Late Bayesian inference in mental transformations.

Many skills rely on performing noisy mental computations on noisy sensory measurements. Bayesian models suggest that humans compensate for measurement noise and reduce behavioral variability by biasing perception toward prior expectations. Whether a similar strategy is employed to compensate for noise in downstream mental and sensorimotor computations is not known. We tested humans in a battery of tasks and found that tasks which involved more complex mental transformations resulted in increased bias, suggesting that humans are able to mitigate the effect of noise in both sensorimotor and mental transformations. These results indicate that humans delay inference in order to account for both measurement noise and noise in downstream computations.

Activation of kappa opioid receptors in the dorsal raphe have sex dependent effects on social behavior in California mice.

Kappa opioid receptor activation has been linked to stress and anxiety behavior, thus leading to kappa antagonists being popularized in research as potential anxiolytics. However, while these findings may hold true in standard models, the neuromodulatory effects of social defeat may change the behavioral outcome of kappa opioid receptor activation. Previous research has shown that social defeat can lead to hyperactivity of serotonergic neurons in the dorsal raphe nucleus, and that inhibition of this increase blocks the social deficits caused by defeat. Kappa opioid receptor activation in the dorsal raphe nucleus works to decrease serotonergic activity. We injected the kappa opioid receptor U50,488 directly into the dorsal raphe nucleus of male and female, defeat and control adult California mice. Here we show evidence that U50,488 induces anxiety behavior in control male California mice, but helps relieve it in defeated males. Consistent with previous literature, we find little effect in females adding evidence that there are marked and important sex differences in the kappa opioid system.