In natural visually guided behavior, observers must separate relevant information from a barrage of irrelevant information. Many studies have investigated the neural underpinnings of this ability using artificial stimuli presented on blank backgrounds. Natural images, however, contain task-irrelevant background elements that might interfere with the perception of object features.
View Article and Find Full Text PDFIn natural behavior, observers must separate relevant information from a barrage of irrelevant information. Many studies have investigated the neural underpinnings of this ability using artificial stimuli presented on simple backgrounds. Natural viewing, however, carries a set of challenges that are inaccessible using artificial stimuli, including neural responses to background objects that are task-irrelevant.
View Article and Find Full Text PDFIt is widely accepted that there is an inextricable link between neural computations, biological mechanisms, and behavior, but it is challenging to simultaneously relate all three. Here, we show that topological data analysis (TDA) provides an important bridge between these approaches to studying how brains mediate behavior. We demonstrate that cognitive processes change the topological description of the shared activity of populations of visual neurons.
View Article and Find Full Text PDFImprovements in perception are frequently accompanied by decreases in correlated variability in sensory cortex. This relationship is puzzling because overall changes in correlated variability should minimally affect optimal information coding. We hypothesize that this relationship arises because instead of using optimal strategies for decoding the specific stimuli at hand, observers prioritize : a single set of neuronal weights to decode any stimuli.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
April 2022
Most systems neuroscience studies fall into one of two categories: basic science work aimed at understanding the relationship between neurons and behavior, or translational work aimed at developing treatments for neuropsychiatric disorders. Here we use these two approaches to inform and enhance each other. Our study both tests hypotheses about basic science neural coding principles and elucidates the neuronal mechanisms underlying clinically relevant behavioral effects of systemically administered methylphenidate (Ritalin).
View Article and Find Full Text PDFCigarette smoke exposure is associated with an increased risk of developing acute respiratory distress syndrome (ARDS) in trauma, transfusion, and nonpulmonary sepsis. It is unknown whether this relationship exists in the general sepsis population. Furthermore, it is unknown if patients with ARDS have differences in underlying biology based on smoking status.
View Article and Find Full Text PDFAlthough spatial and feature attention have differing effects on neuronal responses in visual cortex, it remains unclear why. Response normalization has been implicated in both types of attention (Carandini and Heeger, 2011), and single-unit studies have demonstrated that the magnitude of spatial attention effects on neuronal responses covaries with the magnitude of normalization effects. However, the relationship between feature attention and normalization remains largely unexplored.
View Article and Find Full Text PDFSensory prostheses can restore aspects of natural sensation by delivering electrical current directly into sensory circuits. An effective sensory prosthetic should be capable of generating reliable real-time perceptual signals for hours each day over many years. However, we still know little regarding the stability of percepts produced by electrical microstimulation of cerebral sensory cortex when stimulation is delivered repeatedly over long periods.
View Article and Find Full Text PDFUnderstanding how cognitive processes affect the responses of sensory neurons may clarify the relationship between neuronal population activity and behavior. However, tools for analyzing neuronal activity have not kept up with technological advances in recording from large neuronal populations. Here, we describe prevalent hypotheses of how cognitive processes affect sensory neurons, driven largely by a model based on the activity of single neurons or pools of neurons as the units of computation.
View Article and Find Full Text PDFJ Neurophysiol
September 2017
Spatial attention improves perception of attended parts of a scene, a behavioral enhancement accompanied by modulations of neuronal firing rates. These modulations vary in size across neurons in the same brain area. Models of normalization explain much of this variance in attention modulation with differences in tuned normalization across neurons (Lee J, Maunsell JHR.
View Article and Find Full Text PDFUnderstanding how the brain works requires understanding how different types of neurons contribute to circuit function and organism behavior. Progress on this front has been accelerated by optogenetics and chemogenetics, which provide an unprecedented level of control over distinct neuronal types in small animals. In primates, however, targeting specific types of neurons with these tools remains challenging.
View Article and Find Full Text PDFStimuli that project the same retinal visual angle can appear to occupy very different proportions of the visual field if they are perceived to be at different distances [1-8]. Previous research shows that perceived angular size alters the spatial distribution of activity in early retinotopic visual cortex [7, 9-11]. For example, a sphere superimposed on the far end of a corridor scene appears to occupy a larger visual angle and activates a larger region of primary visual cortex (V1) compared with the same sphere superimposed on the near end of the corridor [7].
View Article and Find Full Text PDFNeuronal assemblies often exhibit stimulus-induced rhythmic activity in the gamma range (30-80 Hz), whose magnitude depends on the attentional load. This has led to the suggestion that gamma rhythms form dynamic communication channels across cortical areas processing the features of behaviorally relevant stimuli. Recently, attention has been linked to a normalization mechanism, in which the response of a neuron is suppressed (normalized) by the overall activity of a large pool of neighboring neurons.
View Article and Find Full Text PDFThe effect of attention on firing rates varies considerably within a single cortical area. The firing rate of some neurons is greatly modulated by attention while others are hardly affected. The reason for this variability across neurons is unknown.
View Article and Find Full Text PDFEven the simplest behaviors depend on a large number of neurons that are distributed across many brain regions. Because electrical microstimulation can change the activity of localized subsets of neurons, it has provided valuable evidence that specific neurons contribute to particular behaviors. Here we review what has been learned about cortical function from behavioral studies using microstimulation in animals and humans.
View Article and Find Full Text PDFRecent advances have documented the development of lung vasculature before and after birth, but less is known of the growth and maturation of airway vasculature. We sought to determine whether airway vasculature changes during the perinatal period and when the typical adult pattern develops. On embryonic day 16.
View Article and Find Full Text PDFBehavioral performance depends on the activity of neurons in sensory cortex, but little is known about the brain's capacity to access specific neuronal signals to guide behavior. Even the individual sensory neurons that are most sensitive to a relevant stimulus are only weakly correlated with behavior, suggesting that behavioral decisions are based on the combined activity of groups of neurons with sensitivities well matched to task demands. To explore how flexibly different patterns of activity can be accessed from a given cortical region, we trained animals to detect electrical microstimulation of local V1 sites.
View Article and Find Full Text PDFThe integrin alpha5beta1 has been previously implicated in tumor angiogenesis, but its role in the remodeling of both blood vessels and lymphatics during inflammation is at an early stage of understanding. We examined this issue using a selective, small-molecule inhibitor of alpha5beta1 integrin, 2-aroylamino-3-{4-[(pyridin-2-ylaminomethyl)heterocyclyl]phenyl}propionic acid (JSM8757), in a model of sustained airway inflammation in mice with Mycoplasma pulmonis infection, which is known to be accompanied by robust blood vessel remodeling and lymphangiogenesis. The inhibitor significantly decreased the proliferation of lymphatic endothelial cells in culture and the number of lymphatic sprouts and new lymphatics in airways of mice infected for 2 weeks but did not reduce remodeling of blood vessels in the same airways.
View Article and Find Full Text PDFBoth Eph receptors and ephrin ligands have been implicated in blood vessel and neuronal development. Recent studies suggested that EphA2 inhibition reduces tumor angiogenesis, but its role in blood vessel development and inflammation is unclear. We examined these issues using either airways of pathogen-free, EphA2-deficient mice at various ages or EphA2-deficient mice whose airways were inflamed by either Mycoplasma pulmonis infection or ovalbumin sensitization and challenge.
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