Articles in 2012

Excitatory connections in cortex are clustered into groups of highly connected neurons. Here the authors examine the effect this clustering has on the dynamics of neuronal networks with balanced excitation and inhibition. Their model suggests that the reported variability in spontaneous and evoked spiking activity may result from clustered cortical architecture.

This study shows that a mouse's trial-and-error learning in the Morris water maze is mediated by a stereotyped sequence of hippocampus activation along its ventral-to-dorsal axis. Using anatomical or molecular lesions and a previously validated morphological readout of mossy fiber circuit refinement, the authors show that the ventral hippocampus in mice has an early role in goal-oriented learning and searching.

Path integration allows animals to track their body position in planar space by relying on both external cues and internal cues. For monitoring internal cues, head direction cells in the anterodorsal thalamic nucleus are one of the best candidates for the neural mechanism underlying path integration. This study shows that head-direction cells in rats act as a mediator of path integration such that their firing matches the level of movement trajectory heading errors in a cumulative manner, and that head-direction cells correct their firing when internal error is corrected by external cues.

Here the authors test the proposal that premotor circuits participate in sensory learning for imitation using convergent approaches in the juvenile zebra finch, including optogenetic disruption and in vivo multiphoton imaging. Their findings provide evidence that premotor circuits help to encode sensory information prior to shaping and executing imitative behaviors.

This work shows that ephrin-B2 from astrocytes provides a critical niche signal for cell fate determination in adult mouse hippocampus, in part by directing neuronal differentiation of adult neural stem cells through EphB4-dependent juxtacrine signaling.

Dentate mossy cells in hippocampal slice can temporarily store stimulus information from the perforant path with persistent up-state–like activity. Here, Hyde and Strowbridge show that hippocampal dentate hilar cells can store several distinct patterns of information simultaneously for several seconds and that the activity of the local network in the dentate gyrus can predict which input conveyed the stimulus information and what temporal sequence of stimuli was presented.

Expression of GluN2 subunit of NMDA receptor (NMDAR) in rodents is developmentally regulated such that GluN2B expression is high during early postnatal period but is replaced by GluN2A in adulthood, thus conferring different NMDAR channel properties and kinetics. This study identifies a molecular mechanism for GluN2A/B switch that is mediated by the transcriptional repressor REST. This process is also shown to be affected by postnatal stress induced by maternal deprivation, leading to long-lasting effects on NMDAR-subunit composition in the hippocampus.

The authors report that, during sleep, a task-related auditory cue biases hippocampal reactivation events towards replaying the spatial memory associated with that cue. These results indicate that sleep replay can be manipulated by external stimulation, and provide further evidence for the role of hippocampal replay in memory consolidation.

Leptin regulates energy balance. The authors show that Rho-kinase 1 (ROCK1) regulates leptin signaling by increasing activation of signaling molecules downstream of leptin receptor. Deletion of ROCK1 from POMC or AgRP neurons leads to obesity and reduced leptin sensitivity.

The pathology in Parkinson's disease is known to extend beyond mesencephalic dopaminergic neurons, but it is unclear why. Here the authors show that vulnerable neurons in the dorsal motor nucleus of the vagus have similar physiological features, including basal mitochondrial oxidant stress, providing an insight into the distributed disease pathology.

Although it is well-known that sleep can strengthen existing memories, this study demonstrates that people can acquire completely new associations (between distinct tones and pleasant/unpleasant smells) during sleep, which are preserved during the awake state.

The authors show that traumatic brain injury can induce peroxidation of cardiolipin, leading to accumulation of numerous oxygenated species and the induction of neuronal cell death. This accumulation of cardiolipin and the associated toxicity can be ameliorated by mitochondria-targeted delivery of an electron scavenger.

In this paper, Bessereau and colleagues identify MOLO-1 as an auxiliary subunit for levamisole-sensitive acetylcholine receptors (L-AChRs) present at the neuromuscular junction of C. elegans. MOLO-1 is the first auxiliary subunit ever found for a member of the Cys-loop receptor superfamily.

The immediate-early gene Arc mediates synaptic plasticity and long-term memory formation. Whether Arc is dysregulated by amyloid-beta or in Alzheimer's disease is controversial. Here, a study used a reporter mouse line expressing destabilized fluorescent protein Venus under the control of the Arc promoter to show that Arc induction pattern, brain regional difference and precise location of active neurons with respect to senile plaque are major determinants of differential Arc response in a mouse model of Alzheimer's disease.

The authors show that K-ATP channels in dopamine (DA) neurons of the medial substantia nigra (m-SN) enable burst firing in vitro and in vivo. Silencing K-ATP channel activity in m-SN DA neurons decreases novelty-dependent exploratory behavior in mice.

In this study, the authors show that, during the development of the enteric nervous system, a subset of enteric neural crest cells migrate from midgut across the mesentery to colonize caudal hindgut. This trans-mesenteric migration requires GDNF and GFRα1 signaling.

In tasks involving goal-directed action selection, striatal neural activity has been shown to represent the value of competing actions. Here the authors show that transient optogenetic stimulation of dorsal striatal D1 and D2 receptor–expressing neurons during decision-making biases choices in a way that mimics an additive change in action value.

The anterior cingulate cortex is known to be involved in determining cost versus benefit, but, by recording from rats choosing to engage in competition with another rat for limited rewards, the authors found that this area is also involved in competitive effort.

The authors report that endogenous myocyte enhance factor 2 (MEF2) levels affect spatial and fear memory formation in adult mice. MEF2-induced memory disruption was rescued by interfering with AMPA receptor endocytosis.

The olfactory system is vulnerable to sensory deprivation owing to the prevalence of rhinosinusitis, but how the brain encodes and maintains odor information under such circumstances remains poorly understood. Using fMRI, the authors find evidence for transient changes in olfactory brain regions that sustain odor perception following disrupted sensory input.