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  1 / 9279 MEDLINE  
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PMID:27775387
Autor:Murillo AL; Safan M; Castillo-Chavez C; Phillips ED; Wadhera D
Endereço:Simon A Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, United States. email: Anarina.Murillo@asu.edu.
Título:Modeling eating behaviors: The role of environment and positive food association learning via a Ratatouille effect.
Fonte:Math Biosci Eng; 13(4):841-855, 2016 08 01.
ISSN:1551-0018
País de publicação:United States
Idioma:eng
Resumo:Eating behaviors among a large population of children are studied as a dynamic process driven by nonlinear interactions in the sociocultural school environment. The impact of food association learning on diet dynamics, inspired by a pilot study conducted among Arizona children in Pre-Kindergarten to 8th grades, is used to build simple population-level learning models. Qualitatively, mathematical studies are used to highlight the possible ramifications of instruction, learning in nutrition, and health at the community level. Model results suggest that nutrition education programs at the population-level have minimal impact on improving eating behaviors, findings that agree with prior field studies. Hence, the incorporation of food association learning may be a better strategy for creating resilient communities of healthy and non-healthy eaters. A Ratatouille effect can be observed when food association learners become food preference learners, a potential sustainable behavioral change, which in turn, may impact the overall distribution of healthy eaters. In short, this work evaluates the effectiveness of population-level intervention strategies and the importance of institutionalizing nutrition programs that factor in economical, social, cultural, and environmental elements that mesh well with the norms and values in the community.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.


  2 / 9279 MEDLINE  
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PMID:28464964
Autor:Giunti G; Benelli G; Palmeri V; Canale A
Endereço:Department of Agriculture,University "Mediterranea" of Reggio Calabria,Loc. Feo di Vito, 89122 Reggio Calabria,Italy.
Título:Bactrocera oleae-induced olive VOCs routing mate searching in Psyttalia concolor males: impact of associative learning.
Fonte:Bull Entomol Res; 108(1):40-47, 2018 Feb.
ISSN:1475-2670
País de publicação:England
Idioma:eng
Resumo:Olfaction is a key sense routing foraging behaviour in parasitoids. Preferences for food, mate and host stimuli can be innate in parasitic wasps. Alternatively, learning-mediated mechanisms play a crucial role. Females of the braconid parasitoid Psyttalia concolor exploit olfactory cues arising from tephritid hosts and related microhabitats. However, little is known on the olfactory stimuli routing males searching for mates. In this study, we focused on the attractiveness of Bactrocera oleae-induced olive volatiles towards P. concolor males. Furthermore, we evaluated learning occurrence in virgin males, when trained for selected unattractive volatile organic compounds (VOCs) associated with mate rewards. (E)-ß-Ocimene, α-pinene and limonene attracted virgin males in Y-tube bioassays. Unattractive VOCs evoked positive chemotaxis after associative learning training. P. concolor males exposed to VOCs during a successful or unsuccessful mating, showed short-term preference for these VOCs (<1 h). However, memory consolidation was strictly dependent on reward value. Indeed, males experiencing a successful mating showed a fast consolidation into protein dependent long-term memory, appearing after 24 h. On the other hand, males experiencing a less valuable training experience (i.e. unsuccessful courtship), did not show consolidated memory after 24 h. Overall, our findings suggest that P. concolor virgin males may exploit VOCs from the host microhabitat to boost their mate searching activity, thus their reproductive success. However, since learning is a costly process, P. concolor males retained durable memories just in presence of a valuable reward, thus avoiding maladaptive behaviours.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Volatile Organic Compounds)


  3 / 9279 MEDLINE  
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PMID:28458074
Autor:Richmond JL; Zhao J; Weidemann G
Endereço:School of Psychology, University of New South Wales, Sydney, New South Wales 2052, Australia. Electronic address: jrichmond@psy.unsw.edu.au.
Título:I like it by mere association: Conditioning preferences in infants.
Fonte:J Exp Child Psychol; 161:19-31, 2017 Sep.
ISSN:1096-0457
País de publicação:United States
Idioma:eng
Resumo:Preferences have a profound impact on our behavior; however, relatively little is known about how preference formation works early in life. Evaluative conditioning occurs when the valence of an initially neutral object changes when it is paired with a positively or negatively valenced stimulus. It is possible that evaluative conditioning may account for early preference learning; however, the extent to which this kind of learning operates during infancy has not been empirically tested. The aim of the current studies was to assess whether infants' preferences for neutral objects is influenced by pairing them with affective stimuli (Experiment 1: happy vs. angry faces, N=20; Experiment 2: mother vs. stranger faces, N=22). Infants' preferences were tested using both looking time and behavioral choice measures. The results showed that infants tended to choose the object that had been paired with the positive stimulus (Experiment 1: 13/20; Experiment 2: 14/22). Gaze behavior at test did not differentiate between the two objects; however, gaze behavior during conditioning predicted infants' behavioral preference. Only infants who looked longer at the affective stimulus than at the object during learning chose the object that had been paired with positive valence more often than chance. These results suggest that infants' preferences may be influenced by learned associations between objects and affective stimuli, a process akin to evaluative conditioning in adults.
Tipo de publicação: JOURNAL ARTICLE


  4 / 9279 MEDLINE  
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PMID:28821662
Autor:Viswanathan P; Nieder A
Endereço:Animal Physiology, Institute of Neurobiology, University of Tübingen, 72076 Tübingen, Germany.
Título:Visual Receptive Field Heterogeneity and Functional Connectivity of Adjacent Neurons in Primate Frontoparietal Association Cortices.
Fonte:J Neurosci; 37(37):8919-8928, 2017 Sep 13.
ISSN:1529-2401
País de publicação:United States
Idioma:eng
Resumo:The basic organization principles of the primary visual cortex (V1) are commonly assumed to also hold in the association cortex such that neurons within a cortical column share functional connectivity patterns and represent the same region of the visual field. We mapped the visual receptive fields (RFs) of neurons recorded at the same electrode in the ventral intraparietal area (VIP) and the lateral prefrontal cortex (PFC) of rhesus monkeys. We report that the spatial characteristics of visual RFs between adjacent neurons differed considerably, with increasing heterogeneity from VIP to PFC. In addition to RF incongruences, we found differential functional connectivity between putative inhibitory interneurons and pyramidal cells in PFC and VIP. These findings suggest that local RF topography vanishes with hierarchical distance from visual cortical input and argue for increasingly modified functional microcircuits in noncanonical association cortices that contrast V1. Our visual field is thought to be represented faithfully by the early visual brain areas; all the information from a certain region of the visual field is conveyed to neurons situated close together within a functionally defined cortical column. We examined this principle in the association areas, PFC, and ventral intraparietal area of rhesus monkeys and found that adjacent neurons represent markedly different areas of the visual field. This is the first demonstration of such noncanonical organization of these brain areas.
Tipo de publicação: JOURNAL ARTICLE


  5 / 9279 MEDLINE  
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PMID:28779019
Autor:Whitaker LR; Warren BL; Venniro M; Harte TC; McPherson KB; Beidel J; Bossert JM; Shaham Y; Bonci A; Hope BT
Endereço:Behavioral Neuroscience Research Branch and leslie.ramsey@nih.gov.
Título:Bidirectional Modulation of Intrinsic Excitability in Rat Prelimbic Cortex Neuronal Ensembles and Non-Ensembles after Operant Learning.
Fonte:J Neurosci; 37(36):8845-8856, 2017 Sep 06.
ISSN:1529-2401
País de publicação:United States
Idioma:eng
Resumo:Learned associations between environmental stimuli and rewards drive goal-directed learning and motivated behavior. These memories are thought to be encoded by alterations within specific patterns of sparsely distributed neurons called neuronal ensembles that are activated selectively by reward-predictive stimuli. Here, we use the Fos promoter to identify strongly activated neuronal ensembles in rat prelimbic cortex (PLC) and assess altered intrinsic excitability after 10 d of operant food self-administration training (1 h/d). First, we used the Daun02 inactivation procedure in male FosLacZ-transgenic rats to ablate selectively Fos-expressing PLC neurons that were active during operant food self-administration. Selective ablation of these neurons decreased food seeking. We then used male FosGFP-transgenic rats to assess selective alterations of intrinsic excitability in Fos-expressing neuronal ensembles (FosGFP ) that were activated during food self-administration and compared these with alterations in less activated non-ensemble neurons (FosGFP ). Using whole-cell recordings of layer V pyramidal neurons in an brain slice preparation, we found that operant self-administration increased excitability of FosGFP neurons and decreased excitability of FosGFP neurons. Increased excitability of FosGFP neurons was driven by increased steady-state input resistance. Decreased excitability of FosGFP neurons was driven by increased contribution of small-conductance calcium-activated potassium (SK) channels. Injections of the specific SK channel antagonist apamin into PLC increased Fos expression but had no effect on food seeking. Overall, operant learning increased intrinsic excitability of PLC Fos-expressing neuronal ensembles that play a role in food seeking but decreased intrinsic excitability of Fos non-ensembles. Prefrontal cortex activity plays a critical role in operant learning, but the underlying cellular mechanisms are unknown. Using the chemogenetic Daun02 inactivation procedure, we found that a small number of strongly activated Fos-expressing neuronal ensembles in rat PLC play an important role in learned operant food seeking. Using GFP expression to identify Fos-expressing layer V pyramidal neurons in prelimbic cortex (PLC) of FosGFP-transgenic rats, we found that operant food self-administration led to increased intrinsic excitability in the behaviorally relevant Fos-expressing neuronal ensembles, but decreased intrinsic excitability in Fos neurons using distinct cellular mechanisms.
Tipo de publicação: JOURNAL ARTICLE


  6 / 9279 MEDLINE  
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PMID:28763436
Autor:Vohra M; Lemieux GA; Lin L; Ashrafi K
Endereço:Department of Physiology, University of California San Francisco, San Francisco, California, United States of America.
Título:The beneficial effects of dietary restriction on learning are distinct from its effects on longevity and mediated by depletion of a neuroinhibitory metabolite.
Fonte:PLoS Biol; 15(8):e2002032, 2017 Aug.
ISSN:1545-7885
País de publicação:United States
Idioma:eng
Resumo:In species ranging from humans to Caenorhabditis elegans, dietary restriction (DR) grants numerous benefits, including enhanced learning. The precise mechanisms by which DR engenders benefits on processes related to learning remain poorly understood. As a result, it is unclear whether the learning benefits of DR are due to myriad improvements in mechanisms that collectively confer improved cellular health and extension of organismal lifespan or due to specific neural mechanisms. Using an associative learning paradigm in C. elegans, we investigated the effects of DR as well as manipulations of insulin, mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), and autophagy pathways-processes implicated in longevity-on learning. Despite their effects on a vast number of molecular effectors, we found that the beneficial effects on learning elicited by each of these manipulations are fully dependent on depletion of kynurenic acid (KYNA), a neuroinhibitory metabolite. KYNA depletion then leads, in an N-methyl D-aspartate receptor (NMDAR)-dependent manner, to activation of a specific pair of interneurons with a critical role in learning. Thus, fluctuations in KYNA levels emerge as a previously unidentified molecular mechanism linking longevity and metabolic pathways to neural mechanisms of learning. Importantly, KYNA levels did not alter lifespan in any of the conditions tested. As such, the beneficial effects of DR on learning can be attributed to changes in a nutritionally sensitive metabolite with neuromodulatory activity rather than indirect or secondary consequences of improved health and extended longevity.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Receptors, N-Methyl-D-Aspartate); H030S2S85J (Kynurenic Acid)


  7 / 9279 MEDLINE  
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PMID:28758996
Autor:Lawson RP; Mathys C; Rees G
Endereço:Wellcome Trust Centre for Neuroimaging, University College London, London, UK.
Título:Adults with autism overestimate the volatility of the sensory environment.
Fonte:Nat Neurosci; 20(9):1293-1299, 2017 Sep.
ISSN:1546-1726
País de publicação:United States
Idioma:eng
Resumo:Insistence on sameness and intolerance of change are among the diagnostic criteria for autism spectrum disorder (ASD), but little research has addressed how people with ASD represent and respond to environmental change. Here, behavioral and pupillometric measurements indicated that adults with ASD are less surprised than neurotypical adults when their expectations are violated, and decreased surprise is predictive of greater symptom severity. A hierarchical Bayesian model of learning suggested that in ASD, a tendency to overlearn about volatility in the face of environmental change drives a corresponding reduction in learning about probabilistically aberrant events, thus putatively rendering these events less surprising. Participant-specific modeled estimates of surprise about environmental conditions were linked to pupil size in the ASD group, thus suggesting heightened noradrenergic responsivity in line with compromised neural gain. This study offers insights into the behavioral, algorithmic and physiological mechanisms underlying responses to environmental volatility in ASD.
Tipo de publicação: JOURNAL ARTICLE


  8 / 9279 MEDLINE  
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PMID:28739583
Autor:Ellwood IT; Patel T; Wadia V; Lee AT; Liptak AT; Bender KJ; Sohal VS
Endereço:Department of Psychiatry.
Título:Tonic or Phasic Stimulation of Dopaminergic Projections to Prefrontal Cortex Causes Mice to Maintain or Deviate from Previously Learned Behavioral Strategies.
Fonte:J Neurosci; 37(35):8315-8329, 2017 Aug 30.
ISSN:1529-2401
País de publicação:United States
Idioma:eng
Resumo:Dopamine neurons in the ventral tegmental area (VTA) encode reward prediction errors and can drive reinforcement learning through their projections to striatum, but much less is known about their projections to prefrontal cortex (PFC). Here, we studied these projections and observed phasic VTA-PFC fiber photometry signals after the delivery of rewards. Next, we studied how optogenetic stimulation of these projections affects behavior using conditioned place preference and a task in which mice learn associations between cues and food rewards and then use those associations to make choices. Neither phasic nor tonic stimulation of dopaminergic VTA-PFC projections elicited place preference. Furthermore, substituting phasic VTA-PFC stimulation for food rewards was not sufficient to reinforce new cue-reward associations nor maintain previously learned ones. However, the same patterns of stimulation that failed to reinforce place preference or cue-reward associations were able to modify behavior in other ways. First, continuous tonic stimulation maintained previously learned cue-reward associations even after they ceased being valid. Second, delivering phasic stimulation either continuously or after choices not previously associated with reward induced mice to make choices that deviated from previously learned associations. In summary, despite the fact that dopaminergic VTA-PFC projections exhibit phasic increases in activity that are time locked to the delivery of rewards, phasic activation of these projections does not necessarily reinforce specific actions. Rather, dopaminergic VTA-PFC activity can control whether mice maintain or deviate from previously learned cue-reward associations. Dopaminergic inputs from ventral tegmental area (VTA) to striatum encode reward prediction errors and reinforce specific actions; however, it is currently unknown whether dopaminergic inputs to prefrontal cortex (PFC) play similar or distinct roles. Here, we used bulk Ca imaging to show that unexpected rewards or reward-predicting cues elicit phasic increases in the activity of dopaminergic VTA-PFC fibers. However, in multiple behavioral paradigms, we failed to observe reinforcing effects after stimulation of these fibers. In these same experiments, we did find that tonic or phasic patterns of stimulation caused mice to maintain or deviate from previously learned cue-reward associations, respectively. Therefore, although they may exhibit similar patterns of activity, dopaminergic inputs to striatum and PFC can elicit divergent behavioral effects.
Tipo de publicação: JOURNAL ARTICLE


  9 / 9279 MEDLINE  
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PMID:28694337
Autor:Oyarzún JP; Morís J; Luque D; de Diego-Balaguer R; Fuentemilla L
Endereço:Department of Cognition, Development and Educational Psychology, University of Barcelona, 08035 Barcelona, Spain, javi.oyarzunb@gmail.com.
Título:Targeted Memory Reactivation during Sleep Adaptively Promotes the Strengthening or Weakening of Overlapping Memories.
Fonte:J Neurosci; 37(32):7748-7758, 2017 Aug 09.
ISSN:1529-2401
País de publicação:United States
Idioma:eng
Resumo:System memory consolidation is conceptualized as an active process whereby newly encoded memory representations are strengthened through selective memory reactivation during sleep. However, our learning experience is highly overlapping in content (i.e., shares common elements), and memories of these events are organized in an intricate network of overlapping associated events. It remains to be explored whether and how selective memory reactivation during sleep has an impact on these overlapping memories acquired during awake time. Here, we test in a group of adult women and men the prediction that selective memory reactivation during sleep entails the reactivation of associated events and that this may lead the brain to adaptively regulate whether these associated memories are strengthened or pruned from memory networks on the basis of their relative associative strength with the shared element. Our findings demonstrate the existence of efficient regulatory neural mechanisms governing how complex memory networks are shaped during sleep as a function of their associative memory strength. Numerous studies have demonstrated that system memory consolidation is an active, selective, and sleep-dependent process in which only subsets of new memories become stabilized through their reactivation. However, the learning experience is highly overlapping in content and thus events are encoded in an intricate network of related memories. It remains to be explored whether and how memory reactivation has an impact on overlapping memories acquired during awake time. Here, we show that sleep memory reactivation promotes strengthening and weakening of overlapping memories based on their associative memory strength. These results suggest the existence of an efficient regulatory neural mechanism that avoids the formation of cluttered memory representation of multiple events and promotes stabilization of complex memory networks.
Tipo de publicação: JOURNAL ARTICLE


  10 / 9279 MEDLINE  
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PMID:28676576
Autor:Sliwinska MW; Violante IR; Wise RJS; Leech R; Devlin JT; Geranmayeh F; Hampshire A
Endereço:Department of Medicine, Imperial College London, London, W12 0NN, United Kingdom, and m.sliwinska@gmail.com.
Título:Stimulating Multiple-Demand Cortex Enhances Vocabulary Learning.
Fonte:J Neurosci; 37(32):7606-7618, 2017 Aug 09.
ISSN:1529-2401
País de publicação:United States
Idioma:eng
Resumo:It is well established that networks within multiple-demand cortex (MDC) become active when diverse skills and behaviors are being learnt. However, their causal role in learning remains to be established. In the present study, we first performed functional magnetic resonance imaging on healthy female and male human participants to confirm that MDC was most active in the initial stages of learning a novel vocabulary, consisting of pronounceable nonwords (pseudowords), each associated with a picture of a real object. We then examined, in healthy female and male human participants, whether repetitive transcranial magnetic stimulation of a frontal midline node of the cingulo-opercular MDC affected learning rates specifically during the initial stages of learning. We report that stimulation of this node, but not a control brain region, substantially improved both accuracy and response times during the earliest stage of learning pseudoword-object associations. This stimulation had no effect on the processing of established vocabulary, tested by the accuracy and response times when participants decided whether a real word was accurately paired with a picture of an object. These results provide evidence that noninvasive stimulation to MDC nodes can enhance learning rates, thereby demonstrating their causal role in the learning process. We propose that this causal role makes MDC candidate target for experimental therapeutics; for example, in stroke patients with aphasia attempting to reacquire a vocabulary. Learning a task involves the brain system within which that specific task becomes established. Therefore, successfully learning a new vocabulary establishes the novel words in the language system. However, there is evidence that in the early stages of learning, networks within multiple-demand cortex (MDC), which control higher cognitive functions, such as working memory, attention, and monitoring of performance, become active. This activity declines once the task is learnt. The present study demonstrated that a node within MDC, located in midline frontal cortex, becomes active during the early stage of learning a novel vocabulary. Importantly, noninvasive brain stimulation of this node improved performance during this stage of learning. This observation demonstrated that MDC activity is important for learning.
Tipo de publicação: JOURNAL ARTICLE



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