Volume 20 Issue 10, October 2017

Central amygdala directs behavioral responses to emotionally salient stimuli. While most studies have focused on aversive responses, some central amygdala neurons promote feeding and are positively reinforcing.

Inputs to the central complex, the navigation center of Drosophila, are strongly modulated by the visual stimulus history. These history effects carry forward to bias turning behavior when flies choose between two visual stimuli.

Human perception can improve through repeated practice, enabling perceptual learning. The authors report findings challenging the fundamental ‘practice makes perfect’ basis of procedural learning theory. They show that brief periods in which visual memory is reactivated are sufficient to improve basic perceptual thresholds, supporting a new account of perceptual learning dynamics.

Using an adeno-associated virus–mediated, direct in vivo CRISPR screen, the authors mapped a quantitative landscape of glioblastoma suppressors. Their study revealed gene combinations that functionally drive gliomagenesis from normal glia in native mouse brains. The authors further demonstrate that mutational background can differentially influence gene expression and chemotherapeutic resistance.

The authors propose a framework for drug repositioning by comparing GWAS-imputed transcriptomes with drug-induced gene expression profiles. The approach was applied to seven psychiatric disorders. Repositioning candidates were significantly enriched for known psychiatric medications or for therapies considered in clinical trials, supporting a role of GWAS in guiding drug discovery.

Brain self-assembly is thought to be initiated by pioneer neurons whose identity is unknown. Rapti et al., addressing this long-standing mystery, uncover key steps in forming the brain-like nerve ring of C. elegans. Glia initiate the structure, using Netrin to guide pioneer neurons, whose identity is characterized. Glia and pioneer neurons then together direct follower-axon guidance using redundant guidance factors.

Recovery of the developing cerebellum after depletion of granule cells, the most plentiful neuron population, depends on adaptive reprogramming of neural progenitors to a new fate and a powerful cell–cell communication system that ensures re-establishment of the correct proportions of different cerebellar cell types and normal circuit formation.

Neocortical resident microglia are long-lived cells. Füger et al. report that approximately half of these cells survive for the entire lifespan of a mouse. While microglial proliferation under homeostatic conditions is low, proliferation is increased in a mouse model of Alzheimer's disease.

How GABAergic interneurons regulate segregation and integration among pyramidal cells to separate brain networks remains unclear. In this study, the authors show that subsets of chandelier cells in prelimbic area mediate directional inhibitory control of both local pyramidal neuron ensembles and global cortical subnetworks.

The amygdala central nucleus (CeA) has been implicated in feeding regulation, but the underlying circuit mechanisms are incompletely understood. The authors show, in mice, that GABAergic serotonin receptor 2a–expressing CeA neurons are active during eating and promote positive reinforcement and food consumption, partly through long-range inhibition of the parabrachial nucleus.

Animals combine multiple cues to navigate the environment. By performing calcium imaging in fruit flies navigating in a virtual space, the authors show that information about recent visual experience and self-motion is separately encoded in parallel neural pathways in the central brain of Drosophila.

Monkeys, like humans, normally have face domains in inferotemporal cortex; however, monkeys raised without exposure to faces do not develop face patches. Normally reared monkeys, like humans, preferentially look at faces, but face-deprived monkeys do not. These results highlight the importance of early experience for normal sensory and cognitive development.

New techniques for visually stimulating and stabilizing the retina reveal that humans control covert attentional resources with high precision at the center of gaze. These findings show that fine attentional deployment occurs within the fovea and enhances high-acuity vision.

This paper reports the availability of a new Resource with RNA-seq, DNA methylation and H3K9Ac QTL results from 411 brain samples. Many xQTL SNPs influence multiple molecular features, and the authors observe epigenetic mediation of eQTLs in some cases. Reanalyzing GWAS with an xQTL-weighted approach detected 20 new CNS disease susceptibility loci.