Random reward priming is task-contingent: The robustness of the 1-trial reward priming effect

Publisher's version (útgefin grein)Consistent financial reward of particular features influences the allocation of visual attention in many ways. More surprising are 1-trial reward priming effects on attention where reward schedules are random and reward on one trial influences attentional allocation on the next. Those findings are thought to reflect that rewarded features become more salient than unrewarded ones on the subsequent trial. Here we attempt to conceptually replicate this effect, testing its generalizability. In three versions of an analogous paradigm to the additional singleton paradigm involving singleton search for a Gabor patch of odd spatial frequency we found no evidence of reward priming, while we only partially replicate the reward priming in the exact original paradigm tested by Hickey and colleagues. The results cast doubt on the proposal that random reward enhances salience, suggested in the original papers, and highlight the need for a more nuanced account. In many other paradigms reward effects have been found to progress gradually, becoming stronger as they build up, and we argue that for robust reward priming, reward schedules need to be more consistent than in the original 1-trial reward priming paradigm.Peer reviewe

Brain abscess - overview.

Heilaígerð er lífshættulegur sjúkdómur sem krefst skjótrar greiningar og meðferðar. Á undanförnum áratugum hafa horfurnar batnað til muna og dánartíðni lækkað úr 50% í 10%. Þessi þróun endurspeglar bætta myndgreiningu, skurðtækni og sýklalyfjameðferð. Ígerð í heila er staðbundin sýking. Fyrst verður til afmörkuð heilabólga sem þróast á tveimur vikum yfir í dauðan vef og samansafn af greftri sem afmarkast af vel blóðnærðu hýði. Sýkingin sem veldur ígerðinni getur borist inn í heilavefinn eftir þremur ólíkum leiðum. Í fyrsta lagi bein dreifing sýkingar frá afholum nefs, tönnum, miðeyra eða stikilbeini. Í öðru lagi blóðborin orsök þar sem sýking hefur dreift sér frá fjarlægum stað til heilans með tilflutningi blóðs. Í þriðja lagi í kjölfar heilaaðgerðar eða höfuðáverka þar sem rof verður á heilakúpunni. Allt að 30% heilaígerða eru af óþekktum orsökum þar sem upprunalegur sýkingarstaður finnst ekki þrátt fyrir ítarlega leit. Algengustu einkennin eru versnandi höfuðverkur og staðbundin taugaeinkenni. Flog koma fram hjá 25-50%. Meðferð heilaígerða er fólgin í skurðaðgerð og sýklalyfjameðferð.Brain abscess is a life threatening illness, demanding rapid diagnosis and treatment. Its development requires seeding of an organism into the brain parenchyma, often in an area of damaged brain tissue or in a region with poor microcirculation. The lesion evolves from a cerebritis stage to capsule formation. Brain abscesses can be caused by contiguous or haematogenous spread of an infection, or by head trauma/ neurosurgical procedure. The most common presentation is that of headache and vomiting due to raised intracranial pressure. Seizures have been reported in up to 50% of cases. Focal neurological deficits may be present, depending on the location of the lesion. Treatment of a brain abscess involves aspiration or excision, along with parenteral antibiotic therapy. The outcome has improved dramatically in the last decades due to improvement in diagnostic techniques, neurosurgery, and broad-spectrum antibiotics. The authors provide an overview of the pathogenesis, diagnosis and management of brain abscesses

Long-term data reveal contrasting impacts of native versus invasive nest predators in Iceland

Bird species on islands are strongly impacted by biological invasions, with the Icelandic common eider (Somateria mollissima borealis) being particularly threatened. Down collection by local families in Breiðafjörður, West Iceland, provided long-term datasets of nests from two archipelagos, covering 95 islands over 123 years and 39 islands over 27 years, respectively. Using these exceptional datasets, we found that the arrival of the invasive semi-aquatic American mink (Neogale vison) was a more impactful driver of population dynamics than climate. This invasive predator heavily reduced eider nest numbers by ca. 60% in the Brokey archipelago. In contrast, we detected an apparently adaptive response to the return of the native fox in the Purkey archipelago, with dense nests on islands inaccessible to the fox and no apparent impact on eider populations. This difference might be due to the eiders lacking a joint evolutionary history with the mink and therefore lacking appropriate antipredator responses

Contributions of feather microstructure to eider down insulation properties

Insulation is an essential component of nest structure that helps provide incubation requirements for birds. Many species of waterfowl breed in high latitudes where rapid heat loss can necessitate a high energetic input from parents and use down feathers to line their nests. Common eider Somateria mollissima nest down has exceptional insulating properties but the microstructural mechanisms behind the feather properties have not been thoroughly examined. Here, we hypothesized that insulating properties of nest down are correlated to down feather (plumule) microstructure. We tested the thermal efficiency (fill power) and cohesion of plumules from nests of two Icelandic colonies of wild common eiders and compared them to properties of plumules of wild greylag goose Anser anser. We then used electron microscopy to examine the morphological basis of feather insulating properties. We found that greylag goose down has higher fill power (i.e. traps more air) but much lower cohesion (i.e. less prone to stick together) compared to common eider down. These differences were related to interspecific variation in feather microstructure. Down cohesion increased with the number of barbule microstructures (prongs) that create strong points of contact among feathers. Eider down feathers also had longer barbules than greylag goose down feathers, likely increasing their air-trapping capacity. Feather properties of these two species might reflect the demands of their contrasting evolutionary history. In greylag goose, a temperate, terrestrial species, plumule microstructure may optimize heat trapping. In common eiders, a diving duck that nests in arctic and subarctic waters, plumule structure may have evolved to maximize cohesion over thermal insulation, which would both reduce buoyancy during their foraging dives and enable nest down to withstand strong arctic winds

Contributions of feather microstructure to eider down insulation properties

Insulation is an essential component of nest structure that helps provide incubation requirements for birds. Many species of waterfowl breed in high latitudes where rapid heat loss can necessitate a high energetic input from parents and use down feathers to line their nests. Common eider Somateria mollissima nest down has exceptional insulating properties but the microstructural mechanisms behind the feather properties have not been thoroughly examined. Here, we hypothesized that insulating properties of nest down are correlated to down feather (plumule) microstructure. We tested the thermal efficiency (fill power) and cohesion of plumules from nests of two Icelandic colonies of wild common eiders and compared them to properties of plumules of wild greylag goose Anser anser. We then used electron microscopy to examine the morphological basis of feather insulating properties. We found that greylag goose down has higher fill power (i.e. traps more air) but much lower cohesion (i.e. less prone to stick together) compared to common eider down. These differences were related to interspecific variation in feather microstructure. Down cohesion increased with the number of barbule microstructures (prongs) that create strong points of contact among feathers. Eider down feathers also had longer barbules than greylag goose down feathers, likely increasing their air-trapping capacity. Feather properties of these two species might reflect the demands of their contrasting evolutionary history. In greylag goose, a temperate, terrestrial species, plumule microstructure may optimize heat trapping. In common eiders, a diving duck that nests in arctic and subarctic waters, plumule structure may have evolved to maximize cohesion over thermal insulation, which would both reduce buoyancy during their foraging dives and enable nest down to withstand strong arctic winds