scholarly journals Fast and nonuniform dynamics of perisaccadic vision in the central fovea

2021 ◽  
Vol 118 (37) ◽  
pp. e2101259118
Author(s):  
Janis Intoy ◽  
Naghmeh Mostofi ◽  
Michele Rucci
Keyword(s):  
Time Course ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Visual Exploration ◽  
Social Grooming ◽  
Foveal Vision ◽  
High Acuity ◽  
Display Control ◽  
Shed Light ◽  
Central Fovea

Humans use rapid eye movements (saccades) to inspect stimuli with the foveola, the region of the retina where receptors are most densely packed. It is well established that visual sensitivity is generally attenuated during these movements, a phenomenon known as saccadic suppression. This effect is commonly studied with large, often peripheral, stimuli presented during instructed saccades. However, little is known about how saccades modulate the foveola and how the resulting dynamics unfold during natural visual exploration. Here we measured the foveal dynamics of saccadic suppression in a naturalistic high-acuity task, a task designed after primates’ social grooming, which—like most explorations of fine patterns—primarily elicits minute saccades (microsaccades). Leveraging on recent advances in gaze-contingent display control, we were able to systematically map the perisaccadic time course of sensitivity across the foveola. We show that contrast sensitivity is not uniform across this region and that both the extent and dynamics of saccadic suppression vary within the foveola. Suppression is stronger and faster in the most central portion, where sensitivity is generally higher and selectively rebounds at the onset of a new fixation. These results shed light on the modulations experienced by foveal vision during the saccade-fixation cycle and explain some of the benefits of microsaccades.

scholarly journals Foveal vision at the time of microsaccades

2021 ◽  
Author(s):  
Naghmeh Mostofi ◽  
Janis Intoy ◽  
Michele Rucci
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Time Course ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Visual Exploration ◽  
Social Grooming ◽  
Foveal Vision ◽  
High Acuity ◽  
Display Control

AbstractHumans use rapid eye movements (saccades) to inspect stimuli with the foveola, the region of the retina where receptors are most densely packed. It is well established that visual sensitivity is generally attenuated during these movements, a phenomenon known as saccadic suppression. This effect is commonly studied with large, often peripheral, stimuli presented during instructed saccades. However, little is known about how saccades modulate the foveola and how the resulting dynamics unfold during natural visual exploration. Here we measured the foveal dynamics of saccadic suppression in a naturalistic high-acuity task, a task designed after primate’s social grooming, which—like most explorations of fine patterns—primarily elicits minute saccades (microsaccades). Leveraging on recent advances in gaze-contingent display control, we were able to systematically map the peri-saccadic time-course of sensitivity across the foveola. We show that contrast sensitivity is not uniform across this region and that both the extent and dynamics of saccadic suppression vary within the foveola. Suppression is stronger and faster in the most central portion, where sensitivity is generally higher and selectively rebounds at the onset of a new fixation. These results shed new light on the modulations experienced by foveal vision during the saccade-fixation cycle and explain some of the benefits of microsaccades.

scholarly journals Saccadic suppression in schizophrenia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebekka Lencer ◽  
Inga Meyhöfer ◽  
Janina Triebsch ◽  
Karen Rolfes ◽  
Markus Lappe ◽  
...  
Keyword(s):  
Time Course ◽  
Visual Disturbance ◽  
Efference Copy ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Backward Masking ◽  
Control Task ◽  
Saccade Onset ◽  
Saccade Control ◽  
Visual Disturbances

AbstractAbout 40% of schizophrenia patients report discrete visual disturbances which could occur if saccadic suppression, the decrease of visual sensitivity around saccade onset, is impaired. Two mechanisms contribute to saccadic suppression: efference copy processing and backwards masking. Both are reportedly altered in schizophrenia. However, saccadic suppression has not been investigated in schizophrenia. 17 schizophrenia patients and 18 healthy controls performed a saccadic suppression task using a Gabor stimulus with individually adjusted contrast, which was presented within an interval 300 ms around saccade onset. Visual disturbance scores were higher in patients than controls, but saccadic suppression strength and time course were similar in both groups with lower saccadic suppression rates being similarly related to smaller saccade amplitudes. Saccade amplitudes in the saccadic suppression task were reduced in patients, in contrast to unaltered amplitudes during a saccade control task. Notably, smaller saccade amplitudes were related to higher visual disturbances scores in patients. Saccadic suppression performance was unrelated to symptom expression and antipsychotic medication. Unaltered saccadic suppression in patients suggests sufficiently intact efference copy processing and backward masking as required for this task. Instead, visual disturbances in patients may be related to restricted saccadic amplitudes arising from cognitive load while completing a task.

scholarly journals Modulations of foveal vision associated with microsaccade preparation

2020 ◽  
Vol 117 (20) ◽  
pp. 11178-11183
Author(s):  
Natalya Shelchkova ◽  
Martina Poletti
Keyword(s):  
Eye Movements ◽  
Visual Discrimination ◽  
Target Location ◽  
Onset Time ◽  
Spatial Vision ◽  
Saccade Target ◽  
Foveal Vision ◽  
Movement Onset ◽  
High Acuity ◽  
Gaze Position

It is known that attention shifts prior to a saccade to start processing the saccade target before it lands in the foveola, the high-resolution region of the retina. Yet, once the target is foveated, microsaccades, tiny saccades maintaining the fixated object within the fovea, continue to occur. What is the link between these eye movements and attention? There is growing evidence that these eye movements are associated with covert shifts of attention in the visual periphery, when the attended stimuli are presented far from the center of gaze. Yet, microsaccades are primarily used to explore complex foveal stimuli and to optimize fine spatial vision in the foveola, suggesting that the influences of microsaccades on attention may predominantly impact vision at this scale. To address this question we tracked gaze position with high precision and briefly presented high-acuity stimuli at predefined foveal locations right before microsaccade execution. Our results show that visual discrimination changes prior to microsaccade onset. An enhancement occurs at the microsaccade target location. This modulation is highly selective and it is coupled with a drastic impairment at the opposite foveal location, just a few arcminutes away. This effect is strongest when stimuli are presented closer to the eye movement onset time. These findings reveal that the link between attention and microsaccades is deeper than previously thought, exerting its strongest effects within the foveola. As a result, during fixation, foveal vision is constantly being reshaped both in space and in time with the occurrence of microsaccades.

scholarly journals A neural locus for spatial-frequency specific saccadic suppression in visual-motor neurons of the primate superior colliculus

2017 ◽  
Vol 117 (4) ◽  
pp. 1657-1673 ◽  
Author(s):  
Chih-Yang Chen ◽  
Ziad M. Hafed
Keyword(s):  
Spatial Frequency ◽  
Superior Colliculus ◽  
Motor Neurons ◽  
Motor Command ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Behavioral Measure ◽  
Visual Responses ◽  
Spatial Frequencies ◽  
Visual Motor

Saccades cause rapid retinal-image shifts that go perceptually unnoticed several times per second. The mechanisms for saccadic suppression have been controversial, in part because of sparse understanding of neural substrates. In this study we uncovered an unexpectedly specific neural locus for spatial frequency-specific saccadic suppression in the superior colliculus (SC). We first developed a sensitive behavioral measure of suppression in two macaque monkeys, demonstrating selectivity to low spatial frequencies similar to that observed in earlier behavioral studies. We then investigated visual responses in either purely visual SC neurons or anatomically deeper visual motor neurons, which are also involved in saccade generation commands. Surprisingly, visual motor neurons showed the strongest visual suppression, and the suppression was dependent on spatial frequency, as in behavior. Most importantly, suppression selectivity for spatial frequency in visual motor neurons was highly predictive of behavioral suppression effects in each individual animal, with our recorded population explaining up to ~74% of behavioral variance even on completely different experimental sessions. Visual SC neurons had mild suppression, which was unselective for spatial frequency and thus only explained up to ~48% of behavioral variance. In terms of spatial frequency-specific saccadic suppression, our results run contrary to predictions that may be associated with a hypothesized SC saccadic suppression mechanism, in which a motor command in the visual motor and motor neurons is first relayed to the more superficial purely visual neurons, to suppress them and to then potentially be fed back to cortex. Instead, an extraretinal modulatory signal mediating spatial-frequency-specific suppression may already be established in visual motor neurons. NEW & NOTEWORTHY Saccades, which repeatedly realign the line of sight, introduce spurious signals in retinal images that normally go unnoticed. In part, this happens because of perisaccadic suppression of visual sensitivity, which is known to depend on spatial frequency. We discovered that a specific subtype of superior colliculus (SC) neurons demonstrates spatial-frequency-dependent suppression. Curiously, it is the neurons that help mediate the saccadic command itself that exhibit such suppression, and not the purely visual ones.

Visual sensitivity across the menstrual cycle

2004 ◽  
Vol 21 (4) ◽  
pp. 513-531 ◽  
Author(s):  
ALVIN EISNER ◽  
SARA N. BURKE ◽  
MAUREEN D. TOOMEY
Keyword(s):  
Oral Contraceptive ◽  
Menstrual Cycle ◽  
Time Course ◽  
Light Adaptation ◽  
Contraceptive Use ◽  
Visual Sensitivity ◽  
Visual Adaptation ◽  
Hormonal Change ◽  
Menstrual Cycles ◽  
Sensitivity Change

This study was designed to evaluate the hypothesis that hormonal change can affect lower level light-adaptation processes, which are likely to be retinally based. Foveal visual sensitivities were measured across several menstrual cycles of four women not using hormonally acting medication and across several menstrual cycles of three women using a triphasic oral contraceptive. One woman, diagnosed with premenstrual syndrome (PMS), was a subject for both groups. Sensitivities were measured for a series of test wavelengths for 580-nm backgrounds of 2.0 and 4.0 log td. Of the six individuals tested, one had clear evidence of visual-adaptation changes occurring in phase with the menstrual cycle. Prior to using the oral contraceptive, this individual (the PMS subject) experienced changes of short-wavelength-sensitive (SWS)-cone-mediated sensitivities of up to about 1.4 log unit on the 4.0 log td background. Her SWS-cone-mediated sensitivities tended to be highest near ovulation and lowest premenstrually. Threshold-versus-illuminance (TVI) curves confirmed that the rate of sensitivity decrease with increasing background illuminance (i.e. the TVI slope) was greater premenstrually. The degree of background-induced desensitization within her middle-wavelength-sensitive (MWS)/long-wavelength-sensitive (LWS) cone pathways also appeared to vary cyclically, but the magnitude of the variation was smaller and the time course appeared to be different. When this subject began oral contraceptive use, the patterns of sensitivity change were all altered. None of the other five subjects experienced changes of SWS-cone-mediated vision that were cyclic and significantly adaptation-state dependent. However, there was evidence for a limited degree of cyclic adaptation change within the MWS/LWS cone pathways of at least one additional subject. We conclude that hormonal change can—for some unknown proportion of women—be linked to alterations of retinal function. However, the alterations are not the same for all visual pathways, and there are pronounced individual differences. The data also demonstrate that individuals' visual adaptation capabilities can vary substantially over periods of weeks.

scholarly journals Suppression without inhibition: A novel mechanism in the retina accounts for saccadic suppression

2020 ◽  
Author(s):  
Saad Idrees ◽  
Matthias-Philipp Baumann ◽  
Maria M. Korympidou ◽  
Timm Schubert ◽  
Alexandra Kling ◽  
...  
Keyword(s):  
Eye Movements ◽  
Visual Perception ◽  
Receptive Field ◽  
Calcium Imaging ◽  
Ganglion Cells ◽  
Saccadic Eye Movements ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Retinal Processing ◽  
Retinal Pathways

AbstractVisual perception remains stable across saccadic eye movements, despite the concurrent strongly disruptive visual flow. This stability is partially associated with a reduction in visual sensitivity, known as saccadic suppression, which already starts in the retina with reduced ganglion cell sensitivity. However, the retinal circuit mechanisms giving rise to such suppression remain unknown. Here, we describe these mechanisms using electrophysiology in mouse, pig, and macaque retina, 2-photon calcium imaging, computational modeling, and human psychophysics. We find a novel retinal processing motif underlying retinal saccadic suppression, “dynamic reversal suppression”, which is triggered by sequential stimuli containing contrast reversals. This motif does not involve inhibition but relies on nonlinear transformation of the inherently slow responses of cone photoreceptors by downstream retinal pathways. Two further components of suppression are present in ON ganglion cells and originate in the cells’ receptive field surround, highlighting a novel disparity between ON and OFF ganglion cells. Our results are relevant for any sequential stimulation encountered frequently in naturalistic scenarios.

scholarly journals A Neural Locus for Perceptually-Relevant Saccadic Suppression in Visual-Motor Neurons of the Primate Superior Colliculus

2016 ◽  
Author(s):  
Chih-Yang Chen ◽  
Ziad M. Hafed
Keyword(s):  
Superior Colliculus ◽  
Motor Neurons ◽  
Critical Role ◽  
Motor Command ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Behavioral Measure ◽  
Visual Responses ◽  
Visual Neurons ◽  
Visual Motor

AbstractSaccadic eye movements cause rapid retinal-image shifts that go perceptually unnoticed several times per second. The mechanisms for perceptual saccadic suppression have been controversial, in part due to sparse understanding of neural substrates. Here we uncovered an unexpectedly specific neural locus for saccadic suppression in the primate superior colliculus (SC). We first developed a sensitive behavioral measure of perceptual suppression in two male macaque monkeys (Macaca mulatta), demonstrating known selectivity to low spatial frequencies. We then investigated visual responses in either purely visual SC neurons or anatomically-deeper visual-motor neurons, which are also involved in saccade generation commands. Surprisingly, visual-motor neurons showed the strongest visual suppression, and the suppression was dependent on spatial frequency like in perception. Most importantly, visual-motor neuron suppression selectivity was highly predictive of behavioral suppression effects in each individual animal, with our recorded population explaining up to ~74% of behavioral variance even on completely different experimental sessions. In contrast, purely visual SC neurons only had mild and unselective suppression (only explaining up to ~48% of behavioral variance). These results run contrary to a hypothesized SC mechanism for saccadic suppression, in which a motor command in the visual-motor and motor neurons is relayed to the more superficial purely visual neurons to suppress them, and to then potentially be fed back to cortex. Instead, our results indicate that an extra-retinal modulatory signal mediating perceptual suppression is already established in visual-motor neurons.New & NoteworthySaccades, which repeatedly re-align the line of sight, introduce spurious signals in retinal images that normally go unnoticed. In part, this happens because of peri-saccadic suppression of visual sensitivity. Here we discovered that a specific sub-type of superior colliculus (SC) neurons may play a critical role in saccadic suppression. Curiously, it is the neurons that help mediate the saccadic command itself that exhibit perceptually-relevant changes in visual sensitivity, not the previously hypothesized purely visual neurons.

scholarly journals Dissociable saccadic suppression of pupillary and perceptual responses to light

2016 ◽  
Vol 115 (3) ◽  
pp. 1243-1251 ◽  
Author(s):  
Alessandro Benedetto ◽  
Paola Binda
Keyword(s):  
Large Fraction ◽  
Pupillary Response ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Light Responses ◽  
Pupillary Light ◽  
Relative Independence ◽  
Pupillary Responses ◽  
Full Screen ◽  
Flash Stimulus

We measured pupillary constrictions in response to full-screen flashes of variable luminance, occurring either at the onset of a saccadic eye movement or well before/after it. A large fraction of perisaccadic flashes were undetectable to the subjects, consistent with saccadic suppression of visual sensitivity. Likewise, pupillary responses to perisaccadic flashes were strongly suppressed. However, the two phenomena appear to be dissociable. Across subjects and luminance levels of the flash stimulus, there were cases in which conscious perception of the flash was completely depleted yet the pupillary response was clearly present, as well as cases in which the opposite occurred. On one hand, the fact that pupillary light responses are subject to saccadic suppression reinforces evidence that this is not a simple reflex but depends on the integration of retinal illumination with complex “extraretinal” cues. On the other hand, the relative independence of pupillary and perceptual responses suggests that suppression acts separately on these systems—consistent with the idea of multiple visual pathways that are differentially affected by saccades.

scholarly journals RNA-seq Analysis of Salt-Stressed Versus Non Salt-Stressed Transcriptomes of Chenopodium quinoa Landrace R49

Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1042 ◽  
Author(s):  
Karina B. Ruiz ◽  
Jonathan Maldonado ◽  
Stefania Biondi ◽  
Herman Silva
Keyword(s):  
Time Course ◽  
Average Length ◽  
Chenopodium Quinoa ◽  
Transcriptional Response ◽  
Sequencing Analysis ◽  
Rna Seq ◽  
Crop Species ◽  
Transcriptional Reprogramming ◽  
Transcriptomic Level ◽  
Shed Light

Quinoa (Chenopodium quinoa Willd.), a model halophytic crop species, was used to shed light on salt tolerance mechanisms at the transcriptomic level. An RNA-sequencing analysis of genotype R49 at an early vegetative stage was performed by Illumina paired-ends method comparing high salinity and control conditions in a time-course pot experiment. Genome-wide transcriptional salt-induced changes and expression profiling of relevant salt-responsive genes in plants treated or not with 300 mM NaCl were analyzed after 1 h and 5 days. We obtained up to 49 million pairs of short reads with an average length of 101 bp, identifying a total of 2416 differentially expressed genes (DEGs) based on the treatment and time of sampling. In salt-treated vs. control plants, the total number of up-regulated and down-regulated genes was 945 and 1471, respectively. The number of DEGs was higher at 5 days than at 1 h after salt treatment, as reflected in the number of transcription factors, which increased with time. We report a strong transcriptional reprogramming of genes involved in biological processes like oxidation-reduction, response to stress and response to abscisic acid (ABA), and cell wall organization. Transcript analyses by real-time RT- qPCR supported the RNA-seq results and shed light on the contribution of roots and shoots to the overall transcriptional response. In addition, it revealed a time-dependent response in the expression of the analyzed DEGs, including a quick (within 1 h) response for some genes, suggesting a “stress-anticipatory preparedness” in this highly salt-tolerant genotype.

scholarly journals Greater magnocellular saccadic suppression in high versus low autistic tendency suggests a causal path to local perceptual style

2015 ◽  
Vol 2 (12) ◽  
pp. 150226 ◽  
Author(s):  
David P. Crewther ◽  
Daniel Crewther ◽  
Stephanie Bevan ◽  
Melvyn A. Goodale ◽  
Sheila G. Crewther
Keyword(s):  
Spatial Frequency ◽  
Visual Information ◽  
Evoked Potential ◽  
High Spatial Frequency ◽  
Autism Spectrum ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Autism Spectrum Quotient ◽  
General Description ◽  
Perceptual Style

Saccadic suppression—the reduction of visual sensitivity during rapid eye movements—has previously been proposed to reflect a specific suppression of the magnocellular visual system, with the initial neural site of that suppression at or prior to afferent visual information reaching striate cortex. Dysfunction in the magnocellular visual pathway has also been associated with perceptual and physiological anomalies in individuals with autism spectrum disorder or high autistic tendency, leading us to question whether saccadic suppression is altered in the broader autism phenotype. Here we show that individuals with high autistic tendency show greater saccadic suppression of low versus high spatial frequency gratings while those with low autistic tendency do not. In addition, those with high but not low autism spectrum quotient (AQ) demonstrated pre-cortical (35–45 ms) evoked potential differences (saccade versus fixation) to a large, low contrast, pseudo-randomly flashing bar. Both AQ groups showed similar differential visual evoked potential effects in later epochs (80–160 ms) at high contrast. Thus, the magnocellular theory of saccadic suppression appears untenable as a general description for the typically developing population. Our results also suggest that the bias towards local perceptual style reported in autism may be due to selective suppression of low spatial frequency information accompanying every saccadic eye movement.

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