Research articles

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.

Just before a rapid eye movement (saccade), attentional performance improves for the targeted position where the saccade will land. This behavioral study finds that attentional performance also improves at the subsequent locations that the target of the saccade will move to, suggesting that attentional remapping occurs at least two steps ahead.

Homeostatic plasticity can be induced by increasing neuronal activity and is mediated, in part, by AMPAR endocytosis. Here Fu et al. describe the involvement of EphA4 in synaptic scaling via ubiquitin-dependent degradation of AMPAR.

Several axonal guidance molecules have a dual function in directing dendritic growth as well. UNC-6 (Netrin) in C. elegans is one such molecule. Here, Teichmann and Shen show how UNC-6's action in axon versus dendrite can be specified.

The auxiliary subunit Cavβ regulates calcium channel density in the plasma membrane, but the mechanism by which this occurs has been poorly defined. Altier et al. find that Cavβ prevents ubiquitination of the Cav1.2 channels by the RFP2 ubiquitin ligase and subsequent targeting of the channels for proteasomal degradation.

Hunger makes Drosophila larvae move faster in search of food. Koon and colleagues show that starvation increases the branching of octopaminergic motoneurons' axonal terminal arbors, driven by octopamine released from these same motoneurons. The increased locomotor activity of starved larvae requires octopaminergic signaling.

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.

Even if it doesn't trigger action potential, a slight somatic depolarization can still spread and modulate the neurotransmitter release at distant sites along axons. Here, the authors find that depolarization in the cerebellar molecular layer interneurons can affect presynaptic neurotransmitter release in a calcium-dependent and voltage-sensitive Ca²⁺ channel–dependent manner.

Anticipation about the timing of an event can improve response speed. Here the authors find that responses of single neurons in primary auditory cortex show enhanced representation of sounds during periods of heightened expectation. Neural activity was also linked to perceptual performance, suggesting that this signal could contribute to the behavioral effects of temporal expectation.

This study finds that thalamic interneurons and downstream projecting relay cells have opposite response properties. Computational modeling suggests that such complementary mechanisms may help preserve more spike-timing information.

In a mouse model of Alzheimer's disease, the authors find that early loss of AMPA receptors at synapses at onset of cognitive dysfunction is a result of activation of the phosphatase calcineurin by caspase-3. Inhibition of caspase activity rescued both synapse density and fear memory in this model.

This electrophysiology study finds that spatial tuning in cat A1 is sharpened when the cats are engaged in a task, as compared with rest. Inhibitory mechanisms are likely to be the source of this sharpening.

The patterns of nociceptive innervation in skin and spinal cord differ in mammals and lower vertebrates. Guo et al. report that nerve growth factor induces the transcription factor Hoxd1 in mouse, but not chick, sensory neurons, and that expression of Hoxd1 is necessary and sufficient for a mammalian-like pattern of nociceptive projections in vivo.

The authors report that, in a subset of rodent hippocampal and neocortical interneurons, evoking hundreds of spikes at normal rates caused persistent firing that outlasted the stimulus by about a minute. Persistent firing was generated in the distal axon, did not require somatic depolarization and could be shared between interneurons via an axo-axonal interaction.

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.

Ca_v1.3 calcium channels are critical for neurotransmitter release in auditory hair cells and cardiac pacemaking. The authors identified a mutation in CACNA1D, which encodes the pore-forming α1-subunit of Ca_v1.3, in deaf humans. These individuals also exhibited bradycardia. The insertion of a glycine residue near the pore resulted in nonconducting channels.

During Drosophila metamorphosis, the γ axons of mushroom bodies are pruned and regrow into their adult morphology. The pruning process requires the ecdysone receptor EcR-B1. The authors find antagonistic transcriptional regulation of EcR-B1 by two closely related nuclear receptors, Ftz-f1 and Hr39.