety disorder (PAD), are a group of common psychiatric conditions. They are characterized by excessive worrying, uneasiness, and fear of future events, such that they affect social and occupational functioning. Anxiety disorders can alter behavior and cognition as well, yet little is known about the particular domains they affect. In this study, we tested the cognitive correlates of medication-free patients with GAD, SAD, and PAD, along with matched healthy participants using a probabilistic category-learning task that allows the dissociation between positive and negative feedback learning. We also fitted all participants' data to a Q-learning model and various actor-critic models that examine learning rate parameters from positive and negative feedback to investigate effects of valence vs. action on performance. SAD and GAD patients were more sensitive to negative feedback than either PAD patients or healthy participants. PAD, SAD, and GAD patients did not differ in positive-feedback learning compared to healthy participants. We found that Q-learning models provide the simplest fit of the data in comparison to other models. However, computational analysis revealed that groups did not differ in terms of learning rate or exploration values. These findings argue that (a) not all anxiety spectrum disorders share similar cognitive correlates, but are rather different in ways that do not link them to the hallmark of anxiety (higher sensitivity to negative feedback); and (b) perception of negative consequences is the core feature of GAD and SAD, but not PAD. Further research is needed to examine the similarities and differences between anxiety spectrum disorders in other cognitive domains and potential implementation of behavioral therapy to remediate cognitive deficits.

Positive and negative regulatory regions control the spatial distribution of polygalacturonase transcription in tomato fruit pericarp.

PubMed Central

Montgomery, J; Pollard, V; Deikman, J; Fischer, R L

1993-01-01

The tomato fruit consists of a thick, fleshy pericarp composed predominantly of highly vacuolated parenchymatous cells, which surrounds the seeds. During ripening, the activation of gene expression results in dramatic biochemical and physiological changes in the pericarp. The polygalacturonase (PG) gene, unlike many fruit ripening-induced genes, is not activated by the increase in ethylene hormone concentration associated with the onset of ripening. To investigate ethylene concentration-independent gene transcription in ripe tomato fruit, we analyzed the expression of chimeric PG promoter-beta-glucuronidase (GUS) reporter gene fusions in transgenic tomato plants. We determined that a 1.4-kb PG promoter directs ripening-regulated transcription in outer pericarp but not in inner pericarp cells, with a sharp boundary of PG promoter activity located midway through the pericarp. Promoter deletion analysis indicated that a minimum of three promoter regions influence the spatial regulation of PG transcription. A positive regulatory region from -231 to -134 promotes gene transcription in the outer pericarp of ripe fruit. A second positive regulatory region from -806 to -443 extends gene activity to the inner pericarp. However, a negative regulatory region from -1411 to -1150 inhibits gene transcription in the inner pericarp. DNase I footprint analysis showed that nuclear proteins in unripe and ripe fruit interact with DNA sequences within each of these three regulatory regions. Thus, temporal and spatial control of PG transcription is mediated by the interaction of negative and positive regulatory promoter elements, resulting in gene activity in the outer pericarp but not the inner pericarp of ripe tomato fruit. The expression pattern of PG suggests that, although they are morphologically similar, there is a fundamental difference between the parenchymatous cells within the inner and outer pericarp. PMID:8400876

Analysis of dental students' written peer feedback from a prospective peer assessment protocol.

PubMed

Tricio, J; Woolford, M; Escudier, M

2016-11-01

Peer assessment and feedback is encouraged to enhance students' learning. The aim of this study was to quantitatively and qualitatively analyse pre-clinical and clinical dental students' written peer feedback provided as part of a continuous, formative and structured peer assessment protocol. A total of 309 Year-2 and Year-5 dental students were invited to participate in a peer assessment and peer feedback protocol. Consenting volunteer students were trained to observe each other whilst working in the skills laboratory (Year-2) and in the dental clinic (Year-5). Subsequently, they followed a structured protocol of peer assessment and peer feedback using specially designed work-based forms during a complete academic year. The content of their written feedback was coded according to the UK General Dental Council domain, sign (positive or negative), specificity (task specific or general), and grouped into themes. A total of 108 participants (40 Year-2 and 68 Year-5) completed 1169 peer assessment work-based forms (516 pre-clinical and 653 clinical); 94% contained written feedback. The large majority (82%) of Year-2 feedback represented the clinical domain, 89% were positive, 77% were task specific, and they were grouped into 14 themes. Year-5 feedback was related mostly to Management and Leadership (37%) and Communication (32%), 64% were positive, 75% task specific, and they were clustered into 24 themes. The content of the feedback showed notable differences between Year-2 and Year-5 students. Senior students focused more on Communication and Management and Leadership skills, whilst juniors were more concerned with clinical skills. Year-5 students provided 13% negative feedback compared to only 2% from Year-2. Regulatory focus theory is discussed to explain these differences. Both groups provided peer feedback on a wide and different range of themes. However, four themes emerged in both groups: efficiency, infection control, time management and working speed. A

The Rice Transcription Factor WRKY53 Suppresses Herbivore-Induced Defenses by Acting as a Negative Feedback Modulator of Mitogen-Activated Protein Kinase Activity1

PubMed Central

Hu, Lingfei; Ye, Meng; Zhang, Tongfang; Zhou, Guoxin; Wang, Qi; Lu, Jing

2015-01-01

The mechanisms by which herbivore-attacked plants activate their defenses are well studied. By contrast, little is known about the regulatory mechanisms that allow them to control their defensive investment and avoid a defensive overshoot. We characterized a rice (Oryza sativa) WRKY gene, OsWRKY53, whose expression is rapidly induced upon wounding and induced in a delayed fashion upon attack by the striped stem borer (SSB) Chilo suppressalis. The transcript levels of OsWRKY53 are independent of endogenous jasmonic acid but positively regulated by the mitogen-activated protein kinases OsMPK3/OsMPK6. OsWRKY53 physically interacts with OsMPK3/OsMPK6 and suppresses their activity in vitro. By consequence, it modulates the expression of defensive, MPK-regulated WRKYs and thereby reduces jasmonic acid, jasmonoyl-isoleucine, and ethylene induction. This phytohormonal reconfiguration is associated with a reduction in trypsin protease inhibitor activity and improved SSB performance. OsWRKY53 is also shown to be a negative regulator of plant growth. Taken together, these results show that OsWRKY53 functions as a negative feedback modulator of MPK3/MPK6 and thereby acts as an early suppressor of induced defenses. OsWRKY53 therefore enables rice plants to control the magnitude of their defensive investment during early signaling. PMID:26453434

Both positive and negative regulatory elements mediate expression of a photoregulated CAB gene from Nicotiana plumbaginifolia.

PubMed Central

Castresana, C; Garcia-Luque, I; Alonso, E; Malik, V S; Cashmore, A R

1988-01-01

We have analyzed promoter regulatory elements from a photoregulated CAB gene (Cab-E) isolated from Nicotiana plumbaginifolia. These studies have been performed by introducing chimeric gene constructs into tobacco cells via Agrobacterium tumefaciens-mediated transformation. Expression studies on the regenerated transgenic plants have allowed us to characterize three positive and one negative cis-acting elements that influence photoregulated expression of the Cab-E gene. Within the upstream sequences we have identified two positive regulatory elements (PRE1 and PRE2) which confer maximum levels of photoregulated expression. These sequences contain multiple repeated elements related to the sequence-ACCGGCCCACTT-. We have also identified within the upstream region a negative regulatory element (NRE) extremely rich in AT sequences, which reduces the level of gene expression in the light. We have defined a light regulatory element (LRE) within the promoter region extending from -396 to -186 bp which confers photoregulated expression when fused to a constitutive nopaline synthase ('nos') promoter. Within this region there is a 132-bp element, extending from -368 to -234 bp, which on deletion from the Cab-E promoter reduces gene expression from high levels to undetectable levels. Finally, we have demonstrated for a full length Cab-E promoter conferring high levels of photoregulated expression, that sequences proximal to the Cab-E TATA box are not replaceable by corresponding sequences from a 'nos' promoter. This contrasts with the apparent equivalence of these Cab-E and 'nos' TATA box-proximal sequences in truncated promoters conferring low levels of photoregulated expression. Images PMID:2901343

mTORC1 Is a Local, Postsynaptic Voltage Sensor Regulated by Positive and Negative Feedback Pathways

PubMed Central

Niere, Farr; Raab-Graham, Kimberly F.

2017-01-01

The mammalian/mechanistic target of rapamycin complex 1 (mTORC1) serves as a regulator of mRNA translation. Recent studies suggest that mTORC1 may also serve as a local, voltage sensor in the postsynaptic region of neurons. Considering biochemical, bioinformatics and imaging data, we hypothesize that the activity state of mTORC1 dynamically regulates local membrane potential by promoting and repressing protein synthesis of select mRNAs. Our hypothesis suggests that mTORC1 uses positive and negative feedback pathways, in a branch-specific manner, to maintain neuronal excitability within an optimal range. In some dendritic branches, mTORC1 activity oscillates between the “On” and “Off” states. We define this as negative feedback. In contrast, positive feedback is defined as the pathway that leads to a prolonged depolarized or hyperpolarized resting membrane potential, whereby mTORC1 activity is constitutively on or off, respectively. We propose that inactivation of mTORC1 increases the expression of voltage-gated potassium alpha (Kv1.1 and 1.2) and beta (Kvβ2) subunits, ensuring that the membrane resets to its resting membrane potential after experiencing increased synaptic activity. In turn, reduced mTORC1 activity increases the protein expression of syntaxin-1A and promotes the surface expression of the ionotropic glutamate receptor N-methyl-D-aspartate (NMDA)-type subunit 1 (GluN1) that facilitates increased calcium entry to turn mTORC1 back on. Under conditions such as learning and memory, mTORC1 activity is required to be high for longer periods of time. Thus, the arm of the pathway that promotes syntaxin-1A and Kv1 protein synthesis will be repressed. Moreover, dendritic branches that have low mTORC1 activity with increased Kv expression would balance dendrites with constitutively high mTORC1 activity, allowing for the neuron to maintain its overall activity level within an ideal operating range. Finally, such a model suggests that recruitment of more

STABILIZED FEEDBACK AMPLIFIER

DOEpatents

Fishbine, H.L.; Sewell, C. Jr.

1957-08-01

Negative feedback amplifiers, and particularly a negative feedback circuit which is economical on amode power consumption, are described. Basically, the disclosed circuit comprises two tetrode tubes where the output of the first tube is capacitamce coupled to the grid of the second tube, which in turn has its plate coupled to the cathode of the first tube to form a degenerative feedback circuit. Operating potential for screen of the second tube is supplied by connecting the cathode resistor of the first tube to the screen, while the screen is by-passed to the cathode of its tube for the amplified frequencies. Also, the amplifier incorporates a circuit to stabilize the transconductance of the tubes by making the grid potential of each tube interdependent on anode currents of both lubes by voltage divider circuitry.

Prefrontal Neural Activity When Feedback Is Not Relevant to Adjust Performance

PubMed Central

Özyurt, Jale; Rietze, Mareike; Thiel, Christiane M.

2012-01-01

It has been shown that the rostral cingulate zone (RCZ) in humans uses both positive and negative feedback to evaluate performance and to flexibly adjust behaviour. Less is known on how the feedback types are processed by the RCZ and other prefrontal brain areas, when feedback can only be used to evaluate performance, but cannot be used to adjust behaviour. The present fMRI study aimed at investigating feedback that can only be used to evaluate performance in a word-learning paradigm. One group of volunteers (N = 17) received informative, performance-dependent positive or negative feedback after each trial. Since new words had to be learnt in each trial, the feedback could not be used for task-specific adaptations. The other group (N = 17) always received non-informative feedback, providing neither information about performance nor about possible task-specific adaptations. Effects of the informational value of feedback were assessed between-subjects, comparing trials with positive and negative informative feedback to non-informative feedback. Effects of feedback valence were assessed by comparing neural activity to positive and negative feedback within the informative-feedback group. Our results show that several prefrontal regions, including the pre-SMA, the inferior frontal cortex and the insula were sensitive to both, the informational value and the valence aspect of the feedback with stronger activations to informative as compared to non-informative feedback and to informative negative compared to informative positive feedback. The only exception was RCZ which was sensitive to the informational value of the feedback, but not to feedback valence. The findings indicate that outcome information per se is sufficient to activate prefrontal brain regions, with the RCZ being the only prefrontal brain region which is equally sensitive to positive and negative feedback. PMID:22615774

Coexistence and relative abundance in plant communities are determined by feedbacks when the scale of feedback and dispersal is local.

PubMed

Mack, Keenan M L; Bever, James D

2014-09-01

1. Negative plant-soil feedback occurs when the presence of an individual of a particular species at a particular site decreases the relative success of individuals of the same species compared to those other species at that site. This effect favors heterospecifics thereby facilitating coexistence and maintaining diversity. Empirical work has demonstrated that the average strengths of these feedbacks correlate with the relative abundance of species within a community, suggesting that feedbacks are an important driver of plant community composition. Understanding what factors contribute to the generation of this relationship is necessary for diagnosing the dynamic forces that maintain diversity in plant communities. 2. We used a spatially explicit, individual-based computer simulation to test the effects of dispersal distance, the size of feedback neighbourhoods, the strength of pairwise feedbacks and community wide variation of feedbacks, community richness, as well as life-history differences on the dependence of relative abundance on strength of feedback. 3. We found a positive dependence of relative abundance of a species on its average feedback for local scale dispersal and feedback. However, we found that the strength of this dependence decreased as either the spatial scale of dispersal and/or the spatial scale of feedback increased. We also found that for spatially local (i.e. relatively small) scale interaction and dispersal, as the mean strength of feedbacks in the community becomes less negative, the greater the increase in abundance produced by a comparable increase in species-specific average feedback. We found that life-history differences such as mortality rate did not generate a pattern with abundance, nor did they affect the relationship between abundance and average feedback. 4. Synthesis . Our results support the claim that empirical observations of a positive correlation between relative abundance and strength of average feedback serves as

Emotion: The Self-regulatory Sense

PubMed Central

2014-01-01

While emotion is a central component of human health and well-being, traditional approaches to understanding its biological function have been wanting. A dynamic systems model, however, broadly redefines and recasts emotion as a primary sensory system—perhaps the first sensory system to have emerged, serving the ancient autopoietic function of “self-regulation.” Drawing upon molecular biology and revelations from the field of epigenetics, the model suggests that human emotional perceptions provide an ongoing stream of “self-relevant” sensory information concerning optimally adaptive states between the organism and its immediate environment, along with coupled behavioral corrections that honor a universal self-regulatory logic, one still encoded within cellular signaling and immune functions. Exemplified by the fundamental molecular circuitry of sensorimotor control in the E coli bacterium, the model suggests that the hedonic (affective) categories emerge directly from positive and negative feedback processes, their good/bad binary appraisals relating to dual self-regulatory behavioral regimes—evolutionary purposes, through which organisms actively participate in natural selection, and through which humans can interpret optimal or deficit states of balanced being and becoming. The self-regulatory sensory paradigm transcends anthropomorphism, unites divergent theoretical perspectives and isolated bodies of literature, while challenging time-honored assumptions. While suppressive regulatory strategies abound, it suggests that emotions are better understood as regulating us, providing a service crucial to all semantic language, learning systems, evaluative decision-making, and fundamental to optimal physical, mental, and social health. PMID:24808986

Convection and the Soil-Moisture Precipitation Feedback

NASA Astrophysics Data System (ADS)

Schar, C.; Froidevaux, P.; Keller, M.; Schlemmer, L.; Langhans, W.; Schmidli, J.

2014-12-01

The soil moisture - precipitation (SMP) feedback is of key importance for climate and climate change. A positive SMP feedback tends to amplify the hydrological response to external forcings (and thereby fosters precipitation and drought extremes), while a negative SMP feedback tends to moderate the influence of external forcings (and thereby stabilizes the hydrological cycle). The sign of the SMP feedback is poorly constrained by the current literature. Theoretical, modeling and observational studies partly disagree, and have suggested both negative and positive feedback loops. Can wet soil anomalies indeed result in either an increase or a decrease of precipitation (positive or negative SMP feedback, respectively)? Here we investigate the local SMP feedback using real-case and idealized convection-resolving simulations. An idealized simulation strategy is developed, which is able to replicate both signs of the feedback loop, depending on the environmental parameters. The mechanism relies on horizontal soil moisture variations, which may develop and intensify spontaneously. The positive expression of the feedback is associated with the initiation of convection over dry soil patches, but the convective cells then propagate over wet patches, where they strengthen and preferentially precipitate. The negative feedback may occur when the wind profile is too weak to support the propagation of convective features from dry to wet areas. Precipitation is then generally weaker and falls preferentially over dry patches. The results highlight the role of the mid-tropospheric flow in determining the sign of the feedback. A key element of the positive feedback is the exploitation of both low convective inhibition (CIN) over dry patches (for the initiation of convection), and high CAPE over wet patches (for the generation of precipitation). The results of this study will also be discussed in relation to climate change scenarios that exhibit large biases in surface temperature and

Neural correlates of anticipation and processing of performance feedback in social anxiety.

PubMed

Heitmann, Carina Y; Peterburs, Jutta; Mothes-Lasch, Martin; Hallfarth, Marlit C; Böhme, Stephanie; Miltner, Wolfgang H R; Straube, Thomas

2014-12-01

Fear of negative evaluation, such as negative social performance feedback, is the core symptom of social anxiety. The present study investigated the neural correlates of anticipation and perception of social performance feedback in social anxiety. High (HSA) and low (LSA) socially anxious individuals were asked to give a speech on a personally relevant topic and received standardized but appropriate expert performance feedback in a succeeding experimental session in which neural activity was measured during anticipation and presentation of negative and positive performance feedback concerning the speech performance, or a neutral feedback-unrelated control condition. HSA compared to LSA subjects reported greater anxiety during anticipation of negative feedback. Functional magnetic resonance imaging results showed deactivation of medial prefrontal brain areas during anticipation of negative feedback relative to the control and the positive condition, and medial prefrontal and insular hyperactivation during presentation of negative as well as positive feedback in HSA compared to LSA subjects. The results indicate distinct processes underlying feedback processing during anticipation and presentation of feedback in HSA as compared to LSA individuals. In line with the role of the medial prefrontal cortex in self-referential information processing and the insula in interoception, social anxiety seems to be associated with lower self-monitoring during feedback anticipation, and an increased self-focus and interoception during feedback presentation, regardless of feedback valence. © 2014 Wiley Periodicals, Inc.

Feedback loop compensates for rectifier nonlinearity

NASA Technical Reports Server (NTRS)

1966-01-01

Signal processing circuit with two negative feedback loops rectifies two sinusoidal signals which are 180 degrees out of phase and produces a single full-wave rectified output signal. Each feedback loop incorporates a feedback rectifier to compensate for the nonlinearity of the circuit.

Threat ≠ prevention, challenge ≠ promotion: the impact of threat, challenge and regulatory focus on attention to negative stimuli.

PubMed

Sassenberg, Kai; Sassenrath, Claudia; Fetterman, Adam K

2015-01-01

The purpose of the current experiment was to distinguish between the impact of strategic and affective forms of gain- and loss-related motivational states on the attention to negative stimuli. On the basis of the counter-regulation principle and regulatory focus theory, we predicted that individuals would attend more to negative than to neutral stimuli in a prevention focus and when experiencing challenge, but not in a promotion focus and under threat. In one experiment (N = 88) promotion, prevention, threat, or challenge states were activated through a memory task, and a subsequent dot probe task was administered. As predicted, those in the prevention focus and challenge conditions had an attentional bias towards negative words, but those in promotion and threat conditions did not. These findings provide support for the idea that strategic mindsets (e.g., regulatory focus) and hot emotional states (e.g., threat vs. challenge) differently affect the processing of affective stimuli.

Local and global stability for Lotka-Volterra systems with distributed delays and instantaneous negative feedbacks

NASA Astrophysics Data System (ADS)

Faria, Teresa; Oliveira, José J.

This paper addresses the local and global stability of n-dimensional Lotka-Volterra systems with distributed delays and instantaneous negative feedbacks. Necessary and sufficient conditions for local stability independent of the choice of the delay functions are given, by imposing a weak nondelayed diagonal dominance which cancels the delayed competition effect. The global asymptotic stability of positive equilibria is established under conditions slightly stronger than the ones required for the linear stability. For the case of monotone interactions, however, sharper conditions are presented. This paper generalizes known results for discrete delays to systems with distributed delays. Several applications illustrate the results.

Effects of invalid feedback on learning and feedback-related brain activity in decision-making.

PubMed

Ernst, Benjamin; Steinhauser, Marco

2015-10-01

For adaptive decision-making it is important to utilize only relevant, valid and to ignore irrelevant feedback. The present study investigated how feedback processing in decision-making is impaired when relevant feedback is combined with irrelevant and potentially invalid feedback. We analyzed two electrophysiological markers of feedback processing, the feedback-related negativity (FRN) and the P300, in a simple decision-making task, in which participants processed feedback stimuli consisting of relevant and irrelevant feedback provided by the color and meaning of a Stroop stimulus. We found that invalid, irrelevant feedback not only impaired learning, it also altered the amplitude of the P300 to relevant feedback, suggesting an interfering effect of irrelevant feedback on the processing of relevant feedback. In contrast, no such effect on the FRN was obtained. These results indicate that detrimental effects of invalid, irrelevant feedback result from failures of controlled feedback processing. Copyright © 2015 Elsevier Inc. All rights reserved.

Social anxiety and the ironic effects of positive interviewer feedback.

PubMed

Budnick, Christopher J; Kowal, Marta; Santuzzi, Alecia M

2015-01-01

Positive interviewer feedback should encourage positive experiences and outcomes for interviewees. Yet, positive feedback is inconsistent with socially anxious interviewees' negative self-views. Socially anxious interviewees might experience increased self-focus while attempting to reconcile the inconsistency between their self-perceptions and that feedback. This could interfere with successful interview performance. This study used a 3 (feedback: positive, negative, no) × 2 (social anxiety: high, low) between-subjects design. Undergraduate students (N = 88) completed a measure of dispositional social anxiety. They then engaged in a simulated interview with a White confederate trained to adhere to a standardized script. Interviewees received positive, negative, or no interviewer feedback. Each interview was video recorded to code anxiety displays, impression management tactics, and interview success. Following positive feedback, socially anxious interviewees displayed more anxiety, less assertiveness, and received lower success ratings. Among anxious interviewees, increased self-focus provided an indirect path between positive feedback and lower success. Consistent with self-verification theory, anxious interviewees had poorer interview performance following positive feedback that contradicted their negative self-views. Thus, socially anxious interviewees might be at a disadvantage when interviewing, especially following positive feedback. Implications for interviewees and interviewers are discussed.

Integrated regulatory network reveals novel candidate regulators in the development of negative energy balance in cattle.

PubMed

Mozduri, Z; Bakhtiarizadeh, M R; Salehi, A

2018-06-01

Negative energy balance (NEB) is an altered metabolic state in modern high-yielding dairy cows. This metabolic state occurs in the early postpartum period when energy demands for milk production and maintenance exceed that of energy intake. Negative energy balance or poor adaptation to this metabolic state has important effects on the liver and can lead to metabolic disorders and reduced fertility. The roles of regulatory factors, including transcription factors (TFs) and micro RNAs (miRNAs) have often been separately studied for evaluating of NEB. However, adaptive response to NEB is controlled by complex gene networks and still not fully understood. In this study, we aimed to discover the integrated gene regulatory networks involved in NEB development in liver tissue. We downloaded data sets including mRNA and miRNA expression profiles related to three and four cows with severe and moderate NEB, respectively. Our method integrated two independent types of information: module inference network by TFs, miRNAs and mRNA expression profiles (RNA-seq data) and computational target predictions. In total, 176 modules were predicted by using gene expression data and 64 miRNAs and 63 TFs were assigned to these modules. By using our integrated computational approach, we identified 13 TF-module and 19 miRNA-module interactions. Most of these modules were associated with liver metabolic processes as well as immune and stress responses, which might play crucial roles in NEB development. Literature survey results also showed that several regulators and gene targets have already been characterized as important factors in liver metabolic processes. These results provided novel insights into regulatory mechanisms at the TF and miRNA levels during NEB. In addition, the method described in this study seems to be applicable to construct integrated regulatory networks for different diseases or disorders.

"I can be happy even when I lose the game": the influence of chronic regulatory focus and primed self-construal on exergamers' mood.

PubMed

Jin, Seung-A Annie

2010-08-01

This research explored the effects of priming interdependent self-construals (collective self ) versus independent self-construals (private self ) on exergame players' mood in response to negative performance feedback. An experiment was conducted to test the interaction effects of self-construal priming as a situational factor and game players' chronic regulatory focus as an individual difference factor. To this end, the author leveraged a video-game console (Wii) and an exergame (Dance Dance Revolution) in a controlled, randomized 2 x 2 (experimental priming: interdependent self-construal vs. independent self-construal x game players' chronic promotion regulatory focus: low vs. high) between-subjects factorial design experiment (N = 58). The results of a two-way analysis of variance demonstrated the proposed interaction effect between primed self-construal and game players' chronic regulatory focus on the game players' mood in response to negative performance. The theoretical mechanism underlying the two-way interaction is explicated by regulatory focus and the primed self-construals is explicated by regulatory focus theory and two-basket theory. Practical implications for game developers and theoretical contributions to video-game research are discussed.

A conserved SREBP-1/phosphatidylcholine feedback circuit regulates lipogenesis in metazoans.

PubMed

Walker, Amy K; Jacobs, René L; Watts, Jennifer L; Rottiers, Veerle; Jiang, Karen; Finnegan, Deirdre M; Shioda, Toshi; Hansen, Malene; Yang, Fajun; Niebergall, Lorissa J; Vance, Dennis E; Tzoneva, Monika; Hart, Anne C; Näär, Anders M

2011-11-11

Sterol regulatory element-binding proteins (SREBPs) activate genes involved in the synthesis and trafficking of cholesterol and other lipids and are critical for maintaining lipid homeostasis. Aberrant SREBP activity, however, can contribute to obesity, fatty liver disease, and insulin resistance, hallmarks of metabolic syndrome. Our studies identify a conserved regulatory circuit in which SREBP-1 controls genes in the one-carbon cycle, which produces the methyl donor S-adenosylmethionine (SAMe). Methylation is critical for the synthesis of phosphatidylcholine (PC), a major membrane component, and we find that blocking SAMe or PC synthesis in C. elegans, mouse liver, and human cells causes elevated SREBP-1-dependent transcription and lipid droplet accumulation. Distinct from negative regulation of SREBP-2 by cholesterol, our data suggest a feedback mechanism whereby maturation of nuclear, transcriptionally active SREBP-1 is controlled by levels of PC. Thus, nutritional or genetic conditions limiting SAMe or PC production may activate SREBP-1, contributing to human metabolic disorders. Copyright © 2011 Elsevier Inc. All rights reserved.

NF-κB regulates neuronal ankyrin-G via a negative feedback loop.

PubMed

König, Hans-Georg; Schwamborn, Robert; Andresen, Silke; Kinsella, Sinéad; Watters, Orla; Fenner, Beau; Prehn, Jochen H M

2017-02-09

The axon initial segment (AIS) is a neuronal compartment defined by ankyrin-G expression. We here demonstrate that the IKK-complex co-localizes and interacts with the cytoskeletal anchor protein ankyrin-G in immunoprecipitation and proximity-ligation experiments in cortical neurons. Overexpression of the 270 kDa variant of ankyrin-G suppressed, while gene-silencing of ankyrin-G expression increased nuclear factor-κB (NF-κB) activity in primary neurons, suggesting that ankyrin-G sequesters the transcription factor in the AIS. We also found that p65 bound to the ank3 (ankyrin-G) promoter sequence in chromatin immunoprecipitation analyses thereby increasing ank3 expression and ankyrin-G levels at the AIS. Gene-silencing of p65 or ankyrin-G overexpression suppressed ank3 reporter activity. Collectively these data demonstrate that p65/NF-κB controls ankyrin-G levels via a negative feedback loop, thereby linking NF-κB signaling with neuronal polarity and axonal plasticity.

[Construction of screening system for mutation of negative regulatory genes in Streptomyces].

PubMed

Zhu, Yu; Feng, Chi; Tan, Huarong; Tian, Yuqing

2013-10-04

We aimed to create a novel report system for screening the mutation of the negative regulatory genes, especially for those repressing the expression of cryptic antibiotics clusters. We used marker-free gene disruption strategy, which combines with the "REDIRECT (Rapid Efficient Directed Recombination Time Saving)" technology and in vivo site-specific recombination by Streptomyces phage phiBT1 integrase, to construct a scbR2/inoA double mutant strain of S. coelicolor M145. This strain was used as the host of the report system. For the construction of the reporter plasmid, the ScbR2 repressed promoter of cpkO from CPK (cryptic polyketide) cluster was used to drive the expression of a promoterless conserved gene inoA of S. coelicolor. Then the reporter plasmid was introduced into the host strain described above to test the availability of inoA as a reporter gene in this system. The scbR2/inoA double mutant strain gave rise to a bald pheno type on MM medium in the absence of inositol, and produced yellow pigmented secondary metabolite by the disruption of scbR2 to release the repression of cpkO, a pathway specific activator gene situated in CPK cluster. After introducing the reporter plasmid into this test stain, the resulting strain recovered the phenotype as wild-type strain, indicating that the promoter of cpkO can drive the expression of inoA in scbR2 mutant and consequently restore the biosynthesis of inositol. Our results indicated that inoA can be used as a novel reporter gene for Streptomyces, especially for detecting the activation of the "silent" promoter. This report system might be available for screening the mutation of the negative regulatory genes for the cryptic secondary metabolic gene clusters.

Positive and negative feedback loops in nutrient phytoplankton interactions related to climate dynamics factors in a shallow temperate estuary (Vistula Lagoon, southern Baltic)

NASA Astrophysics Data System (ADS)

Kruk, Marek; Kobos, Justyna; Nawrocka, Lidia; Parszuto, Katarzyna

2018-04-01

This study aims to demonstrate that factors associated with climate dynamics, such as temperature and wind, affect the ecosystem of the shallow Vistula Lagoon in the southern Baltic and cause nutrient forms phytoplankton interactions: the growth of biomass and constraints of it. This occurs through a network of direct and indirect relationships between environmental and phytoplankton factors, including interactions of positive and negative feedback loops. Path analysis supported by structural equation modeling (SEM) was used to test hypotheses regarding the impact of climate factors on algal assemblages. Increased phytoplankton biomass was affected directly by water temperature and salinity, while the wind speed effect was indirect as it resulted in increased concentrations of suspended solids (SS) in the water column. Simultaneously, the concentration of SS in the water was positively correlated with particulate organic carbon (POC), particulate nitrogen (PN), and particulate phosphorus (PP), and was negatively correlated with the total nitrogen to phosphorus (N:P) ratio. Particulate forms of C, N, and phosphorus (P), concentrations of soluble reactive phosphorus (SRP) and nitrate and nitrite nitrogen (NO3-N + NO2-N), and ratios of the total N:P and DIN:SRP, all indirectly effected Cyanobacteria C concentrations. These processes influence other phytoplankton groups (Chlorophyta, Bacillariophyceae and the picophytoplankton fraction). Increased levels of SRP associated with organic matter (POC), which stemmed from reduced DIN:SRP ratios, contributed to increased Cyanoprokaryota and picophytoplankton C concentrations, which created a positive feedback loop. However, a simultaneous reduction in the total N:P ratio could have inhibited increases in the biomass of these assemblages by limiting N, which likely formed a negative feedback loop. The study indicates that the nutrients-phytoplankton feedback loop phenomenon can intensify eutrophication in a temperate lagoon

Functional characteristics of a double positive feedback loop coupled with autorepression

NASA Astrophysics Data System (ADS)

Banerjee, Subhasis; Bose, Indrani

2008-12-01

We study the functional characteristics of a two-gene motif consisting of a double positive feedback loop and an autoregulatory negative feedback loop. The motif appears in the gene regulatory network controlling the functional activity of pancreatic β-cells. The model exhibits bistability and hysteresis in appropriate parameter regions. The two stable steady states correspond to low (OFF state) and high (ON state) protein levels, respectively. Using a deterministic approach, we show that the region of bistability increases in extent when the copy number of one of the genes is reduced from 2 to 1. The negative feedback loop has the effect of reducing the size of the bistable region. Loss of a gene copy, brought about by mutations, hampers the normal functioning of the β-cells giving rise to the genetic disorder, maturity-onset diabetes of the young (MODY). The diabetic phenotype makes its appearance when a sizable fraction of the β-cells is in the OFF state. Using stochastic simulation techniques we show that, on reduction of the gene copy number, there is a transition from the monostable ON to the ON state in the bistable region of the parameter space. Fluctuations in the protein levels, arising due to the stochastic nature of gene expression, can give rise to transitions between the ON and OFF states. We show that as the strength of autorepression increases, the ON → OFF state transitions become less probable whereas the reverse transitions are more probable. The implications of the results in the context of the occurrence of MODY are pointed out.

Performance feedback, self-esteem, and cardiovascular adaptation to recurring stressors.

PubMed

Brown, Eoin G; Creaven, Ann-Marie

2017-05-01

This study sought to examine the effects of performance feedback and individual differences in self-esteem on cardiovascular habituation to repeat stress exposure. Sixty-six university students (n = 39 female) completed a self-esteem measure and completed a cardiovascular stress-testing protocol involving repeated exposure to a mental arithmetic task. Cardiovascular functioning was sampled across four phases: resting baseline, initial stress exposure, a recovery period, and repeated stress exposure. Participants were randomly assigned to receive fictional positive feedback, negative feedback, or no feedback following the recovery period. Negative feedback was associated with a sensitized blood pressure response to a second exposure of the stress task. Positive feedback was associated with decreased cardiovascular and psychological responses to a second exposure. Self-esteem was also found to predict reactivity and this interacted with the type of feedback received. These findings suggest that negative performance feedback sensitizes cardiovascular reactivity to stress, whereas positive performance feedback increases both cardiovascular and psychological habituation to repeat exposure to stressors. Furthermore, an individual's self-esteem also appears to influence this process.

Distinguishing Feedback Mechanisms in Clock Models

NASA Astrophysics Data System (ADS)

Golden, Alexander; Lubensky, David

Biological oscillators are very diverse but can be classified based on dynamical motifs such as type of feedback. The S. Elongatus circadian oscillator is a novel circadian oscillator that can operate at constant protein number by modifying covalent states. It can be reproduced in vitro with only 3 different purified proteins: KaiA, KaiB, and KaiC. We use computational and analytic techniques to compare models of the S. Elongatus post-translational oscillator that rely on positive feedback with models that rely on negative feedback. We show that introducing a protein that binds competitively with KaiA to the KaiB-KaiC complex can distinguish between positive and negative feedback as the primary driver of the rhythm, which has so far been difficult to address experimentally. NSF Grant DMR-1056456.

The Interplay between Feedback and Buffering in Cellular Homeostasis.

PubMed

Hancock, Edward J; Ang, Jordan; Papachristodoulou, Antonis; Stan, Guy-Bart

2017-11-22

Buffering, the use of reservoirs of molecules to maintain concentrations of key molecular species, and negative feedback are the primary known mechanisms for robust homeostatic regulation. To our knowledge, however, the fundamental principles behind their combined effect have not been elucidated. Here, we study the interplay between buffering and negative feedback in the context of cellular homeostasis. We show that negative feedback counteracts slow-changing disturbances, whereas buffering counteracts fast-changing disturbances. Furthermore, feedback and buffering have limitations that create trade-offs for regulation: instability in the case of feedback and molecular noise in the case of buffering. However, because buffering stabilizes feedback and feedback attenuates noise from slower-acting buffering, their combined effect on homeostasis can be synergistic. These effects can be explained within a traditional control theory framework and are consistent with experimental observations of both ATP homeostasis and pH regulation in vivo. These principles are critical for studying robustness and homeostasis in biology and biotechnology. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Enhancer Variants Synergistically Drive Dysfunction of a Gene Regulatory Network In Hirschsprung Disease

DOE PAGES

Chatterjee, Sumantra; Kapoor, Ashish; Akiyama, Jennifer A.; ...

2016-09-29

Common sequence variants in cis-regulatory elements (CREs) are suspected etiological causes of complex disorders. We previously identified an intronic enhancer variant in the RET gene disrupting SOX10 binding and increasing Hirschsprung disease (HSCR) risk 4-fold. We now show that two other functionally independent CRE variants, one binding Gata2 and the other binding Rarb, also reduce Ret expression and increase risk 2- and 1.7-fold. By studying human and mouse fetal gut tissues and cell lines, we demonstrate that reduced RET expression propagates throughout its gene regulatory network, exerting effects on both its positive and negative feedback components. We also provide evidencemore » that the presence of a combination of CRE variants synergistically reduces RET expression and its effects throughout the GRN. These studies show how the effects of functionally independent non-coding variants in a coordinated gene regulatory network amplify their individually small effects, providing a model for complex disorders.« less

Enhancer Variants Synergistically Drive Dysfunction of a Gene Regulatory Network In Hirschsprung Disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatterjee, Sumantra; Kapoor, Ashish; Akiyama, Jennifer A.

Common sequence variants in cis-regulatory elements (CREs) are suspected etiological causes of complex disorders. We previously identified an intronic enhancer variant in the RET gene disrupting SOX10 binding and increasing Hirschsprung disease (HSCR) risk 4-fold. We now show that two other functionally independent CRE variants, one binding Gata2 and the other binding Rarb, also reduce Ret expression and increase risk 2- and 1.7-fold. By studying human and mouse fetal gut tissues and cell lines, we demonstrate that reduced RET expression propagates throughout its gene regulatory network, exerting effects on both its positive and negative feedback components. We also provide evidencemore » that the presence of a combination of CRE variants synergistically reduces RET expression and its effects throughout the GRN. These studies show how the effects of functionally independent non-coding variants in a coordinated gene regulatory network amplify their individually small effects, providing a model for complex disorders.« less

Feedback Seeking in Early Adolescence: Self-Enhancement or Self-Verification?

PubMed

Rosen, Lisa H; Principe, Connor P; Langlois, Judith H

2013-02-13

The authors examined whether early adolescents ( N = 90) solicit self-enhancing feedback (i.e., positive feedback) or self-verifying feedback (i.e., feedback congruent with self-views, even when these views are negative). Sixth, seventh, and eighth graders first completed a self-perception measure and then selected whether to receive positive or negative feedback from an unknown peer in different domains of self. Results were consistent with self-verification theory; adolescents who perceived themselves as having both strengths and weaknesses were more likely to seek negative feedback regarding a self-perceived weakness compared to a self-perceived strength. The authors found similar support for self-verification processes when they considered the entire sample regardless of perceived strengths and weaknesses; hierarchical linear modeling (HLM) examined the predictive power of ratings of self-perceived ability, certainty, and importance on feedback seeking for all participants and provided additional evidence of self-verification strivings in adolescence.

Feedback Seeking in Early Adolescence: Self-Enhancement or Self-Verification?

PubMed Central

Rosen, Lisa H.; Principe, Connor P.; Langlois, Judith H.

2012-01-01

The authors examined whether early adolescents (N = 90) solicit self-enhancing feedback (i.e., positive feedback) or self-verifying feedback (i.e., feedback congruent with self-views, even when these views are negative). Sixth, seventh, and eighth graders first completed a self-perception measure and then selected whether to receive positive or negative feedback from an unknown peer in different domains of self. Results were consistent with self-verification theory; adolescents who perceived themselves as having both strengths and weaknesses were more likely to seek negative feedback regarding a self-perceived weakness compared to a self-perceived strength. The authors found similar support for self-verification processes when they considered the entire sample regardless of perceived strengths and weaknesses; hierarchical linear modeling (HLM) examined the predictive power of ratings of self-perceived ability, certainty, and importance on feedback seeking for all participants and provided additional evidence of self-verification strivings in adolescence. PMID:23543746

Feedback, Mass Conservation and Reaction Kinetics Impact the Robustness of Cellular Oscillations

PubMed Central

Baum, Katharina; Kofahl, Bente; Steuer, Ralf; Wolf, Jana

2016-01-01

Oscillations occur in a wide variety of cellular processes, for example in calcium and p53 signaling responses, in metabolic pathways or within gene-regulatory networks, e.g. the circadian system. Since it is of central importance to understand the influence of perturbations on the dynamics of these systems a number of experimental and theoretical studies have examined their robustness. The period of circadian oscillations has been found to be very robust and to provide reliable timing. For intracellular calcium oscillations the period has been shown to be very sensitive and to allow for frequency-encoded signaling. We here apply a comprehensive computational approach to study the robustness of period and amplitude of oscillatory systems. We employ different prototype oscillator models and a large number of parameter sets obtained by random sampling. This framework is used to examine the effect of three design principles on the sensitivities towards perturbations of the kinetic parameters. We find that a prototype oscillator with negative feedback has lower period sensitivities than a prototype oscillator relying on positive feedback, but on average higher amplitude sensitivities. For both oscillator types, the use of Michaelis-Menten instead of mass action kinetics in all degradation and conversion reactions leads to an increase in period as well as amplitude sensitivities. We observe moderate changes in sensitivities if replacing mass conversion reactions by purely regulatory reactions. These insights are validated for a set of established models of various cellular rhythms. Overall, our work highlights the importance of reaction kinetics and feedback type for the variability of period and amplitude and therefore for the establishment of predictive models. PMID:28027301

The light cycle controls the hatching rhythm in Bombyx mori via negative feedback loop of the circadian oscillator.

PubMed

Tao, Hui; Li, Xue; Qiu, Jian-Feng; Liu, Heng-Jiang; Zhang, Da-Yan; Chu, Feng; Sima, Yanghu; Xu, Shi-Qing

2017-10-01

Hatching behavior is a key target in silkworm (Bombyx mori) rearing, especially for the control of Lepidoptera pests. According to previous research, hatching rhythms appear to be controlled by a clock mechanism that restricts or "gates" hatching to a particular time. However, the underlying mechanism remains elusive. Under 12-h light:12-h dark photoperiod (LD) conditions, the transcriptional levels of the chitinase5 (Cht5) and hatching enzyme-like (Hel) genes, as well as the enzymatic activities of their gene products, oscillated in time with ambient light cycles, as did the transcriptional levels of the cryptochrome 1, cryptochrome 2, period (per), and timeless genes, which are key components of the negative feedback loop of the circadian rhythm. These changes were related to the expression profile of the ecdysteroid receptor gene and the hatching behavior of B. mori eggs. However, under continuous light or dark conditions, the hatching behavior, the expression levels of Cht5 and Hel, as well as the enzymatic activities of their gene products, were not synchronized unlike under LD conditions. In addition, immunohistochemistry experiments showed that light promoted the translocation of PER from the cytoplasm to the nucleus. In conclusion, LD cycles regulate the hatching rhythm of B. mori via negative feedback loop of the circadian oscillator. © 2017 Wiley Periodicals, Inc.

Clustering in Cell Cycle Dynamics with General Response/Signaling Feedback

PubMed Central

Young, Todd R.; Fernandez, Bastien; Buckalew, Richard; Moses, Gregory; Boczko, Erik M.

2011-01-01

Motivated by experimental and theoretical work on autonomous oscillations in yeast, we analyze ordinary differential equations models of large populations of cells with cell-cycle dependent feedback. We assume a particular type of feedback that we call Responsive/Signaling (RS), but do not specify a functional form of the feedback. We study the dynamics and emergent behaviour of solutions, particularly temporal clustering and stability of clustered solutions. We establish the existence of certain periodic clustered solutions as well as “uniform” solutions and add to the evidence that cell-cycle dependent feedback robustly leads to cell-cycle clustering. We highlight the fundamental differences in dynamics between systems with negative and positive feedback. For positive feedback systems the most important mechanism seems to be the stability of individual isolated clusters. On the other hand we find that in negative feedback systems, clusters must interact with each other to reinforce coherence. We conclude from various details of the mathematical analysis that negative feedback is most consistent with observations in yeast experiments. PMID:22001733

Cross-Cohort Analysis Identifies a TEAD4-MYCN Positive Feedback Loop as the Core Regulatory Element of High-Risk Neuroblastoma.

PubMed

Rajbhandari, Presha; Lopez, Gonzalo; Capdevila, Claudia; Salvatori, Beatrice; Yu, Jiyang; Rodriguez-Barrueco, Ruth; Martinez, Daniel; Yarmarkovich, Mark; Weichert-Leahey, Nina; Abraham, Brian J; Alvarez, Mariano J; Iyer, Archana; Harenza, Jo Lynne; Oldridge, Derek; De Preter, Katleen; Koster, Jan; Asgharzadeh, Shahab; Seeger, Robert C; Wei, Jun S; Khan, Javed; Vandesompele, Jo; Mestdagh, Pieter; Versteeg, Rogier; Look, A Thomas; Young, Richard A; Iavarone, Antonio; Lasorella, Anna; Silva, Jose M; Maris, John M; Califano, Andrea

2018-05-01

High-risk neuroblastomas show a paucity of recurrent somatic mutations at diagnosis. As a result, the molecular basis for this aggressive phenotype remains elusive. Recent progress in regulatory network analysis helped us elucidate disease-driving mechanisms downstream of genomic alterations, including recurrent chromosomal alterations. Our analysis identified three molecular subtypes of high-risk neuroblastomas, consistent with chromosomal alterations, and identified subtype-specific master regulator proteins that were conserved across independent cohorts. A 10-protein transcriptional module-centered around a TEAD4-MYCN positive feedback loop-emerged as the regulatory driver of the high-risk subtype associated with MYCN amplification. Silencing of either gene collapsed MYCN -amplified ( MYCN Amp ) neuroblastoma transcriptional hallmarks and abrogated viability in vitro and in vivo Consistently, TEAD4 emerged as a robust prognostic marker of poor survival, with activity independent of the canonical Hippo pathway transcriptional coactivators YAP and TAZ. These results suggest novel therapeutic strategies for the large subset of MYCN-deregulated neuroblastomas. Significance: Despite progress in understanding of neuroblastoma genetics, little progress has been made toward personalized treatment. Here, we present a framework to determine the downstream effectors of the genetic alterations sustaining neuroblastoma subtypes, which can be easily extended to other tumor types. We show the critical effect of disrupting a 10-protein module centered around a YAP/TAZ-independent TEAD4-MYCN positive feedback loop in MYCN Amp neuroblastomas, nominating TEAD4 as a novel candidate for therapeutic intervention. Cancer Discov; 8(5); 582-99. ©2018 AACR. This article is highlighted in the In This Issue feature, p. 517 . ©2018 American Association for Cancer Research.

Systems-Level Feedbacks of NRF2 Controlling Autophagy upon Oxidative Stress Response

PubMed Central

Kapuy, Orsolya; Papp, Diána; Bánhegyi, Gábor

2018-01-01

Although the primary role of autophagy-dependent cellular self-eating is cytoprotective upon various stress events (such as starvation, oxidative stress, and high temperatures), sustained autophagy might lead to cell death. A transcription factor called NRF2 (nuclear factor erythroid-related factor 2) seems to be essential in maintaining cellular homeostasis in the presence of either reactive oxygen or nitrogen species generated by internal metabolism or external exposure. Accumulating experimental evidence reveals that oxidative stress also influences the balance of the 5′ AMP-activated protein kinase (AMPK)/rapamycin (mammalian kinase target of rapamycin or mTOR) signaling pathway, thereby inducing autophagy. Based on computational modeling here we propose that the regulatory triangle of AMPK, NRF2 and mTOR guaranties a precise oxidative stress response mechanism comprising of autophagy. We suggest that under conditions of oxidative stress, AMPK is crucial for autophagy induction via mTOR down-regulation, while NRF2 fine-tunes the process of autophagy according to the level of oxidative stress. We claim that the cellular oxidative stress response mechanism achieves an incoherently amplified negative feedback loop involving NRF2, mTOR and AMPK. The mTOR-NRF2 double negative feedback generates bistability, supporting the proper separation of two alternative steady states, called autophagy-dependent survival (at low stress) and cell death (at high stress). In addition, an AMPK-mTOR-NRF2 negative feedback loop suggests an oscillatory characteristic of autophagy upon prolonged intermediate levels of oxidative stress, resulting in new rounds of autophagy stimulation until the stress events cannot be dissolved. Our results indicate that AMPK-, NRF2- and mTOR-controlled autophagy induction provides a dynamic adaptation to altering environmental conditions, assuming their new frontier in biomedicine. PMID:29510589

Self-esteem Modulates Medial Prefrontal Cortical Responses to Evaluative Social Feedback

PubMed Central

Kelley, William M.; Heatherton, Todd F.

2010-01-01

Self-esteem is a facet of personality that influences perception of social standing and modulates the salience of social acceptance and rejection. As such, self-esteem may bias neural responses to positive and negative social feedback across individuals. During functional magnetic resonance imaging scanning, participants (n = 42) engaged in a social evaluation task whereby they ostensibly received feedback from peers indicating they were liked or disliked. Results demonstrated that individuals with low self-esteem believed that they received less positive feedback from others and showed enhanced activity to positive versus negative social feedback in the ventral anterior cingulate cortex/medial prefrontal cortex (vACC/mPFC). By contrast, vACC/mPFC activity was insensitive to positive versus negative feedback in individuals with high self-esteem, and these individuals consistently overestimated the amount of positive feedback received from peers. Voxelwise analyses supported these findings; lower self-esteem predicted a linear increase in vACC/mPFC response to positive versus negative social feedback. Taken together, the present findings propose a functional role for the vACC/mPFC in representing the salience of social feedback and shaping perceptions of relative social standing. PMID:20351022

Cross-species antiviral activity of goose interferon lambda against duck plague virus is related to its positive self-regulatory feedback loop.

PubMed

Chen, Shun; Zhang, Wei; Zhou, Qin; Wang, Anqi; Sun, Lipei; Wang, Mingshu; Jia, Renyong; Zhu, Dekang; Liu, Mafeng; Sun, Kunfeng; Yang, Qiao; Wu, Ying; Chen, Xiaoyue; Cheng, Anchun

2017-06-01

Duck plague virus (DPV) is a virus of the Herpesviridae family that leads to acute disease with a high mortality rate in ducks. Control of the disease contributes to the development of poultry breeding. Type III IFN family (IFN-λs) is a novel member of the IFN family, and goose IFN-λ (goIFN-λ) is a newly identified gene whose antiviral function has only been investigated to a limited extent. Here, the cross-species antiviral activity of goIFN-λ against DPV in duck embryo fibroblasts (DEFs) was studied. We found that pre-treatment with goIFN-λ greatly increased the expression of IFN-λ in both heterologous DEFs and homologous goose embryo fibroblasts (GEFs), while differentially inducing IFNα- and IFN-stimulated genes. Additionally, a positive self-regulatory feedback loop of goIFN-λ was blocked by a mouse anti-goIFN-λ polyclonal antibody, which was confirmed in both homologous GEFs and goose peripheral blood mononuclear cells (PBMCs). The suppression of the BAC-DPV-EGFP by goIFN-λ in DEFs was confirmed by fluorescence microscopy, flow cytometry (FCM) analysis, viral copies and titre detection, which can be rescued by mouse anti-goIFN-λ polyclonal antibody incubation. Finally, reporter gene assays indicated that the cross-species antiviral activity of goIFN-λ against BAC-DPV-EGFP is related to its positive self-regulatory feedback loop and subsequent ISG induction. Our data shed light on the fundamental mechanisms of goIFN-λ antiviral function in vitro and extend the considerable range of therapeutic applications in multiple-poultry disease.

Vegetation-rainfall feedbacks across the Sahel: a combined observational and modeling study

NASA Astrophysics Data System (ADS)

Yu, Y.; Notaro, M.; Wang, F.; Mao, J.; Shi, X.; Wei, Y.

2016-12-01

The Sahel rainfall is characterized by large interannual variability. Past modeling studies have concluded that the Sahel rainfall variability is primarily driven by oceanic forcings and amplified by land-atmosphere interactions. However, the relative importance of oceanic versus terrestrial drivers has never been assessed from observations. The current understanding of vegetation's impacts on climate, i.e. positive vegetation-rainfall feedback through the albedo, moisture, and momentum mechanisms, comes from untested models. Neither the positive vegetation-rainfall feedback, nor the underlying mechanisms, has been fully resolved in observations. The current study fills the knowledge gap about the observed vegetation-rainfall feedbacks, through the application of the multivariate statistical method Generalized Equilibrium Feedback Assessment (GEFA) to observational data. According to GEFA, the observed oceanic impacts dominate over terrestrial impacts on Sahel rainfall, except in the post-monsoon period. Positive leaf area index (LAI) anomalies favor an extended, wetter monsoon across the Sahel, largely due to moisture recycling. The albedo mechanism is not responsible for this positive vegetation feedback on the seasonal-interannual time scale, which is too short for a grass-desert transition. A low-level stabilization and subsidence is observed in response to increased LAI - potentially responsible for a negative vegetation-rainfall feedback. However, the positive moisture feedback overwhelms the negative momentum feedback, resulting in an observed positive vegetation-rainfall feedback. We further applied GEFA to a fully-coupled Community Earth System Model (CESM) control run, as an example of evaluating climate models against the GEFA-based observational benchmark. In contrast to the observed positive vegetation-rainfall feedbacks, CESM simulates a negative vegetation-rainfall feedback across Sahel, peaking in the pre-monsoon season. The simulated negative

Changes of Attention during Value-Based Reversal Learning Are Tracked by N2pc and Feedback-Related Negativity

PubMed Central

Oemisch, Mariann; Watson, Marcus R.; Womelsdorf, Thilo; Schubö, Anna

2017-01-01

Previously learned reward values can have a pronounced impact, behaviorally and neurophysiologically, on the allocation of selective attention. All else constant, stimuli previously associated with a high value gain stronger attentional prioritization than stimuli previously associated with a low value. The N2pc, an ERP component indicative of attentional target selection, has been shown to reflect aspects of this prioritization, by changes of mean amplitudes closely corresponding to selective enhancement of high value target processing and suppression of high value distractor processing. What has remained unclear so far is whether the N2pc also reflects the flexible and repeated behavioral adjustments needed in a volatile task environment, in which the values of stimuli are reversed often and unannounced. Using a value-based reversal learning task, we found evidence that the N2pc amplitude flexibly and reversibly tracks value-based choices during the learning of reward associated stimulus colors. Specifically, successful learning of current value-contingencies was associated with reduced N2pc amplitudes, and this effect was more apparent for distractor processing, compared with target processing. In addition, following a value reversal the feedback related negativity(FRN), an ERP component that reflects feedback processing, was amplified and co-occurred with increased N2pc amplitudes in trials following low-value feedback. Importantly, participants that showed the greatest adjustment in N2pc amplitudes based on feedback were also the most efficient learners. These results allow further insight into how changes in attentional prioritization in an uncertain and volatile environment support flexible adjustments of behavior. PMID:29163113

Changes of Attention during Value-Based Reversal Learning Are Tracked by N2pc and Feedback-Related Negativity.

PubMed

Oemisch, Mariann; Watson, Marcus R; Womelsdorf, Thilo; Schubö, Anna

2017-01-01

Previously learned reward values can have a pronounced impact, behaviorally and neurophysiologically, on the allocation of selective attention. All else constant, stimuli previously associated with a high value gain stronger attentional prioritization than stimuli previously associated with a low value. The N2pc, an ERP component indicative of attentional target selection, has been shown to reflect aspects of this prioritization, by changes of mean amplitudes closely corresponding to selective enhancement of high value target processing and suppression of high value distractor processing. What has remained unclear so far is whether the N2pc also reflects the flexible and repeated behavioral adjustments needed in a volatile task environment, in which the values of stimuli are reversed often and unannounced. Using a value-based reversal learning task, we found evidence that the N2pc amplitude flexibly and reversibly tracks value-based choices during the learning of reward associated stimulus colors. Specifically, successful learning of current value-contingencies was associated with reduced N2pc amplitudes, and this effect was more apparent for distractor processing, compared with target processing. In addition, following a value reversal the feedback related negativity(FRN), an ERP component that reflects feedback processing, was amplified and co-occurred with increased N2pc amplitudes in trials following low-value feedback. Importantly, participants that showed the greatest adjustment in N2pc amplitudes based on feedback were also the most efficient learners. These results allow further insight into how changes in attentional prioritization in an uncertain and volatile environment support flexible adjustments of behavior.

Rapid feedback processing in human nucleus accumbens and motor thalamus.

PubMed

Schüller, Thomas; Gruendler, Theo O J; Jocham, Gerhard; Klein, Tilmann A; Timmermann, Lars; Visser-Vandewalle, Veerle; Kuhn, Jens; Ullsperger, Markus

2015-04-01

The nucleus accumbens (NAcc) and thalamus are integral parts in models of feedback processing. Deep brain stimulation (DBS) has been successfully employed to alleviate symptoms of psychiatric conditions including obsessive-compulsive disorder (OCD) and Tourette's syndrome (TS). Common target structures are the NAcc and the ventral anterior and ventro-lateral nuclei (VA/VL) of the thalamus, for OCD and TS, respectively. The feedback related negativity (FRN) is an event-related potential associated with feedback processing reflecting posterior medial frontal cortex (pMFC) activity. Here we report on three cases where we recorded scalp EEG and local field potentials (LFP) from externalized electrodes located in the NAcc or thalamus (VA/VL) while patients engaged in a modified time estimation task, known to engage feedback processing and elicit the FRN. Additionally, scalp EEG were recorded from 29 healthy participants (HP) engaged in the same task. The signal in all structures (pMFC, NAcc, and thalamus) was differently modulated by positive and negative feedback. LFP activity in the NAcc showed a biphasic time course after positive feedback during the FRN time interval. Negative feedback elicited a much weaker and later response. In the thalamus a monophasic modulation was recorded during the FRN time interval. Again, this modulation was more pronounced after positive performance feedback compared to negative feedback. In channels outside the target area no modulation was observed. The surface-FRN was reliably elicited on a group level in HP and showed no significant difference following negative feedback between patients and HP. German Clinical Trial Register: Neurocognitive specification of dysfunctions within basal ganglia-cortex loops and their therapeutic modulation by deep brain stimulation in patients with obsessive compulsive disorder and Tourette syndrome, http://www.drks.de/DRKS00005316. Copyright © 2015 Elsevier Ltd. All rights reserved.

The regulatory function of self-esteem: testing the epistemic and acceptance signaling systems.

PubMed

Stinson, Danu Anthony; Logel, Christine; Holmes, John G; Wood, Joanne V; Forest, Amanda L; Gaucher, Danielle; Fitzsimons, Grainné M; Kath, Jennifer

2010-12-01

The authors draw on sociometer theory (e.g., Leary, 2004) and self-verification theory (e.g., Swann, 1997) to propose an expanded model of the regulatory function of self-esteem. The model suggests that people not only possess an acceptance signaling system that indicates whether relational value is high or low but also possess an epistemic signaling system that indicates whether social feedback is consistent or inconsistent with chronic perceived relational value (i.e., global self-esteem). One correlational study and 5 experiments, with diverse operationalizations of social feedback, demonstrated that the epistemic signaling system responds to self-esteem consistent or inconsistent relational-value feedback with increases or deceases in epistemic certainty. Moreover, Studies 3-6 demonstrated that the acceptance and epistemic signaling systems respond uniquely to social feedback. Finally, Studies 5 and 6 provide evidence that the epistemic signaling system is part of a broader self-regulatory system: Self-esteem inconsistent feedback caused cognitive efforts to decrease the discrepancy between self-views and feedback and caused depleted self-regulatory capacity on a subsequent self-control task. PsycINFO Database Record (c) 2010 APA, all rights reserved.

An Actomyosin-Arf-GEF Negative Feedback Loop for Tissue Elongation under Stress.

PubMed

West, Junior J; Zulueta-Coarasa, Teresa; Maier, Janna A; Lee, Donghoon M; Bruce, Ashley E E; Fernandez-Gonzalez, Rodrigo; Harris, Tony J C

2017-08-07

In response to a pulling force, a material can elongate, hold fast, or fracture. During animal development, multi-cellular contraction of one region often stretches neighboring tissue. Such local contraction occurs by induced actomyosin activity, but molecular mechanisms are unknown for regulating the physical properties of connected tissue for elongation under stress. We show that cytohesins, and their Arf small G protein guanine nucleotide exchange activity, are required for tissues to elongate under stress during both Drosophila dorsal closure (DC) and zebrafish epiboly. In Drosophila, protein localization, laser ablation, and genetic interaction studies indicate that the cytohesin Steppke reduces tissue tension by inhibiting actomyosin activity at adherens junctions. Without Steppke, embryogenesis fails, with epidermal distortions and tears resulting from myosin misregulation. Remarkably, actomyosin network assembly is necessary and sufficient for local Steppke accumulation, where live imaging shows Steppke recruitment within minutes. This rapid negative feedback loop provides a molecular mechanism for attenuating the main tension generator of animal tissues. Such attenuation relaxes tissues and allows orderly elongation under stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Feedback-related Negativity Codes Components of Abstract Inference during Reward-based Decision-making.

PubMed

Reiter, Andrea M F; Koch, Stefan P; Schröger, Erich; Hinrichs, Hermann; Heinze, Hans-Jochen; Deserno, Lorenz; Schlagenhauf, Florian

2016-08-01

Behavioral control is influenced not only by learning from the choices made and the rewards obtained but also by "what might have happened," that is, inference about unchosen options and their fictive outcomes. Substantial progress has been made in understanding the neural signatures of direct learning from choices that are actually made and their associated rewards via reward prediction errors (RPEs). However, electrophysiological correlates of abstract inference in decision-making are less clear. One seminal theory suggests that the so-called feedback-related negativity (FRN), an ERP peaking 200-300 msec after a feedback stimulus at frontocentral sites of the scalp, codes RPEs. Hitherto, the FRN has been predominantly related to a so-called "model-free" RPE: The difference between the observed outcome and what had been expected. Here, by means of computational modeling of choice behavior, we show that individuals employ abstract, "double-update" inference on the task structure by concurrently tracking values of chosen stimuli (associated with observed outcomes) and unchosen stimuli (linked to fictive outcomes). In a parametric analysis, model-free RPEs as well as their modification because of abstract inference were regressed against single-trial FRN amplitudes. We demonstrate that components related to abstract inference uniquely explain variance in the FRN beyond model-free RPEs. These findings advance our understanding of the FRN and its role in behavioral adaptation. This might further the investigation of disturbed abstract inference, as proposed, for example, for psychiatric disorders, and its underlying neural correlates.

Antennally mediated negative feedback regulation of pheromone production in the pine engraver beetle, Ips pini

NASA Astrophysics Data System (ADS)

Ginzel, Matthew D.; Bearfield, Jeremy C.; Keeling, Christopher I.; McCormack, Colin C.; Blomquist, Gary J.; Tittiger, Claus

2007-01-01

Bark beetles use monoterpenoid aggregation pheromones to coordinate host colonization and mating. These chemical signals are produced de novo in midgut cells via the mevalonate pathway, and pheromone production may be regulated by a negative feedback system mediated through the antennae. In this study, we explored the effect of antennectomy on pheromone production and transcript levels of key mevalonate pathway genes in juvenile hormone III-treated male pine engraver beetles, Ips pini (Say). Antennectomized males produced significantly greater amounts of pheromone than podectomized males and those with intact antennae. Likewise, mRNA levels of three mevalonate pathway genes important in pheromone biosynthesis were measured by quantitative real-time PCR and found to be induced to a greater extent with antennectomy, suggesting a transcriptional regulation of pheromone production.

Cardiac Concomitants of Feedback and Prediction Error Processing in Reinforcement Learning.

PubMed

Kastner, Lucas; Kube, Jana; Villringer, Arno; Neumann, Jane

2017-01-01

Successful learning hinges on the evaluation of positive and negative feedback. We assessed differential learning from reward and punishment in a monetary reinforcement learning paradigm, together with cardiac concomitants of positive and negative feedback processing. On the behavioral level, learning from reward resulted in more advantageous behavior than learning from punishment, suggesting a differential impact of reward and punishment on successful feedback-based learning. On the autonomic level, learning and feedback processing were closely mirrored by phasic cardiac responses on a trial-by-trial basis: (1) Negative feedback was accompanied by faster and prolonged heart rate deceleration compared to positive feedback. (2) Cardiac responses shifted from feedback presentation at the beginning of learning to stimulus presentation later on. (3) Most importantly, the strength of phasic cardiac responses to the presentation of feedback correlated with the strength of prediction error signals that alert the learner to the necessity for behavioral adaptation. Considering participants' weight status and gender revealed obesity-related deficits in learning to avoid negative consequences and less consistent behavioral adaptation in women compared to men. In sum, our results provide strong new evidence for the notion that during learning phasic cardiac responses reflect an internal value and feedback monitoring system that is sensitive to the violation of performance-based expectations. Moreover, inter-individual differences in weight status and gender may affect both behavioral and autonomic responses in reinforcement-based learning.

Cardiovascular regulatory response to lower body negative pressure following blood volume loss

NASA Technical Reports Server (NTRS)

Shimizu, M.; Ghista, D. N.; Sandler, H.

1979-01-01

An attempt is made to explain the cardiovascular regulatory responses to lower body negative pressure (LBNP) stress, both in the absence of and following blood or plasma volume loss, the latter being factors regularly observed with short- or long-term recumbency or weightlessness and associated with resulting cardiovascular deconditioning. Analytical expressions are derived for the responses of mean venous pressure and blood volume pooled in the lower body due to LBNP. An analysis is presented for determining the HR change due to LBNP stress following blood volume loss. It is concluded that the reduced orthostatic tolerance following long-term space flight or recumbency can be mainly attributed to blood volume loss, and that the associated cardiovascular responses characterizing this orthostatic intolerance is elicited by the associated central venous pressure response.

Alcohol impairs brain reactivity to explicit loss feedback.

PubMed

Nelson, Lindsay D; Patrick, Christopher J; Collins, Paul; Lang, Alan R; Bernat, Edward M

2011-11-01

Alcohol impairs the brain's detection of performance errors as evidenced by attenuated error-related negativity (ERN), an event-related potential (ERP) thought to reflect a brain system that monitors one's behavior. However, it remains unclear whether alcohol impairs performance-monitoring capacity across a broader range of contexts, including those entailing external feedback. This study sought to determine whether alcohol-related monitoring deficits are specific to internal recognition of errors (reflected by the ERN) or occur also in external cuing contexts. We evaluated the impact of alcohol consumption on the feedback-related negativity (FRN), an ERP thought to engage a similar process as the ERN but elicited by negative performance feedback in the environment. In an undergraduate sample randomly assigned to drink alcohol (n = 37; average peak BAC = 0.087 g/100 ml, estimated from breath alcohol sampling) or placebo beverages (n = 42), ERP responses to gain and loss feedback were measured during a two-choice gambling task. Time-frequency analysis was used to parse the overlapping theta-FRN and delta-P3 and clarified the effects of alcohol on the measures. Alcohol intoxication attenuated both the theta-FRN and delta-P3 brain responses to feedback. The theta-FRN attenuation was stronger following loss than gain feedback. Attenuation of both theta-FRN and delta-P3 components indicates that alcohol pervasively attenuates the brain's response to feedback in this task. That theta-FRN attenuation was stronger following loss trials is consistent with prior ERN findings and suggests that alcohol broadly impairs the brain's recognition of negative performance outcomes across differing contexts.

Understanding the Influence of Emotions and Reflection upon Multi-Source Feedback Acceptance and Use

ERIC Educational Resources Information Center

Sargeant, Joan; Mann, Karen; Sinclair, Douglas; Van der Vleuten, Cees; Metsemakers, Job

2008-01-01

Introduction: Receiving negative performance feedback can elicit negative emotional reactions which can interfere with feedback acceptance and use. This study investigated emotional responses of family physicians' participating in a multi-source feedback (MSF) program, sources of these emotions, and their influence upon feedback acceptance and…

Children's Reasoning about Evaluative Feedback

ERIC Educational Resources Information Center

Heyman, Gail D.; Fu, Genyue; Sweet, Monica A.; Lee, Kang

2009-01-01

Children's reasoning about the willingness of peers to convey accurate positive and negative performance feedback to others was investigated among a total of 179 6- to 11-year-olds from the USA and China. In Study 1, which was conducted in the USA only, participants responded that peers would be more likely to provide positive feedback than…

Unexpected Acceptance? Patients with Social Anxiety Disorder Manifest their Social Expectancy in ERPs During Social Feedback Processing.

PubMed

Cao, Jianqin; Gu, Ruolei; Bi, Xuejing; Zhu, Xiangru; Wu, Haiyan

2015-01-01

Previous studies on social anxiety have demonstrated negative-expectancy bias in social contexts. In this study, we used a paradigm that employed self-relevant positive or negative social feedback, in order to test whether this negative expectancy manifests in event-related potentials (ERPs) during social evaluation among socially anxious individuals. Behavioral data revealed that individuals with social anxiety disorder (SAD) showed more negative expectancy of peer acceptance both in the experiment and in daily life than did the healthy control participants. Regarding ERP results, we found a overally larger P2 for positive social feedback and also a group main effect, such that the P2 was smaller in SAD group. SAD participants demonstrated a larger feedback-related negativity (FRN) to positive feedback than to negative feedback. In addition, SAD participants showed a more positive ΔFRN (ΔFRN = negative - positive). Furthermore, acceptance expectancy in daily life correlated negatively with ΔFRN amplitude, while the Interaction Anxiousness Scale (IAS) score correlated positively with the ΔFRN amplitude. Finally, the acceptance expectancy in daily life fully mediated the relationship between the IAS and ΔFRN. These results indicated that both groups could differentiate between positive and negative social feedback in the early stage of social feedback processing (reflected on the P2). However, the SAD group exhibited a larger FRN to positive social feedback than to negative social feedback, demonstrating their dysfunction in the late stage of social feedback processing. In our opinion, such dysfunction is due to their greater negative social feedback expectancy.

Unexpected Acceptance? Patients with Social Anxiety Disorder Manifest their Social Expectancy in ERPs During Social Feedback Processing

PubMed Central

Cao, Jianqin; Gu, Ruolei; Bi, Xuejing; Zhu, Xiangru; Wu, Haiyan

2015-01-01

Previous studies on social anxiety have demonstrated negative-expectancy bias in social contexts. In this study, we used a paradigm that employed self-relevant positive or negative social feedback, in order to test whether this negative expectancy manifests in event-related potentials (ERPs) during social evaluation among socially anxious individuals. Behavioral data revealed that individuals with social anxiety disorder (SAD) showed more negative expectancy of peer acceptance both in the experiment and in daily life than did the healthy control participants. Regarding ERP results, we found a overally larger P2 for positive social feedback and also a group main effect, such that the P2 was smaller in SAD group. SAD participants demonstrated a larger feedback-related negativity (FRN) to positive feedback than to negative feedback. In addition, SAD participants showed a more positive ΔFRN (ΔFRN = negative – positive). Furthermore, acceptance expectancy in daily life correlated negatively with ΔFRN amplitude, while the Interaction Anxiousness Scale (IAS) score correlated positively with the ΔFRN amplitude. Finally, the acceptance expectancy in daily life fully mediated the relationship between the IAS and ΔFRN. These results indicated that both groups could differentiate between positive and negative social feedback in the early stage of social feedback processing (reflected on the P2). However, the SAD group exhibited a larger FRN to positive social feedback than to negative social feedback, demonstrating their dysfunction in the late stage of social feedback processing. In our opinion, such dysfunction is due to their greater negative social feedback expectancy. PMID:26635659

Negative autoregulation matches production and demand in synthetic transcriptional networks.

PubMed

Franco, Elisa; Giordano, Giulia; Forsberg, Per-Ola; Murray, Richard M

2014-08-15

We propose a negative feedback architecture that regulates activity of artificial genes, or "genelets", to meet their output downstream demand, achieving robustness with respect to uncertain open-loop output production rates. In particular, we consider the case where the outputs of two genelets interact to form a single assembled product. We show with analysis and experiments that negative autoregulation matches the production and demand of the outputs: the magnitude of the regulatory signal is proportional to the "error" between the circuit output concentration and its actual demand. This two-device system is experimentally implemented using in vitro transcriptional networks, where reactions are systematically designed by optimizing nucleic acid sequences with publicly available software packages. We build a predictive ordinary differential equation (ODE) model that captures the dynamics of the system and can be used to numerically assess the scalability of this architecture to larger sets of interconnected genes. Finally, with numerical simulations we contrast our negative autoregulation scheme with a cross-activation architecture, which is less scalable and results in slower response times.

The developmental origins of cognitive vulnerability to depression: temperament, parenting, and negative life events in childhood as contributors to negative cognitive style.

PubMed

Mezulis, Amy H; Hyde, Janet Shibley; Abramson, Lyn Y

2006-11-01

Cognitive models of depression have been well supported with adults, but the developmental origins of cognitive vulnerability are not well understood. The authors hypothesized that temperament, parenting, and negative life events in childhood would contribute to the development of cognitive style, with withdrawal negativity and negative parental feedback moderating the effects of negative life events to predict more depressogenic cognitive styles. These constructs were assessed in 289 children and their parents followed longitudinally from infancy to 5th grade; a subsample (n = 120) also participated in a behavioral task in which maternal feedback to child failure was observed. Results indicated that greater withdrawal negativity in interaction with negative life events was associated with more negative cognitive styles. Self-reported maternal anger expression and observed negative maternal feedback to child's failure significantly interacted with child's negative events to predict greater cognitive vulnerability. There was little evidence of paternal parenting predicting child negative cognitive style.

Feedback and reward processing in high-functioning autism.

PubMed

Larson, Michael J; South, Mikle; Krauskopf, Erin; Clawson, Ann; Crowley, Michael J

2011-05-15

Individuals with high-functioning autism often display deficits in social interactions and high-level cognitive functions. Such deficits may be influenced by poor ability to process feedback and rewards. The feedback-related negativity (FRN) is an event-related potential (ERP) that is more negative following losses than gains. We examined FRN amplitude in 25 individuals with Autism Spectrum Disorder (ASD) and 25 age- and IQ-matched typically developing control participants who completed a guessing task with monetary loss/gain feedback. Both groups demonstrated a robust FRN that was more negative to loss trials than gain trials; however, groups did not differ in FRN amplitude as a function of gain or loss trials. N1 and P300 amplitudes did not differentiate groups. FRN amplitude was positively correlated with age in individuals with ASD, but not measures of intelligence, anxiety, behavioral inhibition, or autism severity. Given previous findings of reduced-amplitude error-related negativity (ERN) in ASD, we propose that individuals with ASD may process external, concrete, feedback similar to typically developing individuals, but have difficulty with internal, more abstract, regulation of performance. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Smart conjugated polymer nanocarrier for healthy weight loss by negative feedback regulation of lipase activity

NASA Astrophysics Data System (ADS)

Chen, Yu-Lei; Zhu, Sha; Zhang, Lei; Feng, Pei-Jian; Yao, Xi-Kuang; Qian, Cheng-Gen; Zhang, Can; Jiang, Xi-Qun; Shen, Qun-Dong

2016-02-01

Healthy weight loss represents a real challenge when obesity is increasing in prevalence. Herein, we report a conjugated polymer nanocarrier for smart deactivation of lipase and thus balancing calorie intake. After oral administration, the nanocarrier is sensitive to lipase in the digestive tract and releases orlistat, which deactivates the enzyme and inhibits fat digestion. It also creates negative feedback to control the release of itself. The nanocarrier smartly regulates activity of the lipase cyclically varied between high and low levels. In spite of high fat diet intervention, obese mice receiving a single dose of the nanocarrier lose weight over eight days, whereas a control group continues the tendency to gain weight. Daily intragastric administration of the nanocarrier leads to lower weight of livers or fat pads, smaller adipocyte size, and lower total cholesterol level than that of the control group. Near-infrared fluorescence of the nanocarrier reveals its biodistribution.Healthy weight loss represents a real challenge when obesity is increasing in prevalence. Herein, we report a conjugated polymer nanocarrier for smart deactivation of lipase and thus balancing calorie intake. After oral administration, the nanocarrier is sensitive to lipase in the digestive tract and releases orlistat, which deactivates the enzyme and inhibits fat digestion. It also creates negative feedback to control the release of itself. The nanocarrier smartly regulates activity of the lipase cyclically varied between high and low levels. In spite of high fat diet intervention, obese mice receiving a single dose of the nanocarrier lose weight over eight days, whereas a control group continues the tendency to gain weight. Daily intragastric administration of the nanocarrier leads to lower weight of livers or fat pads, smaller adipocyte size, and lower total cholesterol level than that of the control group. Near-infrared fluorescence of the nanocarrier reveals its biodistribution

Cardiac Concomitants of Feedback and Prediction Error Processing in Reinforcement Learning

PubMed Central

Kastner, Lucas; Kube, Jana; Villringer, Arno; Neumann, Jane

2017-01-01

Successful learning hinges on the evaluation of positive and negative feedback. We assessed differential learning from reward and punishment in a monetary reinforcement learning paradigm, together with cardiac concomitants of positive and negative feedback processing. On the behavioral level, learning from reward resulted in more advantageous behavior than learning from punishment, suggesting a differential impact of reward and punishment on successful feedback-based learning. On the autonomic level, learning and feedback processing were closely mirrored by phasic cardiac responses on a trial-by-trial basis: (1) Negative feedback was accompanied by faster and prolonged heart rate deceleration compared to positive feedback. (2) Cardiac responses shifted from feedback presentation at the beginning of learning to stimulus presentation later on. (3) Most importantly, the strength of phasic cardiac responses to the presentation of feedback correlated with the strength of prediction error signals that alert the learner to the necessity for behavioral adaptation. Considering participants' weight status and gender revealed obesity-related deficits in learning to avoid negative consequences and less consistent behavioral adaptation in women compared to men. In sum, our results provide strong new evidence for the notion that during learning phasic cardiac responses reflect an internal value and feedback monitoring system that is sensitive to the violation of performance-based expectations. Moreover, inter-individual differences in weight status and gender may affect both behavioral and autonomic responses in reinforcement-based learning. PMID:29163004

A Neurophysiological examination of quality of learning in a feedback-based learning task.

PubMed

Arbel, Yael; Wu, Hao

2016-12-01

The efficiency with which one processes external feedback contributes to the speed and quality of one's learning. Previous findings that the feedback related negativity (FRN) event related potential (ERP) is modulated by learning outcomes suggested that this ERP reflects the extent to which feedback is used by the learner to improve performance. To further test this suggestion, we measured whether the FRN and the fronto-central positivity (FCP) that follows it are modulated by learning slopes, and as a function of individual differences in learning outcomes. Participants were tasked with learning names (non-words) of 42 novel objects in a two-choice feedback-based visual learning task. The items were divided into three sets of 14 items, each presented in five learning blocks and a sixth test block. Individual learning slopes based on performance on the task, as well as FRN and FCP slopes based on positive and negative feedback related activation in each block were created for 53 participants. Our data pointed to an interaction between slopes of the FRN elicited by negative feedback and learning slopes, such that a sharper decrease in the amplitude of the FRN to negative feedback was associated with sharper learning slopes. We further examined the predictive power of the FRN and FCP elicited in the training blocks on the learning outcomes as measured by performance on the test blocks. We found that small FRN to negative feedback, large FRN to positive feedback, and large FCP to negative feedback in the first training block predicted better learning outcomes. These results add to the growing evidence that the processes giving rise to the FRN and FCP are sensitive to individual differences in the extent to which feedback is used for learning. Copyright © 2016 Elsevier Ltd. All rights reserved.

The MYB23 gene provides a positive feedback loop for cell fate specification in the Arabidopsis root epidermis.

PubMed

Kang, Yeon Hee; Kirik, Victor; Hulskamp, Martin; Nam, Kyoung Hee; Hagely, Katherine; Lee, Myeong Min; Schiefelbein, John

2009-04-01

The specification of cell fates during development requires precise regulatory mechanisms to ensure robust cell type patterns. Theoretical models of pattern formation suggest that a combination of negative and positive feedback mechanisms are necessary for efficient specification of distinct fates in a field of differentiating cells. Here, we examine the role of the R2R3-MYB transcription factor gene, AtMYB23 (MYB23), in the establishment of the root epidermal cell type pattern in Arabidopsis thaliana. MYB23 is closely related to, and is positively regulated by, the WEREWOLF (WER) MYB gene during root epidermis development. Furthermore, MYB23 is able to substitute for the function of WER and to induce its own expression when controlled by WER regulatory sequences. We also show that the MYB23 protein binds to its own promoter, suggesting a MYB23 positive feedback loop. The localization of MYB23 transcripts and MYB23-green fluorescent protein (GFP) fusion protein, as well as the effect of a chimeric MYB23-SRDX repressor construct, links MYB23 function to the developing non-hair cell type. Using mutational analyses, we find that MYB23 is necessary for precise establishment of the root epidermal pattern, particularly under conditions that compromise the cell specification process. These results suggest that MYB23 participates in a positive feedback loop to reinforce cell fate decisions and ensure robust establishment of the cell type pattern in the Arabidopsis root epidermis.

Cloud-radiation interactions - Effects of cirrus optical thickness feedbacks

NASA Technical Reports Server (NTRS)

Somerville, Richard C. J.; Iacobellis, Sam

1987-01-01

The paper is concerned with a cloud-radiation feedback mechanism which may be an important component of the climate changes expected from increased atmospheric concentrations of carbon dioxide and other trace greenhouse gases. A major result of the study is that cirrus cloud optical thickness feedbacks may indeed tend to increase the surface warming due to trace gas increases. However, the positive feedback from cirrus appears to be generally weaker than the negative effects due to lower clouds. The results just confirm those of earlier research indicating that the net effect of cloud optical thickness feedbacks may be a negative feedback which may substantially (by a factor of about 2) reduce the surface warming due to the doubling of CO2, even in the presence of cirrus clouds.

A student-centred feedback model for educators.

PubMed

Rudland, Joy; Wilkinson, Tim; Wearn, Andy; Nicol, Pam; Tunny, Terry; Owen, Cathy; O'Keefe, Maree

2013-04-01

Effective feedback is instrumental to effective learning. Current feedback models tend to be educator driven rather than learner-centred, with the focus on how the supervisor should give feedback rather than on the role of the learner in requesting and responding to feedback. An alternative approach emphasising the theoretical principles of student-centred and self-regulated learning is offered, drawing upon the literature and also upon the experience of the authors. The proposed feedback model places the student in the centre of the feedback process, and stresses that the attainment of student learning outcomes is influenced by the students themselves. This model emphasises the attributes of the student, particularly responsiveness, receptiveness and reflection, whilst acknowledging the important role that the context and attributes of the supervisor have in influencing the quality of feedback. Educational institutions should consider strategies to encourage and enable students to maximise the many feedback opportunities available to them. As a minimum, educators should remind students about their central role in the feedback process, and support them to develop confidence in meeting this role. In addition, supervisors may need support to develop the skills to shift the balance of responsibility and support students in precipitating feedback moments. Research is also required to validate the proposed model and to determine how to support students to adopt self-regulatory learning, with feedback as a central platform. © Blackwell Publishing Ltd 2013.

A Developmental Systems Perspective on Epistasis: Computational Exploration of Mutational Interactions in Model Developmental Regulatory Networks

PubMed Central

Gutiérrez, Jayson

2009-01-01

The way in which the information contained in genotypes is translated into complex phenotypic traits (i.e. embryonic expression patterns) depends on its decoding by a multilayered hierarchy of biomolecular systems (regulatory networks). Each layer of this hierarchy displays its own regulatory schemes (i.e. operational rules such as +/− feedback) and associated control parameters, resulting in characteristic variational constraints. This process can be conceptualized as a mapping issue, and in the context of highly-dimensional genotype-phenotype mappings (GPMs) epistatic events have been shown to be ubiquitous, manifested in non-linear correspondences between changes in the genotype and their phenotypic effects. In this study I concentrate on epistatic phenomena pervading levels of biological organization above the genetic material, more specifically the realm of molecular networks. At this level, systems approaches to studying GPMs are specially suitable to shed light on the mechanistic basis of epistatic phenomena. To this aim, I constructed and analyzed ensembles of highly-modular (fully interconnected) networks with distinctive topologies, each displaying dynamic behaviors that were categorized as either arbitrary or functional according to early patterning processes in the Drosophila embryo. Spatio-temporal expression trajectories in virtual syncytial embryos were simulated via reaction-diffusion models. My in silico mutational experiments show that: 1) the average fitness decay tendency to successively accumulated mutations in ensembles of functional networks indicates the prevalence of positive epistasis, whereas in ensembles of arbitrary networks negative epistasis is the dominant tendency; and 2) the evaluation of epistatic coefficients of diverse interaction orders indicates that, both positive and negative epistasis are more prevalent in functional networks than in arbitrary ones. Overall, I conclude that the phenotypic and fitness effects of multiple

Early growth response-1 negative feedback regulates skeletal muscle postprandial insulin sensitivity via activating Ptp1b transcription.

PubMed

Wu, Jing; Tao, Wei-Wei; Chong, Dan-Yang; Lai, Shan-Shan; Wang, Chuang; Liu, Qi; Zhang, Tong-Yu; Xue, Bin; Li, Chao-Jun

2018-03-15

Postprandial insulin desensitization plays a critical role in maintaining whole-body glucose homeostasis by avoiding the excessive absorption of blood glucose; however, the detailed mechanisms that underlie how the major player, skeletal muscle, desensitizes insulin action remain to be elucidated. Herein, we report that early growth response gene-1 ( Egr-1) is activated by insulin in skeletal muscle and provides feedback inhibition that regulates insulin sensitivity after a meal. The inhibition of the transcriptional activity of Egr-1 enhanced the phosphorylation of the insulin receptor (InsR) and Akt, thus increasing glucose uptake in L6 myotubes after insulin stimulation, whereas overexpression of Egr-1 decreased insulin sensitivity. Furthermore, deletion of Egr-1 in the skeletal muscle improved systemic insulin sensitivity and glucose tolerance, which resulted in lower blood glucose levels after refeeding. Mechanistic analysis demonstrated that EGR-1 inhibited InsR phosphorylation and glucose uptake in skeletal muscle by binding to the proximal promoter region of protein tyrosine phosphatase-1B (PTP1B) and directly activating transcription. PTP1B knockdown largely restored insulin sensitivity and enhanced glucose uptake, even under conditions of EGR-1 overexpression. Our results indicate that EGR-1/PTP1B signaling negatively regulates postprandial insulin sensitivity and suggest a potential therapeutic target for the prevention and treatment of excessive glucose absorption.-Wu, J., Tao, W.-W., Chong, D.-Y., Lai, S.-S., Wang, C., Liu, Q., Zhang, T.-Y., Xue, B., Li, C.-J. Early growth response-1 negative feedback regulates skeletal muscle postprandial insulin sensitivity via activating Ptp1b transcription.

Feedback in a clinical setting: A way forward to enhance student's learning through constructive feedback.

PubMed

Sultan, Amber Shamim; Mateen Khan, Muhammad Arif

2017-07-01

Feedback is considered as a dynamic process in which information about the observed performance is used to promote the desirable behaviour and correct the negative ones. The importance of feedback is widely acknowledged, but still there seems to be inconsistency in the amount, type and timing of feedback received from the clinical faculty. No significant effort has been put forward from the educator end to empower the learners with the skills of receiving and using the feedback effectively. Some institutions conduct faculty development workshops and courses to facilitate the clinicians on how best to deliver constructive feedback to the learners. Despite of all these struggles learners are not fully satisfied with the quality of feedback received from their busy clinicians. The aim of this paper is to highlight what actually feedback is, type and structure of feedback, the essential components of a constructive feedback, benefits of providing feedback, barriers affecting the provision of timely feedback and different models used for providing feedback. The ultimate purpose of this paper is to provide sufficient information to the clinical directors that there is a need to establish a robust system for giving feedback to learners and to inform all the clinical educators with the skills required to provide constructive feedback to their learners. For the literature review, we had used the key words glossary as: Feedback, constructive feedback, barriers to feedback, principles of constructive feedback, Models of feedback, reflection, self-assessment and clinical practice etc. The data bases for the search include: Cardiff University library catalogue, Pub Med, Google Scholar, Web of Knowledge and Science direct.

A microRNA negative feedback loop downregulates vesicle transport and inhibits fear memory

PubMed Central

Mathew, Rebecca S; Tatarakis, Antonis; Rudenko, Andrii; Johnson-Venkatesh, Erin M; Yang, Yawei J; Murphy, Elisabeth A; Todd, Travis P; Schepers, Scott T; Siuti, Nertila; Martorell, Anthony J; Falls, William A; Hammack, Sayamwong E; Walsh, Christopher A; Tsai, Li-Huei; Umemori, Hisashi; Bouton, Mark E; Moazed, Danesh

2016-01-01

The SNARE-mediated vesicular transport pathway plays major roles in synaptic remodeling associated with formation of long-term memories, but the mechanisms that regulate this pathway during memory acquisition are not fully understood. Here we identify miRNAs that are up-regulated in the rodent hippocampus upon contextual fear-conditioning and identify the vesicular transport and synaptogenesis pathways as the major targets of the fear-induced miRNAs. We demonstrate that miR-153, a member of this group, inhibits the expression of key components of the vesicular transport machinery, and down-regulates Glutamate receptor A1 trafficking and neurotransmitter release. MiR-153 expression is specifically induced during LTP induction in hippocampal slices and its knockdown in the hippocampus of adult mice results in enhanced fear memory. Our results suggest that miR-153, and possibly other fear-induced miRNAs, act as components of a negative feedback loop that blocks neuronal hyperactivity at least partly through the inhibition of the vesicular transport pathway. DOI: http://dx.doi.org/10.7554/eLife.22467.001 PMID:28001126

Improving the effectiveness of performance feedback by considering personality traits and task demands

PubMed Central

Peterson, Jordan B.

2018-01-01

Although performance feedback is widely employed as a means to improve motivation, the efficacy and reliability of performance feedback is often obscured by individual differences and situational variables. The joint role of these moderating variables remains unknown. Accordingly, we investigate how the motivational impact of feedback is moderated by personality and task-difficulty. Utilizing three samples (total N = 916), we explore how Big Five personality traits moderate the motivational impact of false positive and negative feedback on playful, neutral, and frustrating puzzle tasks, respectively. Conscientious and Neurotic individuals together appear particularly sensitive to task difficulty, becoming significantly more motivated by negative feedback on playful tasks and demotivated by negative feedback on frustrating tasks. Results are discussed in terms of Goal-Setting and Self Determination Theory. Implications for industry and education are considered. PMID:29787593

Enhancing Feedback on Professionalism and Communication Skills in Anesthesia Residency Programs.

PubMed

Mitchell, John D; Ku, Cindy; Diachun, Carol Ann B; DiLorenzo, Amy; Lee, Daniel E; Karan, Suzanne; Wong, Vanessa; Schell, Randall M; Brzezinski, Marek; Jones, Stephanie B

2017-08-01

Despite its importance, training faculty to provide feedback to residents remains challenging. We hypothesized that, overall, at 4 institutions, a faculty development program on providing feedback on professionalism and communication skills would lead to (1) an improvement in the quantity, quality, and utility of feedback and (2) an increase in feedback containing negative/constructive feedback and pertaining to professionalism/communication. As secondary analyses, we explored these outcomes at the individual institutions. In this prospective cohort study (October 2013 to July 2014), we implemented a video-based educational program on feedback at 4 institutions. Feedback records from 3 months before to 3 months after the intervention were rated for quality (0-5), utility (0-5), and whether they had negative/constructive feedback and/or were related to professionalism/communication. Feedback records during the preintervention, intervention, and postintervention periods were compared using the Kruskal-Wallis and χ tests. Data are reported as median (interquartile range) or proportion/percentage. A total of 1926 feedback records were rated. The institutions overall did not have a significant difference in feedback quantity (preintervention: 855/3046 [28.1%]; postintervention: 896/3327 [26.9%]; odds ratio: 1.06; 95% confidence interval, 0.95-1.18; P = .31), feedback quality (preintervention: 2 [1-4]; intervention: 2 [1-4]; postintervention: 2 [1-4]; P = .90), feedback utility (preintervention: 1 [1-3]; intervention: 2 [1-3]; postintervention: 1 [1-2]; P = .61), or percentage of feedback records containing negative/constructive feedback (preintervention: 27%; intervention: 32%; postintervention: 25%; P = .12) or related to professionalism/communication (preintervention: 23%; intervention: 33%; postintervention: 24%; P = .03). Institution 1 had a significant difference in feedback quality (preintervention: 2 [1-3]; intervention: 3 [2-4]; postintervention: 3 [2-4]; P

Feedback Seeking in Early Adolescence: Self-Enhancement or Self-Verification?

ERIC Educational Resources Information Center

Rosen, Lisa H.; Principe, Connor P.; Langlois, Judith H.

2013-01-01

The authors examined whether early adolescents ("N" = 90) solicit self-enhancing feedback (i.e., positive feedback) or self-verifying feedback (i.e., feedback congruent with self-views, even when these views are negative). Sixth, seventh, and eighth graders first completed a self-perception measure and then selected whether to receive…

Performance Feedback Processing Is Positively Biased As Predicted by Attribution Theory.

PubMed

Korn, Christoph W; Rosenblau, Gabriela; Rodriguez Buritica, Julia M; Heekeren, Hauke R

2016-01-01

A considerable literature on attribution theory has shown that healthy individuals exhibit a positivity bias when inferring the causes of evaluative feedback on their performance. They tend to attribute positive feedback internally (e.g., to their own abilities) but negative feedback externally (e.g., to environmental factors). However, all empirical demonstrations of this bias suffer from at least one of the three following drawbacks: First, participants directly judge explicit causes for their performance. Second, participants have to imagine events instead of experiencing them. Third, participants assess their performance only after receiving feedback and thus differences in baseline assessments cannot be excluded. It is therefore unclear whether the classically reported positivity bias generalizes to setups without these drawbacks. Here, we aimed at establishing the relevance of attributions for decision-making by showing an attribution-related positivity bias in a decision-making task. We developed a novel task, which allowed us to test how participants changed their evaluations in response to positive and negative feedback about performance. Specifically, we used videos of actors expressing different facial emotional expressions. Participants were first asked to evaluate the actors' credibility in expressing a particular emotion. After this initial rating, participants performed an emotion recognition task and did--or did not--receive feedback on their veridical performance. Finally, participants re-rated the actors' credibility, which provided a measure of how they changed their evaluations after feedback. Attribution theory predicts that participants change their evaluations of the actors' credibility toward the positive after receiving positive performance feedback and toward the negative after negative performance feedback. Our results were in line with this prediction. A control condition without feedback showed that correct or incorrect performance

Performance Feedback Processing Is Positively Biased As Predicted by Attribution Theory

PubMed Central

Rodriguez Buritica, Julia M.; Heekeren, Hauke R.

2016-01-01

A considerable literature on attribution theory has shown that healthy individuals exhibit a positivity bias when inferring the causes of evaluative feedback on their performance. They tend to attribute positive feedback internally (e.g., to their own abilities) but negative feedback externally (e.g., to environmental factors). However, all empirical demonstrations of this bias suffer from at least one of the three following drawbacks: First, participants directly judge explicit causes for their performance. Second, participants have to imagine events instead of experiencing them. Third, participants assess their performance only after receiving feedback and thus differences in baseline assessments cannot be excluded. It is therefore unclear whether the classically reported positivity bias generalizes to setups without these drawbacks. Here, we aimed at establishing the relevance of attributions for decision-making by showing an attribution-related positivity bias in a decision-making task. We developed a novel task, which allowed us to test how participants changed their evaluations in response to positive and negative feedback about performance. Specifically, we used videos of actors expressing different facial emotional expressions. Participants were first asked to evaluate the actors’ credibility in expressing a particular emotion. After this initial rating, participants performed an emotion recognition task and did—or did not—receive feedback on their veridical performance. Finally, participants re-rated the actors’ credibility, which provided a measure of how they changed their evaluations after feedback. Attribution theory predicts that participants change their evaluations of the actors’ credibility toward the positive after receiving positive performance feedback and toward the negative after negative performance feedback. Our results were in line with this prediction. A control condition without feedback showed that correct or incorrect

Burnout is associated with changes in error and feedback processing.

PubMed

Gajewski, Patrick D; Boden, Sylvia; Freude, Gabriele; Potter, Guy G; Falkenstein, Michael

2017-10-01

Burnout is a pattern of complaints in individuals with emotionally demanding jobs that is often seen as a precursor of depression. One often reported symptom of burnout is cognitive decline. To analyze cognitive control and to differentiate between subclinical burnout and mild to moderate depression a double-blinded study was conducted that investigates changes in the processing of performance errors and feedback in a task switching paradigm. Fifty-one of 76 employees from emotionally demanding jobs showed a sufficient number of errors to be included in the analysis. The sample was subdivided into groups with low (EE-) and high (EE+) emotional exhaustion and no (DE-) and mild to moderate depression (DE+). The behavioral data did not significantly differ between the groups. In contrast, in the EE+ group, the error negativity (Ne/ERN) was enhanced while the error positivity (Pe) did not differ between the EE+ and EE- groups. After negative feedback the feedback-related negativity (FRN) was enhanced, while the subsequent positivity (FRP) was reduced in EE+ relative to EE-. None of these effects were observed in the DE+ vs. DE-. These results suggest an upregulation of error and negative feedback processing, while the later processing of negative feedback was attenuated in employees with subclinical burnout but not in mild to moderate depression. Copyright © 2017 Elsevier B.V. All rights reserved.

Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition

Treesearch

John L. Maron; Alyssa Laney Smith; Yvette K. Ortega; Dean E. Pearson; Ragan M. Callaway

2016-01-01

Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their...

Fear of feedback.

PubMed

Jackman, Jay M; Strober, Myra H

2003-04-01

Nobody likes performance reviews. Subordinates are terrified they'll hear nothing but criticism. Bosses think their direct reports will respond to even the mildest criticism with anger or tears. The result? Everyone keeps quiet. That's unfortunate, because most people need help figuring out how to improve their performance and advance their careers. This fear of feedback doesn't come into play just during annual reviews. At least half the executives with whom the authors have worked never ask for feedback. Many expect the worst: heated arguments, even threats of dismissal. So rather than seek feedback, people try to guess what their bosses are thinking. Fears and assumptions about feedback often manifest themselves in psychologically maladaptive behaviors such as procrastination, denial, brooding, jealousy, and self-sabotage. But there's hope, say the authors. Those who learn adaptive techniques can free themselves from destructive responses. They'll be able to deal with feedback better if they acknowledge negative emotions, reframe fear and criticism constructively, develop realistic goals, create support systems, and reward themselves for achievements along the way. Once you've begun to alter your maladaptive behaviors, you can begin seeking regular feedback from your boss. The authors take you through four steps for doing just that: self-assessment, external assessment, absorbing the feedback, and taking action toward change. Organizations profit when employees ask for feedback and deal well with criticism. Once people begin to know how they are doing relative to management's priorities, their work becomes better aligned with organizational goals. What's more, they begin to transform a feedback-averse environment into a more honest and open one, in turn improving performance throughout the organization.

Anxiety as a Function of Self-Evaluation and Related Feedback

ERIC Educational Resources Information Center

Viney, Linda L.

1971-01-01

The principal result of this study is the demonstration that both positive and negative feedback result in higher diffuse anxiety scores than does congruent feedback while there is no difference in the effects of the two discrepant types of feedback thus confirming a Rogerian hypothesis regarding feedback and anxiety induction. (Author/CG)

The Impact of Positive, Negative and Topical Relevance Feedback

DTIC Science & Technology

2008-11-01

the Netherlands Organization for Scientific Research (NWO, grant # 612.066.513). REFERENCES [1] Y. K. Chang, C. Cirillo, and J . Razon. Evaluation of...feedback retrieval using modified freezing, residual collection and test and control groups. In G. Salton , editor, The SMART retrieval system...information retrieval. In Proceedings SI- GIR 2004, pages 178–185. ACM Press, New York NY, 2004. [3] R. Kaptein and J . Kamps. Web directories as topical context

Effects of stochastic time-delayed feedback on a dynamical system modeling a chemical oscillator.

PubMed

González Ochoa, Héctor O; Perales, Gualberto Solís; Epstein, Irving R; Femat, Ricardo

2018-05-01

We examine how stochastic time-delayed negative feedback affects the dynamical behavior of a model oscillatory reaction. We apply constant and stochastic time-delayed negative feedbacks to a point Field-Körös-Noyes photosensitive oscillator and compare their effects. Negative feedback is applied in the form of simulated inhibitory electromagnetic radiation with an intensity proportional to the concentration of oxidized light-sensitive catalyst in the oscillator. We first characterize the system under nondelayed inhibitory feedback; then we explore and compare the effects of constant (deterministic) versus stochastic time-delayed feedback. We find that the oscillatory amplitude, frequency, and waveform are essentially preserved when low-dispersion stochastic delayed feedback is used, whereas small but measurable changes appear when a large dispersion is applied.

Effects of stochastic time-delayed feedback on a dynamical system modeling a chemical oscillator

NASA Astrophysics Data System (ADS)

González Ochoa, Héctor O.; Perales, Gualberto Solís; Epstein, Irving R.; Femat, Ricardo

2018-05-01

We examine how stochastic time-delayed negative feedback affects the dynamical behavior of a model oscillatory reaction. We apply constant and stochastic time-delayed negative feedbacks to a point Field-Körös-Noyes photosensitive oscillator and compare their effects. Negative feedback is applied in the form of simulated inhibitory electromagnetic radiation with an intensity proportional to the concentration of oxidized light-sensitive catalyst in the oscillator. We first characterize the system under nondelayed inhibitory feedback; then we explore and compare the effects of constant (deterministic) versus stochastic time-delayed feedback. We find that the oscillatory amplitude, frequency, and waveform are essentially preserved when low-dispersion stochastic delayed feedback is used, whereas small but measurable changes appear when a large dispersion is applied.

Positivity effect in healthy aging in observational but not active feedback-learning.

PubMed

Bellebaum, Christian; Rustemeier, Martina; Daum, Irene

2012-01-01

The present study investigated the impact of healthy aging on the bias to learn from positive or negative performance feedback in observational and active feedback learning. In active learning, a previous study had already shown a negative learning bias in healthy seniors older than 75 years, while no bias was found for younger seniors. However, healthy aging is accompanied by a 'positivity effect', a tendency to primarily attend to stimuli with positive valence. Based on recent findings of dissociable neural mechanisms in active and observational feedback learning, the positivity effect was hypothesized to influence older participants' observational feedback learning in particular. In two separate experiments, groups of young (mean age 27) and older participants (mean age 60 years) completed an observational or active learning task designed to differentially assess positive and negative learning. Older but not younger observational learners showed a significant bias to learn better from positive than negative feedback. In accordance with previous findings, no bias was found for active learning. This pattern of results is discussed in terms of differences in the neural underpinnings of active and observational learning from performance feedback.

Identification of novel non-coding RNA-based negative feedback regulating the expression of the oncogenic transcription factor GLI1.

PubMed

Villegas, Victoria E; Rahman, Mohammed Ferdous-Ur; Fernandez-Barrena, Maite G; Diao, Yumei; Liapi, Eleni; Sonkoly, Enikö; Ståhle, Mona; Pivarcsi, Andor; Annaratone, Laura; Sapino, Anna; Ramírez Clavijo, Sandra; Bürglin, Thomas R; Shimokawa, Takashi; Ramachandran, Saraswathi; Kapranov, Philipp; Fernandez-Zapico, Martin E; Zaphiropoulos, Peter G

2014-07-01

Non-coding RNAs are a complex class of nucleic acids, with growing evidence supporting regulatory roles in gene expression. Here we identify a non-coding RNA located head-to-head with the gene encoding the Glioma-associated oncogene 1 (GLI1), a transcriptional effector of multiple cancer-associated signaling pathways. The expression of this three-exon GLI1 antisense (GLI1AS) RNA in cancer cells was concordant with GLI1 levels. siRNAs knockdown of GLI1AS up-regulated GLI1 and increased cellular proliferation and tumor growth in a xenograft model system. Conversely, GLI1AS overexpression decreased the levels of GLI1, its target genes PTCH1 and PTCH2, and cellular proliferation. Additionally, we demonstrate that GLI1 knockdown reduced GLI1AS, while GLI1 overexpression increased GLI1AS, supporting the role of GLI1AS as a target gene of the GLI1 transcription factor. Activation of TGFβ and Hedgehog signaling, two known regulators of GLI1 expression, conferred a concordant up-regulation of GLI1 and GLI1AS in cancer cells. Finally, analysis of the mechanism underlying the interplay between GLI1 and GLI1AS indicates that the non-coding RNA elicits a local alteration of chromatin structure by increasing the silencing mark H3K27me3 and decreasing the recruitment of RNA polymerase II to this locus. Taken together, the data demonstrate the existence of a novel non-coding RNA-based negative feedback loop controlling GLI1 levels, thus expanding the repertoire of mechanisms regulating the expression of this oncogenic transcription factor. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Decorrelation of Neural-Network Activity by Inhibitory Feedback

PubMed Central

Einevoll, Gaute T.; Diesmann, Markus

2012-01-01

Correlations in spike-train ensembles can seriously impair the encoding of information by their spatio-temporal structure. An inevitable source of correlation in finite neural networks is common presynaptic input to pairs of neurons. Recent studies demonstrate that spike correlations in recurrent neural networks are considerably smaller than expected based on the amount of shared presynaptic input. Here, we explain this observation by means of a linear network model and simulations of networks of leaky integrate-and-fire neurons. We show that inhibitory feedback efficiently suppresses pairwise correlations and, hence, population-rate fluctuations, thereby assigning inhibitory neurons the new role of active decorrelation. We quantify this decorrelation by comparing the responses of the intact recurrent network (feedback system) and systems where the statistics of the feedback channel is perturbed (feedforward system). Manipulations of the feedback statistics can lead to a significant increase in the power and coherence of the population response. In particular, neglecting correlations within the ensemble of feedback channels or between the external stimulus and the feedback amplifies population-rate fluctuations by orders of magnitude. The fluctuation suppression in homogeneous inhibitory networks is explained by a negative feedback loop in the one-dimensional dynamics of the compound activity. Similarly, a change of coordinates exposes an effective negative feedback loop in the compound dynamics of stable excitatory-inhibitory networks. The suppression of input correlations in finite networks is explained by the population averaged correlations in the linear network model: In purely inhibitory networks, shared-input correlations are canceled by negative spike-train correlations. In excitatory-inhibitory networks, spike-train correlations are typically positive. Here, the suppression of input correlations is not a result of the mere existence of correlations between

Endocannabinoid Signaling, Glucocorticoid-Mediated Negative Feedback and Regulation of the HPA Axis

PubMed Central

Hill, M. N.; Tasker, J. G.

2012-01-01

The hypothalamic-pituitary-adrenal (HPA) axis regulates the outflow of glucocorticoid hormones under basal conditions and in response to stress. Within the last decade, a large body of evidence has mounted indicating that the endocannabinoid system is involved in the central regulation of the stress response; however, the specific role endocannabinoid signalling plays in phases of HPA axis regulation, or the neural sites of action mediating this regulation, was not mapped out until recently. This review aims to collapse the current state of knowledge regarding the role of the endocannabinoid system in the regulation of the HPA axis to put together a working model of how and where endocannabinoids act within the brain to regulate outflow of the HPA axis. Specifically, we discuss the role of the endocannabinoid system in the regulation of the HPA axis under basal conditions, activation in response to acute stress and glucocorticoid-mediated negative feedback. Interestingly, there appears to be some anatomical specificity to the role of the endocannabinoid system in each phase of HPA axis regulation, as well as distinct roles of both anandamide and 2-arachidonoylglycerol in these phases. Ultimately, the current level of information indicates that endocannabinoid signalling acts to suppress HPA axis activity through concerted actions within the prefrontal cortex, amygdala and hypothalamus. PMID:22214537

Task feedback effects on conflict monitoring and executive control: relationship to subclinical measures of depression.

PubMed

Holmes, Avram J; Pizzagalli, Diego A

2007-02-01

Emerging evidence suggests that depression is associated with executive dysfunction, particularly after committing errors or receiving negative performance feedback. To test this hypothesis, 57 participants performed two executive tasks known to elicit errors (the Simon and Stroop Tasks) during positive or negative performance feedback. Participants with elevated depressive symptoms (Beck Depression Inventory scores >or= 13) were characterized by impaired posterror and postconflict performance adjustments, especially during emotionally negative task-related feedback. Additionally, for both tasks, depressive symptoms were inversely related to postconflict reaction time adjustments following negative, but not positive, feedback. These findings suggest that subclinical depression is associated with impairments in behavioral adjustments after internal (perceived failure) and external feedback about deficient task performance. (c) 2007 APA, all rights reserved.

The MYB23 Gene Provides a Positive Feedback Loop for Cell Fate Specification in the Arabidopsis Root Epidermis[C][W

PubMed Central

Kang, Yeon Hee; Kirik, Victor; Hulskamp, Martin; Nam, Kyoung Hee; Hagely, Katherine; Lee, Myeong Min; Schiefelbein, John

2009-01-01

The specification of cell fates during development requires precise regulatory mechanisms to ensure robust cell type patterns. Theoretical models of pattern formation suggest that a combination of negative and positive feedback mechanisms are necessary for efficient specification of distinct fates in a field of differentiating cells. Here, we examine the role of the R2R3-MYB transcription factor gene, AtMYB23 (MYB23), in the establishment of the root epidermal cell type pattern in Arabidopsis thaliana. MYB23 is closely related to, and is positively regulated by, the WEREWOLF (WER) MYB gene during root epidermis development. Furthermore, MYB23 is able to substitute for the function of WER and to induce its own expression when controlled by WER regulatory sequences. We also show that the MYB23 protein binds to its own promoter, suggesting a MYB23 positive feedback loop. The localization of MYB23 transcripts and MYB23-green fluorescent protein (GFP) fusion protein, as well as the effect of a chimeric MYB23-SRDX repressor construct, links MYB23 function to the developing non-hair cell type. Using mutational analyses, we find that MYB23 is necessary for precise establishment of the root epidermal pattern, particularly under conditions that compromise the cell specification process. These results suggest that MYB23 participates in a positive feedback loop to reinforce cell fate decisions and ensure robust establishment of the cell type pattern in the Arabidopsis root epidermis. PMID:19395683

The role of feedback in young people's academic choices

NASA Astrophysics Data System (ADS)

Skipper, Yvonne; Leman, Patrick J.

2017-03-01

Women are underrepresented in Science, Technology, Engineering and Mathematics subjects with more girls leaving these subjects at every stage in education. The current research used a scenario methodology to examine the impact of teacher feedback on girls' and boys' choices to study a specific science subject, engineering. British participants aged 13 (N = 479) were given scenarios where a new teacher encouraged them to take engineering using person feedback which focussed on their abilities, process feedback which focussed on their effort levels or gave them no reason. Results suggested that both boys and girls were more likely to select to study engineering when they received person feedback rather than process or no feedback. Young people also thought that ability was more important to being successful in science than in non-science subjects.This suggests young people feel that ability is needed to succeed in science subjects and person feedback can lead them to believe that they have this ability. Therefore, teacher feedback which gives ability attributions for possible success could be used to encourage more young people to persist in science. However, the potentially negative longer term outcomes of ability attributions and how they may be negated are also discussed.

A Negative Feedback Loop Between Autophagy and Immune Responses in Mycobacterium leprae Infection.

PubMed

Ma, Yuelong; Zhang, Li; Lu, Jie; Shui, Tiejun; Chen, Jia; Yang, Jun; Yuan, Joanna; Liu, Yeqiang; Yang, Degang

2017-01-01

The obligate intracellular bacterium Mycobacterium leprae is the causative agent of leprosy and primarily infects macrophages, leading to irreversible nerve damage and deformities. So far, the underlying reasons allowing M. leprae to persist and propagate in macrophages, despite the presence of cellular immunity, are still a mystery. Here, we investigated the role of autophagy, a cellular process that degrades cytosolic materials and intracellular pathogens, in M. leprae infection. We found that live M. leprae infection of macrophages resulted in significantly elevated autophagy level. However, macrophages with high autophagy levels preferentially expressed lower levels of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-12, and tumor necrosis factor-α, and preferentially primed anti-inflammatory T cells responses, characterized by high IL-10 and low interferon-γ, granzyme B, and perforin responses. These anti-inflammatory T cells could suppress further induction of autophagy, leading to improved survival of intracellular M. leprae in infected macrophages. Therefore, these data demonstrated that although autophagy had a role in eliminating intracellular pathogens, the induction of autophagy resulted in anti-inflammatory immune responses, which suppressed autophagy in a negative feedback loop and allowed the persistence of M. leprae.

Different Electrophysiological Responses to Informative Value of Feedback Between Children and Adults.

PubMed

Du, Bin; Cao, Bihua; He, Weiqi; Li, Fuhong

2018-01-01

The ability to learn from feedback is important for children's adaptive behavior and school learning. Feedback has two main components, informative value and valence. How to disentangle these two components and what is the developmental neural correlates of using the informative value of feedback is still an open question. In this study, 23 children (7-10 years old) and 19 adults (19-22 years old) were asked to perform a rule induction task, in which they were required to find a rule, based on the informative value of feedback. Behavioral results indicated that the likelihood of correct searching behavior under negative feedback was low for children. Event-related potentials showed that (1) the effect of valence was processed in a wide time window, particularly in the N2 component; (2) the encoding process of the informative value of negative feedback began later for children than for adults; (3) a clear P300 was observed for adults; for children, however, P300 was absent in the frontal region; and (4) children processed the informative value of feedback chiefly in the left sites during the P300 time window, whereas adults did not show this laterality. These results suggested that children were less sensitive to the informative value of negative feedback possibly because of the immature brain.

Sex Differences in the Meaning of Negative Evaluation in Achievement Situations: Determinants and Consequences.

ERIC Educational Resources Information Center

Dweck, Carol S.

Sex differences in children's reactions to failure feedback in school situations were investigated by assessing the ways in which teachers use negative evaluation in the classroom. Three aspects of teachers' evaluative feedback were studied: (1) ratio of negative to positive feedback; (2) contingency vs. noncontingency of feedback; and (3) (the…

Valence and magnitude ambiguity in feedback processing.

PubMed

Gu, Ruolei; Feng, Xue; Broster, Lucas S; Yuan, Lu; Xu, Pengfei; Luo, Yue-Jia

2017-05-01

Outcome feedback which indicates behavioral consequences are crucial for reinforcement learning and environmental adaptation. Nevertheless, outcome information in daily life is often totally or partially ambiguous. Studying how people interpret this kind of information would provide important knowledge about the human evaluative system. This study concentrates on the neural processing of partially ambiguous feedback, that is, either its valence or magnitude is unknown to participants. To address this topic, we sequentially presented valence and magnitude information; electroencephalography (EEG) response to each kind of presentation was recorded and analyzed. The event-related potential components feedback-related negativity (FRN) and P3 were used as indices of neural activity. Consistent with previous literature, the FRN elicited by ambiguous valence was not significantly different from that elicited by negative valence. On the other hand, the FRN elicited by ambiguous magnitude was larger than both the large and small magnitude, indicating the motivation to seek unambiguous magnitude information. The P3 elicited by ambiguous valence and ambiguous magnitude was not significantly different from that elicited by negative valence and small magnitude, respectively, indicating the emotional significance of feedback ambiguity. Finally, the aforementioned effects also manifested in the stage of information integration. These findings indicate both similarities and discrepancies between the processing of valence ambiguity and that of magnitude ambiguity, which may help understand the mechanisms of ambiguous information processing.

Effects of generic versus non-generic feedback on motor learning in children.

PubMed

Chiviacowsky, Suzete; Drews, Ricardo

2014-01-01

Non-generic feedback refers to a specific event and implies that performance is malleable, while generic feedback implies that task performance reflects an inherent ability. The present study examined the influences of generic versus non-generic feedback on motor performance and learning in 10-year-old children. In the first experiment, using soccer ball kicking at a target as a task, providing participants with generic feedback resulted in worse performance than providing non-generic feedback, after both groups received negative feedback. The second experiment measured more permanent effects. Results of a retention test, performed one day after practicing a throwing task, showed that participants who received non-generic feedback during practice outperformed the generic feedback group, after receiving a negative feedback statement. The findings demonstrate the importance of the wording of feedback. Even though different positive feedback statements may not have an immediate influence on performance, they can affect performance, and presumably individuals' motivation, when performance is (purportedly) poor. Feedback implying that performance is malleable, rather than due to an inherent ability, seems to have the potential to inoculate learners against setbacks--a situation frequently encountered in the context of motor performance and learning.

Effects of Generic versus Non-Generic Feedback on Motor Learning in Children

PubMed Central

Chiviacowsky, Suzete; Drews, Ricardo

2014-01-01

Non-generic feedback refers to a specific event and implies that performance is malleable, while generic feedback implies that task performance reflects an inherent ability. The present study examined the influences of generic versus non-generic feedback on motor performance and learning in 10-year-old children. In the first experiment, using soccer ball kicking at a target as a task, providing participants with generic feedback resulted in worse performance than providing non-generic feedback, after both groups received negative feedback. The second experiment measured more permanent effects. Results of a retention test, performed one day after practicing a throwing task, showed that participants who received non-generic feedback during practice outperformed the generic feedback group, after receiving a negative feedback statement. The findings demonstrate the importance of the wording of feedback. Even though different positive feedback statements may not have an immediate influence on performance, they can affect performance, and presumably individuals' motivation, when performance is (purportedly) poor. Feedback implying that performance is malleable, rather than due to an inherent ability, seems to have the potential to inoculate learners against setbacks – a situation frequently encountered in the context of motor performance and learning. PMID:24523947

Social closeness and feedback modulate susceptibility to the framing effect

PubMed Central

Sip, Kamila E.; Smith, David V.; Porcelli, Anthony J.; Kar, Kohitij; Delgado, Mauricio R.

2014-01-01

Although, we often seek social feedback from others to help us make decisions, little is known about how social feedback affects decisions under risk, particularly from a close peer. We conducted two experiments using an established framing task to probe how decision making is modulated by social feedback valence (positive, negative) and the level of closeness with feedback provider (friend, confederate). Participants faced mathematically equivalent decisions framed as either an opportunity to keep (gain frame) or lose (loss frame) part of an initial endowment. Periodically, participants were provided with positive (e.g., “Nice!”) or negative (e.g., “Lame!”) feedback about their choices. Such feedback was provided by either a confederate (Experiment 1), or a gender-matched close friend (Experiment 2). As expected, the framing effect was observed in both experiments. Critically, an individual’s susceptibility to the framing effect was modulated by the valence of the social feedback, but only when the feedback provider was a close friend. This effect was reflected in the activation patterns of ventromedial prefrontal cortex and posterior cingulate cortex, regions involved in complex decision making. Taken together, these results highlight social closeness as an important factor in understanding the impact of social feedback on neural mechanisms of decision making. PMID:25074501

The MtDMI2-MtPUB2 Negative Feedback Loop Plays a Role in Nodulation Homeostasis1[OPEN

PubMed Central

Deng, Jie; Zhu, Fugui; Lu, Zheng

2018-01-01

DOES NOT MAKE INFECTION 2 (MtDMI2) is a Leu rich repeat-type receptor kinase required for signal transduction in the Medicago truncatula/Sinorhizobium meliloti symbiosis pathway. However, the mechanisms through which MtDMI2 participates in nodulation homeostasis are poorly understood. In this study, we identified MtPUB2—a novel plant U-box (PUB)–type E3 ligase—and showed that it interacts with MtDMI2. MtDMI2 and MtPUB2 accumulation were shown to be similar in various tissues. Roots of plants in which MtPUB2 was silenced by RNAi (MtPUB2-RNAi plants) exhibited impaired infection threads, fewer nodules, and shorter primary root lengths compared to those of control plants transformed with empty vector. Using liquid chromatography-tandem mass spectrometry, we showed that MtDMI2 phosphorylates MtPUB2 at Ser-316, Ser-421, and Thr-488 residues. When MtPUB2-RNAi plants were transformed with MtPUB2S421D, which mimics the phosphorylated state, MtDMI2 was persistently ubiquitinated and degraded by MtPUB2S421D, resulting in fewer nodules than observed in MtPUB2/MtPUB2-RNAi-complemented plants. However, MtPUB2S421A/MtPUB2-RNAi-complemented plants showed no MtPUB2 ubiquitination activity, and their nodulation phenotype was similar to that of MtPUB2-RNAi plants transformed with empty vector. Further studies demonstrated that these proteins form a negative feedback loop of the prey (MtDMI2)-predator (MtPUB2) type. Our results suggest that the MtDMI2-MtPUB2 negative feedback loop, which displays crosstalk with the long-distance autoregulation of nodulation via MtNIN, plays an important role in nodulation homeostasis. PMID:29440269

Experimental Comparison of two Active Vibration Control Approaches: Velocity Feedback and Negative Capacitance Shunt Damping

NASA Technical Reports Server (NTRS)

Beck, Benjamin; Schiller, Noah

2013-01-01

This paper outlines a direct, experimental comparison between two established active vibration control techniques. Active vibration control methods, many of which rely upon piezoelectric patches as actuators and/or sensors, have been widely studied, showing many advantages over passive techniques. However, few direct comparisons between different active vibration control methods have been made to determine the performance benefit of one method over another. For the comparison here, the first control method, velocity feedback, is implemented using four accelerometers that act as sensors along with an analog control circuit which drives a piezoelectric actuator. The second method, negative capacitance shunt damping, consists of a basic analog circuit which utilizes a single piezoelectric patch as both a sensor and actuator. Both of these control methods are implemented individually using the same piezoelectric actuator attached to a clamped Plexiglas window. To assess the performance of each control method, the spatially averaged velocity of the window is compared to an uncontrolled response.

Insights from a refined decomposition of cloud feedbacks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zelinka, Mark D.; Zhou, Chen; Klein, Stephen A.

Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloudmore » feedback but its anticorrelation with other components damps overall spread. Furthermore, the ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the “null hypothesis” climate sensitivity from well-understood and robustly simulated feedbacks are discussed.« less

Insights from a refined decomposition of cloud feedbacks

DOE PAGES

Zelinka, Mark D.; Zhou, Chen; Klein, Stephen A.

2016-09-05

Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloudmore » feedback but its anticorrelation with other components damps overall spread. Furthermore, the ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the “null hypothesis” climate sensitivity from well-understood and robustly simulated feedbacks are discussed.« less

Regulation of landslide motion by dilatancy and pore pressure feedback

USGS Publications Warehouse

Iverson, R.M.

2005-01-01

A new mathematical model clarifies how diverse styles and rates of landslide motion can result from regulation of Coulomb friction by dilation or contraction of water-saturated basal shear zones. Normalization of the model equations shows that feedback due to coupling between landslide motion, shear zone volume change, and pore pressure change depends on a single dimensionless parameter ??, which, in turn, depends on the dilatancy angle ?? and the intrinsic timescales for pore pressure generation and dissipation. If shear zone soil contracts during slope failure, then ?? 0, and negative feedback permits slow, steady landslide motion to occur while positive pore pressure is supplied by rain infiltration. Steady state slip velocities v0 obey v0 = -(K/??) p*e, where K is the hydraulic conductivity and p*e is the normalized (dimensionless) negative pore pressure generated by dilation. If rain infiltration and attendant pore pressure growth continue unabated, however, their influence ultimately overwhelms the stabilizing influence of negative p*e. Then, unbounded landslide acceleration occurs, accentuated by an instability that develops if ?? diminishes as landslide motion proceeds. Nonetheless, numerical solutions of the model equations show that slow, nearly steady motion of a clay-rich landslide may persist for many months as a result of negative pore pressure feedback that regulates basal Coulomb friction. Similarly stabilized motion is less likely to occur in sand-rich landslides that are characterized by weaker negative feedback.

Error-related negativities elicited by monetary loss and cues that predict loss.

PubMed

Dunning, Jonathan P; Hajcak, Greg

2007-11-19

Event-related potential studies have reported error-related negativity following both error commission and feedback indicating errors or monetary loss. The present study examined whether error-related negativities could be elicited by a predictive cue presented prior to both the decision and subsequent feedback in a gambling task. Participants were presented with a cue that indicated the probability of reward on the upcoming trial (0, 50, and 100%). Results showed a negative deflection in the event-related potential in response to loss cues compared with win cues; this waveform shared a similar latency and morphology with the traditional feedback error-related negativity.

Regulatory gene networks and the properties of the developmental process

NASA Technical Reports Server (NTRS)

Davidson, Eric H.; McClay, David R.; Hood, Leroy

2003-01-01

Genomic instructions for development are encoded in arrays of regulatory DNA. These specify large networks of interactions among genes producing transcription factors and signaling components. The architecture of such networks both explains and predicts developmental phenomenology. Although network analysis is yet in its early stages, some fundamental commonalities are already emerging. Two such are the use of multigenic feedback loops to ensure the progressivity of developmental regulatory states and the prevalence of repressive regulatory interactions in spatial control processes. Gene regulatory networks make it possible to explain the process of development in causal terms and eventually will enable the redesign of developmental regulatory circuitry to achieve different outcomes.

A Case Study of Representing Signal Transduction in Liver Cells as a Feedback Control Problem

ERIC Educational Resources Information Center

Singh, Abhay; Jayaraman, Arul; Hahn, Juergen

2007-01-01

Cell signaling pathways often contain feedback loops where proteins are produced that regulate signaling. While feedback regulatory mechanisms are commonly found in signaling pathways, there is no example available in the literature that is simple enough to be presented in an undergraduate control class. This paper presents a simulation study of…

The Dishevelled-binding protein CXXC5 negatively regulates cutaneous wound healing

PubMed Central

Lee, Soung-Hoon; Kim, Mi-Yeon; Kim, Hyun-Yi; Lee, Young-Mi; Kim, Heesu; Nam, Kyoung Ae; Roh, Mi Ryung; Min, Do Sik; Chung, Kee Yang

2015-01-01

Wnt/β-catenin signaling plays important roles in cutaneous wound healing and dermal fibrosis. However, its regulatory mechanism has not been fully elucidated, and a commercially available wound-healing agent targeting this pathway is desirable but currently unavailable. We found that CXXC-type zinc finger protein 5 (CXXC5) serves as a negative feedback regulator of the Wnt/β-catenin pathway by interacting with the Dishevelled (Dvl) protein. In humans, CXXC5 protein levels were reduced in epidermal keratinocytes and dermal fibroblasts of acute wounds. A differential regulation of β-catenin, α-smooth muscle actin (α-SMA), and collagen I by overexpression and silencing of CXXC5 in vitro indicated a critical role for this factor in myofibroblast differentiation and collagen production. In addition, CXXC5−/− mice exhibited accelerated cutaneous wound healing, as well as enhanced keratin 14 and collagen synthesis. Protein transduction domain (PTD)–Dvl-binding motif (DBM), a competitor peptide blocking CXXC5-Dvl interactions, disrupted this negative feedback loop and activated β-catenin and collagen production in vitro. Co-treatment of skin wounds with PTD-DBM and valproic acid (VPA), a glycogen synthase kinase 3β (GSK3β) inhibitor which activates the Wnt/β-catenin pathway, synergistically accelerated cutaneous wound healing in mice. Together, these data suggest that CXXC5 would represent a potential target for future therapies aimed at improving wound healing. PMID:26056233

Framing of feedback impacts student's satisfaction, self-efficacy and performance.

PubMed

van de Ridder, J M Monica; Peters, Claudia M M; Stokking, Karel M; de Ru, J Alexander; Ten Cate, Olle Th J

2015-08-01

Feedback is considered important to acquire clinical skills. Research evidence shows that feedback does not always improve learning and its effects may be small. In many studies, a variety of variables involved in feedback provision may mask either one of their effects. E.g., there is reason to believe that the way oral feedback is framed may affect its effect if other variables are held constant. In a randomised controlled trial we investigated the effect of positively and negatively framed feedback messages on satisfaction, self-efficacy, and performance. A single blind randomised controlled between-subject design was used, with framing of the feedback message (positively-negatively) as independent variable and examination of hearing abilities as the task. First year medical students' (n = 59) satisfaction, self-efficacy, and performance were the dependent variables and were measured both directly after the intervention and after a 2 weeks delay. Students in the positively framed feedback condition were significantly more satisfied and showed significantly higher self-efficacy measured directly after the performance. Effect sizes found were large, i.e., partial η (2) = 0.43 and η (2) = 0.32 respectively. They showed a better performance throughout the whole study. Significant performance differences were found both at the initial performance and when measured 2 weeks after the intervention: effects were of medium size, respectively r = -.31 and r = -.32. Over time in both conditions performance and self-efficacy decreased. Framing the feedback message in either a positive or negative manner affects students' satisfaction and self-efficacy directly after the intervention be it that these effects seem to fade out over time. Performance may be enhanced by positive framing, but additional studies need to confirm this. We recommend using a positive frame when giving feedback on clinical skills.

Motivational and metacognitive feedback in SQL-Tutor*

NASA Astrophysics Data System (ADS)

Hull, Alison; du Boulay, Benedict

2015-04-01

Motivation and metacognition are strongly intertwined, with learners high in self-efficacy more likely to use a variety of self-regulatory learning strategies, as well as to persist longer on challenging tasks. The aim of the research was to improve the learner's focus on the process and experience of problem-solving while using an Intelligent Tutoring System (ITS) and including motivational and metacognitive feedback based on the learner's past states and experiences. An existing ITS, SQL-Tutor, was used with first-year undergraduates studying a database module. The study used two versions of SQL-Tutor: the Control group used a base version providing domain feedback and the Study group used an extended version that also provided motivational and metacognitive feedback. This paper summarises the pre- and post-process results. Comparisons between groups showed some differing trends both in learning outcomes and behaviour in favour of the Study group.

Using a Feedback Environment to Improve Creative Performance: A Dynamic Affect Perspective.

PubMed

Gong, Zhenxing; Zhang, Na

2017-01-01

Prior research on feedback and creative performance has neglected the dynamic nature of affect and has focused only on the influence of positive affect. We argue that creative performance is the result of a dynamic process in which a person experiences a phase of negative affect and subsequently enters a state of high positive affect that is influenced by the feedback environment. Hierarchical regression was used to analyze a sample of 264 employees from seven industry firms. The results indicate that employees' perceptions of a supportive supervisor feedback environment indirectly influence their level of creative performance through positive affect (t2); the negative affect (t1) moderates the relationship between positive affect (t2) and creative performance (t2), rendering the relationship more positive if negative affect (t1) is high. The change in positive affect mediates the relationship between the supervisor feedback environment and creative performance; a decrease in negative affect moderates the relationship between increased positive affect and creative performance, rendering the relationship more positive if the decrease in negative affect is large. The implications for improving the creative performances of employees are further discussed.

Using a Feedback Environment to Improve Creative Performance: A Dynamic Affect Perspective

PubMed Central

Gong, Zhenxing; Zhang, Na

2017-01-01

Prior research on feedback and creative performance has neglected the dynamic nature of affect and has focused only on the influence of positive affect. We argue that creative performance is the result of a dynamic process in which a person experiences a phase of negative affect and subsequently enters a state of high positive affect that is influenced by the feedback environment. Hierarchical regression was used to analyze a sample of 264 employees from seven industry firms. The results indicate that employees’ perceptions of a supportive supervisor feedback environment indirectly influence their level of creative performance through positive affect (t2); the negative affect (t1) moderates the relationship between positive affect (t2) and creative performance (t2), rendering the relationship more positive if negative affect (t1) is high. The change in positive affect mediates the relationship between the supervisor feedback environment and creative performance; a decrease in negative affect moderates the relationship between increased positive affect and creative performance, rendering the relationship more positive if the decrease in negative affect is large. The implications for improving the creative performances of employees are further discussed. PMID:28861025

Functional polymorphisms of circadian negative feedback regulation genes are associated with clinical outcome in hepatocellular carcinoma patients receiving radical resection.

PubMed

Zhang, Zhaohui; Ma, Fei; Zhou, Feng; Chen, Yibing; Wang, Xiaoyan; Zhang, Hongxin; Zhu, Yong; Bi, Jianwei; Zhang, Yiguan

2014-12-01

Previous studies have demonstrated that circadian negative feedback loop genes play an important role in the development and progression of many cancers. However, the associations between single-nucleotide polymorphisms (SNPs) in these genes and the clinical outcomes of hepatocellular carcinoma (HCC) after surgical resection have not been studied so far. Thirteen functional SNPs in circadian genes were genotyped using the Sequenom iPLEX genotyping system in a cohort of 489 Chinese HCC patients who received radical resection. Multivariate Cox proportional hazards model and Kaplan-Meier curve were used for the prognosis analysis. Cumulative effect analysis and survival tree analysis were used for the multiple SNPs analysis. Four individual SNPs, including rs3027178 in PER1, rs228669 and rs2640908 in PER3 and rs3809236 in CRY1, were significantly associated with overall survival (OS) of HCC patients, and three SNPs, including rs3027178 in PER1, rs228729 in PER3 and rs3809236 in CRY1, were significantly associated with recurrence-free survival (RFS). Moreover, we observed a cumulative effect of significant SNPs on OS and RFS (P for trend < 0.001 for both). Survival tree analysis indicated that wild genotype of rs228729 in PER3 was the primary risk factor contributing to HCC patients' RFS. Our study suggests that the polymorphisms in circadian negative feedback loop genes may serve as independent prognostic biomarkers in predicting clinical outcomes for HCC patients who received radical resection. Further studies with different ethnicities are needed to validate our findings and generalize its clinical utility.

Effects of Achievement Goals on Challenge Seeking and Feedback Processing: Behavioral and fMRI Evidence

PubMed Central

Lee, Woogul; Kim, Sung-il

2014-01-01

We conducted behavioral and functional magnetic resonance imaging (fMRI) research to investigate the effects of two types of achievement goals—mastery goals and performance-approach goals— on challenge seeking and feedback processing. The results of the behavioral experiment indicated that mastery goals were associated with a tendency to seek challenge, both before and after experiencing difficulty during task performance, whereas performance-approach goals were related to a tendency to avoid challenge after encountering difficulty during task performance. The fMRI experiment uncovered a significant decrease in ventral striatal activity when participants received negative feedback for any task type and both forms of achievement goals. During the processing of negative feedback for the rule-finding task, performance-approach-oriented participants showed a substantial reduction in activity in the dorsolateral prefrontal cortex (DLPFC) and the frontopolar cortex, whereas mastery-oriented participants showed little change. These results suggest that performance-approach-oriented participants are less likely to either recruit control processes in response to negative feedback or focus on task-relevant information provided alongside the negative feedback. In contrast, mastery-oriented participants are more likely to modulate aversive valuations to negative feedback and focus on the constructive elements of feedback in order to attain their task goals. We conclude that performance-approach goals lead to a reluctant stance towards difficulty, while mastery goals encourage a proactive stance. PMID:25251396

The bantam microRNA acts through Numb to exert cell growth control and feedback regulation of Notch in tumor-forming stem cells in the Drosophila brain.

PubMed

Wu, Yen-Chi; Lee, Kyu-Sun; Song, Yan; Gehrke, Stephan; Lu, Bingwei

2017-05-01

Notch (N) signaling is central to the self-renewal of neural stem cells (NSCs) and other tissue stem cells. Its deregulation compromises tissue homeostasis and contributes to tumorigenesis and other diseases. How N regulates stem cell behavior in health and disease is not well understood. Here we show that N regulates bantam (ban) microRNA to impact cell growth, a process key to NSC maintenance and particularly relied upon by tumor-forming cancer stem cells. Notch signaling directly regulates ban expression at the transcriptional level, and ban in turn feedback regulates N activity through negative regulation of the Notch inhibitor Numb. This feedback regulatory mechanism helps maintain the robustness of N signaling activity and NSC fate. Moreover, we show that a Numb-Myc axis mediates the effects of ban on nucleolar and cellular growth independently or downstream of N. Our results highlight intricate transcriptional as well as translational control mechanisms and feedback regulation in the N signaling network, with important implications for NSC biology and cancer biology.

Positive Feedback From Male Authority Figures Boosts Women's Math Outcomes.

PubMed

Park, Lora E; Kondrak, Cheryl L; Ward, Deborah E; Streamer, Lindsey

2018-03-01

People often search for cues in the environment to determine whether or not they will be judged or treated negatively based on their social identities. Accordingly, feedback from gatekeepers-members of majority groups who hold authority and power in a field-may be an especially important cue for those at risk of experiencing social identity threat, such as women in math settings. Across a series of studies, women who received positive ("Good job!") versus objective (score only) feedback from a male (vs. female) authority figure in math reported greater confidence; belonging; self-efficacy; more favorable Science, Technology, Engineering, and Mathematics (STEM) attitudes/identification/interest; and greater implicit identification with math. Men were affected only by the type of math feedback they received, not by the source of feedback. A meta-analysis across studies confirmed results. Together, these findings suggest that positive feedback from gatekeepers is an important situational cue that can improve the outcomes of negatively stereotyped groups.

Learning processes underlying avoidance of negative outcomes.

PubMed

Andreatta, Marta; Michelmann, Sebastian; Pauli, Paul; Hewig, Johannes

2017-04-01

Successful avoidance of a threatening event may negatively reinforce the behavior due to activation of brain structures involved in reward processing. Here, we further investigated the learning-related properties of avoidance using feedback-related negativity (FRN). The FRN is modulated by violations of an intended outcome (prediction error, PE), that is, the bigger the difference between intended and actual outcome, the larger the FRN amplitude is. Twenty-eight participants underwent an operant conditioning paradigm, in which a behavior (button press) allowed them to avoid a painful electric shock. During two learning blocks, participants could avoid an electric shock in 80% of the trials by pressing one button (avoidance button), or by not pressing another button (punishment button). After learning, participants underwent two test blocks, which were identical to the learning ones except that no shocks were delivered. Participants pressed the avoidance button more often than the punishment button. Importantly, response frequency increased throughout the learning blocks but it did not decrease during the test blocks, indicating impaired extinction and/or habit formation. In line with a PE account, FRN amplitude to negative feedback after correct responses (i.e., unexpected punishment) was significantly larger than to positive feedback (i.e., expected omission of punishment), and it increased throughout the blocks. Highly anxious individuals showed equal FRN amplitudes to negative and positive feedback, suggesting impaired discrimination. These results confirm the role of negative reinforcement in motivating behavior and learning, and reveal important differences between high and low anxious individuals in the processing of prediction errors. © 2017 Society for Psychophysiological Research.

Electrophysiological Correlates of Error Monitoring and Feedback Processing in Second Language Learning.

PubMed

Bultena, Sybrine; Danielmeier, Claudia; Bekkering, Harold; Lemhöfer, Kristin

2017-01-01

Humans monitor their behavior to optimize performance, which presumably relies on stable representations of correct responses. During second language (L2) learning, however, stable representations have yet to be formed while knowledge of the first language (L1) can interfere with learning, which in some cases results in persistent errors. In order to examine how correct L2 representations are stabilized, this study examined performance monitoring in the learning process of second language learners for a feature that conflicts with their first language. Using EEG, we investigated if L2 learners in a feedback-guided word gender assignment task showed signs of error detection in the form of an error-related negativity (ERN) before and after receiving feedback, and how feedback is processed. The results indicated that initially, response-locked negativities for correct (CRN) and incorrect (ERN) responses were of similar size, showing a lack of internal error detection when L2 representations are unstable. As behavioral performance improved following feedback, the ERN became larger than the CRN, pointing to the first signs of successful error detection. Additionally, we observed a second negativity following the ERN/CRN components, the amplitude of which followed a similar pattern as the previous negativities. Feedback-locked data indicated robust FRN and P300 effects in response to negative feedback across different rounds, demonstrating that feedback remained important in order to update memory representations during learning. We thus show that initially, L2 representations may often not be stable enough to warrant successful error monitoring, but can be stabilized through repeated feedback, which means that the brain is able to overcome L1 interference, and can learn to detect errors internally after a short training session. The results contribute a different perspective to the discussion on changes in ERN and FRN components in relation to learning, by extending the

Causal structure of oscillations in gene regulatory networks: Boolean analysis of ordinary differential equation attractors.

PubMed

Sun, Mengyang; Cheng, Xianrui; Socolar, Joshua E S

2013-06-01

A common approach to the modeling of gene regulatory networks is to represent activating or repressing interactions using ordinary differential equations for target gene concentrations that include Hill function dependences on regulator gene concentrations. An alternative formulation represents the same interactions using Boolean logic with time delays associated with each network link. We consider the attractors that emerge from the two types of models in the case of a simple but nontrivial network: a figure-8 network with one positive and one negative feedback loop. We show that the different modeling approaches give rise to the same qualitative set of attractors with the exception of a possible fixed point in the ordinary differential equation model in which concentrations sit at intermediate values. The properties of the attractors are most easily understood from the Boolean perspective, suggesting that time-delay Boolean modeling is a useful tool for understanding the logic of regulatory networks.

77 FR 64565 - Solicitation of Feedback and Lessons-Learned from the Pilot of the Revised Construction Reactor...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-22

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0249] Solicitation of Feedback and Lessons-Learned from... or the Commission) is soliciting feedback and lessons-learned from members of the public, licensees... constructed in accordance with the licensing basis. The NRC has applied lessons- learned from the prior plants...

A feedback regulatory loop involving microRNA-9 and nuclear receptor TLX in neural stem cell fate determination.

PubMed

Zhao, Chunnian; Sun, GuoQiang; Li, Shengxiu; Shi, Yanhong

2009-04-01

MicroRNAs have been implicated as having important roles in stem cell biology. MicroRNA-9 (miR-9) is expressed specifically in neurogenic areas of the brain and may be involved in neural stem cell self-renewal and differentiation. We showed previously that the nuclear receptor TLX is an essential regulator of neural stem cell self-renewal. Here we show that miR-9 suppresses TLX expression to negatively regulate neural stem cell proliferation and accelerate neural differentiation. Introducing a TLX expression vector that is not prone to miR-9 regulation rescued miR-9-induced proliferation deficiency and inhibited precocious differentiation. In utero electroporation of miR-9 in embryonic brains led to premature differentiation and outward migration of the transfected neural stem cells. Moreover, TLX represses expression of the miR-9 pri-miRNA. By forming a negative regulatory loop with TLX, miR-9 provides a model for controlling the balance between neural stem cell proliferation and differentiation.

A feedback regulatory loop involving microRNA-9 and nuclear receptor TLX in neural stem cell fate determination

PubMed Central

Zhao, Chunnian; Sun, GuoQiang; Li, Shengxiu; Shi, Yanhong

2009-01-01

Summary MicroRNAs are important players in stem cell biology. Among them, microRNA-9 (miR-9) is expressed specifically in neurogenic areas of the brain. Whether miR-9 plays a role in neural stem cell self-renewal and differentiation is unknown. We showed previously that nuclear receptor TLX is an essential regulator of neural stem cell self-renewal. Here we show that miR-9 suppresses TLX expression to negatively regulate neural stem cell proliferation and accelerate neural differentiation. Introducing a TLX expression vector lacking the miR-9 recognition site rescued miR-9-induced proliferation deficiency and inhibited precocious differentiation. In utero electroporation of miR-9 in embryonic brains led to premature differentiation and outward migration of the transfected neural stem cells. Moreover, TLX represses miR-9 pri-miRNA expression. MiR-9, by forming a negative regulatory loop with TLX, establishes a model for controlling the balance between neural stem cell proliferation and differentiation. PMID:19330006

The role of feedbacks in Antarctic sea ice change

NASA Astrophysics Data System (ADS)

Feltham, D. L.; Frew, R. C.; Holland, P.

2017-12-01

The changes in Antarctic sea ice over the last thirty years have a strong seasonal dependence, and the way these changes grow in spring and decay in autumn suggests that feedbacks are strongly involved. The changes may ultimately be caused by atmospheric warming, the winds, snowfall changes, etc., but we cannot understand these forcings without first untangling the feedbacks. A highly simplified coupled sea ice -mixed layer model has been developed to investigate the importance of feedbacks on the evolution of sea ice in two contrasting regions in the Southern Ocean; the Amundsen Sea where sea ice extent has been decreasing, and the Weddell Sea where it has been expanding. The change in mixed layer depth in response to changes in the atmosphere to ocean energy flux is implicit in a strong negative feedback on ice cover changes in the Amundsen Sea, with atmospheric cooling leading to a deeper mixed layer resulting in greater entrainment of warm Circumpolar Deep Water, causing increased basal melting of sea ice. This strong negative feedback produces counter intuitive responses to changes in forcings in the Amundsen Sea. This feedback is absent in the Weddell due to the complete destratification and strong water column cooling that occurs each winter in simulations. The impact of other feedbacks, including the albedo feedback, changes in insulation due to ice thickness and changes in the freezing temperature of the mixed layer, were found to be of secondary importance compared to changes in the mixed layer depth.

Developmental Change in Feedback Processing as Reflected by Phasic Heart Rate Changes

ERIC Educational Resources Information Center

Crone, Eveline A.; Jennings, J. Richard; Van der Molen, Maurits W.

2004-01-01

Heart rate was recorded from 3 age groups (8-10, 12, and 20-26 years) while they performed a probabilistic learning task. Stimuli had to be sorted by pressing a left versus right key, followed by positive or negative feedback. Adult heart rate slowed following negative feedback when stimuli were consistently mapped onto the left or right key…

Managing Volunteer Performance: The Role of the Feedback Environment.

ERIC Educational Resources Information Center

Paull, Megan

2000-01-01

Volunteers (n=85) in Australian organizations who responded to a survey indicated that they received both positive and negative feedback from supervisors and coworkers. The feedback environment facilitated or hindered its effectiveness. Effectiveness was enhanced by an organizational culture that was supportive and open and development of…

SOCS3 promotes TLR4 response in macrophages by feedback inhibiting TGF-beta1/Smad3 signaling.

PubMed

Liu, Xia; Zhang, Yongliang; Yu, Yizhi; Yang, Xiao; Cao, Xuetao

2008-03-01

Endogenous transforming growth factor-beta1 (TGF-beta1) plays an important role in the negative regulation of toll-like receptor (TLR) signaling in a feedback manner. Suppressors of cytokine signaling 3 (SOCS3) has been shown to be induced by TGF-beta1 in osteoclast/macrophage, while the reports on the role of SOCS3 in regulating TLR4 signaling were controversial. The functional relationship between SOCS3 and TGF-beta1/Smad3 pathway in TLR4 response also remains unclear. In this study, we demonstrate that LPS-induced endogenous TGF-beta1 contributes to the inducible SOCS3 expression in macrophages. SOCS3 silencing could markedly decrease the LPS-induced production of TNF-alpha and IL-6 in macrophages. Interestingly, less decrease of LPS-induced TNF-alpha, IL-6 by SOCS3 silencing was observed in Smad3 null macrophages. Furthermore, we found SOCS3 could interact with Smad3, and inhibit Smad3 nuclear translocation and transcriptional activity. Therefore, our data demonstrate that SOCS3 is a positive regulator of TLR4 response by feedback inhibiting endogenous TGF-beta1/Smad3 signaling, thus outlining a new feedback regulatory manner for TLR4 response in macrophages.

Who Deserves My Trust? Cue-Elicited Feedback Negativity Tracks Reputation Learning in Repeated Social Interactions.

PubMed

Li, Diandian; Meng, Liang; Ma, Qingguo

2017-01-01

Trust and trustworthiness contribute to reciprocal behavior and social relationship development. To make better decisions, people need to evaluate others' trustworthiness. They often assess this kind of reputation by learning through repeated social interactions. The present event-related potential (ERP) study explored the reputation learning process in a repeated trust game where subjects made multi-round decisions of investment to different partners. We found that subjects gradually learned to discriminate trustworthy partners from untrustworthy ones based on how often their partners reciprocated the investment, which was indicated by their own investment decisions. Besides, electrophysiological data showed that the faces of the untrustworthy partners induced larger feedback negativity (FN) amplitude than those of the trustworthy partners, but only in the late phase of the game. The ERP results corresponded with the behavioral pattern and revealed that the learned trustworthiness differentiation was coded by the cue-elicited FN component. Consistent with previous research, our findings suggest that the anterior cue-elicited FN reflects the reputation appraisal and tracks the reputation learning process in social interactions.

The Influence of Teacher Feedback on Children's Perceptions of Student-Teacher Relationships

ERIC Educational Resources Information Center

Skipper, Yvonne; Douglas, Karen

2015-01-01

Background: Teachers can deliver feedback using person ("you are clever") or process terms ("you worked hard"). Person feedback can lead to negative academic outcomes, but there is little experimental research examining the impact of feedback on children's perceptions of the student-teacher relationship. Aim: We examined the…

Adeno-associated virus type 2 rep gene-mediated inhibition of basal gene expression of human immunodeficiency virus type 1 involves its negative regulatory functions.

PubMed Central

Oelze, I; Rittner, K; Sczakiel, G

1994-01-01

Adeno-associated virus type 2 (AAV-2), a human parvovirus which is apathogenic in adults, inhibits replication and gene expression of human immunodeficiency virus type 1 (HIV-1) in human cells. The rep gene of AAV-2, which was shown earlier to be sufficient for this negative interference, also down-regulated the expression of heterologous sequences driven by the long terminal repeat (LTR) of HIV-1. This effect was observed in the absence of the HIV-1 transactivator Tat, i.e., at basal levels of LTR-driven transcription. In this work, we studied the involvement of functional subsequences of the HIV-1 LTR in rep-mediated inhibition in the absence of Tat. Mutated LTRs driving an indicator gene (cat) were cointroduced into human SW480 cells together with rep alone or with double-stranded DNA fragments or RNA containing sequences of the HIV-1 LTR. The results indicate that rep strongly enhances the function of negative regulatory elements of the LTR. In addition, the experiments revealed a transcribed sequence element located within the TAR-coding sequence termed AHHH (AAV-HIV homology element derived from HIV-1) which is involved in rep-mediated inhibition. The AHHH element is also involved in down-regulation of basal expression levels in the absence of rep, suggesting that AHHH also contributes to negative regulatory functions of the LTR of HIV-1. In contrast, positive regulatory elements of the HIV-1 LTR such as the NF kappa B and SP1 binding sites have no significant influence on the rep-mediated inhibition. Images PMID:8289357

The Feedback-Related Negativity and the P300 Brain Potential Are Sensitive to Price Expectation Violations in a Virtual Shopping Task.

PubMed

Schaefer, Alexandre; Buratto, Luciano G; Goto, Nobuhiko; Brotherhood, Emilie V

A large body of evidence shows that buying behaviour is strongly determined by consumers' price expectations and the extent to which real prices violate these expectations. Despite the importance of this phenomenon, little is known regarding its neural mechanisms. Here we show that two patterns of electrical brain activity known to index prediction errors-the Feedback-Related Negativity (FRN) and the feedback-related P300 -were sensitive to price offers that were cheaper than participants' expectations. In addition, we also found that FRN amplitude time-locked to price offers predicted whether a product would be subsequently purchased or not, and further analyses suggest that this result was driven by the sensitivity of the FRN to positive price expectation violations. This finding strongly suggests that ensembles of neurons coding positive prediction errors play a critical role in real-life consumer behaviour. Further, these findings indicate that theoretical models based on the notion of prediction error, such as the Reinforcement Learning Theory, can provide a neurobiologically grounded account of consumer behavior.

The Feedback-Related Negativity and the P300 Brain Potential Are Sensitive to Price Expectation Violations in a Virtual Shopping Task

PubMed Central

Schaefer, Alexandre; Buratto, Luciano G.; Goto, Nobuhiko; Brotherhood, Emilie V.

2016-01-01

A large body of evidence shows that buying behaviour is strongly determined by consumers’ price expectations and the extent to which real prices violate these expectations. Despite the importance of this phenomenon, little is known regarding its neural mechanisms. Here we show that two patterns of electrical brain activity known to index prediction errors–the Feedback-Related Negativity (FRN) and the feedback-related P300 –were sensitive to price offers that were cheaper than participants’ expectations. In addition, we also found that FRN amplitude time-locked to price offers predicted whether a product would be subsequently purchased or not, and further analyses suggest that this result was driven by the sensitivity of the FRN to positive price expectation violations. This finding strongly suggests that ensembles of neurons coding positive prediction errors play a critical role in real-life consumer behaviour. Further, these findings indicate that theoretical models based on the notion of prediction error, such as the Reinforcement Learning Theory, can provide a neurobiologically grounded account of consumer behavior. PMID:27658301

Mental models of audit and feedback in primary care settings.

PubMed

Hysong, Sylvia J; Smitham, Kristen; SoRelle, Richard; Amspoker, Amber; Hughes, Ashley M; Haidet, Paul

2018-05-30

Audit and feedback has been shown to be instrumental in improving quality of care, particularly in outpatient settings. The mental model individuals and organizations hold regarding audit and feedback can moderate its effectiveness, yet this has received limited study in the quality improvement literature. In this study we sought to uncover patterns in mental models of current feedback practices within high- and low-performing healthcare facilities. We purposively sampled 16 geographically dispersed VA hospitals based on high and low performance on a set of chronic and preventive care measures. We interviewed up to 4 personnel from each location (n = 48) to determine the facility's receptivity to audit and feedback practices. Interview transcripts were analyzed via content and framework analysis to identify emergent themes. We found high variability in the mental models of audit and feedback, which we organized into positive and negative themes. We were unable to associate mental models of audit and feedback with clinical performance due to high variance in facility performance over time. Positive mental models exhibit perceived utility of audit and feedback practices in improving performance; whereas, negative mental models did not. Results speak to the variability of mental models of feedback, highlighting how facilities perceive current audit and feedback practices. Findings are consistent with prior research  in that variability in feedback mental models is associated with lower performance.; Future research should seek to empirically link mental models revealed in this paper to high and low levels of clinical performance.

A PLC-γ1 Feedback Pathway Regulates Lck Substrate Phosphorylation at the T-Cell Receptor and SLP-76 Complex.

PubMed

Belmont, Judson; Gu, Tao; Mudd, Ashley; Salomon, Arthur R

2017-08-04

Phospholipase C gamma 1 (PLC-γ1) occupies a critically important position in the T-cell signaling pathway. While its functions as a regulator of both Ca 2+ signaling and PKC-family kinases are well characterized, PLC-γ1's role in the regulation of early T-cell receptor signaling events is incompletely understood. Activation of the T-cell receptor leads to the formation of a signalosome complex between SLP-76, LAT, PLC-γ1, Itk, and Vav1. Recent studies have revealed the existence of both positive and negative feedback pathways from SLP-76 to the apical kinase in the pathway, Lck. To determine if PLC-γ1 contributes to the regulation of these feedback networks, we performed a quantitative phosphoproteomic analysis of PLC-γ1-deficient T cells. These data revealed a previously unappreciated role for PLC-γ1 in the positive regulation of Zap-70 and T-cell receptor tyrosine phosphorylation. Conversely, PLC-γ1 negatively regulated the phosphorylation of SLP-76-associated proteins, including previously established Lck substrate phosphorylation sites within this complex. While the positive and negative regulatory phosphorylation sites on Lck were largely unchanged, Tyr 192 phosphorylation was elevated in Jgamma1. The data supports a model wherein Lck's targeting, but not its kinase activity, is altered by PLC-γ1, possibly through Lck Tyr 192 phosphorylation and increased association of the kinase with protein scaffolds SLP-76 and TSAd.

Saxagliptin co-therapy in C-peptide negative Type 1 diabetes does not improve counter-regulatory responses to hypoglycaemia.

PubMed

George, P S; McCrimmon, R J

2016-09-01

To test the hypothesis that dipeptidyl peptidase-4 inhibition in C-peptide negative Type 1 diabetes would reduce glucose variability and exposure to hypoglycaemia and therefore may indirectly enhance counter-regulatory responses to subsequent hypoglycaemia. We conducted a 12-week double-blind, randomized, placebo-controlled crossover study. The study was conducted in a tertiary hospital outpatient clinic, with additional studies performed in a clinical research centre. After obtaining informed consent, we recruited 14 subjects with moderately well controlled Type 1 diabetes (HbA1c 64 ± 2 mmol/mol) of long duration (20.5 ± 2.7 years). The subjects received 12 weeks' therapy with oral saxagliptin (5 mg) or placebo. Glucose variability, assessed via continuous glucose monitoring, together with frequency of hypoglycaemia, hypoglycaemia awareness and symptomatic, cognitive and counter-regulatory hormone responses to experimental hypoglycaemia, were assessed. Additional outcome measures included HbA1c level, weight, total daily insulin dose and adverse events. Saxagliptin co-therapy did not reduce glucose variability (low blood glucose index, average daily risk range), hypoglycaemia frequency or awareness and did not improve counter-regulatory hormonal responses during experimental hypoglycaemia (area under the curve for adrenaline 25 775 vs. 24 454, for placebo vs saxagliptin, respectively; P = 0.76). No additional benefit of dipeptidyl peptidase-4 inhibition co-therapy with saxagliptin in the management of Type 1 diabetes was observed. © 2015 Diabetes UK.

The interplay between feedback-related negativity and individual differences in altruistic punishment: An EEG study.

PubMed

Mothes, Hendrik; Enge, Sören; Strobel, Alexander

2016-04-01

To date, the interplay betwexen neurophysiological and individual difference factors in altruistic punishment has been little understood. To examine this issue, 45 individuals participated in a Dictator Game with punishment option while the feedback-related negativity (FRN) was derived from the electroencephalogram (EEG). Unlike previous EEG studies on the Dictator Game, we introduced a third party condition to study the effect of fairness norm violations in addition to employing a first person perspective. For the first time, we also examined the role of individual differences, specifically fairness concerns, positive/negative affectivity, and altruism/empathy as well as recipients' financial situation during altruistic punishment. The main results show that FRN amplitudes were more pronounced for unfair than for fair assignments in both the first person and third party perspectives. These findings suggest that FRN amplitudes are sensitive to fairness norm violations and play a crucial role in the recipients' evaluation of dictator assignments. With respect to individual difference factors, recipients' current financial situation affected the FRN fairness effect in the first person perspective, indicating that when being directly affected by the assignments, more affluent participants experienced stronger violations of expectations in altruistic punishment decisions. Regarding individual differences in trait empathy, in the third party condition FRN amplitudes were more pronounced for those who scored lower in empathy. This may suggest empathy as another motive in third party punishment. Independent of the perspective taken, higher positive affect was associated with more punishment behavior, suggesting that positive emotions may play an important role in restoring violated fairness norms.

Constructive Feedback as a Learning Tool to Enhance Students' Self-Regulation and Performance in Higher Education

ERIC Educational Resources Information Center

du Toit, Erna

2012-01-01

If feedback is provided in a way that can develop students' self-regulatory skills, it could enhance learning and, consequently, lead to improved performance. To improve teaching and learning in higher education (HE), this study sought to determine whether the feedback to first-year students affords them an opportunity to learn from it. A…

Signatures of AGN feedback

NASA Astrophysics Data System (ADS)

Wylezalek, Dominika; Zakamska, Nadia L.; MaNGA-GMOS Team

2017-01-01

Feedback from actively accreting SMBHs (Active Galactic Nuclei, AGN) is now widely considered to be the main driver in regulating the growth of massive galaxies. Observational proof for this scenario has, however, been hard to come by. Many attempts at finding a conclusive observational proof that AGN may be able to quench star formation and regulate the host galaxies' growth have shown that this problem is highly complex.I will present results from several projects that focus on understanding the power, reach and impact of feedback processes exerted by AGN. I will describe recent efforts in our group of relating feedback signatures to the specific star formation rate in their host galaxies, where our results are consistent with the AGN having a `negative' impact through feedback on the galaxies' star formation history (Wylezalek+2016a,b). Furthermore, I will show that powerful AGN-driven winds can be easily hidden and not be apparent in the integrated spectrum of the galaxy. This implies that large IFU surveys, such as the SDSS-IV MaNGA survey, might uncover many previously unknown AGN and outflows that are potentially very relevant for understanding the role of AGN in galaxy evolution (Wylezalek+2016c)!

Feedback Synthesizes Neural Codes for Motion.

PubMed

Clarke, Stephen E; Maler, Leonard

2017-05-08

In senses as diverse as vision, hearing, touch, and the electrosense, sensory neurons receive bottom-up input from the environment, as well as top-down input from feedback loops involving higher brain regions [1-4]. Through connectivity with local inhibitory interneurons, these feedback loops can exert both positive and negative control over fundamental aspects of neural coding, including bursting [5, 6] and synchronous population activity [7, 8]. Here we show that a prominent midbrain feedback loop synthesizes a neural code for motion reversal in the hindbrain electrosensory ON- and OFF-type pyramidal cells. This top-down mechanism generates an accurate bidirectional encoding of object position, despite the inability of the electrosensory afferents to generate a consistent bottom-up representation [9, 10]. The net positive activity of this midbrain feedback is additionally regulated through a hindbrain feedback loop, which reduces stimulus-induced bursting and also dampens the ON and OFF cell responses to interfering sensory input [11]. We demonstrate that synthesis of motion representations and cancellation of distracting signals are mediated simultaneously by feedback, satisfying an accepted definition of spatial attention [12]. The balance of excitatory and inhibitory feedback establishes a "focal" distance for optimized neural coding, whose connection to a classic motion-tracking behavior provides new insight into the computational roles of feedback and active dendrites in spatial localization [13, 14]. Copyright © 2017 Elsevier Ltd. All rights reserved.

Linear feedback stabilization of a dispersively monitored qubit

NASA Astrophysics Data System (ADS)

Patti, Taylor Lee; Chantasri, Areeya; García-Pintos, Luis Pedro; Jordan, Andrew N.; Dressel, Justin

2017-08-01

The state of a continuously monitored qubit evolves stochastically, exhibiting competition between coherent Hamiltonian dynamics and diffusive partial collapse dynamics that follow the measurement record. We couple these distinct types of dynamics together by linearly feeding the collected record for dispersive energy measurements directly back into a coherent Rabi drive amplitude. Such feedback turns the competition cooperative and effectively stabilizes the qubit state near a target state. We derive the conditions for obtaining such dispersive state stabilization and verify the stabilization conditions numerically. We include common experimental nonidealities, such as energy decay, environmental dephasing, detector efficiency, and feedback delay, and show that the feedback delay has the most significant negative effect on the feedback protocol. Setting the measurement collapse time scale to be long compared to the feedback delay yields the best stabilization.

Germline Genetic Variants Disturbing the Let-7/LIN28 Double-Negative Feedback Loop Alter Breast Cancer Susceptibility

PubMed Central

Fan, Lei; Li, Ji-Yu; Yang, Chen; Huang, A-Ji; Shao, Zhi-Ming

2011-01-01

Previous studies have shown that let-7 can repress the post-transcriptional translation of LIN28, and LIN28 in turn could block the maturation of let-7, forming a double-negative feedback loop. In this study, we investigated the effect of germline genetic variants on regulation of the homeostasis of the let-7/LIN28 loop and breast cancer risk. We initially demonstrated that the T/C variants of rs3811463, a single nucleotide polymorphism (SNP) located near the let-7 binding site in LIN28, could lead to differential regulation of LIN28 by let-7. Specifically, the C allele of rs3811463 weakened let-7–induced repression of LIN28 mRNA, resulting in increased production of LIN28 protein, which could in turn down-regulate the level of mature let-7. This effect was then validated at the tissue level in that the normal breast tissue of individuals with the rs3811463-TC genotype expressed significantly lower levels of let-7 and higher levels of LIN28 protein than those individuals with the rs3811463-TT genotype. Because previous in vitro and ex vivo experiments have consistently suggested that LIN28 could promote cellular transformation, we then systematically evaluated the relationship between rs3811463 as well as other common LIN28 SNPs and the risk of breast cancer in a stepwise manner. The first hospital-based association study (n = 2,300) demonstrated that two SNPs were significantly associated with breast cancer risk, one of which was rs3811463, while the other was rs6697410. The C allele of the rs3811463 SNP corresponded to an increased risk of breast cancer with an odds ratio (OR) of 1.25 (P = 0.0091), which was successfully replicated in a second independent study (n = 1,156) with community-based controls. The combined P-value of the two studies was 8.0×10−5. Taken together, our study demonstrates that host genetic variants could disturb the regulation of the let-7/LIN28 double-negative feedback loop and alter breast cancer risk. PMID:21912531

Influence of accurate and inaccurate 'split-time' feedback upon 10-mile time trial cycling performance.

PubMed

Wilson, Mathew G; Lane, Andy M; Beedie, Chris J; Farooq, Abdulaziz

2012-01-01

The objective of the study is to examine the impact of accurate and inaccurate 'split-time' feedback upon a 10-mile time trial (TT) performance and to quantify power output into a practically meaningful unit of variation. Seven well-trained cyclists completed four randomised bouts of a 10-mile TT on a SRM™ cycle ergometer. TTs were performed with (1) accurate performance feedback, (2) without performance feedback, (3) and (4) false negative and false positive 'split-time' feedback showing performance 5% slower or 5% faster than actual performance. There were no significant differences in completion time, average power output, heart rate or blood lactate between the four feedback conditions. There were significantly lower (p < 0.001) average [Formula: see text] (ml min(-1)) and [Formula: see text] (l min(-1)) scores in the false positive (3,485 ± 596; 119 ± 33) and accurate (3,471 ± 513; 117 ± 22) feedback conditions compared to the false negative (3,753 ± 410; 127 ± 27) and blind (3,772 ± 378; 124 ± 21) feedback conditions. Cyclists spent a greater amount of time in a '20 watt zone' 10 W either side of average power in the negative feedback condition (fastest) than the accurate feedback (slowest) condition (39.3 vs. 32.2%, p < 0.05). There were no significant differences in the 10-mile TT performance time between accurate and inaccurate feedback conditions, despite significantly lower average [Formula: see text] and [Formula: see text] scores in the false positive and accurate feedback conditions. Additionally, cycling with a small variation in power output (10 W either side of average power) produced the fastest TT. Further psycho-physiological research should examine the mechanism(s) why lower [Formula: see text] and [Formula: see text] scores are observed when cycling in a false positive or accurate feedback condition compared to a false negative or blind feedback condition.

An integrative model linking feedback environment and organizational citizenship behavior.

PubMed

Peng, Jei-Chen; Chiu, Su-Fen

2010-01-01

Past empirical evidence has suggested that a positive supervisor feedback environment may enhance employees' organizational citizenship behavior (OCB). In this study, we aim to extend previous research by proposing and testing an integrative model that examines the mediating processes underlying the relationship between supervisor feedback environment and employee OCB. Data were collected from 259 subordinate-supervisor dyads across a variety of organizations in Taiwan. We used structural equation modeling to test our hypotheses. The results demonstrated that supervisor feedback environment influenced employees' OCB indirectly through (1) both positive affective-cognition and positive attitude (i.e., person-organization fit and organizational commitment), and (2) both negative affective-cognition and negative attitude (i.e., role stressors and job burnout). Theoretical and practical implications are discussed.

Quantifying the Relative Contributions of Divisive and Subtractive Feedback to Rhythm Generation

PubMed Central

Tabak, Joël; Rinzel, John; Bertram, Richard

2011-01-01

Biological systems are characterized by a high number of interacting components. Determining the role of each component is difficult, addressed here in the context of biological oscillations. Rhythmic behavior can result from the interplay of positive feedback that promotes bistability between high and low activity, and slow negative feedback that switches the system between the high and low activity states. Many biological oscillators include two types of negative feedback processes: divisive (decreases the gain of the positive feedback loop) and subtractive (increases the input threshold) that both contribute to slowly move the system between the high- and low-activity states. Can we determine the relative contribution of each type of negative feedback process to the rhythmic activity? Does one dominate? Do they control the active and silent phase equally? To answer these questions we use a neural network model with excitatory coupling, regulated by synaptic depression (divisive) and cellular adaptation (subtractive feedback). We first attempt to apply standard experimental methodologies: either passive observation to correlate the variations of a variable of interest to system behavior, or deletion of a component to establish whether a component is critical for the system. We find that these two strategies can lead to contradictory conclusions, and at best their interpretive power is limited. We instead develop a computational measure of the contribution of a process, by evaluating the sensitivity of the active (high activity) and silent (low activity) phase durations to the time constant of the process. The measure shows that both processes control the active phase, in proportion to their speed and relative weight. However, only the subtractive process plays a major role in setting the duration of the silent phase. This computational method can be used to analyze the role of negative feedback processes in a wide range of biological rhythms. PMID:21533065

Children's feedback preferences in response to an experimentally manipulated peer evaluation outcome: the role of depressive symptoms.

PubMed

Reijntjes, Albert; Dekovic, Maja; Vermande, Marjolijn; Telch, Michael J

2007-06-01

The present study examined the linkage between pre-adolescent children's depressive symptoms and their preferences for receiving positive vs. negative feedback subsequent to being faced with an experimentally manipulated peer evaluation outcome in real time. Participants (n = 142) ages 10 to 13, played a computer contest based on the television show Survivor and were randomized to either a peer rejection (i.e., receiving the lowest total 'likeability' score from a group of peer-judges), a peer success (i.e., receiving the highest score), or a control peer evaluation condition. Children's self-reported feedback preferences were then assessed. Results revealed that participants assigned to the negative evaluation outcome, relative to either the success or the control outcome, showed a significantly higher subsequent preference for negatively tuned feedback. Contrary to previous work and predictions derived from self-verification theory, children higher in depressive symptoms were only more likely to prefer negative feedback in response to the negative peer evaluation outcome. These effects for depression were not accounted for by either state mood at baseline or mood change in response to the feedback manipulation.

Neuroticism and responsiveness to error feedback: adaptive self-regulation versus affective reactivity.

PubMed

Robinson, Michael D; Moeller, Sara K; Fetterman, Adam K

2010-10-01

Responsiveness to negative feedback has been seen as functional by those who emphasize the value of reflecting on such feedback in self-regulating problematic behaviors. On the other hand, the very same responsiveness has been viewed as dysfunctional by its link to punishment sensitivity and reactivity. The present 4 studies, involving 203 undergraduate participants, sought to reconcile such discrepant views in the context of the trait of neuroticism. In cognitive tasks, individuals were given error feedback when they made mistakes. It was found that greater tendencies to slow down following error feedback were associated with higher levels of accuracy at low levels of neuroticism but lower levels of accuracy at high levels of neuroticism. Individual differences in neuroticism thus appear crucial in understanding whether behavioral alterations following negative feedback reflect proactive versus reactive mechanisms and processes. Implications for understanding the processing basis of neuroticism and adaptive self-regulation are discussed.

H19/let-7/LIN28 reciprocal negative regulatory circuit promotes breast cancer stem cell maintenance

PubMed Central

Peng, Fei; Li, Ting-Ting; Wang, Kai-Li; Xiao, Guo-Qing; Wang, Ju-Hong; Zhao, Hai-Dong; Kang, Zhi-Jie; Fan, Wen-Jun; Zhu, Li-Li; Li, Mei; Cui, Bai; Zheng, Fei-Meng; Wang, Hong-Jiang; Lam, Eric W-F; Wang, Bo; Xu, Jie; Liu, Quentin

2017-01-01

Long noncoding RNA-H19 (H19), an imprinted oncofetal gene, has a central role in carcinogenesis. Hitherto, the mechanism by which H19 regulates cancer stem cells, remains elusive. Here we show that breast cancer stem cells (BCSCs) express high levels of H19, and ectopic overexpression of H19 significantly promotes breast cancer cell clonogenicity, migration and mammosphere-forming ability. Conversely, silencing of H19 represses these BCSC properties. In concordance, knockdown of H19 markedly inhibits tumor growth and suppresses tumorigenesis in nude mice. Mechanistically, we found that H19 functions as a competing endogenous RNA to sponge miRNA let-7, leading to an increase in expression of a let-7 target, the core pluripotency factor LIN28, which is enriched in BCSC populations and breast patient samples. Intriguingly, this gain of LIN28 expression can also feedback to reverse the H19 loss-mediated suppression of BCSC properties. Our data also reveal that LIN28 blocks mature let-7 production and, thereby, de-represses H19 expression in breast cancer cells. Appropriately, H19 and LIN28 expression exhibits strong correlations in primary breast carcinomas. Collectively, these findings reveal that lncRNA H19, miRNA let-7 and transcriptional factor LIN28 form a double-negative feedback loop, which has a critical role in the maintenance of BCSCs. Consequently, disrupting this pathway provides a novel therapeutic strategy for breast cancer. PMID:28102845

HMBA Enhances Prostratin-Induced Activation of Latent HIV-1 via Suppressing the Expression of Negative Feedback Regulator A20/TNFAIP3 in NF-κB Signaling.

PubMed

Chen, Duchu; Wang, Huiping; Aweya, Jude Juventus; Chen, Yanheng; Chen, Meihua; Wu, Xiaomeng; Chen, Xiaonan; Lu, Jing; Chen, Ruichuan; Liu, Min

2016-01-01

In the past decade, much emphasis has been put on the transcriptional activation of HIV-1, which is proposed as a promised strategy for eradicating latent HIV-1 provirus. Two drugs, prostratin and hexamethylene bisacetamide (HMBA), have shown potent effects as inducers for releasing HIV-1 latency when used alone or in combination, although their cellular target(s) are currently not well understood, especially under drug combination. Here, we have shown that HMBA and prostratin synergistically release HIV-1 latency via different mechanisms. While prostratin strongly stimulates HMBA-induced HIV-1 transcription via improved P-TEFb activation, HMBA is capable of boosting NF-κB-dependent transcription initiation by suppressing prostratin-induced expression of the deubiquitinase A20, a negative feedback regulator in the NF-κB signaling pathway. In addition, HMBA was able to increase prostratin-induced phosphorylation and degradation of NF-κB inhibitor IκBα, thereby enhancing and prolonging prostratin-induced nuclear translocation of NF-κB, a prerequisite for stimulation of transcription initiation. Thus, by blocking the negative feedback circuit, HMBA functions as a signaling enhancer of the NF-κB signaling pathway.

Inhibitory and toxic effects of extracellular self-DNA in litter: a mechanism for negative plant-soil feedbacks?

PubMed

Mazzoleni, Stefano; Bonanomi, Giuliano; Incerti, Guido; Chiusano, Maria Luisa; Termolino, Pasquale; Mingo, Antonio; Senatore, Mauro; Giannino, Francesco; Cartenì, Fabrizio; Rietkerk, Max; Lanzotti, Virginia

2015-02-01

Plant-soil negative feedback (NF) is recognized as an important factor affecting plant communities. The objectives of this work were to assess the effects of litter phytotoxicity and autotoxicity on root proliferation, and to test the hypothesis that DNA is a driver of litter autotoxicity and plant-soil NF. The inhibitory effect of decomposed litter was studied in different bioassays. Litter biochemical changes were evaluated with nuclear magnetic resonance (NMR) spectroscopy. DNA accumulation in litter and soil was measured and DNA toxicity was assessed in laboratory experiments. Undecomposed litter caused nonspecific inhibition of root growth, while autotoxicity was produced by aged litter. The addition of activated carbon (AC) removed phytotoxicity, but was ineffective against autotoxicity. Phytotoxicity was related to known labile allelopathic compounds. Restricted (13) C NMR signals related to nucleic acids were the only ones negatively correlated with root growth on conspecific substrates. DNA accumulation was observed in both litter decomposition and soil history experiments. Extracted total DNA showed evident species-specific toxicity. Results indicate a general occurrence of litter autotoxicity related to the exposure to fragmented self-DNA. The evidence also suggests the involvement of accumulated extracellular DNA in plant-soil NF. Further studies are needed to further investigate this unexpected function of extracellular DNA at the ecosystem level and related cellular and molecular mechanisms. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

The Greenhouse Effect and Climate Feedbacks

NASA Astrophysics Data System (ADS)

Covey, C.; Haberle, R. M.; McKay, C. P.; Titov, D. V.

This chapter reviews the theory of the greenhouse effect and climate feedback. It also compares the theory with observations, using examples taken from all four known terrestrial worlds with substantial atmospheres: Venus, Earth, Mars, and Titan. The greenhouse effect traps infrared radiation in the atmosphere, thereby increasing surface temperature. It is one of many factors that affect a world's climate. (Others include solar luminosity and the atmospheric scattering and absorption of solar radiation.) A change in these factors — defined as climate forcing — may change the climate in a way that brings other processes — defined as feedbacks — into play. For example, when Earth's atmospheric carbon dioxide increases, warming the surface, the water vapor content of the atmosphere increases. This is a positive feedback on global warming because water vapor is itself a potent greenhouse gas. Many positive and negative feedback processes are significant in determining Earth's climate, and probably the climates of our terrestrial neighbors.

Perioperative feedback in surgical training: A systematic review.

PubMed

McKendy, Katherine M; Watanabe, Yusuke; Lee, Lawrence; Bilgic, Elif; Enani, Ghada; Feldman, Liane S; Fried, Gerald M; Vassiliou, Melina C

2017-07-01

Changes in surgical training have raised concerns about residents' operative exposure and preparedness for independent practice. One way of addressing this concern is by optimizing teaching and feedback in the operating room (OR). The objective of this study was to perform a systematic review on perioperative teaching and feedback. A systematic literature search identified articles from 1994 to 2014 that addressed teaching, feedback, guidance, or debriefing in the perioperative period. Data was extracted according to ENTREQ guidelines, and a qualitative analysis was performed. Thematic analysis of the 26 included studies identified four major topics. Observation of teaching behaviors in the OR described current teaching practices. Identification of effective teaching strategies analyzed teaching behaviors, differentiating positive and negative teaching strategies. Perceptions of teaching behaviors described resident and attending satisfaction with teaching in the OR. Finally models for delivering structured feedback cited examples of feedback strategies and measured their effectiveness. This study provides an overview of perioperative teaching and feedback for surgical trainees and identifies a need for improved quality and quantity of structured feedback. Copyright © 2016 Elsevier Inc. All rights reserved.

When compliments don't hit but critiques do: an fMRI study into self-esteem and self-knowledge in processing social feedback.

PubMed

van Schie, C C; Chiu, C D; Rombouts, S A R B; Heiser, W J; Elzinga, B M

2018-02-27

The way we view ourselves may play an important role in our responses to interpersonal interactions. In this study, we investigate how feedback valence, consistency of feedback with self-knowledge and global self-esteem influence affective and neural responses to social feedback. Participants (N = 46) with a high range of self-esteem levels performed the social feedback task in an MRI scanner. Negative, intermediate and positive feedback was provided, supposedly by another person based on a personal interview. Participants rated their mood and applicability of feedback to the self. Analyses on trial basis on neural and affective responses are used to incorporate applicability of individual feedback words. Lower self-esteem related to low mood especially after receiving non-applicable negative feedback. Higher self-esteem related to increased PCC and precuneus activation (i.e., self-referential processing) for applicable negative feedback. Lower self-esteem related to decreased mPFC, insula, ACC and PCC activation (i.e, self-referential processing) during positive feedback and decreased TPJ activation (i.e., other referential processing) for applicable positive feedback. Self-esteem and consistency of feedback with self-knowledge appear to guide our affective and neural responses to social feedback. This may be highly relevant for the interpersonal problems that individuals face with low self-esteem and negative self-views.

The stability of the feedback negativity and its relationship with depression during childhood and adolescence.

PubMed

Bress, Jennifer N; Meyer, Alexandria; Proudfit, Greg Hajcak

2015-11-01

Feedback negativity (FN) is an event-related potential elicited by monetary reward and loss; it is thought to relate to reward-related neural activity and has been linked to depression in children and adults. In the current study, we examined the stability of FN, and its relationship with depression in adolescents, over 2 years in 45 8- to 13-year-old children. From Time 1 to Time 2, FN in response to monetary loss and in response to monetary gain showed moderate to strong reliability (rs = .64 and .67, respectively); these relationships remained significant even when accounting for related variables. FN also demonstrated high within-session reliability. Moreover, the relationship between a blunted FN and greater depression observed at Time 1 was reproduced at Time 2, and the magnitude of FN at Time 1 predicted depressive symptomatology at Time 2. These findings are consistent with the hypothesis that FN and its relationship with depression remain consistent over the course of development, and that FN may prospectively predict later depressive symptomatology. The current results suggest that FN may be suitable as a biomarker of depressive symptoms during adolescence.

Self-Verification Strivings in Children Holding Negative Self-Views: The Mitigating Effects of a Preceding Success Experience

PubMed Central

Thomaes, Sander; Kamphuis, Jan Henk; de Castro, Bram Orobio; Telch, Michael J.

2010-01-01

Research among adults has consistently shown that people holding negative self-views prefer negative over positive feedback. The present study tested the hypothesis that this preference is less robust among pre-adolescents, such that it will be mitigated by a preceding positive event. Pre-adolescents (n = 75) holding positive or negative global self-esteem were randomized to a favorable or unfavorable peer evaluation outcome. Next, preferences for positive versus negative feedback were assessed using an unobtrusive behavioral viewing time measure. As expected, results showed that after being faced with the success outcome children holding negative self-views were as likely as their peers holding positive self-views to display a significant preference for positive feedback. In contrast, children holding negative self-views displayed a stronger preference for negative feedback after being faced with the unfavorable outcome that matched their pre-existing self-views. PMID:21151482

Self-Verification Strivings in Children Holding Negative Self-Views: The Mitigating Effects of a Preceding Success Experience.

PubMed

Reijntjes, Albert; Thomaes, Sander; Kamphuis, Jan Henk; de Castro, Bram Orobio; Telch, Michael J

2010-12-01

Research among adults has consistently shown that people holding negative self-views prefer negative over positive feedback. The present study tested the hypothesis that this preference is less robust among pre-adolescents, such that it will be mitigated by a preceding positive event. Pre-adolescents (n = 75) holding positive or negative global self-esteem were randomized to a favorable or unfavorable peer evaluation outcome. Next, preferences for positive versus negative feedback were assessed using an unobtrusive behavioral viewing time measure. As expected, results showed that after being faced with the success outcome children holding negative self-views were as likely as their peers holding positive self-views to display a significant preference for positive feedback. In contrast, children holding negative self-views displayed a stronger preference for negative feedback after being faced with the unfavorable outcome that matched their pre-existing self-views.

Using a Dialogical Approach to Examine Peer Feedback during Chemistry Investigative Task Discussion

ERIC Educational Resources Information Center

Gan Joo Seng, Mark; Hill, Mary

2014-01-01

Peer feedback is an inherent feature of classroom collaborative learning. Students invariably turn to their peers for feedback when carrying out an investigative task, and this feedback is usually implicit, unstructured and may positively or negatively influence students' learning when they work on a task. This study explored the characteristics…

Plant-soil feedback in East-African savanna trees.

PubMed

Rutten, Gemma; Prati, Daniel; Hemp, Andreas; Fischer, Markus

2016-02-01

Research in savannas has focused on tree-grass interactions, whereas tree species coexistence received little attention. A leading hypothesis to explain tree coexistence is the Janzen-Connell model, which proposes an accumulation of host-specific enemies, e.g., soil organisms. While it has been shown in several non-savanna case studies that seedlings dispersed away from the mother perform better than seedlings that stay close (home-away effect), few studies tested whether foreign seedling species can replace own seedlings under conspecific adults (replacement effect). Some studies additionally tested for negative effects of conspecific biota (conspecific effect) to demonstrate the accumulation of enemies. We tested these effects by reciprocally growing seedlings of four tree species on soil collected beneath adults of all species, with and without applying a soil sterilization treatment. We found negative home-away effects suggesting that dispersal is advantageous and negative replacement effects suggesting species replacement under adults. While negative conspecific effects indicate accumulated enemies, positive heterospecific effects indicate an accumulation of mutualists rather than enemies for some species. We suggest that plant-soil feedbacks may well contribute to tree coexistence in savannas due to both negative conspecific and positive heterospecific feedbacks.

Blunted feedback processing during risk-taking in adolescents with features of problematic Internet use.

PubMed

Yau, Yvonne H C; Potenza, Marc N; Mayes, Linda C; Crowley, Michael J

2015-06-01

While the conceptualization of problematic Internet use (PIU) as a "behavioral addiction" resembling substance-use disorders is debated, the neurobiological underpinnings of PIU remain understudied. This study examined whether adolescents displaying features of PIU (at-risk PIU; ARPIU) are more impulsive and exhibit blunted responding in the neural mechanisms underlying feedback processing and outcome evaluation during risk-taking. Event-related potentials (ERPs) elicited by positive (i.e. reward) and negative (i.e. loss) feedback were recorded during performance on a modified version of the Balloon Analogue Risk Task (BART) among ARPIU (n=39) and non-ARPIU subjects (n=27). Compared to non-ARPIU, ARPIU adolescents displayed higher levels of urgency and lack of perseverance on the UPPS Impulsive Behavior Scale. Although no between-group difference in BART performance was observed, ERPs demonstrated overall decreased sensitivity to feedback in ARPIU compared to non-ARPIU adolescents, as indexed by blunted feedback-related negativity (FRN) and P300 amplitudes to both negative and positive feedback. The present study provides evidence for feedback processing during risk-taking as a neural correlate of ARPIU. Given recent concerns regarding the growing prevalence of PIU as a health concern, future work should examine the extent to which feedback processing may represent a risk factor for PIU, a consequence of PIU, or possibly both. Copyright © 2015 Elsevier Ltd. All rights reserved.

Patterns and reliability of EEG during error monitoring for internal versus external feedback in schizophrenia.

PubMed

Llerena, Katiah; Wynn, Jonathan K; Hajcak, Greg; Green, Michael F; Horan, William P

2016-07-01

Accurately monitoring one's performance on daily life tasks, and integrating internal and external performance feedback are necessary for guiding productive behavior. Although internal feedback processing, as indexed by the error-related negativity (ERN), is consistently impaired in schizophrenia, initial findings suggest that external performance feedback processing, as indexed by the feedback negativity (FN), may actually be intact. The current study evaluated internal and external feedback processing task performance and test-retest reliability in schizophrenia. 92 schizophrenia outpatients and 63 healthy controls completed a flanker task (ERN) and a time estimation task (FN). Analyses examined the ΔERN and ΔFN defined as difference waves between correct/positive versus error/negative feedback conditions. A temporal principal component analysis was conducted to distinguish the ΔERN and ΔFN from overlapping neural responses. We also assessed test-retest reliability of ΔERN and ΔFN in patients over a 4-week interval. Patients showed reduced ΔERN accompanied by intact ΔFN. In patients, test-retest reliability for both ΔERN and ΔFN over a four-week period was fair to good. Individuals with schizophrenia show a pattern of impaired internal, but intact external, feedback processing. This pattern has implications for understanding the nature and neural correlates of impaired feedback processing in schizophrenia. Published by Elsevier B.V.

Transcription factor trapping by RNA in gene regulatory elements.

PubMed

Sigova, Alla A; Abraham, Brian J; Ji, Xiong; Molinie, Benoit; Hannett, Nancy M; Guo, Yang Eric; Jangi, Mohini; Giallourakis, Cosmas C; Sharp, Phillip A; Young, Richard A

2015-11-20

Transcription factors (TFs) bind specific sequences in promoter-proximal and -distal DNA elements to regulate gene transcription. RNA is transcribed from both of these DNA elements, and some DNA binding TFs bind RNA. Hence, RNA transcribed from regulatory elements may contribute to stable TF occupancy at these sites. We show that the ubiquitously expressed TF Yin-Yang 1 (YY1) binds to both gene regulatory elements and their associated RNA species across the entire genome. Reduced transcription of regulatory elements diminishes YY1 occupancy, whereas artificial tethering of RNA enhances YY1 occupancy at these elements. We propose that RNA makes a modest but important contribution to the maintenance of certain TFs at gene regulatory elements and suggest that transcription of regulatory elements produces a positive-feedback loop that contributes to the stability of gene expression programs. Copyright © 2015, American Association for the Advancement of Science.

Cloud Radiation Forcings and Feedbacks: General Circulation Model Tests and Observational Validation

NASA Technical Reports Server (NTRS)

Lee,Wan-Ho; Iacobellis, Sam F.; Somerville, Richard C. J.

1997-01-01

Using an atmospheric general circulation model (the National Center for Atmospheric Research Community Climate Model: CCM2), the effects on climate sensitivity of several different cloud radiation parameterizations have been investigated. In addition to the original cloud radiation scheme of CCM2, four parameterizations incorporating prognostic cloud water were tested: one version with prescribed cloud radiative properties and three other versions with interactive cloud radiative properties. The authors' numerical experiments employ perpetual July integrations driven by globally constant sea surface temperature forcings of two degrees, both positive and negative. A diagnostic radiation calculation has been applied to investigate the partial contributions of high, middle, and low cloud to the total cloud radiative forcing, as well as the contributions of water vapor, temperature, and cloud to the net climate feedback. The high cloud net radiative forcing is positive, and the middle and low cloud net radiative forcings are negative. The total net cloud forcing is negative in all of the model versions. The effect of interactive cloud radiative properties on global climate sensitivity is significant. The net cloud radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive cloud radiative properties and the schemes with specified properties. The increase in cloud water content in the warmer climate leads to optically thicker middle- and low-level clouds and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in cloud amount simply produces a positive shortwave feedback for the schemes with a specified cloud water path. For the longwave feedbacks, the decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while for the other cases, the longwave feedback is positive. These cloud radiation

The Impact of Teacher Feedback on Student Self-Talk and Self-Concept in Reading and Mathematics.

ERIC Educational Resources Information Center

Burnett, Paul C.

2003-01-01

Investigated the relationships between teacher feedback and students' self-talk and self-concepts in mathematics and reading. Data collected from students in six rural Australian elementary schools indicated that self-talk (positive and negative) mediated between subject-specific teacher feedback (ability, effort, and negative) and academic…

Regulated provider perceptions of feedback reports.

PubMed

O'Rourke, Hannah M; Fraser, Kimberly D; Boström, Anne-Marie; Baylon, Melba Andrea B; Sales, Anne E

2013-11-01

This paper reports on regulated (or licensed) care providers' understanding and perceptions of feedback reports in a sample of Canadian long-term care settings using a cross-sectional survey design. Audit with feedback quality improvement studies have seldom targeted front-line providers in long-term care to receive feedback information. Feedback reports were delivered to front-line regulated care providers in four long-term care facilities for 13 months in 2009-10. Providers completed a postfeedback survey. Most (78%) regulated care providers (n = 126) understood the reports and felt they provided useful information for making changes to resident care (64%). Perceptions of the report differed, depending on the role of the regulated care provider. In multivariable logistic regression, the regulated nurses' understanding of more than half the report was negatively associated with 'usefulness of information for changing resident care', and perceiving the report as generally useful had a positive association. Front-line regulated providers are an appropriate target for feedback reports in long-term care. Long-term care administrators should share unit-level information on care quality with unit-level managers and other professional front-line direct care providers. © 2013 John Wiley & Sons Ltd.

Plant-soil feedbacks and mycorrhizal type influence temperate forest population dynamics

USDA-ARS?s Scientific Manuscript database

Feedback with soil biota is a major driver of diversity within terrestrial plant communities. However, little is known about the factors regulating plant-soil feedback, which can vary from positive to negative among plant species. In a large-scale observational and experimental study involving 55 sp...

When compliments do not hit but critiques do: an fMRI study into self-esteem and self-knowledge in processing social feedback

PubMed Central

van Schie, Charlotte C; Chiu, Chui-De; Rombouts, Serge A R B; Heiser, Willem J; Elzinga, Bernet M

2018-01-01

Abstract The way we view ourselves may play an important role in our responses to interpersonal interactions. In this study, we investigate how feedback valence, consistency of feedback with self-knowledge and global self-esteem influence affective and neural responses to social feedback. Participants (N = 46) with a high range of self-esteem levels performed the social feedback task in an MRI scanner. Negative, intermediate and positive feedback was provided, supposedly by another person based on a personal interview. Participants rated their mood and applicability of feedback to the self. Analyses on trial basis on neural and affective responses are used to incorporate applicability of individual feedback words. Lower self-esteem related to low mood especially after receiving non-applicable negative feedback. Higher self-esteem related to increased posterior cingulate cortex and precuneus activation (i.e. self-referential processing) for applicable negative feedback. Lower self-esteem related to decreased medial prefrontal cortex, insula, anterior cingulate cortex and posterior cingulate cortex activation (i.e. self-referential processing) during positive feedback and decreased temporoparietal junction activation (i.e. other referential processing) for applicable positive feedback. Self-esteem and consistency of feedback with self-knowledge appear to guide our affective and neural responses to social feedback. This may be highly relevant for the interpersonal problems that individuals face with low self-esteem and negative self-views. PMID:29490088

Feedback coupling in dynamical systems

NASA Astrophysics Data System (ADS)

Trimper, Steffen; Zabrocki, Knud

2003-05-01

Different evolution models are considered with feedback-couplings. In particular, we study the Lotka-Volterra system under the influence of a cumulative term, the Ginzburg-Landau model with a convolution memory term and chemical rate equations with time delay. The memory leads to a modified dynamical behavior. In case of a positive coupling the generalized Lotka-Volterra system exhibits a maximum gain achieved after a finite time, but the population will die out in the long time limit. In the opposite case, the time evolution is terminated in a crash. Due to the nonlinear feedback coupling the two branches of a bistable model are controlled by the the strength and the sign of the memory. For a negative coupling the system is able to switch over between both branches of the stationary solution. The dynamics of the system is further controlled by the initial condition. The diffusion-limited reaction is likewise studied in case the reacting entities are not available simultaneously. Whereas for an external feedback the dynamics is altered, but the stationary solution remain unchanged, a self-organized internal feedback leads to a time persistent solution.

The challenge of giving written thesis feedback to nursing students.

PubMed

Tuvesson, Hanna; Borglin, Gunilla

2014-11-01

Providing effective written feedback on nursing student's assignments can be a challenging task for any assessor. Additionally, as the student groups tend to become larger, written feedback is likely to gain an overall more prominent position than verbal feedback. Lack of formal training or regular discussion in the teaching faculty about the skill set needed to provide written feedback could negatively affect the students' learning abilities. In this brief paper, we discuss written feedback practices, whilst using the Bachelor of Science in Nursing thesis as an example. Our aim is to highlight the importance of an informed understanding of the impact written feedback can have on students. Creating awareness about this can facilitate the development of more strategic and successful written feedback strategies. We end by offering examples of some relatively simple strategies for improving this practice. Copyright © 2014 Elsevier Ltd. All rights reserved.

Appearance feedback in intimate relationships: the role of self-verification and self-enhancement.

PubMed

Brown, Jennifer N; Stukas, Arthur A; Evans, Lynette

2013-01-01

To better understand how body image operates within the context of intimate relationships, we investigated women's responses to appearance feedback from an intimate partner. Participants (N=192) imagined receiving feedback from their partner that was either consistent with their own appearance self-view (i.e., self-verifying), more positive (i.e., self-enhancing), or less positive (i.e., devaluing), and then provided their affective and cognitive reactions. As expected, women's perceptions of their own appearance moderated their reactions. Women with more negative self-views felt happier with enhancing feedback, but thought that it meant their partner understood them less well. They also felt less happy when they received verifying feedback, but felt more understood by their partners. Thus, women with body image dissatisfaction may find themselves stuck in the "cognitive-affective crossfire" reacting ambivalently whether their partner enhances their appearance or confirms their negative self-views. Further examination of partners' actual feedback is needed. Copyright © 2012 Elsevier Ltd. All rights reserved.

A conceptual framework for regional feedbacks in a changing climate

NASA Astrophysics Data System (ADS)

Batlle Bayer, L.; van den Hurk, B. J. J. M.; Strengers, B.

2012-04-01

Terrestrial ecosystems and climate influence each other through biogeochemical (e.g. carbon cycle) and biogeophysical (e.g. albedo, water fluxes) processes. These interactions might be disturbed when a climate human-induced forcing takes place (e.g. deforestation); and the ecosystem responses to the climate system might amplify (positive feedback) or dampen (negative feedback) the initial forcing. Research on feedbacks has been mainly based on the carbon cycle at the global scale. However, biogeophysical feedbacks might have a great impact at the local or regional scale, which is the main focus of this article. A conceptual framework, with the major interactions and processes between terrestrial ecosystems and climate, is presented to further explore feedbacks at the regional level. Four hot spots with potential changes in land use/management and climate are selected: sub-Saharan Africa (SSA), Europe, the Amazon Basin and South and Southeast Asia. For each region, diverse climate human-induced forcings and feedbacks were identified based on relevant published literature. For Europe, the positive soil moisture-evapotranspiration (ET) is important for natural vegetation during a heat wave event, while the positive soil moisture-precipitation feedback plays a more important role for droughts in the Amazon region. Agricultural expansion in SSA will depend on the impacts of the changing climate on crop yields and the adopted agro-technologies. The adoption of irrigation in the commonly rainfed systems might turn the positive soil moisture- ET feedback into a negative one. In contrast, South and Southeast Asia might face water shortage in the future, and thus turning the soil moisture-ET feedback into a positive one. Further research is needed for the major processes that affect the ultimate sign of the feedbacks, as well as for the interactions, which effect remains uncertain, such as ET-precipitation interaction. In addition, socio-economic feedbacks need to be added

Children’s Feedback Preferences in Response to an Experimentally Manipulated Peer Evaluation Outcome: The Role of Depressive Symptoms

PubMed Central

Dekovic, Maja; Vermande, Marjolijn; Telch, Michael J.

2007-01-01

The present study examined the linkage between pre-adolescent children’s depressive symptoms and their preferences for receiving positive vs. negative feedback subsequent to being faced with an experimentally manipulated peer evaluation outcome in real time. Participants (n = 142) ages 10 to 13, played a computer contest based on the television show Survivor and were randomized to either a peer rejection (i.e., receiving the lowest total ‘likeability’ score from a group of peer-judges), a peer success (i.e., receiving the highest score), or a control peer evaluation condition. Children’s self-reported feedback preferences were then assessed. Results revealed that participants assigned to the negative evaluation outcome, relative to either the success or the control outcome, showed a significantly higher subsequent preference for negatively tuned feedback. Contrary to previous work and predictions derived from self-verification theory, children higher in depressive symptoms were only more likely to prefer negative feedback in response to the negative peer evaluation outcome. These effects for depression were not accounted for by either state mood at baseline or mood change in response to the feedback manipulation. PMID:17279340

Social closeness and feedback modulate susceptibility to the framing effect.

PubMed

Sip, Kamila E; Smith, David V; Porcelli, Anthony J; Kar, Kohitij; Delgado, Mauricio R

2015-01-01

Although we often seek social feedback (SFB) from others to help us make decisions, little is known about how SFB affects decisions under risk, particularly from a close peer. We conducted two experiments using an established framing task to probe how decision-making is modulated by SFB valence (positive, negative) and the level of closeness with feedback provider (friend, confederate). Participants faced mathematically equivalent decisions framed as either an opportunity to keep (gain frame) or lose (loss frame) part of an initial endowment. Periodically, participants were provided with positive (e.g., "Nice!") or negative (e.g., "Lame!") feedback about their choices. Such feedback was provided by either a confederate (Experiment 1) or a gender-matched close friend (Experiment 2). As expected, the framing effect was observed in both experiments. Critically, an individual's susceptibility to the framing effect was modulated by the valence of the SFB, but only when the feedback provider was a close friend. This effect was reflected in the activation patterns of ventromedial prefrontal cortex and posterior cingulate cortex, regions involved in complex decision-making. Taken together, these results highlight social closeness as an important factor in understanding the impact of SFB on neural mechanisms of decision-making.

OncomiR Addiction Is Generated by a miR-155 Feedback Loop in Theileria-Transformed Leukocytes

PubMed Central

Medjkane, Souhila; Perichon, Martine; Yin, Qinyan; Flemington, Erik; Weitzman, Matthew D.; Weitzman, Jonathan B.

2013-01-01

The intracellular parasite Theileria is the only eukaryote known to transform its mammalian host cells. We investigated the host mechanisms involved in parasite-induced transformation phenotypes. Tumour progression is a multistep process, yet ‘oncogene addiction’ implies that cancer cell growth and survival can be impaired by inactivating a single gene, offering a rationale for targeted molecular therapies. Furthermore, feedback loops often act as key regulatory hubs in tumorigenesis. We searched for microRNAs involved in addiction to regulatory loops in leukocytes infected with Theileria parasites. We show that Theileria transformation involves induction of the host bovine oncomiR miR-155, via the c-Jun transcription factor and AP-1 activity. We identified a novel miR-155 target, DET1, an evolutionarily-conserved factor involved in c-Jun ubiquitination. We show that miR-155 expression led to repression of DET1 protein, causing stabilization of c-Jun and driving the promoter activity of the BIC transcript containing miR-155. This positive feedback loop is critical to maintain the growth and survival of Theileria-infected leukocytes; transformation is reversed by inhibiting AP-1 activity or miR-155 expression. This is the first demonstration that Theileria parasites induce the expression of host non-coding RNAs and highlights the importance of a novel feedback loop in maintaining the proliferative phenotypes induced upon parasite infection. Hence, parasite infection drives epigenetic rewiring of the regulatory circuitry of host leukocytes, placing miR-155 at the crossroads between infection, regulatory circuits and transformation. PMID:23637592

Systematic comparison of the response properties of protein and RNA mediated gene regulatory motifs.

PubMed

Iyengar, Bharat Ravi; Pillai, Beena; Venkatesh, K V; Gadgil, Chetan J

2017-05-30

We present a framework enabling the dissection of the effects of motif structure (feedback or feedforward), the nature of the controller (RNA or protein), and the regulation mode (transcriptional, post-transcriptional or translational) on the response to a step change in the input. We have used a common model framework for gene expression where both motif structures have an activating input and repressing regulator, with the same set of parameters, to enable a comparison of the responses. We studied the global sensitivity of the system properties, such as steady-state gain, overshoot, peak time, and peak duration, to parameters. We find that, in all motifs, overshoot correlated negatively whereas peak duration varied concavely with peak time. Differences in the other system properties were found to be mainly dependent on the nature of the controller rather than the motif structure. Protein mediated motifs showed a higher degree of adaptation i.e. a tendency to return to baseline levels; in particular, feedforward motifs exhibited perfect adaptation. RNA mediated motifs had a mild regulatory effect; they also exhibited a lower peaking tendency and mean overshoot. Protein mediated feedforward motifs showed higher overshoot and lower peak time compared to the corresponding feedback motifs.

Random Feedback Makes Listeners Tone-Deaf.

PubMed

Vuvan, Dominique T; Zendel, Benjamin Rich; Peretz, Isabelle

2018-05-08

The mental representation of pitch structure (tonal knowledge) is a core component of musical experience and is learned implicitly through exposure to music. One theory of congenital amusia (tone deafness) posits that conscious access to tonal knowledge is disrupted, leading to a severe deficit of music cognition. We tested this idea by providing random performance feedback to neurotypical listeners while they listened to melodies for tonal incongruities and had their electrical brain activity monitored. The introduction of random feedback was associated with a reduction of accuracy and confidence, and a suppression of the late positive brain response usually elicited by conscious detection of a tonal violation. These effects mirror the behavioural and neurophysiological profile of amusia. In contrast, random feedback was associated with an increase in the amplitude of the early right anterior negativity, possibly due to heightened attention to the experimental task. This successful simulation of amusia in a normal brain highlights the key role of feedback in learning, and thereby provides a new avenue for the rehabilitation of learning disorders.

Cardiac and electro-cortical concomitants of social feedback processing in women

PubMed Central

van der Molen, Melle J. W.; Gunther Moor, Bregtje; van der Veen, Frederik M.; van der Molen, Maurits W.

2015-01-01

This study provides a joint analysis of the cardiac and electro-cortical—early and late P3 and feedback-related negativity (FRN)—responses to social acceptance and rejection feedback. Twenty-five female participants performed on a social- and age-judgment control task, in which they received feedback with respect to their liking and age judgments, respectively. Consistent with previous reports, results revealed transient cardiac slowing to be selectively prolonged to unexpected social rejection feedback. Late P3 amplitude was more pronounced to unexpected relative to expected feedback. Both early and late P3 amplitudes were shown to be context dependent, in that they were more pronounced to social as compared with non-social feedback. FRN amplitudes were more pronounced to unexpected relative to expected feedback, irrespective of context and feedback valence. This pattern of findings indicates that social acceptance and rejection feedback have widespread effects on bodily state and brain function, which are modulated by prior expectancies. PMID:25870439

Evaluative-feedback stimuli selectively activate the self-related brain area: an fMRI study.

PubMed

Pan, Xiaohong; Hu, Yang; Li, Lei; Li, Jianqi

2009-11-06

Evaluative-feedback, occurring in our daily life, generally contains subjective appraisal of one's specific abilities and personality characteristics besides objective right-or-wrong information. Traditional psychological researches have proved it to be important in building up one's self-concept; however, the neural basis underlying its cognitive processing remains unclear. The present neuroimaging study revealed the mechanism of evaluative-feedback processing at the neural level. 19 healthy Chinese subjects participated in this experiment, and completed the time-estimation task to better their performance according to four types of feedback, namely positive evaluative- and performance-feedback as well as negative evaluative- and performance-feedback. Neuroimaging findings showed that evaluative- rather than performance-feedback can induce increased activities mainly distributed in the cortical midline structures (CMS), including medial prefrontal cortex (BA 8/9)/anterior cigulate cortex (ACC, BA 20), precuneus (BA 7/31) adjacent to posterior cingulate gyrus (PCC, BA 23) of both hemispheres, as well as right inferior lobule (BA 40). This phenomenon can provide evidence that evaluative-feedback may significantly elicit the self-related processing in our brain. In addition, our results also revealed that more brain areas, particularly some self-related neural substrates were activated by the positive evaluative-feedback, in comparative with the negative one. In sum, this study suggested that evaluative-feedback was closely correlated with the self-concept processing, which distinguished it from the performance-feedback.

Perspectives on Regulatory T Cell Therapies

PubMed Central

Probst-Kepper, Michael; Kröger, Andrea; Garritsen, Henk S.P.; Buer, Jan

2009-01-01

Summary Adoptive transfer in animal models clearly indicate an essential role of CD4+ CD25+ FOXP3+ regulatory T (Treg) cells in prevention and treatment of autoimmune and graft-versus-host disease. Thus, Treg cell therapies and development of drugs that specifically enhance Treg cell function and development represent promising tools to establish dominant tolerance. So far, lack of specific markers to differentiate human Treg cells from activated CD4+ CD25+ effector T cells, which also express FOXP3 at different levels, hampered such an approach. Recent identification of the orphan receptor glycoprotein-A repetitions predominant (GARP or LRRC32) as Treg cell-specific key molecule that dominantly controls FOXP3 via a positive feedback loop opens up new perspectives for molecular and cellular therapies. This brief review focuses on the role of GARP as a safeguard of a complex regulatory network of human Treg cells and its implications for regulatory T cell therapies in autoimmunity and graft-versus-host disease. PMID:21076548

CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

NASA Technical Reports Server (NTRS)

Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter N.; Austin, Phillip H.; Bacmeister, Julio T.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; DelGenio, Anthony;

A feedback regulatory model for RifQ-mediated repression of rifamycin export in Amycolatopsis mediterranei.

PubMed

Lei, Chao; Wang, Jingzhi; Liu, Yuanyuan; Liu, Xinqiang; Zhao, Guoping; Wang, Jin

2018-01-29

Due to the important role of rifamycin in curing tuberculosis infection, the study on rifamycin has never been stopped. Although RifZ, which locates within the rifamycin biosynthetic cluster, has recently been characterized as a pathway-specific regulator for rifamycin biosynthesis, little is known about the regulation of rifamycin export. In this work, we proved that the expression of the rifamycin efflux pump (RifP) was regulated by RifQ, a TetR-family transcriptional regulator. Deletion of rifQ had little impact on bacterial growth, but resulted in improved rifamycin production, which was consistent with the reverse transcription PCR results that RifQ negatively regulated rifP's transcription. With electrophoretic mobility shift assay and DNase I Footprinting assay, RifQ was found to directly bind to the promoter region of rifP, and a typical inverted repeat was identified within the RifQ-protected sequences. The transcription initiation site of rifP was further characterized and found to be upstream of the RifQ binding sites, well explaining the RifQ-mediated repression of rifP's transcription in vivo. Moreover, rifamycin B (the end product of rifamycin biosynthesis) remarkably decreased the DNA binding affinity of RifQ, which led to derepression of rifamycin export, reducing the intracellular concentration of rifamycin B as well as its toxicity against the host. Here, we proved that the export of rifamycin B was repressed by RifQ in Amycolatopsis mediterranei, and the RifQ-mediated repression could be specifically relieved by rifamycin B, the end product of rifamycin biosynthesis, based on which a feedback model was proposed for regulation of rifamycin export. With the findings here, one could improve the antibiotic yield by simply inactivating the negative regulator of the antibiotic transporter.

Strong feedback limit of the Goodwin circadian oscillator

NASA Astrophysics Data System (ADS)

Woller, Aurore; Gonze, Didier; Erneux, Thomas

2013-03-01

The three-variable Goodwin model constitutes a prototypical oscillator based on a negative feedback loop. It was used as a minimal model for circadian oscillations. Other core models for circadian clocks are variants of the Goodwin model. The Goodwin oscillator also appears in many studies of coupled oscillator networks because of its relative simplicity compared to other biophysical models involving a large number of variables and parameters. Because the synchronization properties of Goodwin oscillators still remain difficult to explore mathematically, further simplifications of the Goodwin model have been sought. In this paper, we investigate the strong negative feedback limit of Goodwin equations by using asymptotic techniques. We find that Goodwin oscillations approach a sequence of decaying exponentials that can be described in terms of a single-variable leaky integrated-and-fire model.

Multisite Light-Induced Phosphorylation of the Transcription Factor PIF3 Is Necessary for Both Its Rapid Degradation and Concomitant Negative Feedback Modulation of Photoreceptor phyB Levels in Arabidopsis[C][W

PubMed Central

Ni, Weimin; Xu, Shou-Ling; Chalkley, Robert J.; Pham, Thao Nguyen D.; Guan, Shenheng; Maltby, Dave A.; Burlingame, Alma L.; Wang, Zhi-Yong; Quail, Peter H.

2013-01-01

Plants constantly monitor informational light signals using sensory photoreceptors, which include the phytochrome (phy) family (phyA to phyE), and adjust their growth and development accordingly. Following light-induced nuclear translocation, photoactivated phy molecules bind to and induce rapid phosphorylation and degradation of phy-interacting basic Helix Loop Helix (bHLH) transcription factors (PIFs), such as PIF3, thereby regulating the expression of target genes. However, the mechanisms underlying the signal-relay process are still not fully understood. Here, using mass spectrometry, we identify multiple, in vivo, light-induced Ser/Thr phosphorylation sites in PIF3. Using transgenic expression of site-directed mutants of PIF3, we provide evidence that a set of these phosphorylation events acts collectively to trigger rapid degradation of the PIF3 protein in response to initial exposure of dark-grown seedlings to light. In addition, we show that phyB-induced PIF3 phosphorylation is also required for the known negative feedback modulation of phyB levels in prolonged light, potentially through codegradation of phyB and PIF3. This mutually regulatory intermolecular transaction thus provides a mechanism with the dual capacity to promote early, graded, or threshold regulation of the primary, PIF3-controlled transcriptional network in response to initial light exposure, and later, to attenuate global sensitivity to the light signal through reductions in photoreceptor levels upon prolonged exposure. PMID:23903316

Follower-Centered Perspective on Feedback: Effects of Feedback Seeking on Identification and Feedback Environment.

PubMed

Gong, Zhenxing; Li, Miaomiao; Qi, Yaoyuan; Zhang, Na

2017-01-01

In the formation mechanism of the feedback environment, the existing research pays attention to external feedback sources and regards individuals as objects passively accepting feedback. Thus, the external source fails to realize the individuals' need for feedback, and the feedback environment cannot provide them with useful information, leading to a feedback vacuum. The aim of this study is to examine the effect of feedback-seeking by different strategies on the supervisor-feedback environment through supervisor identification. The article consists of an empirical study with a sample of 264 employees in China; here, participants complete a series of questionnaires in three waves. After controlling for the effects of demography, the results indicate that supervisor identification partially mediates the relationship between feedback-seeking (including feedback monitoring and feedback inquiry) and the supervisor-feedback environment. Implications are also discussed.

Follower-Centered Perspective on Feedback: Effects of Feedback Seeking on Identification and Feedback Environment

PubMed Central

Gong, Zhenxing; Li, Miaomiao; Qi, Yaoyuan; Zhang, Na

2017-01-01

In the formation mechanism of the feedback environment, the existing research pays attention to external feedback sources and regards individuals as objects passively accepting feedback. Thus, the external source fails to realize the individuals’ need for feedback, and the feedback environment cannot provide them with useful information, leading to a feedback vacuum. The aim of this study is to examine the effect of feedback-seeking by different strategies on the supervisor-feedback environment through supervisor identification. The article consists of an empirical study with a sample of 264 employees in China; here, participants complete a series of questionnaires in three waves. After controlling for the effects of demography, the results indicate that supervisor identification partially mediates the relationship between feedback-seeking (including feedback monitoring and feedback inquiry) and the supervisor-feedback environment. Implications are also discussed. PMID:28919872

Improving Prompt Temperature Feedback by Stimulating Doppler Broadening in Heterogeneous Composite Nuclear Fuel Forms

NASA Astrophysics Data System (ADS)

Morrison, Christopher

Nuclear fuels with similar aggregate material composition, but with different millimeter and micrometer spatial configurations of the component materials can have very different safety and performance characteristics. This research focuses on modeling and attempting to engineer heterogeneous combinations of nuclear fuels to improve negative prompt temperature feedback in response to reactivity insertion accidents. Improvements in negative prompt temperature feedback are proposed by developing a tailored thermal resistance in the nuclear fuel. In the event of a large reactivity insertion, the thermal resistance allows for a faster negative Doppler feedback by temporarily trapping heat in material zones with strong absorption resonances. A multi-physics simulation framework was created that could model large reactivity insertions. The framework was then used to model a comparison of a heterogeneous fuel with a tailored thermal resistance and a homogeneous fuel without the tailored thermal resistance. The results from the analysis confirmed the fundamental premise of prompt temperature feedback and provide insights into the neutron spectrum dynamics throughout the transient process. A trade study was conducted on infinite lattice fuels to help map a design space to study and improve prompt temperature feedback with many results. A multi-scale fuel pin analysis was also completed to study more realistic geometries. The results of this research could someday allow for novel nuclear fuels that would behave differently than current fuels. The idea of having a thermal barrier coating in the fuel is contrary to most current thinking. Inherent resistance to reactivity insertion accidents could enable certain reactor types once considered vulnerable to reactivity insertion accidents to be reevaluated in light of improved negative prompt temperature feedback.

The role of constructive feedback in patient safety and continuous quality improvement.

PubMed

Altmiller, Gerry

2012-09-01

Constructive feedback is essential for personal and professional growth. It is an integral part of continuous quality improvement and essential in maintaining patient safety in the clinical environment. The perception of feedback can interfere with professionals giving and receiving feedback, which can have negative consequences on patient outcomes. Delivering and receiving feedback effectively are learned skills that should be introduced early in prelicensure education. Faculty have the opportunity to influence the perception of feedback to be viewed as an opportunity so that students can learn to appreciate its value in maintaining patient safety and high-quality care in clinical practice. Copyright © 2012 Elsevier Inc. All rights reserved.

Identification of potential crucial genes and construction of microRNA-mRNA negative regulatory networks in osteosarcoma.

PubMed

Pan, Yue; Lu, Lingyun; Chen, Junquan; Zhong, Yong; Dai, Zhehao

2018-01-01

This study aimed to identify potential crucial genes and construction of microRNA-mRNA negative regulatory networks in osteosarcoma by comprehensive bioinformatics analysis. Data of gene expression profiles (GSE28424) and miRNA expression profiles (GSE28423) were downloaded from GEO database. The differentially expressed genes (DEGs) and miRNAs (DEMIs) were obtained by R Bioconductor packages. Functional and enrichment analyses of selected genes were performed using DAVID database. Protein-protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape. The relationships among the DEGs and module in PPI network were analyzed by plug-in NetworkAnalyzer and MCODE seperately. Through the TargetScan and comparing target genes with DEGs, the miRNA-mRNA regulation network was established. Totally 346 DEGs and 90 DEMIs were found to be differentially expressed. These DEGs were enriched in biological processes and KEGG pathway of inflammatory immune response. 25 genes in the PPI network were selected as hub genes. Top 10 hub genes were TYROBP, HLA-DRA, VWF, PPBP, SERPING1, HLA-DPA1, SERPINA1, KIF20A, FERMT3, HLA-E. PPI network of DEGs followed a pattern of power law network and met the characteristics of small-world network. MCODE analysis identified 4 clusters and the most significant cluster consisted of 11 nodes and 55 edges. SEPP1, CKS2, TCAP, BPI were identified as the seed genes in their own clusters, respectively. The miRNA-mRNA regulation network which was composed of 89 pairs was established. MiR-210 had the highest connectivity with 12 target genes. Among the predicted target of MiR-96, HLA-DPA1 and TYROBP were the hub genes. Our study indicated possible differentially expressed genes and miRNA, and microRNA-mRNA negative regulatory networks in osteosarcoma by bioinformatics analysis, which may provide novel insights for unraveling pathogenesis of osteosarcoma.

Feedback, Lineages and Self-Organizing Morphogenesis

PubMed Central

Calof, Anne L.; Lowengrub, John S.; Lander, Arthur D.

2016-01-01

Feedback regulation of cell lineage progression plays an important role in tissue size homeostasis, but whether such feedback also plays an important role in tissue morphogenesis has yet to be explored. Here we use mathematical modeling to show that a particular feedback architecture in which both positive and negative diffusible signals act on stem and/or progenitor cells leads to the appearance of bistable or bi-modal growth behaviors, ultrasensitivity to external growth cues, local growth-driven budding, self-sustaining elongation, and the triggering of self-organization in the form of lamellar fingers. Such behaviors arise not through regulation of cell cycle speeds, but through the control of stem or progenitor self-renewal. Even though the spatial patterns that arise in this setting are the result of interactions between diffusible factors with antagonistic effects, morphogenesis is not the consequence of Turing-type instabilities. PMID:26989903

From feedback- to response-based performance monitoring in active and observational learning.

PubMed

Bellebaum, Christian; Colosio, Marco

2014-09-01

Humans can adapt their behavior by learning from the consequences of their own actions or by observing others. Gradual active learning of action-outcome contingencies is accompanied by a shift from feedback- to response-based performance monitoring. This shift is reflected by complementary learning-related changes of two ACC-driven ERP components, the feedback-related negativity (FRN) and the error-related negativity (ERN), which have both been suggested to signal events "worse than expected," that is, a negative prediction error. Although recent research has identified comparable components for observed behavior and outcomes (observational ERN and FRN), it is as yet unknown, whether these components are similarly modulated by prediction errors and thus also reflect behavioral adaptation. In this study, two groups of 15 participants learned action-outcome contingencies either actively or by observation. In active learners, FRN amplitude for negative feedback decreased and ERN amplitude in response to erroneous actions increased with learning, whereas observational ERN and FRN in observational learners did not exhibit learning-related changes. Learning performance, assessed in test trials without feedback, was comparable between groups, as was the ERN following actively performed errors during test trials. In summary, the results show that action-outcome associations can be learned similarly well actively and by observation. The mechanisms involved appear to differ, with the FRN in active learning reflecting the integration of information about own actions and the accompanying outcomes.

Influence of the feedback loops in the trp operon of B. subtilis on the system dynamic response and noise amplitude.

PubMed

Zamora-Chimal, Criseida; Santillán, Moisés; Rodríguez-González, Jesús

2012-10-07

In this paper we introduce a mathematical model for the tryptophan operon regulatory pathway in Bacillus subtilis. This model considers the transcription-attenuation, and the enzyme-inhibition regulatory mechanisms. Special attention is paid to the estimation of all the model parameters from reported experimental data. With the aid of this model we investigate, from a mathematical-modeling point of view, whether the existing multiplicity of regulatory feedback loops is advantageous in some sense, regarding the dynamic response and the biochemical noise in the system. The tryptophan operon dynamic behavior is studied by means of deterministic numeric simulations, while the biochemical noise is analyzed with the aid of stochastic simulations. The model feasibility is tested comparing its stochastic and deterministic results with experimental reports. Our results for the wildtype and for a couple of mutant bacterial strains suggest that the enzyme-inhibition feedback loop, dynamically accelerates the operon response, and plays a major role in the reduction of biochemical noise. Also, the transcription-attenuation feedback loop makes the trp operon sensitive to changes in the endogenous tryptophan level, and increases the amplitude of the biochemical noise. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of Video Feedback on Early Coercive Parent–Child Interactions: The Intervening Role of Caregivers’ Relational Schemas

PubMed Central

Smith, Justin D.; Dishion, Thomas J.; Moore, Kevin J.; Shaw, Daniel S.; Wilson, Melvin N.

2013-01-01

Objective We examined the effect of adding a video feedback intervention component to the assessment feedback session of the Family Check-Up intervention (FCU; Dishion & Stormshak, 2007). We hypothesized that the addition of video feedback procedures during the FCU feedback at child age 2 would have a positive effect on caregivers’ negative relational schemas of their child, which in turn would mediate reductions in observed coercive caregiver-child interactions assessed at age 5. Method We observed the caregiver-child interaction videotapes of 79 high-risk families with toddlers exhibiting clinically significant problem behaviors. A quasi-random sample of families were provided with direct feedback on their interactions during the feedback session of the FCU protocol. Results Path analysis indicated that reviewing and engaging in feedback about videotaped age-2 assessment predicted reduced caregivers’ negative relational schemas of the child at age 3, which acted as an intervening variable on the reduction of observed parent–child coercive interactions recorded at age 5. Video feedback predicted improved family functioning over and above level of engagement in the FCU in subsequent years, indicating the important incremental contribution of using video feedback procedures in early family-based preventive interventions for problem behaviors. Conclusions Supportive video feedback on coercive family dynamics is an important strategy for promoting caregiver motivation to reduce negative attributions toward the child, which fuel coercive interactions. Our study also contributes to the clinical and research literature concerning coercion theory and effective intervention strategies by identifying a potential mechanism of change. PMID:23534831

Reducing failures of working memory with performance feedback.

PubMed

Adam, Kirsten C S; Vogel, Edward K

2016-10-01

Fluctuations in attentional control can lead to failures of working memory (WM), in which the subject is no better than chance at reporting items from a recent display. In three experiments, we used a whole-report measure of visual WM to examine the impact of feedback on the rate of failures. In each experiment, subjects remembered an array of colored items across a blank delay, and then reported the identity of items using a whole-report procedure. In Experiment 1, we gave subjects simple feedback about the number of items they correctly identified at the end of each trial. In Experiment 2, we gave subjects additional information about the cumulative number of items correctly identified within each block. Finally, in Experiment 3, we gave subjects weighted feedback in which poor trials resulted in lost points and consistent successful performance received "streak" points. Surprisingly, simple feedback (Exp. 1) was ineffective at improving average performance or decreasing the rate of poor-performance trials. Simple cumulative feedback (Exp. 2) modestly decreased poor-performance trials (by 7 %). Weighted feedback produced the greatest benefits, decreasing the frequency of poor-performance trials by 28 % relative to baseline performance. This set of results demonstrates the usefulness of whole-report WM measures for investigating the effects of feedback on WM performance. Further, we showed that only a feedback structure that specifically discouraged lapses using negative feedback led to large reductions in WM failures.

Prolonged exposure to 1,25(OH)2D3 and high ionized calcium induces FGF-23 production in intestinal epithelium-like Caco-2 monolayer: A local negative feedback for preventing excessive calcium transport.

PubMed

Rodrat, Mayuree; Wongdee, Kannikar; Panupinthu, Nattapon; Thongbunchoo, Jirawan; Teerapornpuntakit, Jarinthorn; Krishnamra, Nateetip; Charoenphandhu, Narattaphol

2018-02-15

Overdose of oral calcium supplement and excessive intestinal calcium absorption can contribute pathophysiological conditions, e.g., nephrolithiasis, vascular calcification, dementia, and cardiovascular accident. Since our previous investigation has indicated that fibroblast growth factor (FGF)-23 could abolish the 1,25-dihydroxyvitamin D 3 [1,25(OH) 2 D 3 ]-enhanced calcium absorption, we further hypothesized that FGF-23 produced locally in the enterocytes might be part of a local negative feedback loop to regulate calcium absorption. Herein, 1,25(OH) 2 D 3 was found to enhance the transcellular calcium transport across the epithelium-like Caco-2 monolayer, and this stimulatory effect was diminished by preceding prolonged exposure to high-dose 1,25(OH) 2 D 3 or high concentration of apical ionized calcium. Pretreatment with a neutralizing antibody for FGF-23 prevented this negative feedback regulation of calcium hyperabsorption induced by 1,25(OH) 2 D 3 . FGF-23 exposure completely abolished the 1,25(OH) 2 D 3 -enhanced calcium transport. Western blot analysis revealed that FGF-23 expression was upregulated in a dose-dependent manner by 1,25(OH) 2 D 3 or apical calcium exposure. Finally, calcium-sensing receptor (CaSR) inhibitors were found to prevent the apical calcium-induced suppression of calcium transport. In conclusion, prolonged exposure to high apical calcium and calcium hyperabsorption were sensed by CaSR, which, in turn, increased FGF-23 expression to suppress calcium transport. This local negative feedback loop can help prevent unnecessary calcium uptake and its detrimental consequences. Copyright © 2018 Elsevier Inc. All rights reserved.

Self-evaluation and peer-feedback of medical students' communication skills using a web-based video annotation system. Exploring content and specificity.

PubMed

Hulsman, Robert L; van der Vloodt, Jane

2015-03-01

Self-evaluation and peer-feedback are important strategies within the reflective practice paradigm for the development and maintenance of professional competencies like medical communication. Characteristics of the self-evaluation and peer-feedback annotations of medical students' video recorded communication skills were analyzed. Twenty-five year 4 medical students recorded history-taking consultations with a simulated patient, uploaded the video to a web-based platform, marked and annotated positive and negative events. Peers reviewed the video and self-evaluations and provided feedback. Analyzed were the number of marked positive and negative annotations and the amount of text entered. Topics and specificity of the annotations were coded and analyzed qualitatively. Students annotated on average more negative than positive events. Additional peer-feedback was more often positive. Topics most often related to structuring the consultation. Students were most critical about their biomedical topics. Negative annotations were more specific than positive annotations. Self-evaluations were more specific than peer-feedback and both show a significant correlation. Four response patterns were detected that negatively bias specificity assessment ratings. Teaching students to be more specific in their self-evaluations may be effective for receiving more specific peer-feedback. Videofragmentrating is a convenient tool to implement reflective practice activities like self-evaluation and peer-feedback to the classroom in the teaching of clinical skills. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Effects of Video Feedback on Early Coercive Parent-Child Interactions: The Intervening Role of Caregivers' Relational Schemas

ERIC Educational Resources Information Center

Smith, Justin D.; Dishion, Thomas J.; Moore, Kevin J.; Shaw, Daniel S.; Wilson, Melvin N.

2013-01-01

We examined the effect of adding a video feedback intervention component to the assessment feedback session of the Family Check-Up (FCU) intervention (Dishion & Stormshak, 2007). We hypothesized that the addition of video feedback procedures during the FCU feedback at child age 2 would have a positive effect on caregivers' negative relational…

Negative regulators in homeostasis of naïve peripheral T cells.

PubMed

Modiano, Jaime F; Johnson, Lisa D S; Bellgrau, Donald

2008-01-01

It is now apparent that naïve peripheral T cells are a dynamic population where active processes prevent inappropriate activation while supporting survival. The process of thymic education makes naïve peripheral T cells dependent on interactions with self-MHC for survival. However, as these signals can potentially result in inappropriate activation, various non-redundant, intrinsic negative regulatory molecules including Tob, Nfatc2, and Smad3 actively enforce T cell quiescence. Interactions among these pathways are only now coming to light and may include positive or negative crosstalk. In the case of positive crosstalk, self-MHC initiated signals and intrinsic negative regulatory factors may cooperate to dampen T cell activation and sustain peripheral tolerance in a binary fashion (on-off). In the case of negative crosstalk, self-MHC signals may promote survival through partial activation while intrinsic negative regulatory factors act as rheostats to restrain cell cycle entry and prevent T cells from crossing a threshold that would break tolerance.

Wnt5a suppresses inflammation-driven intervertebral disc degeneration via a TNF-α/NF-κB-Wnt5a negative-feedback loop.

PubMed

Li, Z; Zhang, K; Li, X; Pan, H; Li, S; Chen, F; Zhang, J; Zheng, Z; Wang, J; Liu, H

2018-04-12

This study was to investigate the molecular role of Wnt5a on inflammation-driven intervertebral disc degeneration (IVDD). The expression of Wnt5a was analyzed in human nucleus pulposus (NP) tissues with immunohistochemical staining. The effects of Wnt5a on matrix production were assessed by RT-qPCR and western blotting. Small interfering RNAs (siRNAs), promoter deletion assay, and promoter binding site mutant were used to reveal the molecular role of Wnt5a in TNF-α-induced matrix metalloproteinase (MMP) expression. The regulatory effects of TNF-α on Wnt5a were investigated with pharmachemical inhibitors and siRNA experiment. The expression of Wnt5a was elevated in moderately degenerated human NP tissue with similar expression pattern of TNF-α. In NP cells, Wnt5a significantly increased aggrecan and collagen II expression. Inhibition of JNK or interfering Sox9 gene expression significantly suppressed Wnt5a-induced matrix production. AP-1(JunB) binding sites were located in Sox9 promoter and mutation of these sites sabotaged Wnt5a-induced Sox9 up-regulation and subsequent matrix genes expression. Notably, Wnt5a, which was induced by TNF-α, on the other way round suppressed TNF-α-NF-κB (p65) signaling and subsequent MMPs expression. In vivo studies with MR imaging confirmed the protective role of Wnt5a in IVDD. Wnt5a, which can be induced by TNF-α, increased matrix production in a Sox9-dependent manner through the activation of JNK-AP1 (JunB) signaling, and antagonized TNF-α-induced up-regulation of MMPs through the inhibition of NF-κB signaling. It indicates that Wnt5a suppresses IVDD through a TNF-α/NF-κB-Wnt5a negative-feedback loop. Copyright © 2018 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Local dominance of exotic plants declines with residence time: a role for plant–soil feedback?

PubMed Central

Speek, Tanja A.A.; Schaminée, Joop H.J.; Stam, Jeltje M.; Lotz, Lambertus A.P.; Ozinga, Wim A.; van der Putten, Wim H.

2015-01-01

Recent studies have shown that introduced exotic plant species may be released from their native soil-borne pathogens, but that they become exposed to increased soil pathogen activity in the new range when time since introduction increases. Other studies have shown that introduced exotic plant species become less dominant when time since introduction increases, and that plant abundance may be controlled by soil-borne pathogens; however, no study yet has tested whether these soil effects might explain the decline in dominance of exotic plant species following their initial invasiveness. Here we determine plant–soil feedback of 20 plant species that have been introduced into The Netherlands. We tested the hypotheses that (i) exotic plant species with a longer residence time have a more negative soil feedback and (ii) greater local dominance of the introduced exotic plant species correlates with less negative, or more positive, plant–soil feedback. Although the local dominance of exotic plant species decreased with time since introduction, there was no relationship of local dominance with plant–soil feedback. Plant–soil feedback also did not become more negative with increasing time since introduction. We discuss why our results may deviate from some earlier published studies and why plant–soil feedback may not in all cases, or not in all comparisons, explain patterns of local dominance of introduced exotic plant species. PMID:25770013

Interferon Regulatory Factor 7 Functions as a Novel Negative Regulator of Pathological Cardiac Hypertrophy

PubMed Central

Jiang, Ding-Sheng; Liu, Yu; Zhou, Heng; Zhang, Yan; Zhang, Xiao-Dong; Zhang, Xiao-Fei; Chen, Ke; Gao, Lu; Peng, Juan; Gong, Hui; Chen, Yingjie; Yang, Qinglin; Liu, Peter P.; Fan, Guo-Chang; Zou, Yunzeng; Li, Hongliang

2017-01-01

Cardiac hypertrophy is a complex pathological process that involves multiple factors including inflammation and apoptosis. Interferon regulatory factor 7 (IRF7) is a multifunctional regulator that participates in immune regulation, cell differentiation, apoptosis, and oncogenesis. However, the role of IRF7 in cardiac hypertrophy remains unclear. We performed aortic banding in cardiac-specific IRF7 transgenic mice, IRF7 knockout mice, and the wild-type littermates of these mice. Our results demonstrated that IRF7 was downregulated in aortic banding–induced animal hearts and cardiomyocytes that had been treated with angiotensin II or phenylephrine for 48 hours. Accordingly, heart-specific overexpression of IRF7 significantly attenuated pressure overload–induced cardiac hypertrophy, fibrosis, and dysfunction, whereas loss of IRF7 led to opposite effects. Moreover, IRF7 protected against angiotensin II–induced cardiomyocyte hypertrophy in vitro. Mechanistically, we identified that IRF7-dependent cardioprotection was mediated through IRF7 binding to inhibitor of κB kinase-β, and subsequent nuclear factor-κB inactivation. In fact, blocking nuclear factor-κB signaling with cardiac-specific inhibitors of κBαS32A/S36A super-repressor transgene counteracted the adverse effect of IRF7 deficiency. Conversely, activation of nuclear factor-κB signaling via a cardiac-specific conditional inhibitor of κB kinase-βS177E/S181E (constitutively active) transgene negated the antihypertrophic effect of IRF7 overexpression. Our data demonstrate that IRF7 acts as a novel negative regulator of pathological cardiac hypertrophy by inhibiting nuclear factor-κB signaling and may constitute a potential therapeutic target for pathological cardiac hypertrophy. PMID:24396025

HER2 in Breast Cancer Stemness: A Negative Feedback Loop towards Trastuzumab Resistance

PubMed Central

Nami, Babak; Wang, Zhixiang

2017-01-01

HER2 receptor tyrosine kinase that is overexpressed in approximately 20% of all breast cancers (BCs) is a poor prognosis factor and a precious target for BC therapy. Trastuzumab is approved by FDA to specifically target HER2 for treating HER2+ BC. However, about 60% of patients with HER2+ breast tumor develop de novo resistance to trastuzumab, partially due to the loss of expression of HER2 extracellular domain on their tumor cells. This is due to shedding/cleavage of HER2 by metalloproteinases (ADAMs and MMPs). HER2 shedding results in the accumulation of intracellular carboxyl-terminal HER2 (p95HER2), which is a common phenomenon in trastuzumab-resistant tumors and is suggested as a predictive marker for trastuzumab resistance. Up-regulation of the metalloproteinases is a poor prognosis factor and is commonly seen in mesenchymal-like cancer stem cells that are risen during epithelial to mesenchymal transition (EMT) of tumor cells. HER2 cleavage during EMT can explain why secondary metastatic tumors with high percentage of mesenchymal-like cancer stem cells are mostly resistant to trastuzumab but still sensitive to lapatinib. Importantly, many studies report HER2 interaction with oncogenic/stemness signaling pathways including TGF-β/Smad, Wnt/β-catenin, Notch, JAK/STAT and Hedgehog. HER2 overexpression promotes EMT and the emergence of cancer stem cell properties in BC. Increased expression and activation of metalloproteinases during EMT leads to proteolytic cleavage and shedding of HER2 receptor, which downregulates HER2 extracellular domain and eventually increases trastuzumab resistance. Here, we review the hypothesis that a negative feedback loop between HER2 and stemness signaling drives resistance of BC to trastuzumab. PMID:28445439

Effects of intrinsic motivation on feedback processing during learning.

PubMed

DePasque, Samantha; Tricomi, Elizabeth

2015-10-01

Learning commonly requires feedback about the consequences of one's actions, which can drive learners to modify their behavior. Motivation may determine how sensitive an individual might be to such feedback, particularly in educational contexts where some students value academic achievement more than others. Thus, motivation for a task might influence the value placed on performance feedback and how effectively it is used to improve learning. To investigate the interplay between intrinsic motivation and feedback processing, we used functional magnetic resonance imaging (fMRI) during feedback-based learning before and after a novel manipulation based on motivational interviewing, a technique for enhancing treatment motivation in mental health settings. Because of its role in the reinforcement learning system, the striatum is situated to play a significant role in the modulation of learning based on motivation. Consistent with this idea, motivation levels during the task were associated with sensitivity to positive versus negative feedback in the striatum. Additionally, heightened motivation following a brief motivational interview was associated with increases in feedback sensitivity in the left medial temporal lobe. Our results suggest that motivation modulates neural responses to performance-related feedback, and furthermore that changes in motivation facilitate processing in areas that support learning and memory. Copyright © 2015. Published by Elsevier Inc.

Effects of Intrinsic Motivation on Feedback Processing During Learning

PubMed Central

DePasque, Samantha; Tricomi, Elizabeth

2015-01-01

Learning commonly requires feedback about the consequences of one’s actions, which can drive learners to modify their behavior. Motivation may determine how sensitive an individual might be to such feedback, particularly in educational contexts where some students value academic achievement more than others. Thus, motivation for a task might influence the value placed on performance feedback and how effectively it is used to improve learning. To investigate the interplay between intrinsic motivation and feedback processing, we used functional magnetic resonance imaging (fMRI) during feedback-based learning before and after a novel manipulation based on motivational interviewing, a technique for enhancing treatment motivation in mental health settings. Because of its role in the reinforcement learning system, the striatum is situated to play a significant role in the modulation of learning based on motivation. Consistent with this idea, motivation levels during the task were associated with sensitivity to positive versus negative feedback in the striatum. Additionally, heightened motivation following a brief motivational interview was associated with increases in feedback sensitivity in the left medial temporal lobe. Our results suggest that motivation modulates neural responses to performance-related feedback, and furthermore that changes in motivation facilitates processing in areas that support learning and memory. PMID:26112370

Self-verification in clinical depression: the desire for negative evaluation.

PubMed

Giesler, R B; Josephs, R A; Swann, W B

1996-08-01

Do clinically depressed individuals seek favorable or unfavorable information about the self? Self-verification theory makes the counterintuitive prediction that depressed individuals solicit feedback that confirms their negative self-views. To test this prediction, participants were classified on the basis of a structured clinical interview and self-report measures into high-esteem, low self-esteem, and depressed groups. All participants were offered a choice between receiving favorable or unfavorable feedback; 82% of the depressed participants chose the unfavorable feedback, compared to 64% of the low self-esteem participants and 25% of the high self-esteem participants. Additional evidence indicated that depressed individuals also failed to exploit fully an opportunity to acquire favorable evaluations that were self-verifying. The authors discuss how seeking negative evaluations and failing to seek favorable evaluations may help maintain depression.

How can positive and negative trainer feedback in the operating theatre impact a surgical trainee’s confidence and well-being: a qualitative study in the north of England

PubMed Central

Kamali, Dariush; Illing, Jan

2018-01-01

Objective To identify the perception of positive feedback (PF) and negative feedback (NF) provided by trainers in the operating theatre on surgical trainees' confidence and well-being. Design Narrative interview study. Setting Twelve hospitals that form part of one deanery within the UK. Participants Maximum variation sampling of 15 higher general surgical trainees provided insight into how PF and NF from trainers in the operating theatre affect confidence and well-being. Methods Narrative telephone interviews were conducted with general surgical trainees between April and June 2016. All interviews were recorded, transcribed and anonymised. Transcriptions were analysed using the five-step framework analysis by two independent researchers. Results Fifteen trainees (age 28–38 years) were interviewed (median interview time: 29 min). Thematic framework analysis identified nine themes within the data. PF, which included corrective feedback, helped the trainees to relax and seemed to enhance their operative performance. All trainees reported significant and unjustified NF, some of which would be defined as undermining and bullying. Many believed this to have a negative impact on their training with minimal educational benefit. Many trainees felt NF adversely affected their performance in the operating theatre with some expressing a wish to leave the profession as a consequence. Conclusion Both PF and NF exist in the operating theatre. Both have an important influence on the trainee, their performance and career. PF, if specific, helped aid progression of learning, increased motivation and performance of surgical trainees. In contrast, NF was perceived to have detrimental effects on trainees’ performance and their well-being and, in some, introduced a desire to pursue an alternative career. PMID:29440141

Technology-Supported Peer Feedback in ESL/EFL Writing Classes: A Research Synthesis

ERIC Educational Resources Information Center

Chen, Tsuiping

2016-01-01

Some studies on technology-supported peer feedback in the writing classroom claim that it reduces the threatening atmosphere caused by face-to-face interaction and that the discourse patterns and language use in the electronic feedback are more flexible than in spoken discourse. Others present a negative view that the comments generated from…

Selective skepticism: American and Chinese children's reasoning about evaluative academic feedback.

PubMed

Heyman, Gail D; Fu, Genyue; Lee, Kang

2013-03-01

Children's reasoning about the credibility of positive and negative evaluations of academic performance was examined. Across 2 studies, 7- and 10-year-olds from the United States and China (N = 334) judged the credibility of academic evaluations that were directed toward an unfamiliar peer. In Study 1, participants from China responded that criticism should be accepted to a greater extent than did participants from the United States, and children from both countries demonstrated a selective skepticism effect by treating negative feedback more skeptically than positive feedback. Study 2 replicated the selective skepticism effect among children from both countries and ruled out the possibility that it can be explained as a rational analysis of perceived base rates. The results suggest that children are selective in their trust of evaluative feedback and that their credibility judgments may be influenced by the desirability of the information that is being conveyed or its anticipated consequences.

How short RNAs impact the human ribonuclease Dicer activity: putative regulatory feedback-loops and other RNA-mediated mechanisms controlling microRNA processing.

PubMed

Koralewska, Natalia; Hoffmann, Weronika; Pokornowska, Maria; Milewski, Marek; Lipinska, Andrea; Bienkowska-Szewczyk, Krystyna; Figlerowicz, Marek; Kurzynska-Kokorniak, Anna

2016-01-01

Ribonuclease Dicer plays a pivotal role in RNA interference pathways by processing long double-stranded RNAs and single-stranded hairpin RNA precursors into small interfering RNAs (siRNAs) and microRNAs (miRNAs), respectively. While details of Dicer regulation by a variety of proteins are being elucidated, less is known about non-protein factors, e.g. RNA molecules, that may influence this enzyme's activity. Therefore, we decided to investigate the question of whether the RNA molecules can function not only as Dicer substrates but also as its regulators. Our previous in vitro studies indicated that the activity of human Dicer can be influenced by short RNA molecules that either bind to Dicer or interact with its substrates, or both. Those studies were carried out with commercial Dicer preparations. Nevertheless, such preparations are usually not homogeneous enough to carry out more detailed RNA-binding studies. Therefore, we have established our own system for the production of human Dicer in insect cells. In this manuscript, we characterize the RNA-binding and RNA-cleavage properties of the obtained preparation. We demonstrate that Dicer can efficiently bind single-stranded RNAs that are longer than ~20-nucleotides. Consequently, we revisit possible scenarios of Dicer regulation by single-stranded RNA species ranging from ~10- to ~60-nucleotides, in the context of their binding to this enzyme. Finally, we show that siRNA/miRNA-sized RNAs may affect miRNA production either by binding to Dicer or by participating in regulatory feedback-loops. Altogether, our studies suggest a broad regulatory role of short RNAs in Dicer functioning.

Evaluating plant-soil feedback together with competition in a serpentine grassland.

PubMed

Casper, Brenda B; Castelli, Jeffrey P

2007-05-01

Plants can alter biotic and abiotic soil characteristics in ways that feedback to change the performance of that same plant species relative to co-occurring plants. Most evidence for this plant-soil feedback comes from greenhouse studies of potted plants, and consequently, little is known about the importance of feedback in relation to other biological processes known to structure plant communities, such as plant-plant competition. In a field experiment with three C4 grasses, negative feedback was expressed through reduced survival and shoot biomass when seedlings were planted within existing clumps of conspecifics compared with clumps of heterospecifics. However, the combined effects of feedback and competition were species-specific. Only Andropogon gerardii exhibited feedback when competition with the clumps was allowed. For Sorghastrum nutans, strong interspecific competition eliminated the feedback expressed in the absence of competition, and Schizachyrium scoparium showed no feedback at all. That arbuscular mycorrhizal (AM) fungi may play a role in the feedback was indicated by higher AM root colonization with conspecific plant neighbours. We suggest that feedback and competition should not be viewed as entirely separate processes and that their importance in structuring plant communities cannot be judged in isolation from each other.

Structures of the Bacillus subtilis Glutamine Synthetase Dodecamer Reveal Large Intersubunit Catalytic Conformational Changes Linked to a Unique Feedback Inhibition Mechanism*

PubMed Central

Murray, David S.; Chinnam, Nagababu; Tonthat, Nam Ky; Whitfill, Travis; Wray, Lewis V.; Fisher, Susan H.; Schumacher, Maria A.

2013-01-01

Glutamine synthetase (GS), which catalyzes the production of glutamine, plays essential roles in nitrogen metabolism. There are two main bacterial GS isoenzymes, GSI-α and GSI-β. GSI-α enzymes, which have not been structurally characterized, are uniquely feedback-inhibited by Gln. To gain insight into GSI-α function, we performed biochemical and cellular studies and obtained structures for all GSI-α catalytic and regulatory states. GSI-α forms a massive 600-kDa dodecameric machine. Unlike other characterized GS, the Bacillus subtilis enzyme undergoes dramatic intersubunit conformational alterations during formation of the transition state. Remarkably, these changes are required for active site construction. Feedback inhibition arises from a hydrogen bond network between Gln, the catalytic glutamate, and the GSI-α-specific residue, Arg62, from an adjacent subunit. Notably, Arg62 must be ejected for proper active site reorganization. Consistent with these findings, an R62A mutation abrogates Gln feedback inhibition but does not affect catalysis. Thus, these data reveal a heretofore unseen restructuring of an enzyme active site that is coupled with an isoenzyme-specific regulatory mechanism. This GSI-α-specific regulatory network could be exploited for inhibitor design against Gram-positive pathogens. PMID:24158439

Valence and agency influence striatal response to feedback in patients with major depressive disorder

PubMed Central

Späti, Jakub; Chumbley, Justin; Doerig, Nadja; Brakowski, Janis; Holtforth, Martin Grosse; Seifritz, Erich; Spinelli, Simona

2015-01-01

Background Reduced sensitivity to positive feedback is common in patients with major depressive disorder (MDD). However, findings regarding negative feedback are ambiguous, with both exaggerated and blunted responses being reported. The ventral striatum (VS) plays a major role in processing valenced feedback, and previous imaging studies have shown that the locus of controls (self agency v. external agency) over the outcome influences VS response to feedback. We investigated whether attributing the outcome to one’s own action or to an external agent influences feedback processing in patients with MDD. We hypothesized that depressed participants would be less sensitive to the feedback attribution reflected by an altered VS response to self-attributed gains and losses. Methods Using functional MRI and a motion prediction task, we investigated the neural responses to self-attributed (SA) and externally attributed (EA) monetary gains and losses in unmedicated patients with MDD and healthy controls. Results We included 21 patients and 25 controls in our study. Consistent with our prediction, healthy controls showed a VS response influenced by feedback valence and attribution, whereas in depressed patients striatal activity was modulated by valence but was insensitive to attribution. This attribution insensitivity led to an altered ventral putamen response for SA – EA losses in patients with MDD compared with healthy controls. Limitations Depressed patients with comorbid anxiety disorder were included. Conclusion These results suggest an altered assignment of motivational salience to SA losses in patients with MDD. Altered striatal response to SA negative events may reinforce the belief of not being in control of negative outcomes contributing to a cycle of learned helplessness. PMID:26107160

Simulation and Feedback in Health Education: A Mixed Methods Study Comparing Three Simulation Modalities.

PubMed

Tait, Lauren; Lee, Kenneth; Rasiah, Rohan; Cooper, Joyce M; Ling, Tristan; Geelan, Benjamin; Bindoff, Ivan

2018-05-03

Background . There are numerous approaches to simulating a patient encounter in pharmacy education. However, little direct comparison between these approaches has been undertaken. Our objective was to investigate student experiences, satisfaction, and feedback preferences between three scenario simulation modalities (paper-, actor-, and computer-based). Methods . We conducted a mixed methods study with randomized cross-over of simulation modalities on final-year Australian graduate-entry Master of Pharmacy students. Participants completed case-based scenarios within each of three simulation modalities, with feedback provided at the completion of each scenario in a format corresponding to each simulation modality. A post-simulation questionnaire collected qualitative and quantitative responses pertaining to participant satisfaction, experiences, and feedback preferences. Results . Participants reported similar levels satisfaction across all three modalities. However, each modality resulted in unique positive and negative experiences, such as student disengagement with paper-based scenarios. Conclusion . Importantly, the themes of guidance and opportunity for peer discussion underlie the best forms of feedback for students. The provision of feedback following simulation should be carefully considered and delivered, with all three simulation modalities producing both positive and negative experiences in regard to their feedback format.

Positive and Negative Feedbacks and Free-Scale Pattern Distribution in Rural-Population Dynamics

PubMed Central

Alados, Concepción L.; Errea, Paz; Gartzia, Maite; Saiz, Hugo; Escós, Juan

2014-01-01

Depopulation of rural areas is a widespread phenomenon that has occurred in most industrialized countries, and has contributed significantly to a reduction in the productivity of agro-ecological resources. In this study, we identified the main trends in the dynamics of rural populations in the Central Pyrenees in the 20th C and early 21st C, and used density independent and density dependent models and identified the main factors that have influenced the dynamics. In addition, we investigated the change in the power law distribution of population size in those periods. Populations exhibited density-dependent positive feedback between 1960 and 2010, and a long-term positive correlation between agricultural activity and population size, which has resulted in a free-scale population distribution that has been disrupted by the collapse of the traditional agricultural society and by emigration to the industrialized cities. We concluded that complex socio-ecological systems that have strong feedback mechanisms can contribute to disruptive population collapses, which can be identified by changes in the pattern of population distribution. PMID:25474704

The influence of teacher feedback on children's perceptions of student-teacher relationships.

PubMed

Skipper, Yvonne; Douglas, Karen

2015-09-01

Teachers can deliver feedback using person ('you are clever') or process terms ('you worked hard'). Person feedback can lead to negative academic outcomes, but there is little experimental research examining the impact of feedback on children's perceptions of the student-teacher relationship. We examined the effects of person, process, and no feedback on children's perceptions of their relationship with a (fictional) teacher following success and failure. Participants were British children (145 aged 9-11 in experiment 1 and 98 aged 7-11 in experiment 2). In experiment 1, participants read three scenarios where they succeeded and received one of two types of praise (person or process) or no praise. Participants then read two scenarios where they failed. In experiment 2, participants read that they had failed in three tasks and received one of two types of criticism (person or process) or no criticism. Participants then read two scenarios where they succeeded. They rated how much they liked the teacher and how much they felt that the teacher liked them. Children felt more positive about the student-teacher relationship following success than failure. Type of praise did not influence perceptions of the student-teacher relationship following success or failure. However, person criticism led children to view the student-teacher relationship more negatively following failure and maintain this negative view following the first success. Success appears to be important for developing positive student-teacher relationships. In response to failure, teachers could avoid person criticism which may negatively influence the student-teacher relationship. © 2015 The British Psychological Society.

Cultural shaping of neural responses: Feedback-related potentials vary with self-construal and face priming.

PubMed

Hitokoto, Hidefumi; Glazer, James; Kitayama, Shinobu

2016-01-01

Previous work shows that when an image of a face is presented immediately prior to each trial of a speeded cognitive task (face-priming), the error-related negativity (ERN) is upregulated for Asians, but it is downregulated for Caucasians. These findings are consistent with the hypothesis that images of "generalized other" vary cross-culturally such that they evoke anxiety for Asians, whereas they serve as safety cues for Caucasians. Here, we tested whether the cross-cultural variation in the face-priming effect would be observed in a gambling paradigm. Caucasian Americans, Asian Americans, and Asian sojourners were exposed to a brief flash of a schematic face during a gamble. For Asian Americans, face-priming resulted in significant increases of both negative-going deflection of ERP upon negative feedback (feedback-related negativity [FRN]) and positive-going deflection of ERP upon positive feedback (feedback-related positivity [FRP]). For Caucasian Americans, face-priming showed a significant reversal, decreasing both FRN and FRP. The cultural difference in the face-priming effect in FRN and FRP was partially mediated by interdependent self-construal. Curiously, Asian sojourners showed a pattern similar to the one for Caucasian Americans. Our findings suggest that culture shapes neural pathways in both systematic and highly dynamic fashion. © 2015 Society for Psychophysiological Research.

Mitogen-Inducible Gene-6 Mediates Feedback Inhibition from Mutated BRAF towards the Epidermal Growth Factor Receptor and Thereby Limits Malignant Transformation

PubMed Central

Milewska, Malgorzata; Romano, David; Herrero, Ana; Guerriero, Maria Luisa; Birtwistle, Marc; Quehenberger, Franz; Hatzl, Stefan; Kholodenko, Boris N.; Segatto, Oreste; Kolch, Walter; Zebisch, Armin

2015-01-01

BRAF functions in the RAS-extracellular signal-regulated kinase (ERK) signaling cascade. Activation of this pathway is necessary to mediate the transforming potential of oncogenic BRAF, however, it may also cause a negative feedback that inhibits the epidermal growth factor receptor (EGFR). Mitogen-inducible gene-6 (MIG-6) is a potent inhibitor of the EGFR and has been demonstrated to function as a tumor suppressor. As MIG-6 can be induced via RAS-ERK signaling, we investigated its potential involvement in this negative regulatory loop. Focus formation assays were performed and demonstrated that MIG-6 significantly reduces malignant transformation induced by oncogenic BRAF. Although this genetic interaction was mirrored by a physical interaction between MIG-6 and BRAF, we did not observe a direct regulation of BRAF kinase activity by MIG-6. Interestingly, a selective chemical EGFR inhibitor suppressed transformation to a similar degree as MIG-6, whereas combining these approaches had no synergistic effect. By analyzing a range of BRAF mutated and wildtype cell line models, we could show that BRAF V600E causes a strong upregulation of MIG-6, which was mediated at the transcriptional level via the RAS-ERK pathway and resulted in downregulation of EGFR activation. This feedback loop is operational in tumors, as shown by the analysis of almost 400 patients with papillary thyroid cancer (PTC). Presence of BRAF V600E correlated with increased MIG-6 expression on the one hand, and with inactivation of the EGFR and of PI3K/AKT signaling on the other hand. Importantly, we also observed a more aggressive disease phenotype when BRAF V600E coexisted with low MIG-6 expression. Finally, analysis of methylation data was performed and revealed that higher methylation of MIG-6 correlated to its decreased expression. Taken together, we demonstrate that MIG-6 efficiently reduces cellular transformation driven by oncogenic BRAF by orchestrating a negative feedback circuit directed

Luck and Learning: Feedback Contingencies and Initial Success in Verbal Discrimination Learning.

ERIC Educational Resources Information Center

Schneider, H. G.; Ferrante, A. P.

1983-01-01

A total of 90 undergraduate volunteers learned a 12-pair, low-frequency verbal discrimination list. Independent variables were feedback (positive only, negative only, or both) and initial success (17, 50, or 83 percent correct on the first trial). While the main effect of feedback was not significant, that of initial success was. (Author/RH)

Praise in Public, Criticize in Private? An Assessment of Performance Feedback Transparency in a Classroom Setting

ERIC Educational Resources Information Center

Seevers, Matthew T.; Rowe, William J.; Skinner, Steven J.

2014-01-01

Conventional wisdom in sales management encourages public delivery of positive feedback, and private delivery of negative feedback. In stark contrast, U.S. educators typically provide all performance feedback in relative (if not strict) privacy to comply with the Family Educational Rights and Privacy Act (FERPA). To investigate this discrepancy,…

Multitask neurovision processor with extensive feedback and feedforward connections

NASA Astrophysics Data System (ADS)

Gupta, Madan M.; Knopf, George K.

1991-11-01

A multi-task neuro-vision parameter which performs a variety of information processing operations associated with the early stages of biological vision is presented. The network architecture of this neuro-vision processor, called the positive-negative (PN) neural processor, is loosely based on the neural activity fields exhibited by thalamic and cortical nervous tissue layers. The computational operation performed by the processor arises from the strength of the recurrent feedback among the numerous positive and negative neural computing units. By adjusting the feedback connections it is possible to generate diverse dynamic behavior that may be used for short-term visual memory (STVM), spatio-temporal filtering (STF), and pulse frequency modulation (PFM). The information attributes that are to be processes may be regulated by modifying the feedforward connections from the signal space to the neural processor.

Perspectives on Regulatory T Cell Therapies.

PubMed

Probst-Kepper, Michael; Kröger, Andrea; Garritsen, Henk S P; Buer, Jan

2009-01-01

Adoptive transfer in animal models clearly indicate an essential role of CD4+ CD25+ FOXP3+ regulatory T (T(reg)) cells in prevention and treatment of autoimmune and graft-versus-host disease. Thus, T(reg) cell therapies and development of drugs that specifically enhance T(reg) cell function and development represent promising tools to establish dominant tolerance. So far, lack of specific markers to differentiate human T(reg) cells from activated CD4+ CD25+ effector T cells, which also express FOXP3 at different levels, hampered such an approach. Recent identification of the orphan receptor glycoprotein-A repetitions predominant (GARP or LRRC32) as T(reg) cell-specific key molecule that dominantly controls FOXP3 via a positive feedback loop opens up new perspectives for molecular and cellular therapies. This brief review focuses on the role of GARP as a safeguard of a complex regulatory network of human T(reg) cells and its implications for regulatory T cell therapies in autoimmunity and graft-versus-host disease.

Acute effects of alcohol on feedback processing and outcome evaluation during risky decision-making: an ERP study.

PubMed

Euser, Anja S; van Meel, Catharina S; Snelleman, Michelle; Franken, Ingmar H A

2011-09-01

Although risky decision-making is one of the hallmarks of alcohol use disorders, relatively little is known about the acute psychopharmacological effects of alcohol on decision-making processes. The present study investigated the acute effects of alcohol on neural mechanisms underlying feedback processing and outcome evaluation during risky decision-making, using event-related brain potentials (ERPs). ERPs elicited by positive and negative feedback were recorded during performance of a modified version of the Balloon Analogue Risk Task in male participants receiving either a moderate dose of alcohol (0.65 g/kg alcohol; n = 32) or a non-alcoholic placebo beverage (n = 32). Overall, there was no significant difference in the mean number of pumps between the alcohol and the placebo condition. However, when analyzing over time, it was found that the alcohol group made more riskier choices at the beginning of the task than the placebo group. ERPs demonstrated that alcohol consumption did not affect early processing of negative feedback, indexed by the feedback-related negativity. By contrast, alcohol-intoxicated individuals showed significantly reduced P300 amplitudes in response to negative feedback as compared to sober controls, suggesting that more elaborate evaluation to losses was significantly diminished. These results suggest that alcohol consumption does not influence the ability to rapidly evaluate feedback valence, but rather the ability to assign sufficient attention to further process motivationally salient outcomes. Blunted P300 amplitudes may reflect poor integration of feedback across trials, particularly adverse ones. Consequently, alcohol may keep people from effectively predicting the probability of future gains and losses based on their reinforcement history.

Neurophysiological correlates of anhedonia in feedback processing

PubMed Central

Mies, Gabry W.; Van den Berg, Ivo; Franken, Ingmar H. A.; Smits, Marion; Van der Molen, Maurits W.; Van der Veen, Frederik M.

2013-01-01

Disturbances in feedback processing and a dysregulation of the neural circuit in which the cingulate cortex plays a key role have been frequently observed in depression. Since depression is a heterogeneous disease, instead of focusing on the depressive state in general, this study investigated the relations between the two core symptoms of depression, i.e., depressed mood and anhedonia, and the neural correlates of feedback processing using fMRI. The focus was on the different subdivisions of the anterior cingulate cortex (ACC). Undergraduates with varying levels of depressed mood and anhedonia performed a time-estimation task in which they received positive and negative feedback that was either valid or invalid (i.e., related vs. unrelated to actual performance). The rostral cingulate zone (RCZ), corresponding to the dorsal part of the ACC, was less active in response to feedback in more anhedonic individuals, after correcting for the influence of depressed mood, whereas the subgenual ACC was more active in these individuals. Task performance was not affected by anhedonia, however. No statistically significant effects were found for depressed mood above and beyond the effects of anhedonia. This study therefore implies that increasing levels of anhedonia involve changes in the neural circuitry underlying feedback processing. PMID:23532800

The FasX Small Regulatory RNA Negatively Regulates the Expression of Two Fibronectin-Binding Proteins in Group A Streptococcus.

PubMed

Danger, Jessica L; Makthal, Nishanth; Kumaraswami, Muthiah; Sumby, Paul

2015-12-01

The group A Streptococcus (GAS; Streptococcus pyogenes) causes more than 700 million human infections each year. The success of this pathogen can be traced in part to the extensive arsenal of virulence factors that are available for expression in temporally and spatially specific manners. To modify the expression of these virulence factors, GAS use both protein- and RNA-based regulators, with the best-characterized RNA-based regulator being the small regulatory RNA (sRNA) FasX. FasX is a 205-nucleotide sRNA that contributes to GAS virulence by enhancing the expression of the thrombolytic secreted virulence factor streptokinase and by repressing the expression of the collagen-binding cell surface pili. Here, we have expanded the FasX regulon, showing that this sRNA also negatively regulates the expression of the adhesion- and internalization-promoting, fibronectin-binding proteins PrtF1 and PrtF2. FasX posttranscriptionally regulates the expression of PrtF1/2 through a mechanism that involves base pairing to the prtF1 and prtF2 mRNAs within their 5' untranslated regions, overlapping the mRNA ribosome-binding sites. Thus, duplex formation between FasX and the prtF1 and prtF2 mRNAs blocks ribosome access, leading to an inhibition of mRNA translation. Given that FasX positively regulates the expression of the spreading factor streptokinase and negatively regulates the expression of the collagen-binding pili and of the fibronectin-binding PrtF1/2, our data are consistent with FasX functioning as a molecular switch that governs the transition of GAS between the colonization and dissemination stages of infection. More than half a million deaths each year are a consequence of infections caused by GAS. Insights into how this pathogen regulates the production of proteins during infection may facilitate the development of novel therapeutic or preventative regimens aimed at inhibiting this activity. Here, we have expanded insight into the regulatory activity of the GAS small

Ask and you shall receive: desire and receipt of feedback via Facebook predicts disordered eating concerns.

PubMed

Hummel, Alexandra C; Smith, April R

2015-05-01

The current study examined whether certain types of Facebook content (i.e., status updates, comments) relate to eating concerns and attitudes. We examined the effects of seeking and receiving negative feedback via Facebook on disordered eating concerns in a sample of 185 undergraduate students followed for approximately 4 weeks. Results indicated that individuals with a negative feedback seeking style who received a high number of comments on Facebook were more likely to report disordered eating attitudes four weeks later. Additionally, individuals who received extremely negative comments in response to their personally revealing status updates were more likely to report disordered eating concerns four weeks later. Results of the current study provide preliminary evidence that seeking and receiving negative feedback via social networking sites can increase risk for disordered eating attitudes, and suggest that reducing maladaptive social networking usage may be an important target for prevention and intervention efforts aimed at reducing disordered eating attitudes. © 2014 Wiley Periodicals, Inc.

The Role and Functionality of Emotions in Feedback at University: A Qualitative Study

ERIC Educational Resources Information Center

Rowe, Anna D.; Fitness, Julie; Wood, Leigh N.

2014-01-01

This paper reports on a qualitative study exploring the role and functionality of emotions in feedback. In-depth interview data from students and lecturers at an Australian university are analysed using cognitive appraisal and prototype theory. Results suggest that students experience a range of positive and negative emotions in feedback contexts…

Does Constructive Performance Feedback Improve Citizenship Intentions and Job Satisfaction? The Roles of Perceived Opportunities for Advancement, Respect, and Mood

ERIC Educational Resources Information Center

Sommer, Kristin L.; Kulkarni, Mukta

2012-01-01

Organizational experts have long touted the importance of delivering negative performance feedback in a manner that enhances employee receptivity to feedback, yet the broader impacts of constructive feedback have received relatively little attention. The present investigation explored the impact of constructive, critical feedback on organizational…

The stress-buffering effect of acute exercise: Evidence for HPA axis negative feedback.

PubMed

Zschucke, Elisabeth; Renneberg, Babette; Dimeo, Fernando; Wüstenberg, Torsten; Ströhle, Andreas

2015-01-01

According to the cross-stressor adaptation hypothesis, physically trained individuals show lower physiological and psychological responses to stressors other than exercise, e.g. psychosocial stress. Reduced stress reactivity may constitute a mechanism of action for the beneficial effects of exercise in maintaining mental health. With regard to neural and psychoneuroendocrine stress responses, the acute stress-buffering effects of exercise have not been investigated yet. A sample of highly trained (HT) and sedentary (SED) young men was randomized to either exercise on a treadmill at moderate intensity (60-70% VO2max; AER) for 30 min, or to perform 30 min of "placebo" exercise (PLAC). 90 min later, an fMRI experiment was conducted using an adapted version of the Montreal Imaging Stress Task (MIST). The subjective and psychoneuroendocrine (cortisol and α-amylase) changes induced by the exercise intervention and the MIST were assessed, as well as neural activations during the MIST. Finally, associations between the different stress responses were analysed. Participants of the AER group showed a significantly reduced cortisol response to the MIST, which was inversely related to the previous exercise-induced α-amylase and cortisol fluctuations. With regard to the sustained BOLD signal, we found higher bilateral hippocampus (Hipp) activity and lower prefrontal cortex (PFC) activity in the AER group. Participants with a higher aerobic fitness showed lower cortisol responses to the MIST. As the Hipp and PFC are brain structures prominently involved in the regulation of the hypothalamus-pituitary-adrenal (HPA) axis, these findings indicate that the acute stress-buffering effect of exercise relies on negative feedback mechanisms. Positive affective changes after exercise appear as important moderators largely accounting for the effects related to physical fitness. Copyright © 2014 Elsevier Ltd. All rights reserved.

Plant-soil feedback and the maintenance of diversity in Mediterranean-climate shrublands.

PubMed

Teste, François P; Kardol, Paul; Turner, Benjamin L; Wardle, David A; Zemunik, Graham; Renton, Michael; Laliberté, Etienne

2017-01-13

Soil biota influence plant performance through plant-soil feedback, but it is unclear whether the strength of such feedback depends on plant traits and whether plant-soil feedback drives local plant diversity. We grew 16 co-occurring plant species with contrasting nutrient-acquisition strategies from hyperdiverse Australian shrublands and exposed them to soil biota from under their own or other plant species. Plant responses to soil biota varied according to their nutrient-acquisition strategy, including positive feedback for ectomycorrhizal plants and negative feedback for nitrogen-fixing and nonmycorrhizal plants. Simulations revealed that such strategy-dependent feedback is sufficient to maintain the high taxonomic and functional diversity characterizing these Mediterranean-climate shrublands. Our study identifies nutrient-acquisition strategy as a key trait explaining how different plant responses to soil biota promote local plant diversity. Copyright © 2017, American Association for the Advancement of Science.

Ultrafast Outflows: Galaxy-scale Active Galactic Nucleus Feedback

NASA Astrophysics Data System (ADS)

Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

2013-01-01

We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagner, A. Y.; Umemura, M.; Bicknell, G. V., E-mail: ayw@ccs.tsukuba.ac.jp

We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves inmore » the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.« less

Relational interaction in occupational therapy: Conversation analysis of positive feedback.

PubMed

Weiste, Elina

2018-01-01

The therapeutic relationship is an important factor for good therapy outcomes. The primary mediator of a beneficial therapy relationship is clinician-client interaction. However, few studies identify the observable interactional attributes of good quality relational interactions, e.g. offering the client positive feedback. The present paper aims to expand current understanding of relational interaction by analyzing the real-time interactional practices therapists use for offering positive feedback, an important value in occupational therapy. The analysis is based on the conversation analysis of 15 video-recorded occupational therapy encounters in psychiatric outpatient clinics. Two types of positive feedback were identified. In aligning feedback, therapists encouraged and complimented clients' positive perspectives on their own achievements in adopting certain behaviour, encouraging and supporting their progress. In redirecting feedback, therapists shifted the perspective from clients' negative experiences to their positive experiences. This shift was interactionally successful if they laid the foundation for the shift in perspective and attuned their expressions to the clients' emotional states. Occupational therapists routinely provide their clients with positive feedback. Awareness of the interactional attributes related to positive feedback is critically important for successful relational interaction.

Effects of Feedback on Achievement Goals and Perceived Motivational Climate in Physical Education

ERIC Educational Resources Information Center

Erturan-Ilker, Gökçe

2014-01-01

The aim of the study is to determine the effects of teacher's positive and negative feedback on high school students' perceived motivational climate and achievement goals in a physical education setting. Forty seven ninth grade students participated in the study. The design was a 2 x 2 between subjects factorial crossing feedback condition…

Is Positive Feedback a Forgotten Classroom Practice? Findings and Implications for At-Risk Students

ERIC Educational Resources Information Center

Sprouls, Katie; Mathur, Sarup R.; Upreti, Gita

2015-01-01

Although using higher rates of positive to negative feedback is one best practice often recommended to teachers, particularly when it comes to students experiencing behavioral problems in classroom settings, research on the use of positive feedback in classroom teaching practice has revealed inconsistent results. Research has documented…

Motivation and emotion predict medical students' attention to computer-based feedback.

PubMed

Naismith, Laura M; Lajoie, Susanne P

2017-12-14

Students cannot learn from feedback unless they pay attention to it. This study investigated relationships between the personal factors of achievement goal orientations, achievement emotions, and attention to feedback in BioWorld, a computer environment for learning clinical reasoning. Novice medical students (N = 28) completed questionnaires to measure their achievement goal orientations and then thought aloud while solving three endocrinology patient cases and reviewing corresponding expert solutions. Questionnaires administered after each case measured participants' experiences of five feedback emotions: pride, relief, joy, shame, and anger. Attention to individual text segments of the expert solutions was modelled using logistic regression and the method of generalized estimating equations. Participants did not attend to all of the feedback that was available to them. Performance-avoidance goals and shame positively predicted attention to feedback, and performance-approach goals and relief negatively predicted attention to feedback. Aspects of how the feedback was displayed also influenced participants' attention. Findings are discussed in terms of their implications for educational theory as well as the design and use of computer learning environments in medical education.