Papers by Jonathan Victor
eLife, Aug 21, 2018
Odor attraction in walking Drosophila melanogaster is commonly used to relate neural function to ... more Odor attraction in walking Drosophila melanogaster is commonly used to relate neural function to behavior, but the algorithms underlying attraction are unclear. Here, we develop a highthroughput assay to measure olfactory behavior in response to well-controlled sensory stimuli. We show that odor evokes two behaviors: an upwind run during odor (ON response), and a local search at odor offset (OFF response). Wind orientation requires antennal mechanoreceptors, but search is driven solely by odor. Using dynamic odor stimuli, we measure the dependence of these two behaviors on odor intensity and history. Based on these data, we develop a navigation model that recapitulates the behavior of flies in our apparatus, and generates realistic trajectories when run in a turbulent boundary layer plume. The ability to parse olfactory navigation into quantifiable elementary sensori-motor transformations provides a foundation for dissecting neural circuits that govern olfactory behavior.
Consequences of Eye’s Optics and Geometry for Retinal Image Motion
Journal of Vision, Sep 27, 2021
Cortical potentials evoked by lateral interactions (A)
Journal of the Optical Society of America, 1983
Title: Cortical potentials evoked by lateral interactions (A). Authors: Ratliff, Floyd; Zemon, Va... more Title: Cortical potentials evoked by lateral interactions (A). Authors: Ratliff, Floyd; Zemon, Vance; Victor, Jonathan D. Publication: J. Opt. Soc. Am., vol. 73, page 1923. Publication Date: 00/1983. Origin: OSA. Keywords: VISION: PHYSIOLOGICAL OPTICS. ...
Author response: Contrast sensitivity reveals an oculomotor strategy for temporally encoding space
Journal of the Optical Society of America, Feb 1, 2007
To date a small palette of isotrigon textures have been available to study how the brain uses hig... more To date a small palette of isotrigon textures have been available to study how the brain uses higher-order spatial correlation information. We introduce several hundred new isotrigon textures. Special modulation properties are illustrated that can be used to extract neural responses to higher-order spatial correlations. We also ask how many textures make an adequate training set and how representative individual examples are of their texture class. Human discrimination of 90 of these patterns was quantified. Modeling those responses shows that humanlike performance can be obtained providing a fourth-order classifier is used, although more than one mechanism is required.
Saccade-amplitude dependent enhancement of visual sensitivity
Journal of Vision, Dec 5, 2022
Cognitive Influences on Ocular Drifts during Visual Discrimination
Journal of Vision, Dec 5, 2022
Neurocritical Care, Nov 10, 2020
Current Biology, Oct 1, 2020
Humans use rapid gaze shifts, known as saccades, to explore visual scenes. These movements yield ... more Humans use rapid gaze shifts, known as saccades, to explore visual scenes. These movements yield abrupt luminance changes on the retina, which elicit robust neural discharges at fixation onsets. Yet little is known about the spatial content of saccade transients. Here, we show that saccades redistribute spatial information within the temporal range of retinal sensitivity following two distinct regimes: saccade modulations counterbalance (whiten) the spectral density of natural scenes at low spatial frequencies and follow the external power distribution at higher frequencies. This redistribution is a consequence of saccade dynamics, particularly the speed/amplitude/duration relation known as the main sequence. It resembles the redistribution resulting from inter-saccadic eye drifts, revealing a continuum in the modulations given by different eye movements, with oculomotor transitions primarily acting by regulating the bandwidth of whitening. Our findings suggest important computational roles for saccade transients in the establishment of spatial representations and lead to testable predictions about their consequences for visual functions and encoding mechanisms.
Why do the response properties of magnocellular and parvocellular neurons differ both in space and time?
Journal of Vision, Sep 1, 2016
Mapping perceptual spaces of objects and low-level features
Journal of Vision, Sep 27, 2021
Subtle differences in the perceptual spaces of low-level features and objects
Journal of Vision, Dec 5, 2022
Active task-dependent control of ocular drift during natural fixation
Journal of Vision, Oct 20, 2020
A continuum in the retinal modulations resulting from eye movements
Journal of Vision, Sep 6, 2019
Temporal Cues to Defocus in Emmetropia and Myopia
Journal of Vision, Sep 1, 2018
Cognitive influences on fixational eye movements
Current Biology, Apr 1, 2023
PLOS Computational Biology, Jul 10, 2018
Many species rely on olfaction to navigate towards food sources or mates. Olfactory navigation is... more Many species rely on olfaction to navigate towards food sources or mates. Olfactory navigation is a challenging task since odor environments are typically turbulent. While time-averaged odor concentration varies smoothly with the distance to the source, instaneous concentrations are intermittent and obtaining stable averages takes longer than the typical intervals between animals' navigation decisions. How to effectively sample from the odor distribution to determine sampling location is the focus in this article. To investigate which sampling strategies are most informative about the location of an odor source, we recorded three naturalistic stimuli with planar lased-induced fluorescence and used an informationtheoretic approach to quantify the information that different sampling strategies provide about sampling location. Specifically, we compared multiple sampling strategies based on a fixed number of coding bits for encoding the olfactory stimulus. When the coding bits were all allocated to representing odor concentration at a single sensor, information rapidly saturated. Using the same number of coding bits in two sensors provides more information, as does coding multiple samples at different times. When accumulating multiple samples at a fixed location, the temporal sequence does not yield a large amount of information and can be averaged with minimal loss. Furthermore, we show that histogram-equalization is not the most efficient way to use coding bits when using the olfactory sample to determine location.
A computer-controlled instrument that creates complex two-dimensional patterns on a CRT monitor i... more A computer-controlled instrument that creates complex two-dimensional patterns on a CRT monitor is described. These patterns are used to elicit visual evoked responses. Patterns are produced on a raster that is rotatable about its center. It is possible to assign to arbitrary regions in the raster any of four independent one-dimensional spatial-temporal functions. For each spatial-temporal function, the experimenter can select an arbitrary spatial profile, the spatial frequency of the profile, the starting phase of the profile, the temporal function, and the depth of modulation. We are presently engaged in a project to bridge a gap between basic research on the neurophysiology of vision and clinical research on visual disorders . Over a period spanning many years, efforts in this laboratory had been devoted exclusively to basic research. During the early years of that period, visual stimuli consisted of small spots of light that could be turned on and off for predetermined' time intervals. Electronic timers controlled electromagnetic shutters that could interrupt light beams emanating from an incandescent light source. These beams were imaged onto individual photoreceptors of the horseshoe crab, Limulus. Methods such as these, although considered primitive today, led to the advanced steady-state theory of excitation and inhibition in Limulus . In later years, to obtain the temporal transfer function of eccentric cells in Limulus, glow modulator tubes that could be sinusoidally modulated replaced the incandescent light source (Ratliff, Knight, Dodge, & Hartline, 1974). Soon thereafter, it became clear that in order to characterize the system under study more fully, a complex spatialtemporal stimulus was required. This led to our development of visual stimulators that produce patterns on a cathode-ray tube (CRT). These patterns consist of flashing or drifting sinusoidal gratings and bars at arbitrary orientations (Milkman, Shapley,
BMC Neuroscience, Dec 1, 2015
Figure 1 1A: Color map of median texture discrimination performance versus isotrigon texture type... more Figure 1 1A: Color map of median texture discrimination performance versus isotrigon texture type. Lab datasets DC (84 HITs) and M1-6 (270 HITs). mTurk datasets Live1 (480 HITs) and Live2 (480 HITs). 1B: Pearson's correlation coefficients between datasets (abbreviations as above).
The contrast sensitivity function (CSF), how sensitivity varies with the spatial frequency of the... more The contrast sensitivity function (CSF), how sensitivity varies with the spatial frequency of the stimulus, is a fundamental assessment of visual performance. The CSF is generally assumed to be determined by low-level sensory processes. However, the sensitivities of neurons in the early visual pathways, as measured in experiments with immobilized eyes, diverge from psychophysical CSF measurements in primates. Under natural viewing conditions, as in typical psychophysical measurements, humans continually move their eyes, drifting in a seemingly erratic manner even when looking at a fixed point. Here, we show that the resulting transformation of the visual scene into a spatiotemporal flow on the retina constitutes a processing stage that reconciles human CSF and the response characteristics of retinal ganglion cells under a broad range of conditions. Our findings suggest a fundamental integration between perception and action: eye movements work synergistically with the sensitivities of retinal neurons to encode spatial information.
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Papers by Jonathan Victor