scholarly journals Temporal vision: measures, mechanisms and meaning

2021 ◽  
Vol 224 (15) ◽  
Author(s):  
Kristian Donner
Keyword(s):  
Visual Processing ◽  
Early Vision ◽  
Hidden Variable ◽  
Light Pulses ◽  
Temporal Properties ◽  
Trade Offs ◽  
Natural Vision ◽  
Retinal Photoreceptors ◽  
Temporal Aspects ◽  
Temporal Vision

ABSTRACT Time is largely a hidden variable in vision. It is the condition for seeing interesting things such as spatial forms and patterns, colours and movements in the external world, and yet is not meant to be noticed in itself. Temporal aspects of visual processing have received comparatively little attention in research. Temporal properties have been made explicit mainly in measurements of resolution and integration in simple tasks such as detection of spatially homogeneous flicker or light pulses of varying duration. Only through a mechanistic understanding of their basis in retinal photoreceptors and circuits can such measures guide modelling of natural vision in different species and illuminate functional and evolutionary trade-offs. Temporal vision research would benefit from bridging traditions that speak different languages. Towards that goal, I here review studies from the fields of human psychophysics, retinal physiology and neuroethology, with a focus on fundamental constraints set by early vision.

scholarly journals Distinguishing Hemodynamics from Function in the Human LGN Using a Temporal Response Model

Vision ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 27 ◽  
Author(s):  
Kevin DeSimone ◽  
Keith A. Schneider
Keyword(s):  
Receptive Field ◽  
Visual Processing ◽  
Field Model ◽  
Ventral Surface ◽  
Impulse Response Functions ◽  
Response Model ◽  
Response Functions ◽  
Temporal Response ◽  
Point Of Entry ◽  
Temporal Properties

We developed a temporal population receptive field model to differentiate the neural and hemodynamic response functions (HRF) in the human lateral geniculate nucleus (LGN). The HRF in the human LGN is dominated by the richly vascularized hilum, a structure that serves as a point of entry for blood vessels entering the LGN and supplying the substrates of central vision. The location of the hilum along the ventral surface of the LGN and the resulting gradient in the amplitude of the HRF across the extent of the LGN have made it difficult to segment the human LGN into its more interesting magnocellular and parvocellular regions that represent two distinct visual processing streams. Here, we show that an intrinsic clustering of the LGN responses to a variety of visual inputs reveals the hilum, and further, that this clustering is dominated by the amplitude of the HRF. We introduced a temporal population receptive field model that includes separate sustained and transient temporal impulse response functions that vary on a much short timescale than the HRF. When we account for the HRF amplitude, we demonstrate that this temporal response model is able to functionally segregate the residual responses according to their temporal properties.

scholarly journals Contrast sensitivity, V1 neural activity, and natural vision

2017 ◽  
Vol 117 (2) ◽  
pp. 492-508 ◽  
Author(s):  
James E. Niemeyer ◽  
Michael A. Paradiso
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Visual Processing ◽  
Brain Area ◽  
Saccadic Eye Movements ◽  
Visual Sensitivity ◽  
Natural Image ◽  
Spatial Frequencies ◽  
Natural Vision ◽  
Common Laboratory

Contrast sensitivity is fundamental to natural visual processing and an important tool for characterizing both visual function and clinical disorders. We simultaneously measured contrast sensitivity and neural contrast response functions and compared measurements in common laboratory conditions with naturalistic conditions. In typical experiments, a subject holds fixation and a stimulus is flashed on, whereas in natural vision, saccades bring stimuli into view. Motivated by our previous V1 findings, we tested the hypothesis that perceptual contrast sensitivity is lower in natural vision and that this effect is associated with corresponding changes in V1 activity. We found that contrast sensitivity and V1 activity are correlated and that the relationship is similar in laboratory and naturalistic paradigms. However, in the more natural situation, contrast sensitivity is reduced up to 25% compared with that in a standard fixation paradigm, particularly at lower spatial frequencies, and this effect correlates with significant reductions in V1 responses. Our data suggest that these reductions in natural vision result from fast adaptation on one fixation that lowers the response on a subsequent fixation. This is the first demonstration of rapid, natural-image adaptation that carries across saccades, a process that appears to constantly influence visual sensitivity in natural vision. NEW & NOTEWORTHY Visual sensitivity and activity in brain area V1 were studied in a paradigm that included saccadic eye movements and natural visual input. V1 responses and contrast sensitivity were significantly reduced compared with results in common laboratory paradigms. The parallel neural and perceptual effects of eye movements and stimulus complexity appear to be due to a form of rapid adaptation that carries across saccades.

scholarly journals Timing of continuous motor imagery: the two-thirds power law originates in trajectory planning

2015 ◽  
Vol 113 (7) ◽  
pp. 2490-2499 ◽  
Author(s):  
Matan Karklinsky ◽  
Tamar Flash
Keyword(s):  
Motor Imagery ◽  
Power Law ◽  
Temporal Structure ◽  
Motor Planning ◽  
Human Movement ◽  
Ratio Test ◽  
Discrete Movements ◽  
Temporal Properties ◽  
Temporal Aspects ◽  
Parameter Values

The two-thirds power law, v = γκ−1/3, expresses a robust local relationship between the geometrical and temporal aspects of human movement, represented by curvature κ and speed v, with a piecewise constant γ. This law is equivalent to moving at a constant equi-affine speed and thus constitutes an important example of motor invariance. Whether this kinematic regularity reflects central planning or peripheral biomechanical effects has been strongly debated. Motor imagery, i.e., forming mental images of a motor action, allows unique access to the temporal structure of motor planning. Earlier studies have shown that imagined discrete movements obey Fitts's law and their durations are well correlated with those of actual movements. Hence, it is natural to examine whether the temporal properties of continuous imagined movements comply with the two-thirds power law. A novel experimental paradigm for recording sparse imagery data from a continuous cyclic tracing task was developed. Using the likelihood ratio test, we concluded that for most subjects the distributions of the marked positions describing the imagined trajectory were significantly better explained by the two-thirds power law than by a constant Euclidean speed or by two other power law models. With nonlinear regression, the β parameter values in a generalized power law, v = γκ−β, were inferred from the marked position records. This resulted in highly variable yet mostly positive β values. Our results imply that imagined trajectories do follow the two-thirds power law. Our findings therefore support the conclusion that the coupling between velocity and curvature originates in centrally represented motion planning.

scholarly journals Temporal Characteristics of Visual Processing in Amblyopia

2021 ◽  
Vol 15 ◽  
Author(s):  
Xia Hu ◽  
Yi Qin ◽  
Xiaoxiao Ying ◽  
Junli Yuan ◽  
Rong Cui ◽  
...  
Keyword(s):  
Temporal Processing ◽  
Visual Processing ◽  
Spatial Vision ◽  
Stimulus Onset ◽  
Orientation Discrimination ◽  
Temporal Window ◽  
Significant Group ◽  
Significant Difference ◽  
Temporal Vision ◽  
Vision Deficits

PurposeAmblyopia affects not only spatial vision but also temporal vision. In this study, we aim to investigate temporal processing deficits in amblyopia.MethodsTwenty amblyopic patients (age: 27.0 ± 5.53 years, 15 males), and 25 normal observers (age: 25.6 ± 4.03 years, 15 males) were recruited in this study. Contrast thresholds in an orientation discrimination task in five target-mask stimulus onset asynchronies (SOA) conditions (16.7 ms, 33.4 ms, 50.0 ms, 83.4 ms, and ∞/no noise) were measured. An elaborated perceptual template model (ePTM) was fit to the behavioral data to derive the temporal profile of visual processing for each participant.ResultsThere were significant threshold differences between the amblyopic and normal eyes [F(1,43) = 10.6, p = 0.002] and a significant group × SOA interaction [F(2.75,118) = 4.98, p = 0.004], suggesting different temporal processing between the two groups. The ePTM fitted the data well (χ2 test, all ps > 0.50). Compared to the normal eye, the amblyopic eye had a lower template gain (p = 0.046), and a temporal window with lower peak and broader width (all ps < 0.05). No significant correlation was found between the observed temporal deficits and visual acuity in amblyopia (ps > 0.50). Similar results were found in the anisometropic amblyopia subgroup. No significant difference was found between the fellow eyes of the monocular amblyopia and the normal eyes.ConclusionAmblyopia is less efficient in processing dynamic visual stimuli. The temporal deficits in amblyopia, represented by a flattened temporal window, are likely independent of spatial vision deficits.

scholarly journals Isolation-Induced Ultrasonic Vocalization in Environmental and Genetic Mice Models of Autism

2021 ◽  
Vol 15 ◽  
Author(s):  
Itay Shekel ◽  
Shaked Giladi ◽  
Eynav Raykin ◽  
May Weiner ◽  
Vered Chalifa-Caspi ◽  
...  
Keyword(s):  
Social Preference ◽  
Repetitive Behavior ◽  
Control Groups ◽  
Knock Out ◽  
Temporal Properties ◽  
Gestational Exposure ◽  
Gene Environment ◽  
Temporal Aspects ◽  
Behavioral Manifestation ◽  
Knock Out Mice

Studies in rodent models suggest that calls emitted by isolated pups serve as an early behavioral manifestation of communication deficits and autistic like behavior. Previous studies in our labs showed that gestational exposure to the pesticide chlorpyrifos (CPF) and the Mthfr-knock-out mice are associated with impaired social preference and restricted or repetitive behavior. To extend these studies, we examine how pup communication via ultrasonic vocalizations is altered in these ASD models. We implemented an unsupervised hierarchical clustering method based on the spectral properties of the syllables in order to exploit syllable classification to homogeneous categories while avoiding over-categorization. Comparative exploration of the spectral and temporal aspects of syllables emitted by pups in two ASD models point to the following: (1) Most clusters showed a significant effect of the ASD factor on the start and end frequencies and bandwidth and (2) The highest percent change due to the ASD factor was on the bandwidth and duration. In addition, we found sex differences in the spectral and temporal properties of the calls in both control groups as well as an interaction between sex and the gene/environment factor. Considering the basal differences in the characteristics of syllables emitted by pups of the C57Bl/6 and Balb/c strains used as a background in the two models, we suggest that the above spectral-temporal parameters start frequency, bandwidth, and duration are the most sensitive USV features that may represent developmental changes in ASD models.

Trade-offs in visual processing for stimuli near the hands

2013 ◽  
Vol 76 (2) ◽  
pp. 383-390 ◽  
Author(s):  
Richard A. Abrams ◽  
Blaire J. Weidler
Keyword(s):  
Visual Processing ◽  
Trade Offs

scholarly journals The perception of colour and material in naturalistic tasks

2018 ◽  
Vol 8 (4) ◽  
pp. 20180012 ◽  
Author(s):  
David H. Brainard ◽  
Nicolas P. Cottaris ◽  
Ana Radonjić
Keyword(s):  
Surface Properties ◽  
Visual Processing ◽  
Early Vision ◽  
Object Surface ◽  
Future Directions ◽  
Vision Science ◽  
Simple Mapping ◽  
Observer Model ◽  
Key Aspects ◽  
Natural Tasks

Perceived object colour and material help us to select and interact with objects. Because there is no simple mapping between the pattern of an object's image on the retina and its physical reflectance, our perceptions of colour and material are the result of sophisticated visual computations. A long-standing goal in vision science is to describe how these computations work, particularly as they act to stabilize perceived colour and material against variation in scene factors extrinsic to object surface properties, such as the illumination. If we take seriously the notion that perceived colour and material are useful because they help guide behaviour in natural tasks, then we need experiments that measure and models that describe how they are used in such tasks. To this end, we have developed selection-based methods and accompanying perceptual models for studying perceived object colour and material. This focused review highlights key aspects of our work. It includes a discussion of future directions and challenges, as well as an outline of a computational observer model that incorporates early, known, stages of visual processing and that clarifies how early vision shapes selection performance.

scholarly journals Demonstrating the Utility of Egocentric Relational Event Modeling Using Focal Follow Data from Congolese BaYaka Children and Adolescents Engaging in Work and Play

Field Methods ◽  
2021 ◽  
pp. 1525822X2098707
Author(s):  
Kate Ellis-Davies ◽  
Sheina Lew-Levy ◽  
Eleanor Fleming ◽  
Adam H. Boyette ◽  
Thom Baguley
Keyword(s):  
Time Allocation ◽  
Statistical Approach ◽  
Child And Adolescent ◽  
Short Term ◽  
Work Activities ◽  
Event Modeling ◽  
Trade Offs ◽  
Activity Frequency ◽  
Temporal Aspects ◽  
Extended Work

Temporal aspects of child and adolescent time allocation in diverse cultural settings have been difficult to model using conventional statistical techniques. A new statistical approach, Egocentric Relational Event Modelling (EREM), allows for the simultaneous modelling of activity frequency, duration, and sequencing. Here, EREM is applied to a focal follow dataset of Congolese BaYaka forager child and adolescent play and work activities. Results show that, as children age, they engage in less frequent and extended play bouts and more frequent and extended work bouts. Bout frequency and duration were a more sensitive measure for early sex differences than overall time allocation. Sequential patterns of work and play suggest that these activities have short-term energetic trade-offs. This article demonstrates that EREM can reveal stable and variable patterns in child development.

Models of Perceptual Learning in Vernier Hyperacuity

1993 ◽  
Vol 5 (5) ◽  
pp. 695-718 ◽  
Author(s):  
Yair Weiss ◽  
Shimon Edelman ◽  
Manfred Fahle
Keyword(s):  
Perceptual Learning ◽  
Visual Processing ◽  
Human Subjects ◽  
Early Vision ◽  
Functional Architecture ◽  
Learning Rules ◽  
Early Visual Processing ◽  
Learning Modes ◽  
Basic Features ◽  
Activity Dependent

Performance of human subjects in a wide variety of early visual processing tasks improves with practice. HyperBF networks (Poggio and Girosi 1990) constitute a mathematically well-founded framework for understanding such improvement in performance, or perceptual learning, in the class of tasks known as visual hyperacuity. The present article concentrates on two issues raised by the recent psychophysical and computational findings reported in Poggio et al. (1992b) and Fahle and Edelman (1992). First, we develop a biologically plausible extension of the HyperBF model that takes into account basic features of the functional architecture of early vision. Second, we explore various learning modes that can coexist within the HyperBF framework and focus on two unsupervised learning rules that may be involved in hyperacuity learning. Finally, we report results of psychophysical experiments that are consistent with the hypothesis that activity-dependent presynaptic amplification may be involved in perceptual learning in hyperacuity.

scholarly journals Reliability of Visual Temporal Thresholds

2007 ◽  
Vol 34 (4) ◽  
pp. 433-437
Author(s):  
L N Brown ◽  
M Eliasziw ◽  
L M Metz
Keyword(s):  
Multiple Sclerosis ◽  
Measurement Error ◽  
Visual Processing ◽  
Control Group ◽  
Retest Reliability ◽  
Functional Changes ◽  
Disability Status ◽  
Temporal Aspects ◽  
Real Change ◽  
Test Retest Reliability

Background:Visual processing deficits involving temporal characteristics are typically not captured by the widely used outcome measures (i.e., Expanded Disability Status Scale, Multiple Sclerosis Functional Composite) in multiple sclerosis (MS). Visual temporal thresholds (i.e., measurements of the temporal aspects in visual processing) are typically significantly higher (i.e., prolonged) in MS patients when compared to controls. The test-retest reliability of these thresholds was examined in patients with MS.Methods:Visual temporal thresholds were measured in 21 stable MS patients during two separate test sessions. Test-retest reliability and the standard error of measurement were calculated. The threshold of change in visual temporal thresholds in MS patients that would correspond to real change beyond measurement error with 95% certainty was also calculated. For comparisons, a control group (n = 10) was included.Results:The test-retest reliability of this measure of visual temporal thresholds was 0.97. The threshold indicating change beyond chance or measurement error with 95% certainty was 11 ms. Higher thresholds were significantly correlated with longer durations of disease.Conclusions:This measure of visual temporal thresholds has excellent test-retest reliability and a change of greater than 11 ms is highly likely to represent real change in MS patients. The findings indicate that these measurements may provide useful clinical information about functional changes regarding the temporal aspects of the visual system, which is currently not captured by the Extended Disability Status Scale.

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