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The International Brain Laboratory presents a brain-wide electrophysiological map obtained from pooling data from 12 laboratories that performed the same standardized perceptual decision-making task in mice.

The face reveals more than just emotion. Cazettes, Reato and colleagues show that subtle facial movements reveal hidden cognitive states, reflecting the brain’s ongoing computations and offering a noninvasive window into unexpressed thoughts and decisions.

Uchida and colleagues consider integration of information for perceptual decision making, focusing on olfactory and visual systems. They argue that there are neural mechanisms that construct discrete sensory samples from a continuous input stream to facilitate important computational functions.

Focused grass-roots collaborations that start small and scale up could overcome technical and sociological barriers to 'big' neuroscience, argue Zachary F. Mainen, Michael Häusser and Alexandre Pouget.

Here, the authors show that rats’ performance on olfactory decision tasks is best explained by a Bayesian model that combines reinforcement-based learning with accumulation of uncertain sensory evidence. The results suggest that learning is a critical factor contributing to speed-accuracy tradeoffs.

How does the brain define a useful decision variable (DV) when many possibilities are available? The authors show that rather than committing to the DV used to solve the task, the mouse’s premotor cortex entertains several strategies in parallel.

Studies using neural ensemble recordings in rats show that cells in the piriform cortex carry a spatial representation of the environment and link locations to olfactory sensory inputs.

Using in vivo recording of neuronal activities in rat secondary motor cortex and devising a novel task of waiting before performing an action, Murakami et al. show a neural correlate of voluntary action initiation. The study also shows population activity and computational modeling data that correspond to action timing of voluntary action that are consistent with integration-to-bound theories of decision making.

The striatum is required for evoking contraversive movements from each brain hemisphere, but it is unclear how. Here, Tecuapetla et al.use optogenetics to inhibit direct and indirect downstream striatal projection pathways, and show that activity in both pathways is necessary for contraversive movements.

Noel et al. show aberrant updating of expectations in three distinct mouse models of autism spectrum disorder. Brain-wide neurophysiology data suggest this stems from excess units encoding deviations from prior mean and a lack of sensory prediction errors in frontal areas.

Using data from rats and humans, the authors study the time it takes to make sensory judgments. The authors define the new regularity as the time–intensity equivalence in discrimination (TIED), which provides a mechanistic basis of Weber’s law.

A recent study in Nature now shows that the main olfactory bulb contains a particular zone required for innate odor aversion, indicating that olfactory receptors have behavioral as well as chemical specificity.

The human brain estimates task controllability by comparing the reliability of internal models predicting future events using only past events, or a mixture of past events and past actions. Exposure to uncontrollable stressors distorts this process.

Serotonin (5-HT) has been suggested to promote waiting through behavioral inhibition. Here, the authors use an active foraging task and optogenetic activation of 5-HT neurons to show that rather than passivity, these neurons enhance persistence in the face of delay.

Traditionally, 'metacognition' has been thought to be the purview of primates, but it is now shown that rats may compute and use estimates of their own confidence when making difficult perceptual decisions. The paper finds correlates of task difficulty and predictors of trial-by-trial outcome in the activity of orbitofrontal cortex, which may be most parsimoniously explained as a representation of subjective confidence.

Serotonin (5-HT) plays many important roles in reward, punishment, patience and beyond, and optogenetic stimulation of 5-HT neurons has not crisply parsed them. The authors report a novel analysis of a reward-based decision-making experiment, and show that 5-HT stimulation increases the learning rate, but only on a select subset of choices.

Lightning Pose is an efficient pose estimation approach that requires few labeled training data owing to its semi-supervised learning strategy and ensembling.

The authors show that a normative approach to olfaction, Bayesian inference, reproduces much of the anatomy, physiology and behavior seen in real organisms. The model provides insight into how the olfactory system demixes odors, and, by extension, how other sensory systems extract relevant information from activity in peripheral organs.

The olfactory bulb is densely innervated by serotonergic fibers. A study now shows that serotonin activates periglomerular interneurons, which release GABA to reduce transmitter release from olfactory sensory neurons.

A modular architecture for managing and sharing electrophysiology, behavior, colony management and other data has been built to support individual laboratories or large consortia.

Snitz et al. develop a web-based olfactory screening tool for COVID-19, which relies on users smelling household odorants. Based on data from participants in 134 countries, the authors report that olfactory ratings are indicative of COVID-19 status.

In this Perspective, the authors discuss the recent surge in the collection of "big behavioral data" and how it might contribute to the understanding of how the brain controls behavior. They also highlight the challenges of making sense of increasing amounts of behavioral data.