Dietary salt levels affect salt preference and learning in larval Drosophila

Drosophila larvae change from exhibiting attraction to aversion as the concentration of salt in a substrate is increased. However, some aversive concentrations appear to act as positive reinforcers, increasing attraction to an odour with which they have been paired. We test whether this surprising dissociation between the unconditioned and conditioned response depends on the larvae's experience of salt concentration in their food. We find that although the point at which a NaCl concentration becomes aversive shifts with different rearing experience, the dissociation remains evident. Testing larvae using a substrate 0.025 M above the NaCl concentration on which the larvae were reared consistently results in aversive choice behaviour but appetitive reinforcement effects.     

Adaptive co-management: How social networks,deliberation and learning affect legitimacy in carnivore management

Adaptive co-management (ACM) is a key concept in science and an increasingly adopted policy response in conservation, associated with a number of positive outcomes. However, the effects and mechanisms of co-management arrangements, including the conditions under which ACM gives rise to higher levels of internal and external legitimacy, are yet to be explored. This endeavor, in turn, requires theoretically driven models providing assumptions and outlining testable hypotheses. Considering the social challenges of ACM and using an institutional change within the Swedish carnivore management system aimed at achieving legitimacy through co-management as an illustrative example, this article develops a conceptual model that encompasses conditions and possible explanations to ACM outcomes. More specifically, drawing on lessons from social theory, we model the impact of three key factors—social networks, deliberation and learning—on the external and internal legitimacy resulting from ACM arrangements. Based on the model proposed, the popular assumptions of ACM outcomes can thus be empirically scrutinized and the conditions for increased legitimacy through ACM arrangements better comprehended.     

Theories of ageing

Ageing is a universal, intrinsic, progressive and deleterious process. Understanding it is of major interest to scientist, physicians as well as to the general population. Critical to this understanding is to formulate comprehensive theories of aging with high predictive and explanatory power. More than 300 theories have been postulated and are reviewed here. The free radical theory of ageing is one of the most prominent and well studied. It was further developed by one of us (JM) in what has become known as the mitochondrial theory of ageing. These theories provide new experimental approaches to further develop our understanding of the phenomenon of ageing.     

Perinatal BPA exposure demasculinizes males in measures of affect but has no effect on water maze learning in adulthood

Bisphenol A (BPA) is an endocrine disrupting agent that can alter the normal gonadal steroid-sensitive sexual differentiation of the brain and behavior. While reproductive behavior and physiology are known to be altered by perinatal exposure to this compound, less is known about BPA's effects on sex differences in learning and measures of affect. In order to evaluate the effects of perinatal BPA treatment on learning and affect in adulthood, we exposed rats to one of five doses of BPA through gestation and lactation then examined adult behavior in the Morris Water Maze (MWM), the Elevated Plus Maze (EPM) and the Forced Swim Test (FST). No effect of BPA was observed in the MWM, but on both the EPM and FST, low doses (5 μg/kg) of BPA eliminated sex differences found between controls; furthermore, a non-monotonic dose-response observed in previous studies was confirmed for these tasks. Overall, our study adds to the growing data suggesting that BPA interferes with the normal development of affective behaviors in a non-linear, dose-dependent manner.     

Economies of affect

Cet article développe le concept des «économies de l'affect>> pour attirer l'attention des anthropologues sur le rôle de l'affect dans la facilitation des transformations économiques. Il s'appuie sur les résultats de deux projets de terrain ethnographiques, l'un au Mexique et l'autre en Indonésie, pour montrer comment l'affect a été mobilisé pour créer des sujets pouvant être appréhendés selon les normes néolibérales. Les auteurs montrent comment l'étreinte, les pleurs et les discours sur l'amour et le chagrin ont été associés à des transformations impliquant la cessation de prestations de l'État et l'application des lois du marché. En faisant de l'affect et de son articulation avec le changement économique un objet d'étude anthropologique, l'article affirme l'utilité d'une notion d'affect se démarquant d'autres approches qui mettent l'accent sur l'émotion. Les auteurs affirment que l'affect est utile parce qu'il est, par nature, réflexif et intersubjectif. L'affect renvoie aux relations pratiquées entre les individus, à la différence de l'émotion, toujours marquée par le spectre d'un individualisme psychologique.     

Theories of Life-History Evolution

In order to assess current scientific understanding of life-historyevolution, the alternative fundamental theories are formulatedin a refutable form and compared with the available empiricalevidence. The hypothesis that life-history does not evolve isrejected on the grounds that life-history can be readily modifiedby artifical selection. The hypothesis that life-history evolvesaccording to mechanisms other than natural selection actingon genetic variation is shown to have no sound experimentalbasis. The hypothesis that life-history evolution depends primarilyon group selection is undermined by the absence of the predictedgroup adaptations. The hypothesis that life-history is a unitarycharacter which evolves in the same fashion as fitness is rejectedbecause of the disparity between life-history genetics and basictheory concerning the evolution of fitness. The hypothesis thatlife-history is composed of a set of autonomous characters whichare subject to mutation accumulation at later ages is refutedby the lack of any detectable increase in genetic variabilitywith age and the evidence for the interdependence of life-historycharacters. It is concluded that the hypothesis of antagonisticinteractions between life-history characters, generalized totake genetic variability into account, is the most satisfactorytheory of life-history evolution available.     

Theories of rotary motors

The bacterial flagellar motor and the ATP-hydrolysing F1 portion of the F1Fo-ATPase are known to be rotary motors, and it seems highly probable that the H+-translocating Fo portion rotates too. The energy source in the case of Fo and the flagellar motor is the flow of ions, either H+ (protons) or Na+, down an electrochemical gradient across a membrane. The fact that ions flow in a particular direction through a well-defined structure in these motors invites the possibility of a type of mechanism based on geometric constraints between the rotor position and the paths of ions flowing through the motor. The two best-studied examples of such a mechanism are the ''turnstile'' model of Khan and Berg and the ''proton turbine'' model of Läuger or Berry. Models such as these are typically represented by a small number of kinetic states and certain allowed transitions between them. This allows the calculation of predictions of motor behaviour and establishes a dialogue between models and experimental results. In the near future structural data and observations of single-molecule events should help to determine the nature of the mechanism of rotary motors, while motor models must be developed that can adequately explain the measured relationships between torque and speed in the flagellar motor.     

Theories of sexual selection

Recent research on sexual selection in animals has begun to indicate that 'handicaps' and 'honest signalling' may play more important roles than hitherto thought. This review reappraises theories of sexual selection in the light of these new developments.     

Theories of episodic memory

Theories of episodic memory need to specify the encoding (representing), storage, and retrieval processes that underlie this form of memory and indicate the brain regions that mediate these processes and how they do so. Representation and re-representation (retrieval) of the spatiotemporally linked series of scenes, which constitute an episode, are probably mediated primarily by those parts of the posterior neocortex that process perceptual and semantic information. However, some role of the frontal neocortex and medial temporal lobes in representing aspects of context and high-level visual object information at encoding and retrieval cannot currently be excluded. Nevertheless, it is widely believed that the frontal neocortex is mainly involved in coordinating episodic encoding and retrieval and that the medial temporal lobes store aspects of episodic information. Establishing where storage is located is very difficult and disagreement remains about the role of the posterior neocortex in episodic memory storage. One view is that this region stores all aspects of episodic memory ab initio for as long as memory lasts. This is compatible with evidence that the amygdala, basal forebrain, and midbrain modulate neocortical storage. Another view is that the posterior neocortex only gradually develops the ability to store some aspects of episodic information as a function of rehearsal over time and that this information is initially stored by the medial temporal lobes. A third view is that the posterior neocortex never stores these aspects of episodic information because the medial temporal lobes store them for as long as memory lasts in an increasingly redundant fashion. The last two views both postulate that the medial temporal lobes initially store contextual markers that serve to cohere featural information stored in the neocortex. Lesion and functional neuroimaging evidence still does not clearly distinguish between these views. Whether the feeling that an episodic memory is familiar depends on retrieving an association between a retrieved episode and this feeling, or by an attribution triggered by a priming process, is unclear. Evidence about whether the hippocampus and medial temporal lobe cortices play different roles in episodic memory is conflicting. Identifying similarities and differences between episodic memory and both semantic memory and priming will require careful componential analysis of episodic memory.