Articles in 2014

This study provides causal evidence demonstrating that consuming a high flavanol diet improves dentate gyrus function and dentate gyrus–dependent cognitive functions in aged humans.

In vertebrate vision, the two types of photoreceptors, rods and cones, operate under low and bright light intensities, respectively. Here the authors show that under bright light conditions, when rods are not sensing light, they act as relay cells for cone-driven surround inhibition.

Shohamy and colleagues found that administration of a placebo can enhance learning from positive outcomes in Parkinson disease's patients. An analysis of fMRI signals recorded during behavior indicated that the drug and placebo both enhanced the representation of expected value in the ventromedial prefrontal cortex and attenuated prediction error signals in the ventral striatum. These results suggest that the mere expectation of reward can drive learning.

Synaptic remodeling in the brain is dependent on the extracellular matrix remodeling mediated by zinc-dependent matrix metalloproteinases (MMPs). Using a rodent model, this study shows that the activity of MMP2 and 9 are differentially increased in the brain region nucleus accumbens after withdrawal from self-administered cocaine, during cue-induced relapse. Along with a similar response following relapse to other drugs of abuse, the study also shows that the increased MMP activity was needed for both relapse behavior and relapse-associated synaptic plasticity that included changes to the glutamate-mediated currents and dendritic spine head diameter.

In this study, the authors show that optogenetic photostimulation of dopaminergic (DA) neurons in the ventral tegmental area during exploration can enhance subsequent sharp wave/ripple-mediated reactivation of spatial memory. These results suggest that midbrain DA neurons are key mediators of hippocampal-dependent memory persistence.

This study uses a combination of human fMRI and computational modeling to show that decision-making can be explained by a hierarchical model involving competition between different options at many different levels of representation. These results do not support a model where competition happens only at a final choice stage.

This recording study shows that attention can increase or decrease correlations between fluctuations in the responses of pairs of neurons, depending on task demands. These results suggest that attention can flexibly modulate such spike count correlations, independent of changes in firing rate and provide constraints on possible neuronal mechanisms.

This study uses fMRI in humans to find that prediction errors about pain are encoded in the periaqueductal gray. Modeling inter-area connectivity suggests that the ventromedial prefrontal cortex and the putamen pass on a value-related signal to this midbrain structure, which then conveys predictor error signals to prefrontal regions that regulate behavior.

Although head direction cells are known to encode information related to an organism's heading, it is unclear how the brain integrates this with information provided by fixed environmental features. In this study, the authors show that the retrosplenial complex is important for encoding heading and facing direction based on local landmarks and that this process generalizes across different environments that have similar geometry.

Radial glial progenitors (RGPs) in the developing mouse cortex generate excitatory neurons during development. This study examines the role of centriole-related protein Sas4, the mutation of which causes microcephaly in human brain, and shows that centrosome and centriole act to anchor RGPs in the ventricular zone during embryonic neurogenesis. By preventing cell death of RGPs without centrioles, the study also shows that cleavage plane orientation of cell division is not essential for radial glial progenitors' self-renewal.

Using in vivo recording of neuronal activities in rat secondary motor cortex and devising a novel task of waiting before performing an action, Murakami et al. show a neural correlate of voluntary action initiation. The study also shows population activity and computational modeling data that correspond to action timing of voluntary action that are consistent with integration-to-bound theories of decision making.

The authors devised a new behavioral task to study cooling perception in head-fixed mice. Using whole-cell recordings from layer 2/3 neurons in the somatosensory cortex, they reveal that the same neurons that respond to mechanical stimulation of the skin also respond to its cooling. In addition, they find that both the perception of cooling and the cooling responses in S1 are eliminated in TRPM8 knockout mice.

Oligodendrocyte precursor cells (OPCs) retain their proliferative/differentiation capacity throughout life. This study uses in vivo and ex vivo imaging to show a specific temporal window between OPC division and oligodendrocyte differentiation in the postnatal mouse brain that is modulated by the microenvironment. The latency between OPC division and differentiation is shortened by myelin damage, while sensory deprivation reduces the survival of divided OPCs undergoing differentiation.

Using the Drosophila system, this study shows that rewarding and motivational properties of water are mediated by different subsets of dopaminergic neurons. The study also shows a satiety state–dependent effect in which thirst can change water avoidance behavior into water-seeking behavior and demonstrates that water wanting versus liking versus learning are separable at the level of behavior and the underlying neural circuit.

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.

Large-scale consortia have benefited many fields chasing big data. In the face of new projects, neuroscientists should consider banding together.

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.

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.