Articles in 2015

It has been suggested that hippocampal sharp-wave ripples (SWR) are important for memory consolidation. Here, the authors found that the activation of a non-serotoninergic subpopulation of median raphe neurons suppresses hippocampal sharp-wave ripples and impairs memory consolidation. These findings uncover a new brainstem influence on SWR and hippocampal memory function.

By examining Parkinson's disease patients undergoing deep brain stimulation (DBS) implantation surgery, this study shows that therapeutic DBS acts on the primary motor cortex to reversibly reduce excessive coupling between the phase of the beta rhythm and the amplitude of broadband activity over a similar time course as the reduction in parkinsonian motor signs.

Using zebrafish, the authors show that neuronal activity influences which axons are selected for myelination by promoting the growth and stability of oligodendrocyte sheaths on axons. Myelination of axons in response to activity could modulate the conduction properties of specific neural circuits, thereby contributing to brain plasticity.

Prolonged persistence toward delayed rewards is beneficial in some environments but counterproductive in others. Human decision makers calibrate persistence according to the statistics of their environment, and delay-period activity in ventromedial prefrontal cortex reflects a dynamic, context-sensitive valuation signal that could underlie adaptive decisions between persisting and quitting.

The authors used new network-analysis algorithms to examine how distributed networks of brain areas are reorganized as humans learn a new motor skill. Using fMRI, the authors found that learning induced autonomy of sensorimotor systems and that a release of cognitive control hubs predicted individual differences in learning.

The authors use developmental changes in chromatin accessibility to identify thousands of enhancer elements that are active at different postnatal developmental stages in granule neurons of the cerebellum. Zic transcription factors were found to promote gene expression patterns key for neuronal maturation by binding to late-acting enhancer elements.

Hormone-induced brain masculinization occurs during a perinatal sensitive period but endures into adulthood. Researchers explored DNA methylation as a candidate mechanism. Methylation is higher in female brain and suppresses masculinization genes, which are liberated by hormone-induced reductions in DNMT activity in males. Pharmacological inhibition of DNMTs reduces methylation, masculinizes female brain and behavior and reopens the sensitive period.

Socioeconomic status is associated with cognitive development, but the extent to which this reflects neuroanatomical differences is unclear. In 1,099 children and adolescents, family income was nonlinearly associated with brain surface area, and this association was greatest among disadvantaged children. Further, surface area mediated links between income and executive functioning.

Furutachi et al. identified a slowly dividing subpopulation of embryonic progenitors that later gives rise to most adult neural stem cells (NSCs) in the subependymal zone. Moreover, they found that p57 is responsible for the slow cell cycle of this embryonic population and acts causally in the emergence of adult NSCs.

Processing multiple sensory modalities is critical for executing complex behaviors. This study finds that single cerebellar granule cells integrate inputs from both vestibular and visual input pathways, each exhibiting characteristic synaptic strengths and plasticities. These are translated into output dynamics that enhance the network's representation of complex sensory contexts.

DISC1 is believed to be a genetic risk factor for schizophrenia, but its pathophysiological functions are not fully understood. Using proteomics, Tsuboi et al. identify several RNA-binding proteins, including HZF, as DISC1 interactors and reveal that DISC1, together with HZF, regulates the dendritic transport of ITPR1 mRNA to modulate synaptic plasticity.

The authors show that chronic neonatal hypoxia reduces GABA_A receptor–mediated signaling to oligodendrocyte precursor cells in the cerebellar white matter and enhances their proliferation, delays oligodendrocyte maturation and disrupts myelination. Following hypoxia, treatment with a GABA uptake blocker restores myelination.

The authors show that haploinsufficiency of TBK1 causes familial forms of the neurodegenerative diseases ALS and FTD. Loss of binding of a TBK1 protein interaction domain to optineurin, a protein previously linked to ALS, is sufficient to cause the disease. Both proteins regulate autophagy and inflammation.

Although it has been widely hypothesized that decisions can be guided by mental simulation of their likely consequences, there has not been direct evidence linking prospection to choices. Here, using fMRI, the authors show that neural representation of future outcomes is related to the choices that participants make.

The relationship between EEG oscillations and underlying neural activity is unclear. The authors find a U-shaped relationship between the two in visual cortex that is linked to visuospatial attention performance in monkeys. A neural network model indicates a critical role for selective inputs to inhibitory neurons.

Forgetting can at times serve an adaptive purpose. Here the authors develop a method for dynamically tracking neocortical activity patterns related to the retrieval of individual episodic memories. They show that remembering gradually enhances relevant memories but also suppresses the cortical traces of interfering memories, causing adaptive forgetting.

Expression of TET1 dioxygenase, which catalyzes the conversion of 5-methylcytosine to 5-hydroxymethylcytosine, is downregulated by repeated cocaine administration in mouse nucleus accumbens, where it controls cocaine reward. Genome-wide mapping of 5-hydroxymethylcytosine in this brain region reveals novel modes of epigenetic regulation by cocaine.

This study shows how somatostatin (SOM)-expressing interneurons contribute to odor coding in mouse olfactory cortex. Odor-tuned SOM cells regulate neuronal output through a purely subtractive operation that is independent of odor identity or intensity. This operation enhances the salience of odor-evoked activity without changing cortical odor tuning.

The authors demonstrate that the anti-stress peptide neuropeptide Y reduces binge drinking in monkeys and mice by inhibiting neurons in the amygdala that contain the stress peptide corticotropin-releasing factor. Further, the authors find that chronic drinking leads to changes in anti-stress peptide systems that may underlie the pathology stemming from binge drinking.

The developing human cortex contains diverse populations of neural progenitor cells, including a large proportion of outer radial glia (ORG), a progenitor type that is rare in the mouse. The authors identify a transcriptional signature of ORG characterized by markers of neuronal lineage fate and use single-cell analyses to contrast the heterogeneity of cortical progenitors across human, mouse and ferret.