Brief Communications in 2015

Gancarz et al. identify Activin-receptor signaling—including the downstream transcription factor Smad3—as an intracellular signaling pathway that is regulated in the nucleus accumbens following abstinence from cocaine. The authors demonstrate that altering Activin-receptor signaling bi-directionally regulates relapse behavior and dendritic spine plasticity.

This study shows that ocular dominance plasticity (ODP) is accompanied by changes to DNA methylation at specific genes in the mouse visual cortex. The authors also show that pharmacological inhibition of the DNA methylation process can alter the functional consequence of ODP.

Mensch et al. investigate how neuronal activity regulates CNS myelination in vivo, using zebrafish as a model. They find that blocking synaptic vesicle release reduces, and that stimulating neuronal activity increases, the number of myelin sheath made by the myelinating glia of the CNS (oligodendrocytes). These data show that neuronal activity regulates the myelinating capacity of individual oligodendrocytes.

Using a quantitative perfusion imaging technique, the authors investigated in healthy humans what brain regions encode a slowly varying tonic pain state. Only a small region in the contralateral dorsal posterior insula tracked the full pain experience, suggesting it is the homolog of a nociception-specific region found in animals.

The authors used rewarding stimulations triggered by place cell activity during sleep to create a place preference for the related place field in mice once they woke up. This shows that an explicit memory trace can be created during sleep and demonstrates a causal role of place cells in spatial navigation.

This study utilizes in vivo clonal lineage tracing of adult subependymal zone neural stem cells in mice to reveal frequent stem cells divisions and significant progeny expansion, thus allowing rapid clonal growth. The authors also show that neural stem cells lacked significant long-term self-renewal abilities which led to clonal exhaustion. Olfactory bulb neuronal diversity emerges at the population level, as single stem cells show restricted diversity in neuronal subtype production.

Ling and colleagues report evidence for orientation selective responses in the human lateral geniculate nucleus (LGN). Moreover, they found that the nature of these orientation representations depend on attentional feedback, suggesting that the LGN serves as an early filter for sensory information, altering contour signals before they reach cortex.

This study shows that cocaine strengthens glutamatergic transmission, reduces K⁺ channel function and drives hyperexcitability in lateral habenula neurons projecting to the rostromedial tegmental nucleus. The authors also show that GluA1 trafficking mediates these cellular modifications and is instrumental in a drug-mediated depressive-like phenotype.

Using optogenetic manipulations and bioluminescence imaging of suprachiasmatic nucleus (SCN) firing rate, this study examines the interaction between molecular, electrical and behavioral circadian rhythms in mice. The study shows that alteration of clock neuron firing can reset molecular and behavioral circadian rhythms, and this effect required neuronal network interaction within the SCN. Thus, clock neuron spiking is fundamental to circadian pacemaking as both an input to and output of the neuronal network responsible for circadian behavior.

Microdeletions of chromosome 16p11.2 can cause autism, but the pathogenic mechanisms remain unclear. Here the authors show that in a 16p11.2 mouse model, mGluR5 synaptic plasticity and protein synthesis are altered and that a modulator of mGluR5 reverses the cognitive deficits.

This study shows that auditory development is guided by multiple adaptive processes. This flexibility can help maintain accurate perception in different environments and provides a more unified account of developmental plasticity across species. The adaptive plasticity observed also provides insight into the nature of distributed neural representations underlying spatial hearing.