Articles in 2010

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.

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.

The nuclei of radial glia divide and complete mitosis at the apical surface of the embryonic brain. They then migrate to the basal surface and back before dividing again. This study shows that these nuclei travel along microtubules, driven by KIF1A in the basal direction and by dynein in the apical direction.

A screen for mutations depressing AMPA receptor expression in C. elegans revealed a gene encoding a putative RNA binding protein, dubbed GRLD-1. Wang et al. find that GRLD-1 acts on the glr-1 introns to boost expression and speculate that it may excise a destabilizing intron.

Using optogenetic tools, Carter et al. find a frequency-dependent causal relationship between locus coeruleus firing, sleep-to-wake transitions and locomotor arousal in mice.

Primary auditory cortex is organized tonotopically along one axis. Using laser scanning photostimulation in acute slices, the authors find that local connections along the tonotopic axis differ from those along the orthogonal, isofrequency axis.

Using optogenetic techniques, Dhawale et al. find that, although sister mitral cells (which receive input from the same olfactory glomerulus) have highly correlated average spike rate responses, their spike timing with respect to respiration differs. This suggests that sister cells carry both correlated and independent information.

Could similar changes in SOD1 underlie both familial and sporadic ALS? Here, Bosco et al. find that wild-type SOD1 from sporadic ALS tissues shows conformational changes similar to those seen in familial ALS and that aberrant wild-type SOD1 can be pathogenic, potentially as a result of the same SOD1-dependent mechanism seen in familial ALS.

Lomber and colleagues find that enhanced visual localization and motion detection in deaf cats is subserved by cross-modal reorganization of cortex that is typically dedicated to auditory function. Furthermore, the authors localize the individual visual functions to discrete portions of reorganized auditory cortex.

How extracellular signals, such as BDNF, regulate axonal branching is unclear. Here, Jeanneteau et al. find that MAP kinase phosphatase 1 expression is induced by BDNF signaling to deactivate JNK. This negatively regulates phosphorylation of JNK substrates that impinge on microtubule destabilization. Neurons from mkp-1 null mice were unable to produce BDNF-induced axon branches.

This study demonstrates that Fbw7, a component of ubiquitin ligase complex, regulates neural progenitor cell viability and differentiation by controlling Notch and JNK/c-Jun signaling.

Hereditary spastic paraplegia (HSP) is manifested as motor dysfunction stemming from axonal degeneration. Of the known 19 spastic paraplegia genes (SPGs), SPG3a encodes a multimeric integral membrane protein Atlastin. Here, the authors use zebrafish system to demonstrate the interplay between Atlastin and bone morphogenic protein signaling in motor axon development and stability.