Articles in 2013

The primary visual cortex (V1) carries signals related to visual speed, and its responses are also affected by run speed. Here the authors report that nearly half of the V1 neurons were reliably driven by combinations of visual speed and run speed. As a population, V1 neurons predicted a linear combination of visual and run speed better than visual or run speeds alone.

Electrical coupling in the brain usually occurs between inhibitory neurons that are anatomically and functionally similar. Here the authors show that the excitability of inhibitory interneurons in the dorsal cochlear nucleus is controlled by electrical synapses with excitatory projection cells.

The neurodegeneration found in human ataxia-telangiectasia (A-T) is caused by mutations in the ATM (A-T mutated) gene. Li et al. have identified the polycomb group protein with histone methyltransferase activity called EZH2 as a target of the ATM kinase. The study shows that ATM deficiency increases EZH2 stability, thus increasing methylated histone marks. This results in epigenetic changes in transcription that compromise the health and survival of CNS neurons.

The authors find that GABA_AR-mediated tonic currents recorded in rodent cerebellar granules cells can be modulated by ethanol in opposite directions in different strains exhibiting opposite preferences in alcohol consumption. These differences in ethanol sensitivity across strains are linked to differential levels of expression of presynaptic neuronal nitric oxide synthase and postsynaptic PKC activity.

How do dendrites contribute to neuronal computations in intact circuits? Using dual whole-cell recordings from the soma and dendrites of retinal ganglion cells, Sivyer and Williams demonstrate that the engagement and inhibitory synaptic control of a cascade of active dendritic integration compartments underlies the computation of image motion by direction-selective rabbit retinal ganglion cells—placing dendritic integration at the heart of physiologically engaged neuronal-circuit operation.

Cholinergic transmission from the basal forebrain provides neuromodulatory control over brain states such as wakefulness and sleep. Here the authors show that cholinergic input bidirectionally and dynamically modulates cortical processing of sensory inputs and influences visual perception in awake, behaving mice.

In this study, the authors show that, during the retinogeniculate refinement period, astrocyte-derived TGF-β regulates the expression and synaptic localization of C1q, a classical complement protein. They find that TGF-β signaling and C1q expression in neurons are key regulators of microglia-mediated synaptic pruning in the dorsal lateral geniculate nucleus.

The authors use dendritic imaging to examine odor response properties of individual synaptic sites of mushroom body neurons. They find that mushroom body neurons receive input from different glomerular channels and require several of those inputs to be co-active to spike, a likely foundation for their remarkable stimulus selectivity.

Adaptive control to improve performance after making mistakes in a given task is known to involve prediction error signaling in the anterior cingulate cortex (ACC). The current study examines adaptive control in humans and rats by using comparable time-estimation tasks for each organism, and the authors show that low-frequency oscillations within the ACC in humans and the medial frontal cortex (MFC) in rats are correlated with adaptive behavioral control. They also show that these frontal oscillations are phase locked to the oscillation in the motor regions in the brain and that inactivation of the MFC in rats can disrupt both behavioral control and oscillatory coupling.

In this study, the authors show that a subset of cerebellar granule neurons originate not from the granule neuron precursors (GNPs) but from a population of Nestin-expressing progenitors (NEPs) in the deep external germinal layer. In addition, they find that these NEPs are more susceptible to Sonic Hedgehog–induced genomic instability and tumor formation.

The authors study fMRI responses to colors and achromatic images to address the fundamental organizational principles of monkey inferior temporal cortex. They report color-biased regions adjacent and ventral to face patches, at locations predicted by a series of coarse eccentricity maps.

The authors investigated the mechanisms underlying hippocampal sharp waves. They found that CA3 axo-axonic cells (AACs) stopped firing during sharp waves in vivo. They also identified GABAergic cells in the medial septum that are activated during sharp waves and project to CA3; these cells may inhibit AACs during sharp waves.

Diverse species use ineraural time differences to locate the origin of sounds in space. Here the authors show that GABA_B receptor–mediated feedback onto the medial superior olive modulates the gain of auditory space coding, leading to systematic shifts in the percept of sound location.

α7-nicotinic acetylcholine receptors (α7nAChRs) modulate the effects of the main psychoactive ingredient of marijuana, Δ⁹-tetrahydrocannabinol (THC), in the brain. Here the authors show that pharmacologically enhancing kynurenic acid, an endogenous modulator of α7nAChRs, attenuated the rewarding properties of THC and prevented drug relapse in monkeys and rats.

The authors show that type 2 dopamine receptors (D2Rs) negatively regulate spine morphogenesis in the hippocampi of adolescent mice. Spine deficiency resulting from D2R overactivation was associated with dysconnectivity in the entorhinal-hippocampal circuit and working memory deficits. These phenotypes could be rescued by D2R antagonists given during adolescence.

GABAergic cortical interneurons have important roles in the computations of neural circuits, but their developmental origin in primates is controversial. Here the authors characterize neural stem cell and progenitor cell organization in the developing human ganglionic eminences and reveal that, just as in rodents, they give rise to a majority of cortical GABAergic neurons.

The self renewal and long-term maintenance of neural stem cells (NSCs) is related to how quickly they pass through the cell cycle. Here the authors describe a new role for the cyclin-dependent kinase inhibitor p21 and show that it maintains an active NSC pool through repression of Bmp2.

Here the authors demonstrate a causal role for the barrel cortex in the detection of single whisker stimuli. Whisker deflection evoked an early (<50 ms) reliable sensory response that was encoded through cell-specific reversal potentials. A secondary late (50–400 ms) depolarization was enhanced in hit trials compared to misses. Optogenetic inactivation revealed a causal role for late excitation.

The origin and functional importance of noise in mammalian cones is poorly understood. Here, the authors find that channel noise and fluctuations in cGMP dominate cone noise, that adaptation in cones affects signal and noise differently, and that cones generate less noise than previously thought. These results help reconcile cone noise and behavioral sensitivity.

In primates, the developmental origin of neocortical interneurons is controversial. Here the authors map out expression patterns of key transcription factors in the developing human and monkey brain and reveal that, just as in rodents, the majority of cortical GABAergic neurons originate from the ganglionic eminences.