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Our visual perception seems effortless, but the brain has a limited processing capacity which curtails the amount of sensory information that can be brought into conscious awareness at any moment in time. A widely studied exemplar of this limitation is the ‘attentional blink’ (AB), in which observers are unable to report the second of two rapidly sequential targets if it appears within 200-500 ms of the first. Despite the apparent ubiquity of the AB effect, its computational and neurophysiological underpinnings have remained elusive. Here we propose a simple computational model of temporal attention that unifies the AB with spatial and feature-based attention. We took a novel, integrative approach involving human psychophysics and functional brain imaging, along with neuronal recordings in mice to test this model. Specifically, we demonstrate that the AB only arises when visual targets have dissimilar representations in the brain but is absent when both targets have the same representation. Similarity in this context can be determined either by elementary features such as edge orientation, or by acquired, high-level factors such as numerical or alphabetical order. In this parsimonious model of the AB, attention to an initial target establishes a perceptual filter that is tuned to its unique representation in the brain. Subsequent items that match the filter remain available for conscious report, whereas those that do not match elude awareness altogether.

A. aegypti has evolved to become an efficient vector for arboviruses such as Dengue but the mechanisms of host-pathogen immune tolerance are unknown. Toll receptors and Spaetzle (Spz) ligands have undergone duplication raising the possibility of neofunctionalization and mutualism to develop between arboviruses and mosquitoes. Here we present cryo-EM structures and biophysical characterisation of low affinity Toll5A-Spz1C complexes that display transient but specific interactions. Binding of the first ligand alters receptor-receptor interactions and promotes asymmetric contacts in the vicinity of the Z-loop in Toll5A. This conformation then restricts binding of a second ligand, while temporarily bridging the C-termini that promote signalling. Increased receptor concentrations promote inactivating head-to-head receptor assemblies. Furthermore, the transcriptional signature of Spz1C differs from other Spz cytokines in the control of genes involved in innate immunity, lipid metabolism and tissue regeneration. Given the remarkable DENV-induced expression patterns of these proteins, our data rationalises how Spz1C upregulation might promote antimicrobial defence in the midgut, and Toll5A upregulation, viral tolerance in the salivary glands.

The efficiency of sensory coding is affected both by past events (adaptation) and by expectation of future events (prediction). Here we employed a novel visual stimulus paradigm to determine whether expectation influences orientation selectivity in the primary visual cortex. We used two-photon calcium imaging (GCaMP6f) in awake mice viewing visual stimuli with different levels of predictability. The stimuli consisted of sequences of grating stimuli that randomly shifted in orientation or systematically rotated with occasionally unexpected rotations. At the single neuron and population level, there was significantly enhanced orientation-selective response to unexpected visual stimuli through a boost in gain, which was prominent in awake mice but also present to a lesser extent under anesthesia. We implemented a computational model to demonstrate how neuronal responses were best characterized when adaptation and expectation parameters were combined. Our results demonstrated that adaptation and prediction have unique signatures on activity of V1 neurons.