Viscoelastic testing of fibrinolytic capacity in acutely infected critically ill patients: Protocol for a scoping review.

Introduction: Viscoelastic testing (VET) has been implemented in clinical care to diagnose and manage coagulation in patients with manifest or high risk of major bleeding. However, the breakdown of formed blood clots, that is, fibrinolysis, has been comparatively less studied. There is an increasing recognition that acute infections trigger a dysregulated immunothrombotic response, which has focused attention on viscoelastic testing to identify in particular fibrinolysis resistant states.

V1 neurons are tuned to perceptual borders in natural scenes.

The visual system needs to identify perceptually relevant borders to segment complex natural scenes. The primary visual cortex (V1) is thought to extract local borders, and higher visual areas are thought to identify the perceptually relevant borders between objects and the background. To test this conjecture, we used natural images that had been annotated by human observers who marked the perceptually relevant borders.

Border-ownership tuning determines the connectivity between V4 and V1 in the macaque visual system.

Cortical feedback connections are extremely numerous but the logic of connectivity between higher and lower areas remains poorly understood. Feedback from higher visual areas to primary visual cortex (V1) has been shown to enhance responses on perceptual figures compared to backgrounds, an effect known as figure-background modulation (FBM). A likely source of this feedback are border-ownership (BO) selective cells in mid-tier visual areas (e.

The direct and indirect pathways of the basal ganglia antagonistically influence cortical activity and perceptual decisions.

The striatum, the main input nucleus of the basal ganglia, receives topographically organized input from the cortex and gives rise to the direct and indirect output pathways, which have antagonistic effects on basal ganglia output directed to the cortex. We optogenetically stimulated the direct and indirect pathways in a visual and a working memory task in mice that responded by licking. Unilateral direct pathway stimulation increased the probability of lick responses toward the contralateral, non-stimulated side and increased cortical activity globally.

Involvement of superior colliculus in complex figure detection of mice.

Object detection is an essential function of the visual system. Although the visual cortex plays an important role in object detection, the superior colliculus can support detection when the visual cortex is ablated or silenced. Moreover, it has been shown that superficial layers of mouse SC (sSC) encode visual features of complex objects, and that this code is not inherited from the primary visual cortex.

Experience shapes chandelier cell function and structure in the visual cortex.

Detailed characterization of interneuron types in primary visual cortex (V1) has greatly contributed to understanding visual perception, yet the role of chandelier cells (ChCs) in visual processing remains poorly characterized. Using viral tracing we found that V1 ChCs predominantly receive monosynaptic input from local layer 5 pyramidal cells and higher-order cortical regions. Two-photon calcium imaging and convolutional neural network modeling revealed that ChCs are visually responsive but weakly selective for stimulus content.

The representation of occluded image regions in area V1 of monkeys and humans.

Neuronal activity in the primary visual cortex (V1) is driven by feedforward input from within the neurons' receptive fields (RFs) and modulated by contextual information in regions surrounding the RF. The effect of contextual information on spiking activity occurs rapidly and is therefore challenging to dissociate from feedforward input. To address this challenge, we recorded the spiking activity of V1 neurons in monkeys viewing either natural scenes or scenes where the information in the RF was occluded, effectively removing the feedforward input.

Contextual drive of neuronal responses in mouse V1 in the absence of feedforward input.

Neurons in the primary visual cortex (V1) respond to stimuli in their receptive field (RF), which is defined by the feedforward input from the retina. However, V1 neurons are also sensitive to contextual information outside their RF, even if the RF itself is unstimulated. Here, we examined the cortical circuits for V1 contextual responses to gray disks superimposed on different backgrounds.

Oscillations support short latency co-firing of neurons during human episodic memory formation.

Theta and gamma oscillations in the medial temporal lobe are suggested to play a critical role for human memory formation via establishing synchrony in neural assemblies. Arguably, such synchrony facilitates efficient information transfer between neurons and enhances synaptic plasticity, both of which benefit episodic memory formation. However, to date little evidence exists from humans that would provide direct evidence for such a specific role of theta and gamma oscillations for episodic memory formation.

Intracranial human recordings reveal association between neural activity and perceived intensity for the pain of others in the insula.

Based on neuroimaging data, the insula is considered important for people to empathize with the pain of others. Here, we present intracranial electroencephalographic (iEEG) recordings and single-cell recordings from the human insula while seven epilepsy patients rated the intensity of a woman's painful experiences seen in short movie clips. Pain had to be deduced from seeing facial expressions or a hand being slapped by a belt.

A neuronal basis of iconic memory in macaque primary visual cortex.

After a briefly presented visual stimulus disappears, observers retain a detailed representation of this stimulus for a short period of time. This sensory storage is called iconic memory. We measured iconic memory in the perception of monkeys and its neuronal correlates in the primary visual cortex (area V1).

Theta-phase dependent neuronal coding during sequence learning in human single neurons.

The ability to maintain a sequence of items in memory is a fundamental cognitive function. In the rodent hippocampus, the representation of sequentially organized spatial locations is reflected by the phase of action potentials relative to the theta oscillation (phase precession). We investigated whether the timing of neuronal activity relative to the theta brain oscillation also reflects sequence order in the medial temporal lobe of humans.

A Quantitative Comparison of Inhibitory Interneuron Size and Distribution between Mouse and Macaque V1, Using Calcium-Binding Proteins.

The mouse is a useful and popular model for studying of visual cortical function. To facilitate the translation of results from mice to primates, it is important to establish the extent of cortical organization equivalence between species and to identify possible differences. We focused on the different types of interneurons as defined by calcium-binding protein (CBP) expression in the layers of primary visual cortex (V1) in mouse and rhesus macaque.

The essential role of recurrent processing for figure-ground perception in mice.

The segregation of figures from the background is an important step in visual perception. In primary visual cortex, figures evoke stronger activity than backgrounds during a delayed phase of the neuronal responses, but it is unknown how this figure-ground modulation (FGM) arises and whether it is necessary for perception. Here, we show, using optogenetic silencing in mice, that the delayed V1 response phase is necessary for figure-ground segregation.

Mouse visual cortex contains a region of enhanced spatial resolution.

The representation of space in mouse visual cortex was thought to be relatively uniform. Here we reveal, using population receptive-field (pRF) mapping techniques, that mouse visual cortex contains a region in which pRFs are considerably smaller. This region, the "focea," represents a location in space in front of, and slightly above, the mouse.

Human Hippocampal Neurons Track Moments in a Sequence of Events.

An indispensable feature of episodic memory is our ability to temporally piece together different elements of an experience into a coherent memory. Hippocampal time cells-neurons that represent temporal information-may play a critical role in this process. Although these cells have been repeatedly found in rodents, it is still unclear to what extent similar temporal selectivity exists in the human hippocampus.

Activity in Lateral Visual Areas Contributes to Surround Suppression in Awake Mouse V1.

Neuronal response to sensory stimuli depends on the context. The response in primary visual cortex (V1), for instance, is reduced when a stimulus is surrounded by a similar stimulus [1-3]. The source of this surround suppression is partially known.

Neuroscience: Figured Out by Feedback to the Thalamus.

The lateral geniculate nucleus of the thalamus (LGN) is a relay nucleus between the retina and the visual cortex. A new brain imaging study shows that LGN activity is modulated by figure-ground organization, even when the figure and ground are presented to different eyes: a hallmark of a cortical feedback effect.

The Segmentation of Proto-Objects in the Monkey Primary Visual Cortex.

During visual perception, the brain enhances the representations of image regions that belong to figures and suppresses those that belong to the background. Natural images contain many regions that initially appear to be part of a figure when analyzed locally (proto-objects) but are actually part of the background if the whole image is considered. These proto-grounds must be correctly assigned to the background to allow correct shape identification and guide behavior.

Figure-ground perception in the awake mouse and neuronal activity elicited by figure-ground stimuli in primary visual cortex.

Figure-ground segregation is the process by which the visual system identifies image elements of figures and segregates them from the background. Previous studies examined figure-ground segregation in the visual cortex of monkeys where figures elicit stronger neuronal responses than backgrounds. It was demonstrated in anesthetized mice that neurons in the primary visual cortex (V1) of mice are sensitive to orientation contrast, but it is unknown whether mice can perceptually segregate figures from a background.

The influence of attention and reward on the learning of stimulus-response associations.

We can learn new tasks by listening to a teacher, but we can also learn by trial-and-error. Here, we investigate the factors that determine how participants learn new stimulus-response mappings by trial-and-error. Does learning in human observers comply with reinforcement learning theories, which describe how subjects learn from rewards and punishments? If yes, what is the influence of selective attention in the learning process? We developed a novel redundant-relevant learning paradigm to examine the conjoint influence of attention and reward feedback.

Interocularly merged face percepts eliminate binocular rivalry.

Faces are important visual objects for humans and other social animals. A complex network of specialized brain areas is involved in the recognition and interpretation of faces. This network needs to strike a balance between being sensitive enough to distinguish between different faces with similar features, and being tolerant of low-level visual changes so that a given face is stably perceived as a particular individual.

Benchmarking laminar fMRI: Neuronal spiking and synaptic activity during top-down and bottom-up processing in the different layers of cortex.

High resolution laminar fMRI is beginning to probe responses in the different layers of cortex. What can we expect this exciting new technique to discover about cortical processing and how can we verify that it is producing an accurate picture of the underlying laminar differences in neural processing? This review will address our knowledge of laminar cortical circuitry gained from electrophysiological studies in macaque monkeys with a focus on the primary visual cortex, as this area has been most often targeted in both laminar electrophysiological and fMRI studies. We will review how recent studies are attempting to verify the accuracy of laminar fMRI by recreating the known laminar profiles of various neural tuning properties.

Neuroscience: Out of Sight but Not Out of Mind.

How does the brain hold information about multiple stimuli online after they have disappeared? A new study shows that neurons in the human medial temporal remain active while images are memorized, demonstrating that spiking activity keeps multiple memories online.