Volume 17 Issue 10, October 2014

The tactile sensors in our fingers have variable sensitivity across the skin. Does this variability harm or help the CNS in touch perception? Work now shows that this variability may provide the CNS with more information about micropositioning and stimulus orientation.

How do enhancers facilitate transcription of plasticity-related genes in response to synaptic stimulation? A study implicates a specific histone modification and suggests that FOS regulates enhancer function.

Long axonal projections seem to be metabolically coupled to ensheathing glial cells. Targeting LKB1, a regulator of energy homeostasis, specifically in Schwann cells causes a loss of predominantly small unmyelinated fibers.

As we learn through visual experience, where does that memory form? A study now shows that neural responses at even the earliest stage of visual cortex get reshaped in a way that faithfully reflects ongoing learning.

Orexins (hypocretins) are involved in a large variety of behaviors and physiological processes including feeding, sleep/wake regulation, and reward. In this perspective, the authors propose a unifying function for orexins in translating motivational activation into sets of processes that support adaptive behaviors.

Navratilova and Porreca discuss recent advances in our understanding of brain mechanisms of pain in animal models and humans, focusing on the role of the meso-corticolimbic system in processing pain and pain relief. The authors also present their views on how such knowledge can be leveraged to generate new therapies.

Olfactory bulb mitral and tufted cells are thought to be particularly active at rest and to respond weakly to odors during wakefulness. By using blind, whole cell recordings in awake mice, Kollo and colleagues now reveal the existence of a previously overlooked subpopulation of mitral/tufted cells that are silent at rest but respond greatly to odors.

This study uses fMRI to find that the previously reported amyloid-β-associated hyperactivation is likely to represent a compensatory mechanism, rather than pathological overexcitation. The authors found that older adults with amyloid-β depositions had more activation during a memory task, and the degree of detailed memory formation varied with this activity.

This study uses data from patients with damage to specific parts of the frontal cortex to provide causal evidence for the role of the dorsolateral prefrontal cortex in enabling honest behavior. Damage to this area was associated with decisions that prioritized the decision-maker's own self-interest, at the cost of honesty.

Sox10 and Nuclear Factor I-A (NFIA) are transcriptional regulators of oligodendrocyte and astrocyte generation in the mammalian brain, respectively. This study describes reciprocal antagonism between these transcription factors whereby NFIA directly antagonizes Sox10 regulation of myelin gene expression in oligodendrocytes, and Sox10 negatively regulates NFIA during astrocyte differentiation. The work also demonstrates this mutual antagonism being involved in tumorigenesis, particularly during oligodendroglioma to astrocytoma conversion.

In this study, the authors describe the subset of activity-regulated enhancers that modulate transcription in cultured neurons and that participate in the regulation of synaptic maturation. In addition, they demonstrate Fos binding to these enhancers is essential for this activity-dependent regulation of transcription.

Uptake of the neurotransmitter GABA by transporters called GATs is known to influence neuronal GABAergic tone. Here Muthukumar et al. show that the wave of synaptogenesis in Drosophila brains occurs during the second half of pupal development in an astrocyte-dependent manner. The study also shows that the upregulation of GAT during this process requires astrocytic metabotropic GABA receptors, and this pathway mediates mechanosensory-induced seizure activity in GABAergic mutants with hyperexcitable neurons.

Axonal maintenance is known to rely, in part, on non-cell-autonomous support from myelinating glia, but the mechanisms are still unclear. In this study, the authors show that loss of the serine/threonine kinase LKB1 in Schwann cells leads to changes in nerve metabolism and axonal degeneration, even in the absence of demyelination.

Theta oscillations are thought to propagate unidirectionally along the hippocampal circuitry, from CA3 to CA1 and the subiculum. In this paper, Jackson and colleagues demonstrate that, in the intact rat hippocampus, theta activity can also flow in reverse from subiculum to CA3, and find that this phenomenon depends on long-range GABAergic inhibition.

The synchronization of fast-spiking cortical interneurons (FS) produces gamma-like oscillations or ‘FS-gamma’. In this study, Siegle and colleagues found that the induction of FS gamma in the primary sensory cortex of mice performing a tactile task could enhance their detection of less salient stimuli.

Using chronic microelectrode arrays in monkeys, this study finds that progressive learning on a visual task is largely explained by changes in the response of primary visual cortex neurons. The decoding accuracy of a linear classifier trained on V1 aggregate responses suggests that as learning proceeds, the primary visual cortex codes more task-relevant information.

In the visual system, familiarization to an image results in reduced neural responses to it. Here the AUs find that with dynamic visual displays, neurons in the inferotemporal cortex respond more strongly to familiar than novel images. This indicates that familiarization sharpens the response dynamics of neurons in extrastriate visual cortex.

The lateral intraparietal area (LIP) in monkeys plays an important role in decision-making. Here the authors use a statistical approach to decode the activity of LIP spikes and find multiplexed and temporally heterogeneous signals. This provides a framework for studying complex coding in higher brain areas.

It is known that the primary sensory neurons that mediate tactile sensation exhibit elaborate receptive fields because of dendritic branching in the skin. In this study, the authors show that such branching allows neurons that innervate the human fingertips to extract geometric features of touched objects and signal them via both temporal and intensity codes.

Correlations of noise in neural population activity are thought to limit the amount of information contained in such population activity, whereas decorrelation is suggested to increase information content. Here the authors show that decorrelation does not imply an increase in information, and only certain types of correlations limit information content.

Expression quantitative trait loci (eQTLs) are genomic regions that regulate gene expression. Here the authors provide a publicly available data set of exon-level eQTLs across the human brain. This includes many genome-wide association study (GWAS) hits for neurological and psychiatric disorders.