Visual stimuli

…bouton activity in mouse primary visual cortex (V1), while the animal's face was simultaneously videotaped. We aim to understand how face motion is related to the population activity of both cortical neurons and their lateral geniculate nucleus (LGN) afferents, during both visual stimul

…the brain needs to process the visual environment, compute an appropriate pattern, and then orchestrate the expansion and contraction of hundreds of thousands of pigment filled sacs to generate it. How they accomplish this feat is unknown. Furthermore, cuttlefish do not camouflage by simply matching a substrate pixel by pixel; rather they produce an imperfect approximation of the substrate. Despite this they are able to evade detection by predator, prey, and ev

Primate amygdala neuron process the value of visual stimuli to guide decision-making and social interactions (Grabenhorst et al., 2019; Grabenhorst et al., 2023). However, it remains unclear whether different amygdala neurons are sensitive to distinct value components, such as reward probability and magnitude, and whether they integrate these components to decision variables, including risk and expected value. To address these questions, we recorded activity of amygdala neurons while monkeys viewed sequentially presented stimuli that provided separate information about the probability, magnitu

…block design experiment with auditory, visual, and audio-visual stimuli, by removing non-neuronal signals from fNIRS long channels. We tested three analysis pipelines with and without SC correction. fNIRS signal was deconvoluted using Generalized Linear Model (GLM) in which orthogonalized SC signal (first analysis), n

Retinal ganglion cells (RGCs) transmit visual information from the retina to the brain and are conserved among vertebrates. In zebrafish, RGCs project their axons to downstream brain areas known as arborization fields (AFs). Previous anatomical studies have demonstrated that each RGC axon targets one or a few of AF1-9 and 10 distinct layers of AF10 (optic tectum). Although it was proposed that each projection type represents one functional type, the correspondence between morphology and function of genetically defined RGC subtypes is still unclear. To address this question, we focused on RGC s

Electroencephalographic neurofeedback (EEG-NF) protocols commonly present visual stimuli, modified at fast frequency-rates, in order to inform participants about their EEG signal fluctuations in real-time. The current study addresses methodological issues in understanding the resulting neuromodulation induced by these protocols. Specifically, we investigate whether classically targeted EEG features: 1) tend to fluctuate naturally over time, 2) are influenced by the presentation of a continuously modified visual stimulus and by 3) the frequency at which the stimulus is modified. We enroll 32 he

…were trained to discriminate between visual stimuli indicating the location of a water reward. To evaluate their reliance on conspecific cues under conditions of uncertainty, we positioned the reward on the same sid

…coupling, rather than actively select visual input, due to the absence of a retinal fovea and their reliance on non-visual senses. But does this hold true during naturalistic behaviour?To study mouse eye movements in a naturalistic context featuring self-initiated visual flow and the need for visual target tracking, we designed a foraging task presented in a virtual reality, projected onto a 210-degree immersive environment (Fig1A). The saccades w

The ability to learn associations between sensory stimuli, actions and outcomes is crucial for adaptive perceptual decision-making. A key brain area supporting this ability is the striatum, which receives extensive signals from several cortical areas. These cortico-striatal pathways are shaped by two neuromodulators, dopamine and acetylcholine, whose levels are among the highest in the brain. Yet, how dopamine and acetylcholine interact to facilitate adaptive perceptual decision-making is unclear. To address this question, we characterized dopamine and acetylcholine release in the dorsolateral

…are taught to associate pairs of visual stimuli (faces and fish) during the acquisition phase. Subsequently, in the test phase, they are required to recall and generalize these learned associations. We introduced a novel test (Polygon) that employs simpler visual stimuli with less semantic content, mirroring RAET's structure. This study was conducted to examine how the complexity and semantic content of visual stimuli impact the performance of migraine sufferers.The psychophysical responses of 41 migraine patients were evaluated acr

…instinctual processes in response to visual cues are robust during wakefulness. However, since the study of visual processes of the sleeping brain has been limited by the closed eyelids, we do not know what neuronal activity these stimuli trigger during sleep. Using sleep compatible virtual reality goggles, we aimed to investigate which visual functions persisted during NREM sleep in humans sleeping with eyes open. Here we designed a series of experiments to elic

The classical sparse coding (SC) model represents visual stimuli as a convex combination of a handful of learned basis functions that are Gabor-like when trained on natural image data. However, the Gabor-like filters learned by classical sparse coding far overpredict well-tuned simple cell receptive field profiles observed empirically. While neurons fire sparsely, neuronal populations are also organized in physical space by their sensitivity to certain features. In V1, this organization is a smooth progression of orientations along the cortical sheet. A number of subsequent models have either

Neurons are equipped with powerful analog processing units – dendrites. However, the role linear and nonlinear dendritic properties play in shaping a neuron’s output to filter behaviorally relevant information and subsequently drive behavior, is poorly understood. Here, we address this question using wide-field neurons of the mouse superior colliculus; a genetically targetable midbrain cell-type that receives direct input from the retina and mediates innate defensive and hunting behaviors. To understand how wide-field neurons combine their inputs, we measured their output: the responses to beh

Pyramidal neurons have apical dendrites that are both physically and electrically segregated from their cell bodies. In sensory cortex, these apical dendrites receive primarily top-down signals from associative and motor regions, while the cell bodies and nearby dendrites of these same pyramidal neurons are mostly targeted by bottom-up or locally recurrent inputs from the sensory periphery. Due to these differences, a number of theories in computational neuroscience postulate a unique role for apical dendrites in shaping sensory processing and plasticity in the face of new or surprising stimul

Recent studies show that behaving animals transition between discrete strategies during sensory decision-making and that arousal modulates task performance. However, it remains a challenge to understand (i) the relationships between arousal and task strategy during sensory discrimination and (ii) the neural mechanisms underlying optimal performance states. To address these topics, we combined behavioral, neurophysiological, and computational approaches to uncover the neural mechanisms underlying arousal-dependent sensory discrimination. We implemented two-alternative-choice tasks, prompting mi

…of direction and speed of motion in visual stimuli. In both humans and monkeys, it has been extensively investigated in terms of its retinotopic properties and selectivity for direction of moving stimuli; however, only in recent years there has been an increasing interest in how neurons in MT encode the speed of motion. In this talk, I will explore the proposed mechanism of speed encoding questioning whether hMT+ neuronal populations encode the stimulus speed directly, or whether they s

…of direction and speed of motion in visual stimuli. In both humans and monkeys, it has been extensively investigated in terms of its retinotopic properties and selectivity for direction of moving stimuli; however, only in recent years there has been an increasing interest in how neurons in MT encode the speed of motion. In this talk, I will explore the proposed mechanism of speed encoding questioning whether hMT+ neuronal populations encode the stimulus speed directly, or whether they s

Vision begins in the eye, and what the “retina tells the brain” is a major interest in visual neuroscience. To deduce what the retina encodes (“tells”), computational models are essential. The most important models in the retina currently aim to understand the responses of the retinal output neurons – the ganglion cells. Typically, these models make simplifying assumptions about the neurons in the retinal network upstream of ganglion cells. One important assumption is linear spatial integration. In this talk, I first define what it means for a neuron to be spatially linear or nonlinear and how

…amount of attention is the Synthetic Visual Reasoning Test (SVRT). The SVRT consists of a range of problems where simple visual stimuli must be categorised into one of two categories based on an unknown rule that must be induced. Conventional machine learning approaches perform well only when trained to categorise based on a single rule and are unable to generalise without e

Real-time rendering of closed-loop visual environments is important for next-generation understanding of brain function and behaviour, but is often prohibitively difficult for non-experts to implement and is limited to few laboratories worldwide. We developed BonVision as an easy-to-use open-source software for the display of virtual or augmented reality, as well as standard visual stimuli. BonVision has been tested on humans and mice, and is capable of supporting new experimental designs in other animal models of vision. As the architecture is based on the open-source Bonsai graphical program

Several studies have showed that face stimuli elicit extremely fast and involuntary saccadic responses toward them, relative to other categories of visual stimuli. In the talk, I will mainly focus on a quite recent research done in our team that investigated to what extent face stimuli influence the programming and execution of saccades. In this research, two experiments were performed using a saccadic choice task: two images (one with a face, one with a vehicle) were simultaneously displayed in the left and right visual fields of participants who had to execute a saccade toward the image (Exp

…two nose-pokes and FED3 responds with visual stimuli, auditory stimuli, and by dispensing pellets. As it is used in the home-cage FED3 can be used for around-the-clock training of mice over several weeks. FED3 is open-source and can be built by users for ~10-20x less than commercial solutions for training mice. The control code is also open-source and was designed to be easily modified by users.

Popular notions of how the retina encodes visual stimuli typically focus on the center-surround receptive fields of retinal ganglion cells, the output neurons of the retina. In this view, the receptive field acts as a linear filter on the visual stimulus, highlighting spatial contrast and providing efficient representations of natural images. Yet, we also know that many ganglion cells respond vigorously to fine spatial gratings that should not activate the linear filter of the receptive field. Thus, ganglion cells may integrate visual signals nonlinearly across space. In this talk, I will disc