Articles in 2016

Active neurons increase their energy supply by dilating nearby arterioles and capillaries to increase blood flow, but the mechanisms underlying neurovascular coupling are debated. In this paper, the authors show that different calcium-dependent signaling pathways regulate blood flow at the level of capillary pericytes and arteriole smooth muscle.

In neuronal cultures, synaptic strengths scale with the network size to preserve balance between excitation and inhibition, maintain variable spiking statistics and reduce correlations in spiking as predicted by theory and observed in the intact brain.

During tactile exploration, neural activity related to movement of digits or whiskers is suppressed to facilitate high signal-to-noise ratio encoding of touch. The authors show that in mouse this computation occurs in layer 4 of the barrel cortex and is mediated by fast-spiking interneurons.

The authors identify two genetic markers defining non-overlapping populations of principal cells in the amygdala that respond to stimuli of opposite valence. These two populations of cells contribute to behavioral responses to aversive or rewarding experiences, are distributed along antero-posterior gradients that run in opposite directions, and synaptically suppress each other.

Animals are sensitive to the rate of temperature change, in addition to absolute temperature. Using Drosophila larvae as a model, Luo et al. decipher the cellular and molecular mechanism controlling this behavior, which depends in part on the TRPA1 channel.

Sleep rearranges the firing patterns of excitatory projection neurons in zebra finch songbirds. Patterned inhibition is implicated in maintaining stable songs in spite of the instability in the projection neuron population.

In this study, Sivadasan et al. show that the interactome of the C9ORF72 protein contains cofilin and other actin-binding proteins. They also demonstrate that actin dynamics are reduced in patient-derived motor neurons and tissues with ALS-related intronic expansion of the C9ORF72 gene, leading to altered axon growth and growth cone dynamics.

Resting-state functional connectivity has helped reveal the brain's network organization, yet its relevance to cognitive task activations has been unclear. The authors found that estimating activity flow over resting-state networks allows prediction of held-out activations, suggesting activity flow as a linking mechanism between resting-state networks and cognitive task activations.

In a GWAS study of 32,438 adults, the authors discovered five novel loci for intracranial volume and confirmed two known signals. Variants for intracranial volume were also related to childhood and adult cognitive function and to Parkinson's disease, and enriched near genes involved in growth pathways, including PI3K-AKT signaling.

The biological mechanisms underlying memory are complex and typically involve multiple molecular processes operating on timescales ranging from fractions of a second to years. The authors show using a mathematical model of synaptic plasticity and consolidation that this complexity can help explain the formidable memory capacity of biological systems.

The authors developed experimental and computational approaches to study moment-to-moment changes in the activity of populations of cortical neurons as mice accumulated evidence during decision-making in virtual reality. They propose that evidence accumulation may not require winner-take-all competitions but instead emerges from general dynamical properties that instantiate short-term memory.

De novo mutations in CHD8 are associated with autism spectrum disorder, but the basic biology of CHD8 remains poorly understood. Here the authors find that Chd8 knockdown during cortical development results in defective neural progenitor proliferation and differentiation that ultimately manifests in abnormal neuronal morphology and behaviors in adult mice.

Using whole-exome sequencing, the authors identified 244,246 coding-sequence and splice-site ultra-rare variants (URVs) and found that gene-disruptive and putatively protein-damaging URVs were significantly more abundant in schizophrenia cases than in controls. The excess of protein-compromising URVs was concentrated in brain-specific genes, particularly in neuronally expressed genes whose proteins are located at the synapse.

Loss of Hdac1 and Hdac2 in adult brain is detrimental to neuronal survival and triggers dysregulation of Sapap3 in the striatum in a MeCP2-dependent manner that results in an exacerbated repetitive behavior phenotype.

The CommonMind Consortium sequenced RNA from dorsolateral prefrontal cortex of subjects with schizophrenia (N = 258) and control subjects (N = 279), creating a resource of gene expression and its genetic regulation. Using this resource, they found that ∼20% of schizophrenia loci have variants that may contribute to altered gene expression and liability.

The ability to estimate environmental state under limited sensory observation is essential for many behaviors and can be realized using dynamic Bayesian inference. The authors use in vivo two-photon calcium imaging and probabilistic population decoding to show that cortical neurons implement prediction and updating, the fundamental features of dynamic Bayesian inference.

AgRP neurons of the arcuate nucleus of the hypothalamus promote homeostatic feeding yet are rapidly suppressed by food-related sensory cues. The authors identify a population of inhibitory DMH-LepR neurons that relays real-time information about the nature and availability of food to dynamically modulate ARC-AgRP neuron activity and feeding behavior.

Much of what is known about nervous system development is based on chemical signaling. In this study, Koser et al. demonstrate that developing neurons also respond to mechanical signals and that local tissue stiffness is a regulator of neuronal growth in vivo.

The authors find that activity in rodent visual cortex can depend on the animal's location in a virtual environment and can predict upcoming visual stimuli. Omitting a stimulus that a mouse expects to see results in a strong mismatch signal, implying that visual cortex compares visual signals to expectations in familiar environments.

The authors demonstrate that attention slowly fluctuates at a rhythm that resembles resting-state oscillations. During periods of attention, the brain aligns its neuronal oscillations and the cortical operations they orchestrate to the timing of external stimuli, while attentional lapses are characterized by operations aligned to internally timed alpha oscillations.