Volume 21 Issue 11, November 2018

Two recent studies have expanded our understanding of the circuits controlling urination: one described a projection from brainstem to spinal cord that relaxes the urethral sphincter, and the other revealed a subpopulation of brainstem-projecting layer 5 pyramidal neurons in primary motor cortex that direct the initiation of urination.

A new theory derives the sequential nature of hippocampal replay from first principles and, moreover, predicts the specific patterns of replay that are actually observed in multiple different experiments.

Somatic mutations occur after fertilization and are present in only some cells of an individual. Somatic mutations contribute to normal and abnormal brain development, including neurodevelopmental disorders like autism spectrum disorder.

Using genetic tools of neural circuit tracing and manipulation, we identify a novel projection from the amygdala to the zona incerta—a nucleus not previously implicated in fear memory—that is essential for recent and remote fear memories.

Venniro et al. report that drug-addicted rats reliably choose contact with another rat over drugs, even when group-housed between tests. They also do not show the increase in drug craving that normally occurs during forced abstinence.

BRS3 is a receptor regulating energy metabolism. The authors find that DMH Brs3 neurons control body temperature, energy expenditure, and heart rate, but not food intake. In contrast, PVH Brs3 neurons regulate food intake but not energy expenditure.

A small cluster of brainstem-projecting layer 5 neurons in primary motor cortex elicit contraction of the bladder muscle and trigger urination. These findings open new directions for treating urination-related disorders.

Mátyás, Komlósi, et al. describe a highly specialized, calretinin-containing cell population in the dorsal medial thalamus. Connectivity, activity, and optogenetic manipulations identify these neurons as key mediators of forebrain arousal.

As naive mice learn a stimulus–reward association, DA neuron activity first reflects the timing of reward-seeking actions relative to predictable stimuli & rewards. As actions are refined by learning, DA neuron activity can reflect prediction errors.

Imaging during a virtual ‘Door Stop’ task shows that medial entorhinal cortex (MEC) represents elapsed time in immobile mice, suggesting there are largely distinct MEC subcircuits that encode either time during immobility or space during locomotion.

The authors investigated the neocortical representations that mediate sensory–motor transformations in active sensing behavior. Layer 5 of vibrissae cortex generates a diverse, distributed network representation via active dendritic integration.

Saccadic eye movements during free viewing exhibit patterns that reflect a strategy to increase neural responses by matching motor behavior with the statistics of the natural world and with the processing limitations of sensory systems.

Distributed networks in visual cortex precisely link the fine-scale functional architecture with distant network elements and appear early in development, when heterogeneous local connections may seed long-range network interactions.

Mattar and Daw propose a normative theory predicting which memories should be accessed at each moment to optimize future decisions. This theory offers a simple explanation for numerous findings about hippocampal replay, bridging planning and learning.

Widespread differences in H3K27ac, a key histone modification, are associated with Alzheimer’s disease. H3K27ac differences were enriched in genomic regions containing loci involved in the progression of Aβ and tau pathology.

Bienkowski et al. have created a new subregional atlas of the mouse hippocampus that integrates gene expression with anatomical connectivity to reveal the multiscale organization of the hippocampus and its connections throughout the brain.