Research articles

The authors report a transcriptional profile of the discrete stages of spontaneous remyelination following toxin-induced focal demyelination in rats. They find an enrichment of retinoid X receptor (RXR) signaling pathways over the course of remyelination and show that RXR activation stimulates oligodendrocyte differentiation to enhance remyelination.

Motoneuron recruitment is thought to occur in an orderly matter to generate the appropriate movements. Here, the authors find that recruitment threshold is not dictated by input resistance, as was previously believed, but by a combination of biophysical properties and the strength of the synaptic currents.

Synaptic vesicles release neurotransmitters both at rest and when stimulated. Wilhelm et al. use a variety of assays to show that the same vesicles participate in both active and spontaneous release.

Whether the same pool of synaptic vesicles participates in both spontaneous and activity-dependent release remains controversial. Using a combination of new and established probes, the authors find cross-depletion of spontaneously and activity-dependent pools, indicating that both types of release draw from a common pool.

The receptor sortilin has been implicated in pro-apoptotic signaling of proneurotrophins. In this study, the authors uncover another role for sortilin in neurotrophin signaling: it interacts with Trk family receptors to promote their anterograde transport to nerve endings, thereby enhancing neurotrophin-dependent cell survival.

Volitional control over object viewing improves subsequent memory for these objects in normal subjects. A comparison between subjects with and without hippocampal damage, as well as fMRI imaging during the task, suggest that the hippocampus is a key locus for changes during volitional versus passive object viewing.

Sensory adaptation is thought to improve perceptual discriminability of sensory stimuli. Using simultaneous recordings in aligned thalamic and cortical cells in the vibrissal pathway, the authors find evidence suggesting that adaptation of cortical signals is not apparent in the firing of individual thalamic neurons, but is reflected in thalamic synchrony.

Using a rat model of PD, the authors find a progressive decline in autonomous globus pallidus pacemaking. This loss was reversed by viral expression of the HCN channel. However, the motor disability induced by DA depletion was not reversed, suggesting that the loss of pacemaking was a consequence, not a cause, of key network pathophysiology.

The authors show that synaptic activation of group I metabotropic glutamate receptors in indirect, but not direct, pathway nucleus accumbens medium spiny neurons causes endocannabinoid production. This in turn triggers a form of long-term depression that is dependent on postsynaptic TRPV1 cation channels and endocytosis of AMPA receptors.

There are thought to be canonical patterns of connectivity between excitatory neurons of different layers within a column, but whether such patterns exist for inhibitory connectivity remained unclear. Here the authors identify stereotypical connectivity motifs across M1, V1 and S1, but find that their abundance varies among regions and cell types.

Rosenzweig and colleagues show that incomplete cervical spinal cord injury in macaques triggers substantially greater sprouting of spared corticospinal axons below the lesion. The monkeys also recovered significant locomotor ability, correlating with the extent of anatomical 'repair'.

Cortical visual area V4 contains cells with diverse response properties, including preference for color, orientation, disparity and higher order features. Tanigawa et al. used intrinsic optical imaging to reveal that regions with preferential response to color or luminance are largely separate from orientation-selective regions.

The authors report that the cation channel TRPV1 suppresses excitatory synaptic transmission in dentate gyrus via a Ca²⁺-calcineurin and clathrin-dependent internalization of AMPA receptors. Activation of TRPV-1 triggers a form of LTD that is mediated by anandamide, but is independent of type 1 endocannabinoid receptors.

He et al. identify the transcription factor YY1 as being critical for peripheral myelination. YY1 phosphorylation by neuregulin is required for transcriptional activation of Egr2/Krox20, a critical regulator of peripheral myelination.

This study shows that the transcriptional repressor Otx2 negatively regulates the expression of the dopamine transporter DAT in dopaminergic neurons of the ventral tegmental area (VTA). Elevated Otx2 confers resistance to the neurotoxin MPTP and may explain why a subpopulation of VTA neurons resist degeneration in Parkinson's disease.

Evidence suggests that covert visual attention can improve behavioral performance by modulating contrast or response gain. Herrmann et al. find that the size of the stimulus and the attention field determine which mechanism is used. These results support predictions of the normalization model of attention.

The authors compare the whole-genome expression profiles of peri-infarct neurons that show axonal sprouting after stroke to their non-sprouting neighbors. They describe a 'sprouting transcriptome' and perform further gain- and loss-of-function studies, finding novel roles in sprouting for a DNA-modifying molecule, a growth factor, and inhibitory myelin receptors.

Liu and colleagues report that toll-like receptor 7 (TLR7), which is typically thought to be expressed in immune cells and to function to regulate innate immunity, is expressed and acts in C-fiber primary sensory neurons. In mice, they find that TLR7 is important for inducing itch, but is not necessary for eliciting pain.

5-hydroxytryptamine 2C receptors (5-HT2CRs) in the brain have been shown to regulate glucose homeostasis. Xu and colleagues find that 5-HT2CRs expressed specifically by hypothalamic pro-opiomelanocortin neurons are involved in the regulation of insulin sensitivity and glucose homeostasis in liver.

It had been thought that microscopic relocations of gaze (microsaccades) were suppressed during fine spatial judgments. Ko et al. find that microsaccades move the eye to locations of interest and are influenced by task demands. This suggests that they may actively contribute to the acquisition of fine spatial detail.