Research articles

A single fear-inducing stimulus increased GluR2 abundance and promoted incorporation of GluR2-containing AMPA glutamate receptors in mouse cerebellar cells, making the receptors impermeable to calcium and altering the activity of this inhibitory neural network. This switch was mediated by noradrenaline and action potential prolongation.

The amyloid beta (Aβ) peptide has been implicated in the pathogenesis of Alzheimer's disease. The authors report that overproduction of axonal or dendritic Aβ in rat organotypic slices reduces spine density and plasticity at nearby dendrites. Aβ production is dependent on action potentials and nicotinic receptors, whereas the effects of Aβ are dependent on NMDA receptors.

The authors detect cytosolic histone deacetylase-1 (HDAC1), a nuclear transcriptional repressor, in damaged axons in brains of humans with multiple sclerosis and of mice with cuprizone-induced demyelination. They show a cytotoxic mechanism in which the exported HDAC1 impairs mitochondrial transport, independent of its nuclear function.

It remains controversial whether the neocortex harbors progenitors that are capable of neurogenesis in vivo. Here the authors show that there is a population of mitotic cells in cortical layer I that are activated after ischemia to proliferate and generate GABAergic neurons.

Recording from hippocampal slices, the authors find that brief stimulation triggers long-lasting synaptic barrages in mossy cells and hilar interneurons that arise from persistent firing in semilunar granule cells. Transient stimulation of different entorhinal cortex pathways activated distinct assemblies of hilar neurons, representing a previously unknown mechanism of short-term information storage that persisted for up to 10 seconds.

The authors use chromophore-targeted laser photolysis to selectively kill pyramidal neurons that project from auditory cortex to the inferior colliculus. They find that this eliminates the experience-dependent recalibration of sound localization, while leaving normal sound localization intact, implicating this pathway in learning-induced plasticity.

Personality differences related to how equally people prefer to share rewards modulate amygdala activity, reports this fMRI study. This suggests that these personality differences are more likely to be due to automatic emotional processing.

Accurate taste perception relies on a properly functioning olfactory system. The authors demonstrate a reciprocal connection between taste and olfaction by showing that inactivation of the taste cortex also affects olfactory perception.

The shell subregion of nucleus LMAN is an output for the basal ganglia in song birds. The authors report that lesions of the this region do not immediately disrupt vocal behavior but do prevent the development of stable vocal sequences and the ability to imitate vocal sounds.

Visual resolution is best at the center of the retina, where the cones are packed together most closely, and decreases outside of this area, where cones are farther apart. Combining adaptive optics imaging and psychophysical testing, the authors reveal that resolution actually falls off much more quickly than cone spacing would predict.

This Resource paper describes a set of five new reporter mice, derived from Rosa26, driving Cre-dependent strong and ubiquitous expression of fluorescent proteins. In particular, the new mice show clear and specific expression patterns in the adult brain. The mice are available through Jackson Laboratories, and growing expression datasets can be accessed at http://transgenicmouse.alleninstitute.org/.

The authors report that the frequency of in vitro gamma oscillations in mouse hippocampus is increased by the activation of specific NMDA receptors on interneurons. This increase is countered by GABA_A receptor–mediated tonic inhibition of interneurons.

Selecting relevant information to make perceptual judgements is usually thought to be a cortical function. By reversibly deactivating the superior colliculus in monkeys, this study demonstrates that activity in a subcortical structure can also inform perceptual judgements, even in the absence of orienting movements (a function previously attributed to the superior colliculus).

Previous work has suggested that triggering transmitter release might require the opening of many Ca²⁺ channels. Here the authors show that at the inhibitory basket cell–granule cell synapse in rat hippocampus, the opening of three or fewer Ca²⁺ channels is sufficient to trigger transmitter release with high temporal precision.

The authors describe cell-based neurotransmitter fluorescent engineered reporters (CNiFERs), a new biosensor for monitoring neurotransmitter receptor activation. CNiFERs are cells engineered to express both a metabotropic receptor that triggers the G_q protein–coupled receptor cascade to increase calcium concentrations and a genetically encoded fluorescent calcium sensor for visualization.

People and animals are capable of making decisions using information about the probabilistic associations between a combination of cues and an outcome. Here the authors use computational theory to suggest that the posterior ratio, an important quantity for forming probabilistic inferences, can be learned and encoded by synapses that have bounded weights and undergo reward-dependent Hebbian plasticity.

In rodents, descending corticospinal tracts can be rerouted to innervate new targets after a spinal cord injury. Here, Ghosh et al. show that such anatomical rearrangement in the injured spinal cord is accompanied by sensory remapping at the cortical level.

Drosophila mutants that have defective Shaker K⁺ channel or SLEEPLESS, a GPI-anchored protein of Ly-6/neurotoxin family, have very short sleep cycles. Here the authors show that SLEEPLESS binds to Shaker to regulate its localization, membrane excitability and homeostatic sleep drive.

Mammalian cochlea inner hair cells (IHCs) can code a continuous grading of sound intensities. This is because neurotransmitter release at mature sensory ribbon synapses is linearly dependent on calcium influx, which has the effect of broadening the cells' dynamic range. Immature IHC neurotransmitter release is quite different. Here, the authors show that a switch from syanptogamin I and II to synaptogamin IV underlies this developmental change.

This study shows that continuous synthesis and availability of the phosphoinositide PIP₃ at the postsynaptic terminal is necessary for synaptic transmission in rat hippocampal neurons. A slow but constant turnover of PIP₃ was required for maintaining postsynaptic AMPA receptor, but not NMDA receptor, clustering.