Brief Communications in 2012

The authors use patch clamp recordings and computer simulations to determine the number of molecules of glutamate released at two central synapses. They find that the amount of glutamate released maximizes the synaptic current per glutamate molecule and maximizes the signal's information content, suggesting that synapses operate under conditions that optimize resources.

GABAergic neurogliaform cells are thought to use volume transmission and provide widespread cortical inhibition, indiscriminately. To their surprise, Chittajallu et al. found that that neurogliaform cells exert a spatially restricted inhibitory influence on the mouse canonical thalamocortical circuit, as they selectively suppress feed-forward inhibition while sparing feed-forward excitation.

The authors report that medium spiny neurons in the mouse nucleus accumbens receive inputs from the cortex, thalamus and hippocampus, but the differential subcellular connectivity of hippocampal inputs makes them much weaker onto neurons in the indirect pathway.

In this study, the authors show that subjecting adult animals to prolonged social isolation results in impaired heterochromatin formation in oligodendrocytes and decreased myelin thickness, specifically in the prefrontal cortex. This suggests that social experience can regulate myelin plasticity in the adult via an epigenetic program.

Neural progenitor cells (NPCs) are known to be influenced by their local environment. However, in the current study, the authors show that NPCs can also secrete signaling proteins that regulate microglial cell function.

This paper reports that there are substantial differences in DNA methylation patterns between nurses and forager caste phenotypes in honeybees, and that reverting foragers back to nurses reestablishes methylation levels for a majority of genes.

Neurons in the parietal cortex have been shown to encode position in external reference frames. This work demonstrates that parietal cortex neurons can simultaneously register spatial information in multiple external reference frames. The form this takes suggests a mechanism for encoding relationships between parts and the whole that they compose.

Noise-induced sensorineural hearing loss selectively worsens peripheral temporal coding in noisy compared with quiet conditions reports this study in chinchillas. This may explain why noisy conditions are particularly difficult for hearing-impaired people.

Alcoholism and post-traumatic stress disorder are frequently co-morbid. The authors show that chronic intermittent exposure to ethanol impairs extinction of fear conditioning in mice. In vivo recordings showed that extinction encoding was impaired in infralimbic medial prefrontal cortical (mPFC) neurons, which are associated with downregulation of the NMDA receptor subunit GluN1 in mPFC.

Optogenetic manipulations of behavior in primates have largely been unsuccessful. Here, the authors report that monkeys reliably shift their gaze toward the receptive field of optically driven channelrhodopsin-2–expressing V1 neurons.

By examining natural behavioral variation of an outbred strain of mice on a Pavlovian-to-instrumental transfer task, the authors show that the level of polysialylated neural cell adhesion molecule (PSA-NCAM) in the ventromedial prefrontal cortex (vmPFC) can predict the extinction and cue-induced reinstatement of alcohol seeking. The study also shows that depleting endogenous PSA-NCAM in the vmPFC in mice confers resistance to the extinction of alcohol seeking.

NG2 proteoglycan⁺ cells are neural and oligodendrocyte progenitors, and NG2⁺ cells in the developing barrel cortex receive glutamatergic thalamocortical inputs. Here, the authors show that NG2⁺ cells are primarily localized in barrel septa and that sensory deprivation induces NG2⁺ cell proliferation and differential localization in and around the barrels.

The identity of the mechanosensitive channel responsible for sound transduction in the ear has remained elusive. Here the authors show, using interferometry, that the gating compliance of the fly's hearing organ is disrupted after deletion of TRPN1, identifying this channel as the sound transducer and/or its gating springs.

The authors show that spontaneous transmission from inhibitory synapses, in contrast with excitatory synapses, is triggered by voltage-dependent calcium channel activity. In addition, they find that spontaneous GABA release involves coincident opening of multiple closely packed calcium channels.

The authors find that aged mice have decreased expression of the DNA methyltransferase Dnmt3a2 in the hippocampus. Rescue of Dnmt3a2 expression in aged mice reversed learning and memory deficits, whereas decreasing Dnmt3a2 expression in young mice impaired memory formation.

In a longitudinal brain imaging study, patients with subacute back pain were followed over the course of 1 year. Initially greater functional connectivity of nucleus accumbens with prefrontal cortex predicted pain persistence, implying that corticostriatal circuitry is causally involved in the transition from acute to chronic pain.

Here the authors find that auditory cues presented quietly during a nap influence motor sequence learning. When one of two sequences was cued following initial learning, performance was disproportionately improved for that sequence, reflecting sleep-based reactivation and consolidation of skill memory.

In this study, the authors show that optogenetic silencing of neurons with a commonly used light-driven chloride pump can result in alterations in GABAergic synaptic transmission that persist after the stimulation period and that may result in changes to neuronal excitability.

The projection from the lateral habenula (LHb) to the rostromedial tegmental nucleus (RMTg) transmits negative reward–related information. Here the authors show that aversive stimuli increase LHb excitatory drive onto RMTg neurons, and optogenetic stimulation of this pathway is sufficient to induce active, passive and conditioned behavioral avoidance.

AgRP neurons in the hypothalamus elicit feeding behavior. Here the authors show that interfering with AgRP neuron function, either by selective knockout of Sirt1 or by early postnatal ablation, leads to increased exploratory behavior and enhanced response to cocaine, which is associated with increased forebrain dopamine levels.