Articles in 2010

Down syndrome is caused by the triplication of chromosome 21, which results in extra copies of hundreds of genes. Chakrabarti et al. used the Ts65Dn mouse model of Down syndrome to show that Olig1 and Olig2, two transcription factor genes that are triplicated in Down syndrome and in the Ts65Dn mouse, are involved in the manifestation of the inhibition/excitation imbalance phenotype.

The hippocampus has place cells that preferentially fire at a particular location of spatial arena. Dupret et al. report that place fields remapped as a result of goal-directed spatial learning and that sharp wave/ripple reactivation events seen during memory consolidation predicted the strength of subsequent spatial memory. Jeffery and Cacucci highlight this work in their News and View.

The authors find that disruption of primary motor cortex or dorsolateral prefrontal cortex with transcranial magnetic stimulation has differential effects on motor memory retention depending on whether training was done in blocks of trials or with different tasks interleaved. This suggests that the neural substrate for motor-memory consolidation depends on the practice structure used for training.

Fritz et al. compared activity in ferret frontal cortex and primary auditory cortex (A1) during auditory and visual tasks requiring discrimination and found that A1 and frontal cortex establish a dynamic, functional connection during auditory behavior that shapes sensory information flow and maintains a persistent trace of recent task-relevant stimulus features.

Understanding of the fly visual circuitry has been hampered by the difficulty of recording from the small neurons involved. Reiff and colleagues present a technique to record visually evoked responses and find that the L2 interneurons in the medulla encode brightness decrements rather than motion.

The authors combine optogenetics, two-photon microscopy and glutamate uncaging to study D2-type dopamine receptor modulation of glutamatergic transmission in mouse striatopallidal neurons. They find that dopamine regulates spine calcium via multiple pathways.

Fear conditioning results from the association that develops between a neutral conditioned stimulus and an aversive unconditioned stimulus (UCS), which is thought to be supported by plasticity in the amygdala. Here, the authors find that information about the UCS is conveyed to the amygdala by neurons in the periaqueductal gray.

In Drosophila, activation by Wingless results in cleavage of its Frizzled2 receptor and translocation of the C terminus (Fz2-C) from the postsynaptic density to the nuclei. Mosca and Schwarz find that nuclear Fz2-C entry requires the nuclear import factors Importin-β11 and Importin-α2. This pathway promotes postsynaptic development of the subsynaptic reticulum.

All research on human subjects requires their informed consent. Obtaining valid consent from isolated minorities can be particularly challenging, but scientists need to avoid the temptingly easy way out, so as to prevent further exclusion of these vulnerable populations from biomedical research.

A study reports a new method for wholesale labeling of neuronal proteins in situ that can visualize newly synthesized protein in a manner compatible with standard immunostaining techniques.

Melanocortin signaling in the CNS, which crucially regulates feeding and energy expenditure, also regulates the expression of a hepatic cholesterol re-uptake receptor. Thus, the brain in rodents directly controls the levels of circulating high-density cholesterol species. The relevance to human cholesterol metabolism remains unknown.

Acupuncture entails stimulating discrete points on the body with needles to alleviate pain. A study in this issue finds that local activation of adenosine A₁ receptors in mice contributes to the anti-nociceptive effects of acupuncture.

High Na⁺ channel density is thought to underlie the axon initial segment's (AIS's) low action potential initiation threshold, but a new study estimates functional Na⁺ channel density in the AIS is only threefold higher than in the soma.

A genome-wide association study (GWAS) allows for unbiased discovery of genetic bases for various diseases in both familial and sporadic forms. Using two recent GWASs of Alzheimer's disease and Parkinson's disease as examples, Wood and Gandhi discuss the underlying principles of the GWAS and highlight the progress of these studies of neurodegenerative disease and the road lying ahead.

Building on their previous observation that neuronal calcium spike activity can drive neurotransmitter specification during development, these authors report that cJun phosphorylation integrates activity-dependent and intrinsic transmitter specification through the regulation of tlx3 transcription in Xenopus sensory neurons.

The authors find that a person's estimate of a time interval exhibits biases that depend on both its duration and the distribution from which it is drawn. This behavioral pattern could be described using a Bayesian model. These findings suggest that internal timing mechanisms can adapt to the temporal statistics of the environment to minimize uncertainty.

Some brain areas, such as the olfactory bulb, can decorrelate (that is, separate out) very general inputs. However, the mechanisms enabling such decorrelation are unclear. This study presents a computational model that shows that efficient pattern decorrelation can emerge from a combination of nonlinear input-output functions and recurrent, sparse and strong inter-neuronal connectivity.

This paper reports the development of a K⁺-selective glutamate receptor, HyLighter, that reversibly inhibits neuronal activity in response to light. The low light requirement and bi-stability of HyLighter could be useful for studying neural circuitry.

Spinal muscular atrophy (SMA) is a form of childhood neurodegenerative disease due to the lack of SMA protein in motor neurons. This Perspective article discusses the recent progress in our understanding of pathological mechanisms, past efforts in SMA therapy developments, and future directions for translational research.