Research articles

Animals have a remarkable ability to adjust their behavioral response to the same stimulus based on the immediate behavioral context. The authors show that the nucleus basalis broadcasts a contextual signal to the auditory cortex that is then translated by inhibitory networks to regulate excitatory neuronal output and behavior.

The activity of cortical neurons is extremely noisy. This study builds a mathematical theory linking the spatial scales of cortical wiring to how noise is generated and distributed over a population of neurons. Predictions from the theory are validated using population recordings in primate visual area V1.

Self-movement estimation is critical to motor control and navigation; however, the neural circuits that accurately track body motion are poorly understood. This study shows that Drosophila optic-flow-processing neurons receive three distinct locomotor-related signals that are used to encode a quantitative estimate of the fly's walking movements, even in the absence of visual stimuli.

Previous work on mammalian motor cortex has focused on the role of this region in movement generation. Here the authors demonstrate that activity of vibrissa motor cortex neurons decreases during various forms of vibrissal touch, suggesting that a primary function of vibrissa motor cortex is to suppress whisking behavior.

The ability to target and manipulate specific neuronal populations is crucial for understanding brain function. In this report, the authors describe a novel virus that restricts gene expression to telencephalic GABAergic interneurons, allowing for morphological visualization, activity monitoring and functional manipulation of interneurons in mice and in non-genetically tractable species.

The authors describe neurons in the macaque anterior thalamus tuned to pitch and roll orientation relative to gravity, independently of visual landmarks. Individual cells exhibit two-dimensional tuning curves peaking at a preferred vertical orientation. These results identify a thalamic pathway for gravity cues to influence three-dimensional spatial orientation.

In the CNS, the primary signal initiating myelination and its cellular origin remain unclear. Goebbels et al. find that deleting PTEN from cerebellar granule cells drives radial axon growth, oligodendrocyte progenitor cell (OPC) proliferation, oligodendrocyte differentiation and de novo myelination of parallel fibers. This suggests that myelination is downstream of a neuronal PI(3,4,5)P₃-dependent signal.

In this paper, the authors show that dishonesty gradually increases with repetition. This escalation is supported by a reduction in response to self-serving dishonesty over time in the amygdala.

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.

Top-down control is important for sensory processing. In this study, the authors used virus-assisted circuit mapping to identify the brain networks for top-down modulation of multiple sensory modalities and the subnetworks within the visual network, thus providing an anatomical foundation for understanding the brain mechanisms underlying top-down control of behavior.

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.