Cognitive phenotype and differential gene expression in a hippocampal homologue in two species of frog

The complexity of an animal's interaction with its physical and/or social environment is thought to be associated with behavioral flexibility and cognitive phenotype, though we know little about this relationship in amphibians. We examined differences in cognitive phenotype in two species of frog with divergent natural histories. The greenand- black poison frog (Dendrobates auratus) is diurnal, displays enduring social interactions, and uses spatially distributed resources during parental care. Tungara frogs (Physalaemus=Engystomops pustulosus) are nocturnal, express only fleeting social interactions, and use ephemeral puddles to breed in a lek-type mating system. Comparing performance in identical discrimination tasks, we find that D. auratus made fewer errors when learning and displayed greater behavioral flexibility in reversal learning tasks than tungara frogs. Further, tungara frogs preferred to learn beacons that can be used in direct guidance whereas D. auratus preferred position cues that could be used to spatially orient relative to the goal. Behavioral flexibility and spatial cognition are associated with hippocampal function in mammals. Accordingly, we examined differential gene expression in the medial pallium, the amphibian homolog of the hippocampus. Our preliminary data indicate that genes related to learning and memory, synaptic plasticity, and neurogenesis were upregulated in D. auratus, while genes related to apoptosis were upregulated in tungara frogs, suggesting that these cellular processes could contribute to the differences in behavioral flexibility and spatial learning we observed between poison frogs and tungara frogs

Sex differences during place learning in the túngara frog

The adaptive specialization hypothesis states that sex differences in cognition are shaped by differences in cognitive demands to solve ecological problems. While it is widely accepted that female mate choice can lead to the evolution of exaggerated male traits, mate choice might also select for different cognitive abilities in males and females. In the túngara frog, Physalaemus (= Engystomops) pustulosus, males call from a fixed position in breeding ponds while females visit multiple males before returning to the preferred mate. Thus, we predicted that females have better place memory than males. We tested this prediction in a place-learning task in which the rewarded arm of a maze was associated with a visual cue. We found that females were able to use the visual cue to solve the task while males were not, even though both males and females could discriminate the cues in an optomotor test. In contrast, males attempted to solve the task using egocentric cues (remember body-turn direction) in spite of the fact that our training procedure interrupted their use of such cues. Finally, we found that males and females had similar motivation to solve the task but females showed a greater ability to inhibit incorrect responses, leading to improved learning. Our finding that females could use a visual cue to remember locations in space is consistent with the idea that place memory could improve sequential mate assessment in túngara frogs

Integrative comparative cognition: Can neurobiology and neurogenomics inform comparative analyses of cognitive phenotype?

A long-standing question in animal behavior is what are the patterns and processes that shape the evolution of cognition? One effective way to address this question is to study cognitive abilities in a broad spectrum of animals. While comparative psychologists have traditionally focused on a narrow range of organisms, today they may work with any number of species, from frogs to birds or bees. This broader range of study species has greatly enriched our understanding of the diversity of cognitive processes among animals. Yet, this diversity has highlighted the fundamental challenge of comparing cognitive processes across animals. An analysis of the neural and molecular mechanisms of cognition may be necessary to solve this problem. The goal of our symposium was to bring together speakers studying a range of species to gain a broadly integrative perspective on cognition while at the same time considering the potentially important role of neurobiology and genomics in addressing the difficult problem of comparing cognition across species. For example, work by MaBouDi et al. indicates that neural constraints on computing power may impact the cognitive processes underlying numerical discrimination in bees. A presentation by Lara LaDage demonstrated how neurobiology can be used to better understand cognition and its evolution in reptiles while Edwards et al. identify the cerebellum as potentially important in the performance of the complex process of nest building. We see that molecular approaches highlight the contributions of the prefrontal cortex and hippocampus to cognitive phenotype across vertebrates while, at the same time, identifying the genes and cellular processes that may contribute to evolution of cognition. The potentially important role of neurogenesis and synaptic plasticity emerge clearly from such studies. Still unanswered is the question of whether molecular tools will contribute to our ability to discriminate convergent/parallel evolution from homology in the evolution of cognitive phenotype

Structure of FcRY, an avian immunoglobulin receptor related to mammalian mannose receptors, and its complex with IgY

Fc receptors transport maternal antibodies across epithelial cell barriers to passively immunize newborns. FcRY, the functional counterpart of mammalian FcRn (a major histocompatibility complex homolog), transfers IgY across the avian yolk sac, and represents a new class of Fc receptor related to the mammalian mannose receptor family. FcRY and FcRn bind immunoglobulins at pH ≤6.5, but not pH ≥7, allowing receptor–ligand association inside intracellular vesicles and release at the pH of blood. We obtained structures of monomeric and dimeric FcRY and an FcRY–IgY complex and explored FcRY's pH-dependent binding mechanism using electron cryomicroscopy (cryoEM) and small-angle X-ray scattering. The cryoEM structure of FcRY at pH 6 revealed a compact double-ring “head,” in which the N-terminal cysteine-rich and fibronectin II domains were folded back to contact C-type lectin-like domains 1–6, and a “tail” comprising C-type lectin-like domains 7–8. Conformational changes at pH 8 created a more elongated structure that cannot bind IgY. CryoEM reconstruction of FcRY dimers at pH 6 and small-angle X-ray scattering analysis at both pH values confirmed both structures. The cryoEM structure of the FcRY–IgY revealed symmetric binding of two FcRY heads to the dimeric FcY, each head contacting the CH4 domain of one FcY chain. FcRY shares structural properties with mannose receptor family members, including a head and tail domain organization, multimerization that may regulate ligand binding, and pH-dependent conformational changes. Our results facilitate understanding of immune recognition by the structurally related mannose receptor family and comparison of diverse methods of Ig transport across evolution

Getting physicians to open the survey: little evidence that an envelope teaser increases response rates

BACKGROUND: Physician surveys are an important tool to assess attitudes, beliefs and self-reported behaviors of this policy relevant group. In order for a physician to respond to a mailed survey, they must first open the envelope. While there is some evidence that package elements can impact physician response rates, the impact of an envelope teaser is unknown. Here we assess this by testing the impact of adding a brightly colored "$25 incentive" sticker to the outside of an envelope on response rates and nonresponse bias in a survey of physicians. METHODS: In the second mailing of a survey assessing physicians' moral beliefs and views on controversial health care topics, initial nonrespondents were randomly assigned to receive a survey in an envelope with a colored "$25 incentive" sticker (teaser group) or an envelope without a sticker (control group). Response rates were compared between the teaser and control groups overall and by age, gender, region of the United States, specialty and years in practice. Nonresponse bias was assessed by comparing the demographic composition of the respondents to the nonrespondents in the experimental and control condition. RESULTS: No significant differences in response rates were observed between the experimental and control conditions overall (p = 0.38) or after stratifying by age, gender, region, or practice type. Within the teaser condition, there was some variation in response rate by years since graduation. There was no independent effect of the teaser on response when simultaneously controlling for demographic characteristics (OR = 0.875, p = 0.4112). CONCLUSIONS: Neither response rates nor nonresponse bias were impacted by the use of an envelope teaser in a survey of physicians in the United States

Learning to learn: Advanced behavioural flexibility in a poison frog

Behavioural flexibility is essential for survival in a world with changing contingencies and its evolution is linked to complex physical and social environments. Serial reversal learning, in which reward contingencies change frequently, is a key indicator of behavioural flexibility. While many vertebrates are capable of serial reversal learning, only birds and mammals have previously been shown to use rule-based decision strategies (e.g. win-stay/lose-shift) to become better at learning changes in reward contingencies across reversals. While the lifestyles of many amphibians have a degree of complexity, the evidence to date suggests limited levels of behavioural flexibility. Here, we show that the poison frog Dendrobates auratus, which has evolved complex parental behaviours that likely depend on remembering locations in a flexible manner, can use a win-stay/lose-shift strategy to increase their behavioural flexibility across sequential changes in the reward contingencies in a visual discrimination task. Furthermore, probe trials demonstrate that the frogs used the provided visual cues to spatially orient in the maze in a manner reminiscent of complex spatial cognition. Our study provides the first evidence of serial reversal learning in frogs and is the first to demonstrate the use of a rule-based learning strategy in a nonavian, nonmammalian species

Charge pumping in a quantum wire driven by a series of local time-periodic potentials

We develop a method to calculate electronic transport properties through a mesoscopic scattering region in the presence of a series of time-periodic potentials. Using the method, the quantum charge pumping driven by time-periodic potentials is studied. Jumps in the pumped current are observed at the peak positions of the Wigner delay time. Our main results in both the weak pumping and strong pumping regimes are consistent with experimental results. More interestingly, we also observed the nonzero pumping at the phase difference phi=0 and addressed its relevance to the experimental result.Comment: 5 page

Phase diagram for morphological transitions of wetting films on chemically structured substrates

Using an interface displacement model we calculate the shapes of thin liquidlike films adsorbed on flat substrates containing a chemical stripe. We determine the entire phase diagram of morphological phase transitions in these films as function of temperature, undersaturation, and stripe widthComment: 15 pages, RevTeX, 7 Figure

Quantum transport and momentum conserving dephasing

We study numerically the influence of momentum-conserving dephasing on the transport in a disordered chain of scatterers. Loss of phase memory is caused by coupling the transport channels to dephasing reservoirs. In contrast to previously used models, the dephasing reservoirs are linked to the transport channels between the scatterers, and momentum conserving dephasing can be investigated. Our setup provides a model for nanosystems exhibiting conductance quantization at higher temperatures in spite of the presence of phononic interaction. We are able to confirm numerically some theoretical predictions.Comment: 7 pages, 4 figure

New determination of the mass of the eta meson at COSY-ANKE

A value for the mass of the eta meson has been determined at the COSY-ANKE facility through the measurement of a set of deuteron laboratory beam momenta and associated 3He center-of-mass momenta in the d+p -> 3He+X reaction. The eta was then identified by the missing-mass peak and the production threshold determined. The individual beam momenta were fixed with a relative precision of 3 x 10^-5 for values around 3 GeV/c by using a polarized deuteron beam and inducing an artificial depolarizing spin resonance, which occurs at a well-defined frequency. The final-state momenta in the two-body d+p -> 3He+eta reaction were investigated in detail by studying the size of the 3He momentum ellipse with the forward detection system of the ANKE spectrometer. Final alignment of the spectrometer for this high precision experiment was achieved through a comprehensive study of the 3He final-state momenta as a function of the center-of-mass angles, taking advantage of the full geometrical acceptance. The value obtained for the mass, m(eta)=(547.873 +- 0.005(stat) +- 0.027(syst)) MeV/c^2, is consistent and competitive with other recent measurements, in which the meson was detected through its decay products.Comment: 11 pages, 11 figures, 3 tables, published versio