Brain Mechanisms for Active Vision

Daedalus ◽  
2015 ◽  
Vol 144 (1) ◽  
pp. 10-21 ◽  
Author(s):  
Robert H. Wurtz
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
High Resolution ◽  
Brain Activity ◽  
Active Vision ◽  
Visual Disturbance ◽  
Critical Function ◽  
Systems Neuroscience ◽  
Neuronal Systems ◽  
The Brain

Active vision refers to the exploration of the visual world with rapid eye movements, or saccades, guided by shifts of visual attention. Saccades perform the critical function of directing the high-resolution fovea of our eyes to any point in the visual field two to three times per second. However, the disadvantage of saccades is that each one disrupts vision, causing significant visual disturbance for which the brain must compensate. Exploring the interaction of vision and eye movements provides the opportunity to study the organization of one of the most complex, yet best-understood, brain systems. Outlining this exploration also illustrates some of the ways in which neuroscientists study neuronal systems in the brain and how they relate this brain activity to behavior. It shows the advantages and limitations of current approaches in systems neuroscience, as well as a glimpse of its potential future.

Information-based Analysis of the Coupling between Dynamic Visual Stimuli, Eye Movements, and Brain Signals

2021 ◽  
pp. 2150048
Author(s):  
Hamidreza Namazi ◽  
Avinash Menon ◽  
Ondrej Krejcar
Keyword(s):  
Eye Movements ◽  
Moving Objects ◽  
Brain Activity ◽  
Visual Stimuli ◽  
Strongly Correlated ◽  
Eeg Signals ◽  
Vision Science ◽  
Brain Signals ◽  
Information Contents ◽  
The Brain

Our eyes are always in search of exploring our surrounding environment. The brain controls our eyes’ activities through the nervous system. Hence, analyzing the correlation between the activities of the eyes and brain is an important area of research in vision science. This paper evaluates the coupling between the reactions of the eyes and the brain in response to different moving visual stimuli. Since both eye movements and EEG signals (as the indicator of brain activity) contain information, we employed Shannon entropy to decode the coupling between them. Ten subjects looked at four moving objects (dynamic visual stimuli) with different information contents while we recorded their EEG signals and eye movements. The results demonstrated that the changes in the information contents of eye movements and EEG signals are strongly correlated ([Formula: see text]), which indicates a strong correlation between brain and eye activities. This analysis could be extended to evaluate the correlation between the activities of other organs versus the brain.

Introduction to the Six Eye Movement Systems and the Visual Fixation System

2008 ◽  
Author(s):  
Agnes Wong
Keyword(s):  
Visual Acuity ◽  
Eye Movements ◽  
High Resolution ◽  
Information Overload ◽  
Survival Rates ◽  
Large Field ◽  
Field Of Vision ◽  
Very High Spatial Resolution ◽  
Different Characteristics ◽  
The Brain

One main reason that we make eye movements is to solve a problem of information overload. A large field of vision allows an animal to survey the environment for food and to avoid predators, thus increasing its survival rate. Similarly, a high visual acuity also increases survival rates by allowing an animal to aim at a target more accurately, leading to higher killing rates and more food. However, there are simply not enough neurons in the brain to support a visual system that has high resolution over the entire field of vision. Faced with the competing evolutionary demands for high visual acuity and a large field of vision, an effective strategy is needed so that the brain will not be overwhelmed by a large amount of visual input. Some animals, such as rabbits, give up high resolution in favor of a larger field of vision (rabbits can see nearly 360°), whereas others, such as hawks, restrict their field of vision in return for a high visual acuity (hawks have vision as good as 20/2, about 10 times better than humans). In humans, rather than using one strategy over the other, the retina develops a very high spatial resolution in the center (i.e., the fovea), and a much lower resolution in the periphery. Although this “foveal compromise” strategy solves the problem of information overload, one result is that unless the image of an object of interest happens to fall on the fovea, the image is relegated to the low-resolution retinal periphery. The evolution of a mechanism to move the eyes is therefore necessary to complement this foveal compromise strategy by ensuring that an object of interest is maintained or brought to the fovea. To maintain the image of an object on the fovea, the vestibulo-ocular (VOR) and optokinetic systems generate eye movements to compensate for head motions. Likewise, the saccadic, smooth pursuit, and vergence systems generate eye movements to bring the image of an object of interest on the fovea. These different eye movements have different characteristics and involve different parts of the brain.

Visual Responses of the Human Superior Colliculus: A High-Resolution Functional Magnetic Resonance Imaging Study

2005 ◽  
Vol 94 (4) ◽  
pp. 2491-2503 ◽  
Author(s):  
Keith A. Schneider ◽  
Sabine Kastner
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
High Resolution ◽  
Superior Colliculus ◽  
Visual Fields ◽  
Visual Response ◽  
Visual Responses ◽  
Subcortical Structures ◽  
Stimulus Motion ◽  
Low Contrast

The superior colliculus (SC) is a multimodal laminar structure located on the roof of the brain stem. The SC is a key structure in a distributed network of areas that mediate saccadic eye movements and shifts of attention across the visual field and has been extensively studied in nonhuman primates. In humans, it has proven difficult to study the SC with functional MRI (fMRI) because of its small size, deep location, and proximity to pulsating vascular structures. Here, we performed a series of high-resolution fMRI studies at 3 T to investigate basic visual response properties of the SC. The retinotopic organization of the SC was determined using the traveling wave method with flickering checkerboard stimuli presented at different polar angles and eccentricities. SC activations were confined to stimulation of the contralateral hemifield. Although a detailed retinotopic map was not observed, across subjects, the upper and lower visual fields were represented medially and laterally, respectively. Responses were dominantly evoked by stimuli presented along the horizontal meridian of the visual field. We also measured the sensitivity of the SC to luminance contrast, which has not been previously reported in primates. SC responses were nearly saturated by low contrast stimuli and showed only small response modulation with higher contrast stimuli, indicating high sensitivity to stimulus contrast. Responsiveness to stimulus motion in the SC was shown by robust activations evoked by moving versus static dot stimuli that could not be attributed to eye movements. The responses to contrast and motion stimuli were compared with those in the human lateral geniculate nucleus. Our results provide first insights into basic visual responses of the human SC and show the feasibility of studying subcortical structures using high-resolution fMRI.

scholarly journals Effects of Stimulus Processing on Event-Related Brain Potentials of Close Others

2018 ◽  
Author(s):  
Maud Haffar ◽  
Hugo Pantecouteau ◽  
Sheila Bouten ◽  
Jacques Bruno Debruille
Keyword(s):  
Visual Field ◽  
Brain Activity ◽  
Physical Nature ◽  
International Affective Picture System ◽  
Brain Potentials ◽  
Stimulus Processing ◽  
Nerve Impulses ◽  
The Brain ◽  
3D Movie

We take what we see, hear, smell and feel for the reality. However, as neuroscientists, we know that this reality, that is, our perceptual world, is in fact made up by the brain from the processing of the nerve impulses coming from receptors. Ancient Greeks used to think that this perceptual world, sometimes called our 3D movie (Chalmers), is emitted and has its own physical nature. Given how real the 3D movie looks to us, it is still difficult today to consider that all we would be dealing with would be patterns of brain activity The present study thus aimed at testing whether the perceptual world could have some physical existence in addition to that of the neural patterns responsible for it. To achieve that goal, we tried to see whether brains could be sensitive to the 3D movie of others. This, admittedly unusual, operational hypothesis was based on two assumptions. First, brains are sensitive to the 3D movie, as our experience includes reactions to our perceptual world. Second, the physicality at stake does not differ across individuals. We recorded the event-related brain potentials (ERPs) evoked by stimuli of the international affective picture system in pairs of closely-related participants. Most importantly, they could neither see the stimuli simultaneously presented to their partners nor their reactions to them. As in Bouten et al. (2015), around 400 ms after the onset of the stimuli, ERPs started being more positive in inconsistent conditions. Namely, when the two subjects of each pair were presented with the same stimulus whereas they were told it would be a different one and vice-versa (i.e., different-stimuli expected to be same). ERPs were less positive when the two subjects of a pair were presented with the same stimuli and were told they were the same and conversely (i.e., different-stimuli expected to be different). The same experiment was then run in pairs of strangers. No significant effect of consistency on ERPs was observed even though participants could, this time, see, in the very periphery of their visual field, the reactions of their partner to the stimuli. We thus use the results of both studies to support a new version of the emission theory of consciousness and to suggest that the sensitivity to the perceptual world of others may depend on their prior familiarity with it.

scholarly journals Brain2Pix: Fully convolutional naturalistic video reconstruction from brain activity

2021 ◽  
Author(s):  
Lynn Le ◽  
Luca Ambrogioni ◽  
Katja Seeliger ◽  
Yağmur Güçlütürk ◽  
Marcel van Gerven ◽  
...  
Keyword(s):  
Visual Field ◽  
Spatial Information ◽  
Brain Activity ◽  
Region Of Interest ◽  
Magnetic Resonance Data ◽  
Recent Success ◽  
Machine Learning Applications ◽  
Video Reconstruction ◽  
The Brain ◽  
Image Network

AbstractReconstructing complex and dynamic visual perception from brain activity remains a major challenge in machine learning applications to neuroscience. Here we present a new method for reconstructing naturalistic images and videos from very large single-participant functional magnetic resonance data that leverages the recent success of image-to-image transformation networks. This is achieved by exploiting spatial information obtained from retinotopic mappings across the visual system. More specifically, we first determine what position each voxel in a particular region of interest would represent in the visual field based on its corresponding receptive field location. Then, the 2D image representation of the brain activity on the visual field is passed to a fully convolutional image-to-image network trained to recover the original stimuli using VGG feature loss with an adversarial regularizer. In our experiments, we show that our method offers a significant improvement over existing video reconstruction techniques.

scholarly journals The Track of Brain Activity during the Observation of TV Commercials with the High-Resolution EEG Technology

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
Laura Astolfi ◽  
Giovanni Vecchiato ◽  
Fabrizio De Vico Fallani ◽  
Serenella Salinari ◽  
Febo Cincotti ◽  
...  
Keyword(s):  
High Resolution ◽  
Brain Activity ◽  
Normal Subjects ◽  
Significant Information ◽  
Cortical Areas ◽  
Brodmann Areas ◽  
Tv Commercials ◽  
Tv Commercial ◽  
The Brain ◽  
High Resolution Eeg

We estimate cortical activity in normal subjects during the observation of TV commercials inserted within a movie by using high-resolution EEG techniques. The brain activity was evaluated in both time and frequency domains by solving the associate inverse problem of EEG with the use of realistic head models. In particular, we recover statistically significant information about cortical areas engaged by particular scenes inserted within the TV commercial proposed with respect to the brain activity estimated while watching a documentary. Results obtained in the population investigated suggest that the statistically significant brain activity during the observation of the TV commercial was mainly concentrated in frontoparietal cortical areas, roughly coincident with the Brodmann areas 8, 9, and 7, in the analyzed population.

scholarly journals Representational pattern similarity of electrical brain activity reveals rapid and specific prediction during language comprehension

2020 ◽  
Author(s):  
Ryan J. Hubbard ◽  
Kara D. Federmeier
Keyword(s):  
Time Window ◽  
Brain Activity ◽  
Activity Patterns ◽  
Early Time ◽  
Final Word ◽  
Critical Function ◽  
Electrical Brain Activity ◽  
Pattern Similarity ◽  
Use Context ◽  
The Brain

AbstractPredicting upcoming stimuli and events is a critical function of the brain, and understanding the mechanisms of prediction has thus become a central topic in neuroscientific research. Language provides a fertile testing ground for examining predictive mechanisms, as comprehenders use context to predict different features of upcoming words. Although there is a substantive body of research on prediction in language, many aspects of the mechanisms of prediction remain elusive, in part due to a lack of methodological tools to probe prediction formation in the moment. To elucidate what features are neurally pre-activated and when, we used representational similarity analysis (RSA) on data from a sentence reading task (Federmeier et al., 2007). We compared EEG activity patterns elicited by expected and unexpected sentence final words to patterns from the preceding words of the sentence, in both strongly and weakly constraining sentences. Pattern similarity with the final word was increased in an early time window (suggestive of visual feature activation) following the presentation of the pre-final word, and this increase was modulated by both expectancy and constraint (greatest for strongly constrained expected words). This was not seen at earlier words, suggesting that predictions are precisely timed. Additionally, pre-final word activity – the predicted representation - had negative similarity with later final word activity, but only for strongly expected words. Together, these findings shed light on the mechanisms of prediction in the brain: features of upcoming stimuli are rapidly pre-activated following related cues, but the predicted information may receive reduced subsequent processing upon confirmation.

scholarly journals Visual mapping on the brain - caveats for multifocal fMRI

2019 ◽  
Author(s):  
David P. Crewther ◽  
Shaun A. S. Seixas ◽  
Sheila G. Crewther
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Evoked Responses ◽  
Normal Vision ◽  
Visual Mapping ◽  
M Sequence ◽  
Cortical Magnification ◽  
Visual Field Mapping ◽  
The Brain ◽  
Correlational Model

AbstractWhile multifocal electroretinography has become a standard ophthalmological technique, its use in cortical neuroimaging has been lesser. Vanni et al. (2005) presented the first exploration of the multifocal visual mapping methodology with fMRI. This commentary confirms the utility of this method, but also presents empirical results which suggest caveats for the use of the technique. In the current study rapid multifocal fMRI was established using m-sequence pseudo-random binary stimuli applied to visual field mapping in six young adults with normal vision. Nine contiguous regions of visual field – two rings of 4 patches with a central patch, areas scaled for cortical magnification, were pseudo-randomly stimulated, with patterned or grey images. The decorrelation of stimulus patches allowed all 256 volumes to be used for the analysis of each of the nine stimulus areas. Strong localized activation was observed for each of the four peripheral regions with the location of the activation conforming to the expected visual field retinotopy. The inner regions, including the foveal patch, did not significantly activate. We propose, on the basis of a simple correlational model of simulated eye movements, that the loss of signal is due to gaze instability. Thus, while the rapid multifocal method can be successfully applied to fMRI, the results appear quite sensitive to eye movements, the effects of which may have been overlooked by smoothing evoked responses to achieve a retinotopic map.

scholarly journals Neurophysiology of visually guided eye movements: critical review and alternative viewpoint

2018 ◽  
Vol 120 (6) ◽  
pp. 3234-3245 ◽  
Author(s):  
Laurent Goffart ◽  
Clara Bourrelly ◽  
Jean-Charles Quinton
Keyword(s):  
Eye Movements ◽  
Time Course ◽  
Brain Activity ◽  
Physical World ◽  
Population Coding ◽  
Critical Examination ◽  
Transmission Delays ◽  
Pursuit Eye Movements ◽  
Neurophysiological Studies ◽  
The Brain

In this article, we perform a critical examination of assumptions that led to the assimilation of measurements of the movement of a rigid body in the physical world to parameters encoded within brain activity. In many neurophysiological studies of goal-directed eye movements, equivalence has indeed been made between the kinematics of the eyes or of a targeted object and the associated neuronal processes. Such a way of proceeding brings up the reduction encountered in projective geometry when a multidimensional object is being projected onto a one-dimensional segment. The measurement of a movement indeed consists of generation of a series of numerical values from which magnitudes such as amplitude, duration, and their ratio (speed) are calculated. By contrast, movement generation consists of activation of multiple parallel channels in the brain. Yet, for many years, kinematic parameters were supposed to be encoded in brain activity, even though the neuronal image of most physical events is distributed both spatially and temporally. After explaining why the “neuronalization” of such parameters is questionable for elucidating the neural processes underlying the execution of saccadic and pursuit eye movements, we propose an alternative to the framework that has dominated the last five decades. A viewpoint is presented in which these processes follow principles that are defined by intrinsic properties of the brain (population coding, multiplicity of transmission delays, synchrony of firing, connectivity). We propose reconsideration of the time course of saccadic and pursuit eye movements as the restoration of equilibria between neural populations that exert opposing motor tendencies.

Sign in / Sign up

Export Citation Format

Share Document