Brief Communications in 2010

The volume of the human amygdala correlates with the size and complexity of individual social networks, reports this study. This correlation still exists after correcting for intracranial volume, and seems to be specific to the amygdala and not other subcortical structures.

P2X receptor channels, which have three α-helical transmembrane domains, are found throughout the nervous system. Using site-directed mutagenesis, the authors find that each of the three subunits contributes equally to the open channel permeation pathway and that the closed-to-open transition involves a symmetrical separation of the three channel subunits.

This study identifies proteins from the postsynaptic density (PSD) of human neocortex and finds that the PSD shows enrichment of genes involved in cognitive and affective phenotypes and that PSD mutations are associated with neurological and psychiatric disease.

This study finds that mice's biological clocks are permanently influenced by the seasonal photoperiod at and after birth. In mice raised under summer-like light periods, rhythmic gene expression in the suprachiasmatic nucleus was tightly correlated with lights-off under both summer- and winter-like cycles. In 'winter-born' mice, these rhythms were tightly correlated only under winter-like light cycles.

This study reports that the size of the primary visual cortex correlates negatively with the magnitude of two common visual illusions. The size of primary visual cortex may therefore modulate conscious visual experience.

The roles of striatopallidal (indirect) and striatonigral (direct) pathway neurons in regulating behavior is of great interest. Ferguson et al. selectively and transiently disrupt either one pathway or the other. They find that disrupting striatopallidal neuronal activity facilitated behavioral sensitization, whereas disrupting striatonigral neurons impaired its persistence.

Synaptic vesicles release neurotransmitters both at rest and when stimulated. Wilhelm et al. use a variety of assays to show that the same vesicles participate in both active and spontaneous release.

Whether the same pool of synaptic vesicles participates in both spontaneous and activity-dependent release remains controversial. Using a combination of new and established probes, the authors find cross-depletion of spontaneously and activity-dependent pools, indicating that both types of release draw from a common pool.

Liu and colleagues report that toll-like receptor 7 (TLR7), which is typically thought to be expressed in immune cells and to function to regulate innate immunity, is expressed and acts in C-fiber primary sensory neurons. In mice, they find that TLR7 is important for inducing itch, but is not necessary for eliciting pain.

5-hydroxytryptamine 2C receptors (5-HT2CRs) in the brain have been shown to regulate glucose homeostasis. Xu and colleagues find that 5-HT2CRs expressed specifically by hypothalamic pro-opiomelanocortin neurons are involved in the regulation of insulin sensitivity and glucose homeostasis in liver.

The established conductance hierarchy of voltage-gated calcium channels, where conductance of Ca_V1 is greater than Ca_V2, which is in turn greater than Ca_V3, was determined using nonphysiological divalent ion concentrations. Weber et al. find that Ca_V2.2 conductance is greater than that of Ca_V1 and Ca_V3 and investigate implications for Ca²⁺ nanodomain signaling.

Rouaux and Arlotta show that expression of a single transcription factor, Fezf2, suffices to turn ventral forebrain progenitors committed to a striatal GABAergic fate into glutamatergic corticofugal projection neurons—which nevertheless migrate to the striatum.

Agetsuma and colleagues find that the pathway between the lateral subnucleus of the dorsal habenula (dHbL) and the interpeduncular nucleus is involved in mediating experience-dependent fear responses in zebrafish. Genetic inactivation of the dHbL biased fish towards freezing, rather than the typical flight behavior, in response to a conditioned fear stimulus.

Corticotrophin releasing factor (CRF) and its receptors are involved in the neuroendocrine and behavioral responses to stress. Here, Elliot and colleagues describe alterations in DNA methylation of the Crf gene that regulate its expression and show that these alterations correlate with resilience to social stress.

AKAP79/150 is a protein scaffold that is thought to position specific kinases and phosphastases in their appropriate synaptic domains. The authors report that AKAP interacts with calcineurin to regulate NMDA receptor–dependent plasticity in rat hippocampal slices.

Földy et al. find that GABA_A receptor–mediated synaptic inputs from murine parvalbumin-expressing basket cells are selectively modulated by the membrane voltage– and intracellular chloride–dependent chloride channel ClC-2. Their data reveal a cell type–specific regulation of intracellular chloride homeostasis in the perisomatic region of hippocampal pyramidal neurons.

The authors report that the voltage-gated K⁺ channel Kv12.2 regulates firing threshold and excitability in hippocampal pyramidal neurons.

The authors find that rat central auditory neurons fire action potentials in a stereotyped pattern of mini-bursts prior to hearing onset and that this pattern is initiated by cochlear hair cells.

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.

The authors chronically stimulated cultured cortical cell networks. They observed changes in the timing of neural activity that depended on the intervals used during training.