Papers for the week, 6/18 – 6/23

Visual analysis of geocoded twin data puts nature and nurture on the map

“…what if the balance of nature and nurture varies depending on where we grow up? Here we use statistical and visual analysis of geocoded data from over 6700 families to show that genetic and environmental contributions to 45 childhood cognitive and behavioral phenotypes vary geographically in the United Kingdom.”

Learning to simulate others’ decisions

“Using behavior, modeling, and fMRI, we show that simulation involves two learning signals in a hierarchical arrangement. A simulated-other’s reward prediction error processed in ventromedial prefrontal cortex mediated simulation by direct recruitment, being identical for valuation of the self and simulated-other. However, direct recruitment was insufficient for learning, and also required observation of the other’s choices to generate a simulated-other’s action prediction error encoded in dorsomedial/dorsolateral prefrontal cortex.”

On the relationship between the ‘default mode network’ and the ‘social brain’

“Social cognition, particularly higher-order tasks such as attributing mental states to others, has been suggested to activate a network of areas at least partly overlapping with the DMN. Here, we explore this claim, drawing on evidence from meta-analyses of functional MRI data and recent studies investigating the structural and functional connectivity of the social brain.”

Punishment can promote defection in group-structured populations

“Pro-social punishment, whereby cooperators punish defectors, is often suggested as a mechanism that maintains cooperation in large human groups…Here we formally investigate how two demographic factors, group size and dispersal frequency, affect selection pressures on pro- and anti-social punishment. Contrary to the suggestions of previous work, we find that anti-social punishment can prevent the evolution of pro-social punishment and cooperation under a range of group structures.”

Direct reciprocity in structured populations

“Direct reciprocity is considered to be a powerful mechanism for the evolution of cooperation, and it is generally assumed that it can lead to high levels of cooperation. Here we explore an open-ended, infinite strategy space, where every strategy that can be encoded by a finite state automaton is a possible mutant.  Surprisingly, we find that direct reciprocity alone does not lead to high levels of cooperation. Instead we observe perpetual oscillations between cooperation and defection, with defection being substantially more frequent than cooperation…Another mechanism for the evolution of cooperation, which has received as much attention, is assortment because of population structure. Here we develop a theory that allows us to study the synergistic interaction between direct reciprocity and assortment.”

Economic incentives and social preferences: substitutes or complements?

“Explicit economic incentives designed to increase contributions to public goods and to promote other pro-social behavior sometimes are counterproductive or less effective than would be predicted among entirely self-interested individuals.  This may occur when incentives adversely affect individuals’ altruism, ethical norms, intrinsic motives to serve the public, and other social preferences. The opposite also occurs—crowding in—though it appears less commonly. In the fifty experiments that we survey, these effects are common, so that incentives and social preferences may be either substitutes (crowding out) or complements (crowding in). We provide evidence for four mechanisms that may account for these incentive effects on preferences: namely that incentives may (i) provide information about the person who implemented the incentive, (ii) frame the decision situation so as to suggest appropriate behavior, (iii) compromise a control averse individual’s sense of autonomy, and (iv) affect the process by which people learn new preferences.”

Emasculation: gloves-off strategy enhances eunuch spider endurance

“Males of sexually cannibalistic spiders commonly mutilate parts of their paired genitals (palps) during copulation…” (!) “We found that by reducing body weight up to 4 per cent in half-eunuchs and 9 per cent in full-eunuchs through emasculation, endurance increases significantly in half-eunuchs (32%) and particularly strongly in full-eunuchs (80%).”

Anterior prefrontal cortex contributes to action selection through tracking of recent reward trends

“A predominant current theory regarding the most anterior sector, the frontopolar cortex (FPC), is that it is involved in exploring alternative courses of action, but the detailed causal mechanisms remain unknown. Here we investigated this issue using the lesion method, together with a novel model-based analysis…Model-based analyses of learning demonstrated a selective deficit in the ability to extrapolate the most recent trend, despite an intact general ability to learn from past rewards. Whereas both brain-damaged and healthy controls used comparisons between the two most recent choice outcomes to infer trends that influenced their decision about the next choice, the group with anterior prefrontal lesions showed a complete absence of this component and instead based their choice entirely on the cumulative reward history.”

Dissociating activity in the lateral intraparietal area from value using a visual foraging task

“…we compared the neural responses of LIP neurons in two subjects with their saccadic behavior and three estimates of stimulus value. These measures were extracted from the subjects’ performance in a visual foraging task, in which we parametrically controlled the number of objects on the screen. We found that the firing rates of LIP neurons did not correlate well with the animals’ behavior or any of our estimated measures of value. However, if the LIP activity was further normalized, it became highly correlated with the animals’ decisions.”

Joint control of Drosophila male courtship behavior by motion cues and activation of male-specific P1 neurons

“Whereas visual information alone is not sufficient to induce courtship behavior in Drosophila melanogaster males, when a subset of male-specific fruitless (fru)- and doublesex (dsx)-expressing neurons that respond to chemosensory cues (P1 neurons) were artificially activated via a temperature-sensitive cation channel (dTRPA1), males followed and extended their wing toward moving objects (even a moving piece of rubber band) intensively. When stationary, these objects were not courted.”


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