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Developmental Cognitive Neuroscience Jun 2017This review provides an introduction to two eyetracking measures that can be used to study cognitive development and plasticity: pupil dilation and spontaneous blink... (Review)
Review
This review provides an introduction to two eyetracking measures that can be used to study cognitive development and plasticity: pupil dilation and spontaneous blink rate. We begin by outlining the rich history of gaze analysis, which can reveal the current focus of attention as well as cognitive strategies. We then turn to the two lesser-utilized ocular measures. Pupil dilation is modulated by the brain's locus coeruleus-norepinephrine system, which controls physiological arousal and attention, and has been used as a measure of subjective task difficulty, mental effort, and neural gain. Spontaneous eyeblink rate correlates with levels of dopamine in the central nervous system, and can reveal processes underlying learning and goal-directed behavior. Taken together, gaze, pupil dilation, and blink rate are three non-invasive and complementary measures of cognition with high temporal resolution and well-understood neural foundations. Here we review the neural foundations of pupil dilation and blink rate, provide examples of their usage, describe analytic methods and methodological considerations, and discuss their potential for research on learning, cognitive development, and plasticity.
Topics: Attention; Brain; Cognition; Female; Fixation, Ocular; Humans; Male; Pupil
PubMed: 27908561
DOI: 10.1016/j.dcn.2016.11.001 -
Journal of Neurophysiology Feb 2004Primates use a combination of smooth pursuit and saccadic eye movements to stabilize the retinal image of selected objects within the high-acuity region near the fovea.... (Review)
Review
Primates use a combination of smooth pursuit and saccadic eye movements to stabilize the retinal image of selected objects within the high-acuity region near the fovea. Pursuit has traditionally been viewed as a relatively automatic behavior, driven by visual motion signals and mediated by pathways that connect visual areas in the cerebral cortex to motor regions in the cerebellum. However, recent findings indicate that this view needs to be reconsidered. Rather than being controlled primarily by areas in extrastriate cortex specialized for processing visual motion, pursuit involves an extended network of cortical areas, and, of these, the pursuit-related region in the frontal eye fields appears to exert the most direct influence. The traditional pathways through the cerebellum are important, but there are also newly identified routes involving structures previously associated with the control of saccades, including the basal ganglia, the superior colliculus, and nuclei in the brain stem reticular formation. These recent findings suggest that the pursuit system has a functional architecture very similar to that of the saccadic system. This viewpoint provides a new perspective on the processing steps that occur as descending control signals interact with circuits in the brain stem and cerebellum responsible for gating and executing voluntary eye movements. Although the traditional view describes pursuit and saccades as two distinct neural systems, it may be more accurate to consider the two movements as different outcomes from a shared cascade of sensory-motor functions.
Topics: Animals; Brain; Fixation, Ocular; Humans; Neural Pathways; Pursuit, Smooth; Saccades
PubMed: 14762145
DOI: 10.1152/jn.00801.2003 -
Journal of Vision Jan 2017During natural vision, humans make frequent eye movements but perceive a stable visual world. It is therefore likely that the human visual system contains...
During natural vision, humans make frequent eye movements but perceive a stable visual world. It is therefore likely that the human visual system contains representations of the visual world that are invariant to eye movements. Here we present an experiment designed to identify visual areas that might contain eye-movement-invariant representations. We used functional MRI to record brain activity from four human subjects who watched natural movies. In one condition subjects were required to fixate steadily, and in the other they were allowed to freely make voluntary eye movements. The movies used in each condition were identical. We reasoned that the brain activity recorded in a visual area that is invariant to eye movement should be similar under fixation and free viewing conditions. In contrast, activity in a visual area that is sensitive to eye movement should differ between fixation and free viewing. We therefore measured the similarity of brain activity across repeated presentations of the same movie within the fixation condition, and separately between the fixation and free viewing conditions. The ratio of these measures was used to determine which brain areas are most likely to contain eye movement-invariant representations. We found that voxels located in early visual areas are strongly affected by eye movements, while voxels in ventral temporal areas are only weakly affected by eye movements. These results suggest that the ventral temporal visual areas contain a stable representation of the visual world that is invariant to eye movements made during natural vision.
Topics: Adult; Brain; Eye Movements; Female; Fixation, Ocular; Humans; Magnetic Resonance Imaging; Male; Visual Perception
PubMed: 28114479
DOI: 10.1167/17.1.11 -
Vision Research Sep 2019Good vision requires a near stationary image if motion blur is to be avoided. All animals with good eyesight (principally the vertebrates, arthropods and cephalopod... (Comparative Study)
Comparative Study
Good vision requires a near stationary image if motion blur is to be avoided. All animals with good eyesight (principally the vertebrates, arthropods and cephalopod molluscs) have adopted a very similar strategy for achieving this: fixations in which gaze is kept still, with saccades to change gaze direction as fast as possible. In all these groups the stability of fixations is maintained by reflexes that oppose the effects of head or body movement (the vestibulo-ocular reflex in vertebrates), and that oppose drift of the image on the retina (optokinetic and optomotor reflexes). A small number of species of molluscs and arthropods have adopted a different strategy: allowing the retinas to scan across the surroundings to acquire information. The retinas in these animals are all linear structures a few receptors wide, and scan at right angles to their long dimension. The speed of scanning varies with retinal resolution, ensuring that scan speed does not produce deleterious blur.
Topics: Animals; Eye Movements; Fixation, Ocular; Humans; Nystagmus, Optokinetic; Reflex, Vestibulo-Ocular
PubMed: 31254533
DOI: 10.1016/j.visres.2019.06.004 -
Sensors (Basel, Switzerland) Apr 2024In mobile eye-tracking research, the automatic annotation of fixation points is an important yet difficult task, especially in varied and dynamic environments such as...
In mobile eye-tracking research, the automatic annotation of fixation points is an important yet difficult task, especially in varied and dynamic environments such as outdoor urban landscapes. This complexity is increased by the constant movement and dynamic nature of both the observer and their environment in urban spaces. This paper presents a novel approach that integrates the capabilities of two foundation models, YOLOv8 and Mask2Former, as a pipeline to automatically annotate fixation points without requiring additional training or fine-tuning. Our pipeline leverages YOLO's extensive training on the MS COCO dataset for object detection and Mask2Former's training on the Cityscapes dataset for semantic segmentation. This integration not only streamlines the annotation process but also improves accuracy and consistency, ensuring reliable annotations, even in complex scenes with multiple objects side by side or at different depths. Validation through two experiments showcases its efficiency, achieving 89.05% accuracy in a controlled data collection and 81.50% accuracy in a real-world outdoor wayfinding scenario. With an average runtime per frame of 1.61 ± 0.35 s, our approach stands as a robust solution for automatic fixation annotation.
Topics: Humans; Fixation, Ocular; Eye-Tracking Technology; Video Recording; Algorithms; Eye Movements
PubMed: 38732772
DOI: 10.3390/s24092666 -
Vision Research Jan 2016
Topics: Fixation, Ocular; Humans; Visual Perception
PubMed: 26686666
DOI: 10.1016/j.visres.2015.12.001 -
The Journal of Neuroscience : the... Jan 2022To competently navigate the world, individuals must flexibly balance distinct aspects of social gaze, orienting toward others and inhibiting orienting responses,...
To competently navigate the world, individuals must flexibly balance distinct aspects of social gaze, orienting toward others and inhibiting orienting responses, depending on the context. These behaviors are often disrupted amongst patient populations treated with serotonergic drugs. However, those in the field lack a clear understanding of how the serotonergic system mediates social orienting and inhibiting behaviors. Here, we tested how increasing central concentrations of serotonin with the direct precursor 5-hydroxytryptophan (5-HTP) would modulate the ability of rhesus macaques (both sexes) to use eye movements to flexibly orient to, or inhibit orienting to, faces. Systemic administrations of 5-HTP effectively increased central serotonin levels and impaired flexible orientation and inhibition. Critically, 5-HTP selectively impaired the ability of monkeys to inhibit orienting to face images, whereas it similarly impaired orienting to face and control images. 5-HTP also caused monkeys to perseverate on their gaze responses, making them worse at flexibly switching between orienting and inhibiting behaviors. Furthermore, the effects of 5-HTP on performance correlated with a constriction of the pupil, an increased time to initiate trials, and an increased reaction time, suggesting that the disruptive effects of 5-HTP on social gaze behaviors are likely driven by a downregulation of arousal and motivational states. Together, these findings provide causal evidence for a modulatory relationship between 5-HTP and social gaze behaviors in nonhuman primates and offer translational insights for the role of the serotonergic system in social gaze. Behavioral changes arising from pharmacological agents that target serotonergic functions are complex and difficult to predict. Here, we examined the causal impacts of administering the direct precursor of serotonin, 5-HTP, on orienting and inhibiting social gaze in nonhuman primates. 5-HTP increased central concentrations of serotonin and selectively impaired the ability of monkeys to inhibit orienting to faces while similarly impairing the ability of monkeys to orient to face and control images. These behavioral gaze impairments were systematically associated with a downregulation of arousal and motivational states, indexed by pupil constriction, increased time to initiate trials, and increased reaction time. These findings provide a causal link between 5-HTP and social gaze behaviors in nonhuman primates and provide translational insights about serotonergic interventions.
Topics: 5-Hydroxytryptophan; Animals; Female; Fixation, Ocular; Injections, Intramuscular; Macaca mulatta; Male; Orientation; Photic Stimulation; Primates; Serotonin; Social Interaction
PubMed: 34862190
DOI: 10.1523/JNEUROSCI.0413-21.2021 -
Proceedings of the National Academy of... May 2019Both patients with eye movement disorders and healthy participants whose oculomotor range had been experimentally reduced have been reported to show attentional deficits... (Clinical Trial)
Clinical Trial
Both patients with eye movement disorders and healthy participants whose oculomotor range had been experimentally reduced have been reported to show attentional deficits at locations unreachable by their eyes. Whereas previous studies were mainly based on the evaluation of reaction times, we measured visual sensitivity before saccadic eye movements and during fixation at locations either within or beyond participants' oculomotor range. Participants rotated their heads to prevent them from performing large rightward saccades. In this posture, an attentional cue was presented inside or outside their oculomotor range. Participants either made a saccade to the cue or maintained fixation while they discriminated the orientation of a visual noise patch. In contrast to previous reports, we found that the cue attracted visual attention regardless of whether it was presented within or beyond participants' oculomotor range during both fixation and saccade preparation. Moreover, when participants aimed to look to a cue that they could not reach with their eyes, we observed no benefit at their actual saccade endpoint. This demonstrates that spatial attention is not coupled to the executed oculomotor program but instead can be deployed unrestrictedly also toward locations to which no saccade can be executed. Our results are compatible with the view that covert and overt attentional orienting are guided by feedback projections of visual and visuomotor neurons of the gaze control system, irrespective of oculomotor limitations.
Topics: Adult; Attention; Female; Fixation, Ocular; Humans; Male; Orientation; Saccades
PubMed: 31004064
DOI: 10.1073/pnas.1813465116 -
Journal of Vision Dec 2008During visual fixation, human eyes are never still. Instead, they constantly produce involuntary "fixational eye movements." Fixational eye movements overcome neural... (Comparative Study)
Comparative Study Review
During visual fixation, human eyes are never still. Instead, they constantly produce involuntary "fixational eye movements." Fixational eye movements overcome neural adaptation and prevent visual fading: thus they are an important tool to understand how the brain makes the environment visible. The last decade has seen a growing interest in the analysis of fixational eye movements in humans and primates, as well as in their perceptual and physiological consequences. However, no comprehensive comparison of fixational eye movements across species has been offered. Here we review five decades of fixational eye movement studies in non-human vertebrates, and we discuss the existing evidence concerning their physiological and perceptual effects. We also provide a table that summarizes the physical parameters of the different types of fixational eye movements described in non-human vertebrates.
Topics: Animals; Eye Movements; Fixation, Ocular; Vertebrates; Visual Perception
PubMed: 19146329
DOI: 10.1167/8.14.28 -
Psychonomic Bulletin & Review Oct 2020Gaze-where one looks, how long, and when-plays an essential part in human social behavior. While many aspects of social gaze have been reviewed, there is no... (Review)
Review
Gaze-where one looks, how long, and when-plays an essential part in human social behavior. While many aspects of social gaze have been reviewed, there is no comprehensive review or theoretical framework that describes how gaze to faces supports face-to-face interaction. In this review, I address the following questions: (1) When does gaze need to be allocated to a particular region of a face in order to provide the relevant information for successful interaction; (2) How do humans look at other people, and faces in particular, regardless of whether gaze needs to be directed at a particular region to acquire the relevant visual information; (3) How does gaze support the regulation of interaction? The work reviewed spans psychophysical research, observational research, and eye-tracking research in both lab-based and interactive contexts. Based on the literature overview, I sketch a framework for future research based on dynamic systems theory. The framework holds that gaze should be investigated in relation to sub-states of the interaction, encompassing sub-states of the interactors, the content of the interaction as well as the interactive context. The relevant sub-states for understanding gaze in interaction vary over different timescales from microgenesis to ontogenesis and phylogenesis. The framework has important implications for vision science, psychopathology, developmental science, and social robotics.
Topics: Facial Recognition; Fixation, Ocular; Humans; Social Interaction; Social Perception
PubMed: 32367351
DOI: 10.3758/s13423-020-01715-w