Fasting for 24 Hours Heightens Reward from Food and Food-Related Cues

Introduction

We examined the impact of a 24 hour complete fast (vs. fed state) on two measures of food reward: 1) ‘wanting’, as measured by response to food images and by the relative-reinforcing value of food (RRV), and 2) ‘liking’, as measured by response to food images and the hedonic evaluation of foods consumed.

Methods

Utilizing a randomized crossover design, 15 subjects (9 male; 6 female) aged 28.6±4.5 yrs with body mass index 25.3±1.4 kg/m² were randomized and counterbalanced to normal feeding (FED) and 24-hour fast (FASTED) conditions. Trait characteristics were measured with the Three Factor Eating Questionnaire. Two computer tasks measured food reward: 1) RRV progressive ratio task, 2) explicit ‘liking’ and ‘wanting’ (Leeds Food Preference Questionnaire, LFPQ). Also measured were ad libitum energy intake (EI; buffet) and food ‘liking’ (visual analogue scale) of personalized stimuli.

Results

There were no significant anthropometric changes between conditions. Appetite scores, hedonic ratings of ‘liking’, and ad libitum EI all significantly increased under the FASTED condition (p<0.05). Under the FASTED condition there were significant increases in the RRV of snack foods; similarly, explicit ‘wanting’ and ‘liking’ significantly increased for all food categories. ‘Liking’ of sweet foods remained high across-meals under FASTED, but savory foods decreased in hedonic saliency.

Conclusion

Relative to a fed state, we observed an increase in hedonic ratings of food, the rewarding value of food, and food intake after a 24 hr fast. Alliesthesia to food and food cues is suggested by heightened hedonic ratings under the FASTED condition relative to FED.     

Tinnitus-like “hallucinations” elicited by sensory deprivation in an entropy maximization recurrent neural network

Sensory deprivation has long been known to cause hallucinations or “phantom” sensations, the most common of which is tinnitus induced by hearing loss, affecting 10–20% of the population. An observable hearing loss, causing auditory sensory deprivation over a band of frequencies, is present in over 90% of people with tinnitus. Existing plasticity-based computational models for tinnitus are usually driven by homeostatic mechanisms, modeled to fit phenomenological findings. Here, we use an objective-driven learning algorithm to model an early auditory processing neuronal network, e.g., in the dorsal cochlear nucleus. The learning algorithm maximizes the network’s output entropy by learning the feed-forward and recurrent interactions in the model. We show that the connectivity patterns and responses learned by the model display several hallmarks of early auditory neuronal networks. We further demonstrate that attenuation of peripheral inputs drives the recurrent network towards its critical point and transition into a tinnitus-like state. In this state, the network activity resembles responses to genuine inputs even in the absence of external stimulation, namely, it “hallucinates” auditory responses. These findings demonstrate how objective-driven plasticity mechanisms that normally act to optimize the network’s input representation can also elicit pathologies such as tinnitus as a result of sensory deprivation.     

Functional Brain Networks Develop from a “Local to Distributed” Organization

The mature human brain is organized into a collection of specialized functional networks that flexibly interact to support various cognitive functions. Studies of development often attempt to identify the organizing principles that guide the maturation of these functional networks. In this report, we combine resting state functional connectivity MRI (rs-fcMRI), graph analysis, community detection, and spring-embedding visualization techniques to analyze four separate networks defined in earlier studies. As we have previously reported, we find, across development, a trend toward ‘segregation’ (a general decrease in correlation strength) between regions close in anatomical space and ‘integration’ (an increased correlation strength) between selected regions distant in space. The generalization of these earlier trends across multiple networks suggests that this is a general developmental principle for changes in functional connectivity that would extend to large-scale graph theoretic analyses of large-scale brain networks. Communities in children are predominantly arranged by anatomical proximity, while communities in adults predominantly reflect functional relationships, as defined from adult fMRI studies. In sum, over development, the organization of multiple functional networks shifts from a local anatomical emphasis in children to a more “distributed” architecture in young adults. We argue that this “local to distributed” developmental characterization has important implications for understanding the development of neural systems underlying cognition. Further, graph metrics (e.g., clustering coefficients and average path lengths) are similar in child and adult graphs, with both showing “small-world”-like properties, while community detection by modularity optimization reveals stable communities within the graphs that are clearly different between young children and young adults. These observations suggest that early school age children and adults both have relatively efficient systems that may solve similar information processing problems in divergent ways.     

A Moist Crevice for Word Aversion: In Semantics Not Sounds

Why do people self-report an aversion to words like “moist”? The present studies represent an initial scientific exploration into the phenomenon of word aversion by investigating its prevalence and cause. Results of five experiments indicate that about 10–20% of the population is averse to the word “moist.” This population often speculates that phonological properties of the word are the cause of their displeasure. However, data from the current studies point to semantic features of the word–namely, associations with disgusting bodily functions–as a more prominent source of peoples’ unpleasant experience. “Moist,” for averse participants, was notable for its valence and personal use, rather than imagery or arousal–a finding that was confirmed by an experiment designed to induce an aversion to the word. Analyses of individual difference measures suggest that word aversion is more prevalent among younger, more educated, and more neurotic people, and is more commonly reported by females than males.     

The traits of “trait ecologists”: An analysis of the use of trait and functional trait terminology

Trait and functional trait approaches have revolutionized ecology improving our understanding of community assembly, species coexistence, and biodiversity loss. Focusing on traits promotes comparability across spatial and organizational scales, but terms must be used consistently. While several papers have offered definitions, it remains unclear how ecologists operationalize “trait” and “functional trait” terms. Here, we evaluate how researchers and the published literatures use these terms and explore differences among subdisciplines and study systems (taxa and biome). By conducting both a survey and a literature review, we test the hypothesis that ecologists’ working definition of “trait” is adapted or altered when confronting the realities of collecting, analyzing and presenting data. From 486 survey responses and 712 reviewed papers, we identified inconsistencies in the understanding and use of terminology among researchers, but also limited inclusion of definitions within the published literature. Discrepancies were not explained by subdiscipline, system of study, or respondent characteristics, suggesting there could be an inconsistent understanding even among those working in related topics. Consistencies among survey responses included the use of morphological, phonological, and physiological traits. Previous studies have called for unification of terminology; yet, our study shows that proposed definitions are not consistently used or accepted. Sources of disagreement include trait heritability, defining and interpreting function, and dealing with organisms in which individuals are not clearly recognizable. We discuss and offer guidelines for overcoming these disagreements. The diversity of life on Earth means traits can represent different features that can be measured and reported in different ways, and thus, narrow definitions that work for one system will fail in others. We recommend ecologists embrace the breadth of biodiversity using a simplified definition of “trait” more consistent with its common use. Trait‐based approaches will be most powerful if we accept that traits are at least as diverse as trait ecologists.     

Desire and Dread from the Nucleus Accumbens: Cortical Glutamate and Subcortical GABA Differentially Generate Motivation and Hedonic Impact in the Rat

Background

GABAergic signals to the nucleus accumbens (NAc) shell arise from predominantly subcortical sources whereas glutamatergic signals arise mainly from cortical-related sources. Here we contrasted GABAergic and glutamatergic generation of hedonics versus motivation processes, as a proxy for comparing subcortical and cortical controls of emotion. Local disruptions of either signals in medial shell of NAc generate intense motivated behaviors corresponding to desire and/or dread, along a rostrocaudal gradient. GABA or glutamate disruptions in rostral shell generate appetitive motivation whereas disruptions in caudal shell elicit fearful motivation. However, GABA and glutamate signals in NAc differ in important ways, despite the similarity of their rostrocaudal motivation gradients.

Methodology/Principal Findings

Microinjections of a GABA_A agonist (muscimol), or of a glutamate AMPA antagonist (DNQX) in medial shell of rats were assessed for generation of hedonic “liking” or “disliking” by measuring orofacial affective reactions to sucrose-quinine taste. Motivation generation was independently assessed measuring effects on eating versus natural defensive behaviors. For GABAergic microinjections, we found that the desire-dread motivation gradient was mirrored by an equivalent hedonic gradient that amplified affective taste “liking” (at rostral sites) versus “disliking” (at caudal sites). However, manipulation of glutamatergic signals completely failed to alter pleasure-displeasure reactions to sensory hedonic impact, despite producing a strong rostrocaudal gradient of motivation.

Conclusions/Significance

We conclude that the nucleus accumbens contains two functional affective keyboards for amino-acid signals: a motivation-generating keyboard and a hedonic-generating keyboard. Corticolimbic glutamate signals and subcortical GABA signals equivalently engage the motivation keyboard to generate desire and-or dread. Only subcortical GABA signals additionally engage the hedonic keyboard to amplify affective “liking” and “disliking” reactions. We thus suggest that top-down cortical glutamate signals powerfully regulate motivation components, but are relatively unable to penetrate core hedonic components of emotion. That may carry implications of limits to therapeutic regulation of pathological emotions.     

Ultrastructure of Thiothrix spp. and “Type 021N” Bacteria

The ultrastructural features of two groups of filamentous sulfur bacteria, Thiothrix spp. and an unnamed organism designated “type 021N,” were examined by transmission electron microscopy. Negative staining of whole cells and filaments with uranyl acetate revealed the presence of tufts of fimbriae located at the ends of individual gonidia of Thiothrix sp. strain A1 and “type 021N” strain N7. Holdfast material present at the center of mature rosettes was observed in thin sections stained with ruthenium red. A clearly defined sheath enveloped the trichomes of two of three Thiothrix strains but was absent from “type 021N” filaments. The outer cell wall appeared more complex in “type 021N” strains than in Thiothrix isolates. Bulbs or clusters of irregularly shaped cells, often present in filaments of “type 021N” bacteria, appeared to result from crosswalls which formed at angles oblique to the filament axis. The multicellular nature of these sulfur bacteria was apparent in that only the cytoplasmic membrane and peptidoglycan layer of the cell wall were involved in the septation process. Sulfur inclusions which developed in the presence of sodium thiosulfate were enclosed by a single-layered envelope and located within invaginations of the cytoplasmic membrane.     

“Candidatus Accumulibacter” Population Structure in Enhanced Biological Phosphorus Removal Sludges as Revealed by Polyphosphate Kinase Genes

We investigated the fine-scale population structure of the “Candidatus Accumulibacter” lineage in enhanced biological phosphorus removal (EBPR) systems using the polyphosphate kinase 1 gene (ppk1) as a genetic marker. We retrieved fragments of “Candidatus Accumulibacter” 16S rRNA and ppk1 genes from one laboratory-scale and several full-scale EBPR systems. Phylogenies reconstructed using 16S rRNA genes and ppk1 were largely congruent, with ppk1 granting higher phylogenetic resolution and clearer tree topology and thus serving as a better genetic marker than 16S rRNA for revealing population structure within the “Candidatus Accumulibacter” lineage. Sequences from at least five clades of “Candidatus Accumulibacter” were recovered by ppk1-targeted PCR, and subsequently, specific primer sets were designed to target the ppk1 gene for each clade. Quantitative real-time PCR (qPCR) assays using “Candidatus Accumulibacter”-specific 16S rRNA and “Candidatus Accumulibacter” clade-specific ppk1 primers were developed and conducted on three laboratory-scale and nine full-scale EBPR samples and two full-scale non-EBPR samples to determine the abundance of the total “Candidatus Accumulibacter” lineage and the relative distributions and abundances of the five “Candidatus Accumulibacter” clades. The qPCR-based estimation of the total “Candidatus Accumulibacter” fraction as a proportion of the bacterial community as measured using 16S rRNA genes was not significantly different from the estimation measured using ppk1, demonstrating the power of ppk1 as a genetic marker for detection of all currently defined “Candidatus Accumulibacter” clades. The relative distributions of “Candidatus Accumulibacter” clades varied among different EBPR systems and also temporally within a system. Our results suggest that the “Candidatus Accumulibacter” lineage is more diverse than previously realized and that different clades within the lineage are ecologically distinct.     

Short Peptide Induces an “Uncultivable” Microorganism To Grow In Vitro

Microorganisms comprise the bulk of biodiversity, but only a small fraction of this diversity grows on artificial media. This phenomenon was noticed almost a century ago, repeatedly confirmed, and termed the “great plate count anomaly.” Advances in microbial cultivation improved microbial recovery but failed to explain why most microbial species do not grow in vitro. Here we show that at least some of such species can form domesticated variants capable of growth on artificial media. We also present evidence that small signaling molecules, such as short peptides, may be essential factors in initiating growth of nongrowing cells. We identified one 5-amino-acid peptide, LQPEV, that at 3.5 nM induces the otherwise “uncultivable” strain Psychrobacter sp. strain MSC33 to grow on standard media. This demonstrates that the restriction preventing microbial in vitro growth may be different from those offered to date to explain the “great plate count anomaly,” such as deficiencies in nutrient composition and concentrations in standard media, medium toxicity, and inappropriate incubation time. Growth induction of MSC33 illustrates that some microorganisms do not grow in vitro because they are removed from their native communities and the signals produced therein. “Uncultivable” species represent the largest source of unexplored biodiversity, and provide remarkable opportunities for both basic and applied research. Access to cultures of some of these species should be possible through identification of the signaling compounds necessary for growth, their addition to standard medium formulations, and eventual domestication.     

Differential Sensitivity of “Old” versus “New” APOBEC3G to Human Immunodeficiency Virus Type 1 Vif

HIV-1 Vif counteracts the antiviral activity of APOBEC3G by inhibiting its encapsidation into virions. Here, we compared the relative sensitivity to Vif of APOBEC3G in stable HeLa cells containing APOBEC3G (HeLa-A3G cells) versus that of newly synthesized APOBEC3G. We observed that newly synthesized APOBEC3G was more sensitive to degradation than preexisting APOBEC3G. Nevertheless, preexisting and transiently expressed APOBEC3G were packaged with similar efficiencies into vif-deficient human immunodeficiency virus type 1 (HIV-1) virions, and Vif inhibited the encapsidation of both forms of APOBEC3G into HIV particles equally well. Our results suggest that HIV-1 Vif preferentially induces degradation of newly synthesized APOBEC3G but indiscriminately inhibits encapsidation of “old” and “new” APOBEC3G.     

“整合物种概念”和“分化路上的物种”

已有的各个物种概念对物种的认识类似盲人摸象, 只包含了物种的某一个方面; 而一个分化后期的成熟物种应涵盖了所有的物种概念。但是, 尚未到达分化后期的物种往往又已开始新一轮的物种分化; 自然中存在的多数“物种”处于分化路上。这种循环往复连续分化产生的物种, 存在种间生殖隔离不彻底、基因流频繁发生、网状进化突出等现象。此外, 对于不同的物种对, 最早开始分化的基因以及不同物种概念所要求的条件的分化顺序不是统一的, 而是随机的。定义一个适合所有“分化路上的物种”概念存在较大困难。但是, 应采用尽可能多的物种概念来界定分化路上的物种、发表新种和进行分类处理; 也应承认种间可能广泛存在不完全的生殖隔离和有限的基因流, 即有不属于两个物种群体的杂交或回交个体的存在。这样划分的物种比只依据一个物种概念认定的物种具有更高的客观性和科学性。     

Putting the brakes on phagocytosis: “don't‐eat‐me” signaling in physiology and disease

Timely removal of dying or pathogenic cells by phagocytes is essential to maintaining host homeostasis. Phagocytes execute the clearance process with high fidelity while sparing healthy neighboring cells, and this process is at least partially regulated by the balance of “eat‐me” and “don''t‐eat‐me” signals expressed on the surface of host cells. Upon contact, eat‐me signals activate “pro‐phagocytic” receptors expressed on the phagocyte membrane and signal to promote phagocytosis. Conversely, don''t‐eat‐me signals engage “anti‐phagocytic” receptors to suppress phagocytosis. We review the current knowledge of don''t‐eat‐me signaling in normal physiology and disease contexts where aberrant don''t‐eat‐me signaling contributes to pathology.     

Chemokines act as phosphatidylserine-bound “find-me” signals in apoptotic cell clearance

Removal of apoptotic cells is essential for maintenance of tissue homeostasis. Chemotactic cues termed “find-me” signals attract phagocytes toward apoptotic cells, which selectively expose the anionic phospholipid phosphatidylserine (PS) and other “eat-me” signals to distinguish healthy from apoptotic cells for phagocytosis. Blebs released by apoptotic cells can deliver find-me signals; however, the mechanism is poorly understood. Here, we demonstrate that apoptotic blebs generated in vivo from mouse thymus attract phagocytes using endogenous chemokines bound to the bleb surface. We show that chemokine binding to apoptotic cells is mediated by PS and that high affinity binding of PS and other anionic phospholipids is a general property of many but not all chemokines. Chemokines are positively charged proteins that also bind to anionic glycosaminoglycans (GAGs) on cell surfaces for presentation to leukocyte G protein–coupled receptors (GPCRs). We found that apoptotic cells down-regulate GAGs as they up-regulate PS on the cell surface and that PS-bound chemokines, unlike GAG-bound chemokines, are able to directly activate chemokine receptors. Thus, we conclude that PS-bound chemokines may serve as find-me signals on apoptotic vesicles acting at cognate chemokine receptors on leukocytes.

Chemokines attract leukocytes by activating chemokine receptors, but many also bind anionic phospholipids. This study shows that phosphatidylserine-binding chemokines endow extracellular apoptotic bodies with “find-me” signals that trigger phagocyte migration for potential apoptotic cell clearance.     

Cloning of the spoT Gene of “Candidatus Phlomobacter fragariae” and Development of a PCR-Restriction Fragment Length Polymorphism Assay for Detection of the Bacterium in Insects

Marginal chlorosis is a new disease of strawberry in which the uncultured phloem-restricted proteobacterium “Candidatus Phlomobacter fragariae” is involved. In order to identify the insect(s) vector(s) of this bacterium, homopteran insects have been captured. Because a PCR test based on the 16S rRNA gene (rDNA) applied to these insects was unable to discriminate between “P. fragariae” and other insect-associated proteobacteria, isolation of “P. fragariae” genes other than 16S rDNA was undertaken. Using comparative randomly amplified polymorphic DNAs, an amplicon was specifically amplified from “P. fragariae”-infected strawberry plants. It encodes part of a “P. fragariae” open reading frame sharing appreciable homology with the spoT gene from other proteobacteria. A spoT-based PCR test combined with restriction fragment length polymorphisms was developed and was able to distinguish “P. fragariae” from other insect bacteria. None of the many leafhoppers and psyllids captured during several years in and around infected strawberry fields was found to carry “P. fragariae.” Interestingly however, the “P. fragariae” spoT sequence could be easily detected in whiteflies proliferating on “P. fragariae”-infected strawberry plants under confined greenhouse conditions but not on control whiteflies, indicating that these insects can become infected with the bacterium.     

Temporal Characteristics of Online Syntactic Sentence Planning: An Event-Related Potential Study

During sentence production, linguistic information (semantics, syntax, phonology) of words is retrieved and assembled into a meaningful utterance. There is still debate on how we assemble single words into more complex syntactic structures such as noun phrases or sentences. In the present study, event-related potentials (ERPs) were used to investigate the time course of syntactic planning. Thirty-three volunteers described visually animated scenes using naming formats varying in syntactic complexity: from simple words (‘W’, e.g., “triangle”, “red”, “square”, “green”, “to fly towards”), to noun phrases (‘NP’, e.g., “the red triangle”, “the green square”, “to fly towards”), to a sentence (‘S’, e.g., “The red triangle flies towards the green square.”). Behaviourally, we observed an increase in errors and corrections with increasing syntactic complexity, indicating a successful experimental manipulation. In the ERPs following scene onset, syntactic complexity variations were found in a P300-like component (‘S’/‘NP’>‘W’) and a fronto-central negativity (linear increase with syntactic complexity). In addition, the scene could display two actions - unpredictable for the participant, as the disambiguation occurred only later in the animation. Time-locked to the moment of visual disambiguation of the action and thus the verb, we observed another P300 component (‘S’>‘NP’/‘W’). The data show for the first time evidence of sensitivity to syntactic planning within the P300 time window, time-locked to visual events critical of syntactic planning. We discuss the findings in the light of current syntactic planning views.     

A Burst-Based “Hebbian” Learning Rule at Retinogeniculate Synapses Links Retinal Waves to Activity-Dependent Refinement

Patterned spontaneous activity in the developing retina is necessary to drive synaptic refinement in the lateral geniculate nucleus (LGN). Using perforated patch recordings from neurons in LGN slices during the period of eye segregation, we examine how such burst-based activity can instruct this refinement. Retinogeniculate synapses have a novel learning rule that depends on the latencies between pre- and postsynaptic bursts on the order of one second: coincident bursts produce long-lasting synaptic enhancement, whereas non-overlapping bursts produce mild synaptic weakening. It is consistent with “Hebbian” development thought to exist at this synapse, and we demonstrate computationally that such a rule can robustly use retinal waves to drive eye segregation and retinotopic refinement. Thus, by measuring plasticity induced by natural activity patterns, synaptic learning rules can be linked directly to their larger role in instructing the patterning of neural connectivity.     

The most unkindest cut

When universities need to make staffing cuts to balance the books, do they always do so in the fairest and most rational manner?

Universities, like most other large organizations, undergo periodic restructuring, expansions and contractions, driven largely by changes in their balance sheet. The contractions are often abrupt and painful. Typically, this outcome is preceded by a period when the top management already perceived a growing problem but postponed action because of its debilitating effects on morale and on the organization’s core functions, in the hope that “something might turn up” that would obviate the need for drastic cuts. Most often, something does not turn up, and the cuts end up being even more severe.The first sign of trouble is usually a “message to all staff” that seems to come out of the blue, couched in the most anodyne of terms, or even trying to put a positive spin on what is a fundamentally destructive process. But staff about to be made redundant do not appreciate being referred to as “person‐years”. It also seems completely pointless to dress up more or less arbitrary decisions on whom to terminate as “negotiations”, thus apportioning a share of blame to the union representatives who have not much say in these “negotiations” anyway. Although the cuts typically affect non‐academic staff, such as lab technicians, IT and audiovisual support, financial administrators, providers of student welfare services or travel and hospitality arrangers, academic staff at all levels are sometimes affected as well.Most of us can read between the lines and find disingenuous statements of this type insulting rather than reassuring. Let me translate this for you into plain English:“Due to the fact that our senior management has totally screwed up the university’s finances, we need to decrease our staff costs by 20%. Since most staff would not accept to do the same work for 20% less pay, we will instead just fire 20% of the staff. If you are one of the 20% who are able to do your job and have been properly trained, we strongly advise you to immediately seek employment elsewhere. After all, you might find yourselves fired in the next round of cuts, if these ones don’t prove sufficient”.The duties of the 20% who leave will be transferred to the 80% who remain. Since they will be required to carry out additional tasks beyond those that they currently undertake but were never trained to perform in the first place, it is natural that many of them will go on permanent sick leave or retire early, thus reducing our staff costs further and avoiding undue stress on persons we have failed to train properly.As a result, academic staff currently engaged on less quantifiable activities such as research and teaching must shoulder some of the burden. We hope to avoid firing academic staff but be aware that you may also be terminated if performance targets are missed, especially if you are unable to undertake simple obligations to help the university to function properly instead of wasting all your energy on research and teaching.The next phase of this process will be the outsourcing of many of the duties that the poorly trained 80% of staff and academics cannot do or are unwilling to do. We will invite tenders from different companies and always pick the lowest bidder, regardless of the quality of the services they are able to perform. However, be aware that academic staff who make use of these services must employ the companies contracted by the university and no others. You will also have to pay for these services from research grants or other income.Spin‐off companies that you have created could also bid for some of these services, which might enable you to cover the costs during the 2–3 years before your fledgling company goes bankrupt.Please also consider if and how you can outsource your own research and teaching, which would enable us to fire academic staff as well, in any future cost‐cutting exercise.If this process is successful, the university hopes to recycle any excess savings into a new round of Strategic Interconvertibility and Sustainable Innovation (SISI) grants.And above all, please do remember and implement our university’s new slogan “The only useful research is market research”. Kit from HR, aka Howy Jacobs