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A human spatial atlas of gene expression in liver based on live donors shows marked porto–central zonation of hepatocytes and non-parenchymal cells, and transcriptomic changes in early steatosis.

Humans display biases in evaluations of social groups, such as the negativity bias. Shin and Niv present a model that suggests that this bias may arise from inferring the hidden causes of group members’ behaviours.

Whether emotional state affects the perception of outcomes, and the possible consequences of this interaction remain unclear. Here the authors use behavioural tests and brain imaging to study the bidirectional interaction between emotional state and learning in humans and find that this interaction may play a role in mood instability.

We thought we had figured out dopamine, a neuromodulator involved in everything from learning to addiction. But the finding that dopamine levels ramp up as rats navigate to a reward may overthrow current theories. See Letter p.575

Knowledge is not just power. Even if advance information can not influence an upcoming event, people (and animals) prefer to know ahead of time what the outcome will be. According to the firing patterns of neurons in the lateral habenula, from the brain's perspective, knowledge is also water—or at least its equivalent in terms of reward.

A study of mice exposed to cigarette smoke suggests that smoking-cessation-induced weight gain is associated with a dysbiotic state that is driven by smoking-related metabolites.

The orbitofrontal cortex (OFC) has been hypothesized to carry information regarding the value of expected rewards. Such information could be used for generating instructive error signals conveyed by dopamine neurons. Here the authors report that this is indeed the case. However, contrary to the simplest hypothesis, OFC lesions did not result in the loss of all value information. Instead, lesions caused the loss of value information derived from model-based representations.

Applying computational models of reinforcement learning can help to improve psychotherapeutic interventions by helping to identify the therapeutic mechanisms of change and identifying for whom therapies will be most effective.

Yardena Samuels and colleagues report the analysis of 501 melanoma exomes and the identification of RASA2 as a tumor-suppressor gene mutated in 5% of melanomas. RASA2 mutations led to increased RAS activation, and RASA2 loss was associated with shorter patient survival times.

A comprehensive spatial expression atlas of the adult human proximal small intestine reveals branched villi, immune activation at the villus tip, and a switch of migrating enterocytes from lipid droplet assembly and iron uptake at the villus bottom to chylomicron biosynthesis and iron release at the tip.

Learning to predict reward is thought to be driven by dopaminergic prediction errors, which reflect discrepancies between actual and expected value. Here the authors show that learning to predict neutral events is also driven by prediction errors and that such value-neutral associative learning is also likely mediated by dopaminergic error signals.

Dopamine neurons are proposed to signal the reward prediction error in model-free reinforcement learning algorithms. Here, the authors show that when given during an associative learning task, optogenetic activation of dopamine neurons causes associative, rather than value, learning.

Zorowitz et al. show how careless and inattentive online participants can lead to false-positive correlations in computational psychiatry studies.

A computational account of how schemas are learned through experience is lacking. In this Perspective, Bein and Niv synthesize schema theory and reinforcement learning research to derive computational principles that might govern schema learning and then propose their mediation via dimensionality reduction in the medial prefrontal cortex.

When crossing the street, you can ignore the color of oncoming cars, but for hailing a taxi color is important. How do we learn what to represent neurally for each task? Here, Niv summarizes a decade of work on representation learning in the brain.

A study of the functional microbiome in a mouse model of ALS shows that several gut bacteria may modulate the severity of the disease.

Non-caloric artificial sweeteners (NAS), widely used food additives considered to be safe and beneficial alternatives to sugars, are shown here to lead to the development of glucose intolerance through compositional and functional changes in the gut microbiota of mice, and the deleterious metabolic effects are transferred to germ-free mice by faecal transplant; NAS-induced dysbiosis and glucose intolerance are also demonstrated in healthy human subjects.

Here the authors show that measures of pupil diameter, which are thought to track levels of LC-NE activity and neural gain, are correlated with the degree to which learning is focused on stimulus dimensions that individual human participants are more predisposed to process. They further show that the pupillary and behavioral variables are correlated with global changes in the strength and clustering of functional connectivity, as brain-wide fluctuations of gain would predict.

Dopaminergic neurons are thought to inform decisions by reporting errors in reward prediction. A new study reports dopaminergic responses as monkeys make choices, supporting one computational theory of appetitive learning.

In a Registered Report, Eldar et al. measure pupillary responses in six different tasks to adjudicate between two accounts of biases in decision-making: do biases reflect a lack of effort and deliberation or do they arise from gradual information integration?

A revolution is underway in cognitive neuroscience, where tools and techniques from computer science and the tech industry are helping to extract more meaningful cognitive signals from noisy and increasingly large fMRI datasets. In this paper, the authors review the cutting edge of such computational analyses and discuss future opportunities and challenges.

Here the authors review evidence suggesting that cocaine-induced changes in orbitofrontal cortex disrupt the representation of states and transition functions that form the basis of flexible behavioral control, resulting in reliance on less flexible control systems and consequently in the pattern of maladaptive behaviors associated with cocaine addiction.

This protocol describes an experimental–computational methodology for mapping the small RNA interactome in bacteria.