Articles in 2008

Spontaneous cortical waves have been widely observed, although previous evidence from humans has been indirect, using functional magnetic resonance imaging. This study reports that there are slow modulations in neuronal firing rates and gamma local field potentials in human auditory cortex in the absence of sensory stimuli or task.

Ambient light can acutely modulate sleep and can be detected by the retina independently of photoreceptors. A new study from Foster and colleagues shows that photosensitive retinal ganglion cells, with their activation of sleep-promoting centers, mediate this irradiance-dependent sleep induction.

To better understand the development of the binocular circuit and the nature of visual information processing, Ramdya and Engert examine the neuronal activity of zebrafish optic tectum when it was rewired to receive inputs from both eyes.

Several signaling pathways have been previously implicated in memory persistence, but new data suggests that circadian oscillations of cAMP production and protein phosphorylation in the hippocampus are important for the reactivation of a transcriptional pathway and memory consolidation.

Using a combination of behavioral measures and transcranial magnetic stimulation (TMS), this study finds that elite basketball players are better at predicting whether a free basketball throw will land in the basket or out and that they also have higher TMS-evoked motor potentials for when the ball misses its mark.

The shuttling of AMPA receptors to and from the synaptic membrane determines the strength of synaptic transmission. This study shows that ephrinB2 is part of the mechanism that stabilizes AMPA receptors at the synaptic surface. EphrinB2 and AMPA receptors are linked by two PDZ domains in the intracellular adaptor protein GRIP.

Although certain ion channels can be gated by temperature, it is currently unknown how this occurs. Here, the authors identify regions of TRPV3 that are critical for heat sensation, yet independent of other channel gating mechanisms.

The response of some cortical neurons seems to exceed psychophysical sensitivity. Recording in rat barrel cortex, this study finds that neuronal sensitivity is degraded under more life-like conditions of stimulus uncertainity. However, pooled spike-timing information from the most sensitive neurons still correlates with subjects' psychophysical sensitivity.

Invertebrates engage in complex aggressive behaviors that involve several neurotransmitters. The circuitry that regulates aggression is unknown. Zhou et al. show here that aggression in male fruit flies correlates with levels of octopamine and that a small group of octopaminergic neurons in the subesophageal is crucial for aggressive behaviors.

This study demonstrates that relapse in heroin-addicted rats requires endocytosis of the AMPA receptor subunit GluR2 in the medial prefrontal cortex. When endocytosis was inhibited in this specific brain structure, the addicted, but abstinent, rats were less intent on seeking heroin when re-exposed to drug-associated cues.

It is currently unknown how some animals maintain such precise temperature sensation. Ramot et al. report that the thermosensory neurons in C. elegans utilize cGMP-dependent signaling machinery to alter ionic current responses and maintain a dynamic range of sensitivity.

In this article, the authors report that the temporal precision of the reward prediction error signal encoded by midbrain dopamine neurons declines as the delay between a reward predicting stimulus and an expected reward increases. The temporal precision of the neural signal is qualitatively similar to that of anticipatory behavior.

Pregnancy in mice is aborted if a female smells the urine of a new male up to 3 days after insemination, but not later. What changes? Dopamine increased in the female main olfactory bulb after copulation, peaking at 4 days. This diminished the mice's ability to recognize male urine. A dopamine receptor inhibitor improved recognition of male urine, and thereby increased the probability of abort.

This study identifies a dystroglycan-interacting protein, pikachurin, that is localized in the extracellular space between photoreceptors and bipolar cells. The authors also demonstrate its requirement in normal ribbon synapse development and function. Kevin Campbell and Jakob Satz discuss this paper in an accompanying News and Views article.

Mice lacking the metabotropic glutamate receptor mGluR7 are hypersensitive to convulsant drugs. But how does mGluR7 act to prevent seizures? Here the authors show that interfering with the interaction between mGluR7 and the intracellular adaptor protein PICK1 causes a phenotype in mice and rats that is reminiscent of human absence epilepsy.

Adult neurogenesis in hippocampus yields newly born granule cells that receive synaptic inputs from existing neurons. Characterizing morphological and functional features of newborn neurons in adult mice, Toni et al. demonstrate the functional maturation of their synaptic output onto the appropriate target cells in the hippocampus.

DARPP-32 phosphorylation is crucial to the actions of both psychostimulant and antipsychotic drugs. By using BAC transgenic mice to tag DARPP32 selectively in either striatonigral or striatopallidal neurons, the authors show that cocaine (a psychostimulant) and haloperidol (an antipsychotic) exert different effects on DARPP-32 in these two neuronal populations. This may help explain the opposing behavioral effects of these drugs.

Spatial attention works to modulate neuronal responses as early as V1, according to this study. Using electrophysiological recordings in monkey primary visual cortex, the authors found that there are two distinct cell populations (differentiated by direction selectivity, spike width, interspike interval distribution and contrast sensitivity) whose responses are either suppressed or enhanced by attention.

C.elegans do not possess eyes and are believed to lack responses to light. Ward et al. report a photophobic response in these worms and map this behavior to a group of sensory neurons. Their results also suggest that there could be some conservation in phototransduction between nematodes and vertebrates.

The neural circuitry of primary auditory cortex is known to have a critical period during which the representation of sound frequency is shaped to represent the external world. De Villers-Sidani and colleagues now show that the end of this critical period is driven by local patterns of activity reflecting environmental stimuli.