Maltese et al. show in mice that experiencing an adverse event affects future interaction with others experiencing the same stressor. These self-experience socioemotional reactions are orchestrated by the corticotropin-releasing factor system in the medial prefrontal cortex.

Axons have always been assumed to be cylindrical. Using in silico modeling and cryopreservation of tissues, Griswold et al. demonstrate that unmyelinated axons of the mammalian central nervous system exhibit pearls-on-a-string morphology through their entire length.

Individuals with autism spectrum disorder show neural patterns different from those of neurotypical individuals. Here the authors show that this variation reflects a computational trade-off between accurate encoding and fast adaptation tuned by the neural population response.

Lüthi and colleagues show that activity of the locus coeruleus (LC) is crucial for the cyclic alternation between non-rapid-eye-movement and rapid-eye-movement sleep. Stressful experiences during waking can disrupt LC activity in sleep, which disorganizes the sleep cycle and increases microarousals.

Mice expressing humanized mutant tau exhibit synaptic loss and behavioral abnormalities in the absence of abnormal tau conformers, suggesting that hyperphosphorylated tau can be pathological, at least in tauopathies caused by tau isoform imbalance.

The trans-Tango genetic strategy, which mediates signaling across synapses, was adapted to identify neural connections in a vertebrate nervous system, with synaptic partners confirmed in the retina and spinal cord of larval zebrafish.

In recent years, valuable mRNA-based developmental atlases of the mouse brain have been made available. Here, the authors use single-cell mass cytometry to build a protein-based single-cell profiling of the developing embryonic and postnatal mouse brain.

Using intracranial recordings in pairs of humans cooperating in interactive games, this study shows fine-grained cooperation dynamics featured by state-dependent motives and the intrabrain and interbrain profiles of high-gamma activity in the amygdala and temporoparietal junction.

Duplication of the MECP2 gene (encoding methyl-CpG-binding protein 2) causes MECP2 duplication syndrome. Here the authors develop a Cas13Y system capable of _targeting the MECP2 mRNA for degradation and reducing protein levels in the brain of humanized MECP2-transgenic mice and nonhuman primates.

Brain function requires the formation of diverse and specific synapses. The authors show that the molecular code specifying excitatory connectivity on Purkinje cells evolves in an input-specific manner with postnatal circuit maturation.

Single-cell genomics is deepening our understanding of the nervous system and shedding light on the heterogeneity of its cells. This focus issue of Nature Neuroscience celebrates recent methodological and analytical advances in single-cell genomics, highlights principles of study design, and aims to encourage collaboration between cellular, molecular and systems neuroscientists.