Contrast sensitivity of cats and humans in scotopic and mesopic conditions (original) (raw)
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A mechanistic inter-species comparison of spatial contrast sensitivity
Vision Research, 2008
The validity of the Rovamo-Barten modulation transfer function model for describing spatial contrast sensitivity in vertebrates was examined using published data for the human, macaque, cat, goldfish, pigeon and rat. Under photopic conditions, the model adequately described overall contrast sensitivity for changes in both stimulus luminance and stimulus size for each member of this diverse range of species. From this examination, optical, retinal and post-retinal neural processes subserving contrast sensitivity were quantified. An important retinal process is lateral inhibition and values of its associated point spread function (PSF) were obtained for each species. Some auxiliary contrast sensitivity data obtained from the owl monkey were included for these calculations. Modeled values of the lateral inhibition PSF were found to correlate well with ganglion cell receptive field surround size measurements obtained directly from electrophysiology. The range of vertebrates studied was then further extended to include the squirrel monkey, tree shrew, rabbit, chicken and eagle. To a first approximation, modeled estimates of lateral inhibition PSF width were found to be inversely proportional to the square root of ganglion cell density. This finding is consistent with a receptive field surround diameter that changes in direct proportion to the distance between ganglion cells for central vision. For the main species examined, contrast sensitivity is considerably less than that for the human. Although this is due in part to a reduction in the performance of both optical and retinal mechanisms, the model indicates that poor cortical detection efficiency plays a significant role.
Contrast gain control in the cat's visual system
Journal of Neurophysiology
We have examined the idea that the adaptation of cortical neurons to local contrast levels in a visual stimulus is functionally advantageous. Specifically, cortical cells may have large differential contrast sensitivity as a result of adjustments that center a limited response range around a mean level of contrast. To evaluate this notion, we measured contrast-response functions of cells in striate cortex while systematically adapting them to different contrast levels of stimulus gratings. For the majority of cortical neurons tested, the results of this basic experiment show that contrast-response functions shift laterally along a log-contrast axis so that response functions match mean contrast levels in the stimulus. This implies a contrast-dependent change in the gain of the cell's contrast-response relationship. We define this process as contrast gain control. The degree to which this contrast adjustment occurs varies considerably from cell to cell. There are no obvious diffe...
Comparative neurophysiology of spatial luminance contrast sensitivity
Psychology and Neuroscience, 2011
The luminance contrast sensitivity function has been investigated using behavioral and electrophysiological methods in many vertebrate species. Some features are conserved across species as a shape of the function, but other features, such as the contrast sensitivity peak value, spatial frequency contrast sensitivity peak, and visual acuity have changed. Here, we review contrast sensitivity across different classes of vertebrates, with an emphasis on the frequency contrast sensitivity peak and visual acuity. We also correlate the data obtained from the literature to test the power of the association between visual acuity and the spatial frequency of the contrast sensitivity function peak.
Contrast adaptation and contrast gain control
Experimental Brain Research, 1991
Electrophysiological measurements have shown that contrast adaptation can increase the contrast gain of cortical cells of the cat and the monkey. This implies that adaptation could enhance the contrast discrimination sensitivity. Psychophysical contrast discrimination experiments were performed with and without contrast adaptation. The stimuli were spatially separated stationary Gabor patterns. The pedestal contrast was varied from 6 to 75 per cent. The spatial frequency was 1.5, 5.0 or 20 cpd. After adaptation the contrast detection thresholds are elevated and the subjective contrast is lowered. The contrast discrimination thresholds remain unchanged.
Scotopic and mesopic light adaptation in the cat's retina
Pfl�gers Archiv European Journal of Physiology, 1969
Zusammen]assung. Die Auswirkungen der Ilella.daptation auf das Entladungsverhalten von on-Zentrum Neuronen der Katzenretina wurden im skotopischen und mesopisehen Leuehtdichtebereich untersueht (10-5-1 ed/m2). Bei Verwendung diffuserLichtreize steigt die Daueraktivit~t aller on-Zentrum Neurone mit steigender Adaptationleuehtdichte bis zu Leuehtdichten zwisehen 10-a und 10-2 ed/m 2 an. Bei weiterer Erh6hung der Leuehtdiehte bleibt die Daueraktivitgt konstant oder nimmt wieder ab. Der Verlauf der Daueraktivitgt eines Neurons bei steigender Adaptationsleuchtdichte steht in Zusammenhang mit Vergnderungen der receptiven Feldstruktur und der Empfindliehkeit der Retina. Die Empfindliehkeit der Retina wurde bei versehiedenen Adaptationsleuchtdiehten IA dureh die Leuebtdichte AI eines Testreizes gemessen, der zu einer konstanten Schwellenreaktion ffihrte. Bei ansteigendem IA nimmt AI proportional IA n zu, wobei n zwischen 0,45 und 0,75 Iiegt. Entspreehend wurde die Reiz-l~eaktionskennlinie eines Neurons bei Ver-~nderung des Adaptationszustandes um weniger als die logarithmische Differenz der Adaptationsleuchtdiehten auf der Intenistgtsaehse verschoben. Die Reiz-Reaktionskennlinien eines Neurons bei verschiedenen Adaptationszust~nden sind bei halblogarithmischer Auftragung parallel zueinander versehoben. Sie sind S-f6rmig mit einem geraden Anteil fiber 1,5 log Einheiten. Bei allen Adaptations-zust~nden wurden sic am besten dutch eine Logarithmus-Funktion besehrieben. Es wird gefolgert, d~l? Adaptation and rgumliehe Summation Funktionen versehiedener Sehiehten der I{etina sind und die Ganglienzellen nicht aktiv am Adaptationsmeehanismus beteiligt sind.
The time course of adaptation to spatial contrast
1991
We explored the buildup and decay of threshold elevation during and after adaptation to sinewave gratings in a series of experiments investigating the effects of adapting time, adapting contrast, spatial frequency and retinal eccentricity. Contrast thresholds for vertical sinewave gratings truncated in space by a one-dimensional Gaussian envelope were measured before and after adaptation to a full-field suprathreshold grating of the same spatial frequency and orientation. Thresholds were measured intermittently after adaptation in a "seen/not-seen" single presentation procedure until these thresholds returned to baseline values. The first test grating was presented 300 msec after the offset of the adapting stimulus, and thereafter at regular intervals. At different times after adaptation, contrast thresholds were estimated by off-line analysis of the data using the QUEST algorithm. Adapting time was either 1, 10, 108 or 1000 set and adapting contrast was either 9, 19, 29 or 39 dB (re. 1%). The test gratings were presented centered either at the fixation point or at 5 and 10 deg eccentricity along the horizontal meridian. The results suggest that up to the saturation level the buildup and the decay of adaptation to contrast is well described by a power function of time. The slope of the best fitting line on log-log axes is fairly constant for the adaptation times tested. As reported earlier, thresholds increased with adapting contrast and these contrast-dependent differences were evident 3OOmsec after the termination of adaptation. Adaptation at 10 deg eccentricity yielded slightly higher threshold elevations than for central vision. Based on these results, a description is given of the dynamic response of the underlying neural mechanisms.
Contrast increment thresholds of rhesus monkeys
Vision Research, 1982
Increment contrast thresholds were determined behaviouraliy as a function of background contrast for sinusoidal gratings with spatial frequencies between 0.5 and KOc/deg. As has been previously reported for humans, the contrast discrimination functions were characterized by a facilitation effect for low background contrasts and a masking effect for high background contrasts. The shapes of the functions varied with spatial frequency, but for all spatial frequencies, portions of the functions were adequately described by a power law. The shapes of the reaction time distributions obtained for near threshold stimuli suggested that at least two mechanisms with different spatio-temporal sensitivities were involved in detecting the stimulus and that the exact shape of the contrast discrimination function was dependent on which mechanism dominated detection.
Vision Research, 1974
The detectability of luminance modulated gratings of different spatial frequencies was determined at five different adaptation levels for three macaque monkeys and five normal human observers. The human and macaque observers gave results which were identical in form and similar in absolute values. Both species showed optimal contrast sensitivity in the middle spatial frequency range of about 3-5 c/deg with both low and high frequency attenuation, at high light levels. Contrast sensitivity to high frequencies dropped rapidly as adaptation levels were lowered, with a resulting shift in peak sensitivity to lower spatial frequencies. At the lowest adaptation level studied, neither macaque nor human observers showed any low frequency attenuation in the spatial luminance contrast sensitivity function.