Contextual novelty changes reward representations in the striatum

Reward representation in ventral striatum is boosted by perceptual novelty, although the mechanism of this effect remains elusive. Animal studies indicate a functional loop (Lisman and Grace, 2005) that includes hippocampus, ventral striatum, and midbrain as being important in regulating salience attribution within the context of novel stimuli. According to this model, reward responses in ventral striatum or midbrain should be enhanced in the context of novelty even if reward and novelty constitute unrelated, independent events. Using fMRI, we show that trials with reward-predictive cues and subsequent outcomes elicit higher responses in the striatum if preceded by an unrelated novel picture, indicating that reward representation is enhanced in the context of novelty. Notably, this effect was observed solely when reward occurrence, and hence reward-related salience, was low. These findings support a view that contextual novelty enhances neural responses underlying reward representation in the striatum and concur with the effects of novelty processing as predicted by the model of Lisman and Grace (2005)

Dopamine restores reward prediction errors in old age.

Senescence affects the ability to utilize information about the likelihood of rewards for optimal decision-making. Using functional magnetic resonance imaging in humans, we found that healthy older adults had an abnormal signature of expected value, resulting in an incomplete reward prediction error (RPE) signal in the nucleus accumbens, a brain region that receives rich input projections from substantia nigra/ventral tegmental area (SN/VTA) dopaminergic neurons. Structural connectivity between SN/VTA and striatum, measured by diffusion tensor imaging, was tightly coupled to inter-individual differences in the expression of this expected reward value signal. The dopamine precursor levodopa (L-DOPA) increased the task-based learning rate and task performance in some older adults to the level of young adults. This drug effect was linked to restoration of a canonical neural RPE. Our results identify a neurochemical signature underlying abnormal reward processing in older adults and indicate that this can be modulated by L-DOPA

Learning across Settings and Time in the Digital Age

Recent scholarship in the interdisciplinary field of the learning sciences has focused on the ways that young people use digital tools to connect learning experiences across different settings and over time. Two aspects stand out in this research: (i) the potency of youth agency in creating new activities, communities, and pathways for interest-related pursuits and (ii) the ways that peers, adults, and different sociocultural contexts afford and constrain opportunity. These contexts, or settings, include peer groups and families; schools, neighbourhoods and cities, and also nationwide infrastructures that foster connections between school-based and out-of-school learning. The articles in this special issue of Digital Education Review shed light on these topics and advance our understanding of the theories that deal with learning across various settings and times, and how to promote more equitable youth learning across these settings

Contextual novelty modulates the neural dynamics of reward anticipation

We investigated how rapidly the reward-predicting properties of visual cues are signaled in the human brain and the extent these reward prediction signals are contextually modifiable. In a magnetoencephalography study, we presented participants with fractal visual cues that predicted monetary rewards with different probabilities. These cues were presented in the temporal context of a preceding novel or familiar image of a natural scene. Starting at similar to 100 ms after cue onset, reward probability was signaled in the event-related fields (ERFs) over temporo-occipital sensors and in the power of theta (5-8 Hz) and beta (20-30 Hz) band oscillations over frontal sensors. While theta decreased with reward probability beta power showed the opposite effect. Thus, in humans anticipatory reward responses are generated rapidly, within 100 ms after the onset of reward-predicting cues, which is similar to the timing established in non-human primates. Contextual novelty enhanced the reward anticipation responses in both ERFs and in beta oscillations starting at similar to 100 ms after cue onset. This very early context effect is compatible with a physiological model that invokes the mediation of a hippocampal-VTA loop according to which novelty modulates neural response properties within the reward circuitry. We conclude that the neural processing of cues that predict future rewards is temporally highly efficient and contextually modifiable

Learning across settings and time in the digital age.

Recent scholarship in the interdisciplinary field of the learning sciences has focused on the ways that young people use digital tools to connect learning experiences across different settings and over time. Two aspects stand out in this research: (i) the potency of youth agency in creating new activities, communities, and pathways for interest-related pursuits and (ii) the ways that peers, adults, and different sociocultural contexts afford and constrain opportunity. These contexts, or settings, include peer groups and families; schools, neighbourhoods and cities, and also nationwide infrastructures that foster connections between school-based and out-of-school learning. The articles in this special issue of Digital Education Review shed light on these topics and advance our understanding of the theories that deal with learning across various settings and times, and how to promote more equitable youth learning across these settings

Structural integrity of the substantia nigra and subthalamic nucleus predicts flexibility of instrumental learning in older-age individuals

Flexible instrumental learning is required to harness the appropriate behaviors to obtain rewards and to avoid punishments. The precise contribution of dopaminergic midbrain regions (substantia nigra/ventral tegmental area [SN/VTA]) to this form of behavioral adaptation remains unclear. Normal aging is associated with a variable loss of dopamine neurons in the SN/VTA. We therefore tested the relationship between flexible instrumental learning and midbrain structural integrity. We compared task performance on a probabilistic monetary go/no-go task, involving trial and error learning of: "go to win," "no-go to win," "go to avoid losing," and "no-go to avoid losing" in 42 healthy older adults to previous behavioral data from 47 younger adults. Quantitative structural magnetization transfer images were obtained to index regional structural integrity. On average, both some younger and some older participants demonstrated a behavioral asymmetry whereby they were better at learning to act for reward ("go to win" > "no-go to win"), but better at learning not to act to avoid punishment ("no-go to avoid losing" > "go to avoid losing"). Older, but not younger, participants with greater structural integrity of the SN/VTA and the adjacent subthalamic nucleus could overcome this asymmetry. We show that interindividual variability among healthy older adults of the structural integrity within the SN/VTA and subthalamic nucleus relates to effective acquisition of competing instrumental responses

PaaS-IaaS Inter-Layer Adaptation in an Energy-Aware Cloud Environment

Cloud computing providers resort to a variety of techniques to improve energy consumption at each level of the cloud computing stack. Most of these techniques consider resource-level energy optimization at IaaS layer. This paper argues energy gains can be obtained by creating a cooperation between the PaaS layer (in charge of hosting the application/service) and the IaaS layer (in charge of handling the computing resources). It presents a novel method based on steering information and decision taking to trigger the PaaS and IaaS layers to adapt their energy mode in service operation, therefore enabling the Cloud stack to actively adapt to changing situations. Experimental results demonstrate such adaptation achieves dynamic energy management in each of the PaaS and IaaS cloud layers

Energy Efficiency Support through Intra-Layer Cloud Stack Adaptation

Energy consumption is a key concern in cloud computing. The paper reports on a cloud architecture to support energy efficiency at service construction, deployment, and operation. This is achieved through SaaS, PaaS and IaaS intra-layer self-adaptation in isolation. The self-adaptation mechanisms are discussed, as well as their implementation and evaluation. The experimental results show that the overall architecture is capable of adapting to meet the energy goals of applications on a per layer basis

Changing Patient and Public Beliefs About Antimicrobials and Antimicrobial Resistance (AMR) Using a Brief Digital Intervention.

BBackground: A key driver of antimicrobial resistance (AMR) is patient demand for unnecessary antibiotics, which is driven by patients’ beliefs about antibiotics and AMR. Few interventions have targeted beliefs to reduce inappropriate demand. Objective: To examine whether a brief, online algorithm-based intervention can change beliefs that may lead to inappropriate antibiotic demand (i.e. perceptions of antibiotic necessity and lack of concern about antibiotic harm). Design: Pre- and post-intervention study. Participants: Participants were 18 years or older, and residing in the United Kingdom, who self-selected to participate via Amazon mTurk, an online survey plaform, and via research networks. Intervention: Participants were presented with a hypothetical situation of cold and flu symptoms, then exposed to the intervention. The online intervention comprised: 1) a profiling tool identifying individual beliefs (antibiotic necessity, concerns, and knowledge) driving inappropriate antibiotic demand; 2) messages designed to change beliefs and knowledge (i.e. reduce antibiotic necessity, and increase antibiotic concerns and knowledge), and 3) an algorithm linking specific messages to specific beliefs and knowledge. Main measures: The profiling tool was repeated immediately after the intervention and compared with baseline scores to assess change in beliefs. A paired samples t-test was used to determine intervention effect. Key Results: A total of 100 respondents completed the study. A significant change in beliefs relating to inappropriate demand was observed after the intervention, with a reduction in beliefs about antibiotic necessity (t = 7.254; p < 0.0001), an increase in antibiotic concerns (t = −7.214; p < 0.0001), and increases in antibiotic and AMR knowledge (t = −4.651; p < 0.0001). Conclusion: This study is the first to demonstrate that patient beliefs about antibiotics and AMR associated with inappropriate demand can be changed by a brief, tailored online intervention. This has implications for the design of future interventions to reduce unnecessary antimicrobial use

Intoxicación por paraquat : revisión

En este trabajo se revisan las características de la intoxicación por paraquat, y se presentan 15 casos clínicos altamente sugestivos de dicha intoxicación. El paraquat es un compuesto bipiridilo ampliamente usado en agricultura. Debido a que la intoxicación tiene efectos progresivos e irreversibles, es importante conocer la posibilidad de acceso al tóxico, pero ello muchas veces no es posible. Dado que el diagnóstico muchas veces es difícil para el clínico, la observación de un distress respiratorio severo, que empeora progresivamente en ausencia de signos radiológicos significativos, justifica un diagnóstico presuntivo de intoxicación por paraquat.In this work, we review the characteristics of paraquat poisoning and compare it with 15 clinical cases highly suggestive of this poisoning. Paraquat is a bipyridzlium compound, widely used as a contact herbicide in agriculture. Because the poisoning has progressive and irreversible effects, it's important to know a definitive history of acces to paraquat, but it 's difficult. Because the problem of diagnosis remains difficult for the practitioner; a clinical features of progressively worsening respiratory distress, in absence of radiógraphic demonstration of adequate cause of dyspnoea, justify a pressumptive diagnosis of paraquat poisoning