scholarly journals Spatial summation of individual cones in human color vision

2019 ◽  
Author(s):  
Brian P. Schmidt ◽  
Alexandra E. Boehm ◽  
William S. Tuten ◽  
Austin Roorda
Keyword(s):  
Adaptive Optics ◽  
Spatial Summation ◽  
Relative Activity ◽  
Excitatory Input ◽  
Color Information ◽  
Parvocellular Pathway ◽  
Spectral Class ◽  
Target Individual ◽  
Single Cone ◽  
Human Color Vision

AbstractThe human retina contains three classes of cone photoreceptors each sensitive to different portions of the visual spectrum: long (L), medium (M) and short (S) wavelengths. Color information is computed by downstream neurons that compare relative activity across the three cone types. How cone signals are combined at a cellular scale has been more difficult to resolve. This is especially true near the fovea, where spectrally-opponent neurons in the parvocellular pathway draw excitatory input from a single cone and thus even the smallest stimulus will engage multiple color-signaling neurons. We used an adaptive optics microstimulator to target individual and pairs of cones with light. Consistent with prior work, we found that color percepts elicited from individual cones were predicted by their spectral sensitivity, although there was considerable variability even between cones within the same spectral class. The appearance of spots targeted at two cones were predicted by an average of their individual activations. However, two cones of the same subclass elicited percepts that were systematically more saturated than predicted by an average. Together, these observations suggest both spectral opponency and prior experience influence the appearance of small spots.

A Self-Organizing Model of “Color Blob” Formation

1996 ◽  
Vol 8 (7) ◽  
pp. 1427-1448 ◽  
Author(s):  
Harry G. Barrow ◽  
Alistair J. Bray ◽  
Julian M. L. Budd
Keyword(s):  
Visual Processing ◽  
Striate Cortex ◽  
Hebbian Learning ◽  
Principal Component ◽  
Self Organization ◽  
Color Information ◽  
Color Processing ◽  
Parvocellular Pathway ◽  
Optimal Linear ◽  
Contrast Information

This paper explores the possibility that the formation of color blobs in primate striate cortex can be partly explained through the process of activity-based self-organization. We present a simulation of a highly simplified model of visual processing along the parvocellular pathway, that combines precortical color processing, excitatory and inhibitory cortical interactions, and Hebbian learning. The model self-organizes in response to natural color images and develops islands of unoriented, color-selective cells within a sea of contrast-sensitive, orientation-selective cells. By way of understanding this topography, a principal component analysis of the color inputs presented to the network reveals that the optimal linear coding of these inputs keeps color information and contrast information separate.

Lagged Y cells in the cat lateral geniculate nucleus

1991 ◽  
Vol 7 (3) ◽  
pp. 191-200 ◽  
Author(s):  
David N. Mastronarde ◽  
Allen L. Humphrey ◽  
Alan B. Saul
Keyword(s):  
Electrical Stimulation ◽  
Lateral Geniculate Nucleus ◽  
Spatial Summation ◽  
Excitatory Input ◽  
Antidromic Activation ◽  
Inhibitory Processes ◽  
Lateral Geniculate ◽  
Response Profile ◽  
Initial Dip ◽  
Y Cells

AbstractWe report on the existence of lagged Y (YL) cells in the A laminae of the cat lateral geniculate nucleus (LGN) and on criteria for identifying them using visual and electrical stimulation. Like the lagged X (XL) cells described previously (Mastronarde, 1987a; Humphrey & Weller, 1988a), YL cells responded to a spot stimulus with an initial dip in firing and a delayed latency to discharge after spot onset, and an anomalously prolonged firing after spot offset. However, the cells received excitatory input from retinal Y rather than X afferents, and showed nonlinear spatial summation and other Y-like receptive-field properties. Three YL cells tested for antidromic activation from visual cortex were found to be relay cells, with long conduction latencies similar to those of XL cells.Simultaneous recordings of a YL cell and its retinal Y afferents show striking parallels between lagged X and Y cells in retinogeniculate functional connectivity, and suggest that the YL-cell response profile reflects inhibitory processes occurring within the LGN. The YL cells comprised -5% of Y cells and -1% of all cells in the A laminae. Although infrequently encountered in the LGN, they may be roughly as numerous as Y cells in the retina, and hence could fulfill an important role in vision.

scholarly journals Spatial summation of individual cones in human color vision

PLoS ONE ◽  
2019 ◽  
Vol 14 (7) ◽  
pp. e0211397 ◽  
Author(s):  
Brian P. Schmidt ◽  
Alexandra E. Boehm ◽  
William S. Tuten ◽  
Austin Roorda
Keyword(s):  
Color Vision ◽  
Spatial Summation ◽  
Human Color Vision

scholarly journals Finding new sub-stellar co-moving companion candidates - the case of CT Cha

2007 ◽  
Vol 3 (S249) ◽  
pp. 65-69
Author(s):  
Tobias Schmidt ◽  
Ralph Neuhäuser
Keyword(s):  
Adaptive Optics ◽  
T Tauri Stars ◽  
Imaging Data ◽  
Color Information ◽  
Star Forming ◽  
T Tauri ◽  
Faint Object ◽  
Background Object ◽  
Object Form ◽  
Band Image

AbstractWe have searched for close and faint companions around T Tauri stars in the Chamaeleon star forming region. Two epochs of direct imaging data were taken with the VLT Adaptive Optics instrument NaCo in February 2006 and March 2007 in Ks band for the classical T Tauri star CT Cha together with a Hipparcos binary for astrometric calibration. Moreover a J band image was taken in March 2007 to get color information. We found CT Cha to have a very faint companion (Ks0=14.6 mag) of ∼2.67” separation corresponding to ∼440AU. We show that CT Cha A and the faint object form a common proper motion pair and that the companion is not a non-moving background object (with 4σ significance).

scholarly journals COLOR SEGMENTATION OF MGG COLORED CYTOLOGICAL IMAGES USING NON LINEAR OPPONENT COLOR SPACES

2013 ◽  
Vol 32 (3) ◽  
pp. 167
Author(s):  
Hélène Gouinaud ◽  
Lara Leclerc
Keyword(s):  
Color Image ◽  
Color Image Segmentation ◽  
Segmentation Method ◽  
Color Information ◽  
Viable Cells ◽  
Extension Model ◽  
Visual Color ◽  
Opponent Color ◽  
Human Color Vision ◽  
Logarithmic Image Processing

This paper presents a color image segmentation method for the quantification of viable cells from samples obtained after cytocentrifugation process and May Grunwald Giemsa (MGG) coloration and then observed by optical microscopy. The method is based on color multi-thresholding and mathematical morphology processing using color information on human visual system based models such as CIELAB model, LUX (Logarithmic hUe eXtension) model and CoLIP (Color Logarithmic Image Processing) model, a new human color vision based model also presented in this article. The results show that the CoLIP model, developed following each step of the human visual color perception, is particularly well adapted for this type of images.

scholarly journals Spatial summation in the human fovea: the effect of optical aberrations and fixational eye movements

2018 ◽  
Author(s):  
William S. Tuten ◽  
Robert F. Cooper ◽  
Pavan Tiruveedhula ◽  
Alfredo Dubra ◽  
Austin Roorda ◽  
...  
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Adaptive Optics ◽  
Ganglion Cells ◽  
Spatial Summation ◽  
Spatial Vision ◽  
Optical Aberrations ◽  
Stimulus Motion ◽  
Fixational Eye Movements ◽  
Magnocellular Visual Pathway

AbstractPsychophysical inferences about the neural mechanisms supporting spatial vision can be undermined by uncertainties introduced by optical aberrations and fixational eye movements, particularly in fovea where the neuronal grain of the visual system is fine. We examined the effect of these pre-neural factors on photopic spatial summation in the human fovea using a custom adaptive optics scanning light ophthalmoscope that provided control over optical aberrations and retinal stimulus motion. Consistent with previous results, Ricco’s area of complete summation encompassed multiple photoreceptors when measured with ordinary amounts of ocular aberrations and retinal stimulus motion. When both factors were minimized experimentally, summation areas were essentially unchanged, suggesting that foveal spatial summation is limited by post-receptoral neural pooling. We compared our behavioral data to predictions generated with a physiologically-inspired front-end model of the visual system, and were able to capture the shape of the summation curves obtained with and without pre-retinal factors using a single post-receptoral summing filter of fixed spatial extent. Given our data and modeling, neurons in the magnocellular visual pathway, such as parasol ganglion cells, provide a candidate neural correlate of Ricco’s area in the central fovea.

Quantification of color vision with cone contrast sensitivity

2004 ◽  
Vol 21 (3) ◽  
pp. 483-485 ◽  
Author(s):  
JEFF RABIN
Keyword(s):  
Color Vision ◽  
Letter Recognition ◽  
Normal Color Vision ◽  
Novel Approach ◽  
Cone Type ◽  
Cone Function ◽  
Single Cone ◽  
Human Color Vision ◽  
Cone Photopigments ◽  
Cone Sensitivity

Human color vision is based fundamentally on three separate cone photopigments. Hereditary color deficiency, which affects up to 10% of males, results from an absorption shift or lack of L or M cone phototoreceptors. While hereditary S cone deficiency is rare, decreased S cone sensitivity occurs early in eye disease, underscoring the importance of quantifying S cone function. Our purpose is to describe a novel approach for quantifying human color vision based on the photopigments of normal color vision. Colored letters, visible to a single cone type, are presented in graded steps of cone contrast to determine the threshold for letter recognition. This approach quantifies normal color vision, indicates type and severity of hereditary deficiency, and reveals sensitivity decrements in various diseases.

scholarly journals Weighted LabPQR Interim Connection Space Based on Human Color Vision for Spectral Color Reproduction

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Guangyuan Wu ◽  
Zhen Liu ◽  
Shengwei Yang ◽  
Ming Zhu ◽  
Pan Liu
Keyword(s):  
Weight Function ◽  
Color Vision ◽  
The Other ◽  
Weight Functions ◽  
Matching Function ◽  
Color Reproduction ◽  
Color Information ◽  
Visual Color ◽  
Human Color Vision ◽  
Connection Space

A weighted LabPQR interim connection space, based on human color vision, is proposed for retaining more visual color information. A new weight function proposed in our paper is connected with color-matching function and then further weighted the PQR dimensions of LabPQR compared with the other two weight functions and nonweight function. The results indicated that weighting obviously improved the colorimetric representing accuracy and robustness compared with nonweighting, and the new weight function outperformed the other two weight functions. The weighted LabPQR of the new weight function is most suitable for spectral color reproduction.

scholarly journals Sensations from a single M-cone depend on the activity of surrounding S-cones

2018 ◽  
Author(s):  
Brian P. Schmidt ◽  
Ramkumar Sabesan ◽  
William S. Tuten ◽  
Jay Neitz ◽  
Austin Roorda
Keyword(s):  
Adaptive Optics ◽  
Relative Activity ◽  
The Other ◽  
White Background ◽  
Coarse Scale ◽  
Retinal Position ◽  
Natural Movement ◽  
Short Wavelength Light ◽  
Wavelength Light ◽  
Stimulation Of

ABSTRACTColor vision requires the activity of cone photoreceptors to be compared in post-receptoral circuitry. Decades of psychophysical measurements have quantified the nature of these comparative interactions on a coarse scale. How such findings generalize to a cellular scale remains unclear. To answer that question, we quantified the influence of surrounding light on the appearance of spots targeted to individual cones. The eye’s aberrations were corrected with adaptive optics and retinal position was precisely tracked in real-time to compensate for natural movement. Subjects reported the color appearance of each spot. A majority of L-and M-cones consistently gave rise to the sensation of white, while a smaller group repeatedly elicited hue sensations. When blue sensations were reported they were more likely mediated by M- than L-cones. Blue sensations were elicited from M-cones against a short-wavelength light that preferentially elevated the quantal catch in surrounding S-cones, while stimulation of the same cones against a white background elicited green sensations. In one of two subjects, proximity to S-cones increased the probability of blue reports when M-cones were probed. We propose that M-cone increments excited both green and blue opponent pathways, but the relative activity of neighboring cones favored one pathway over the other.

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