scholarly journals Neuronal basis of perceptual learning in striate cortex

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Zhen Ren ◽  
Jiawei Zhou ◽  
Zhimo Yao ◽  
Zhengchun Wang ◽  
Nini Yuan ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Perceptual Learning ◽  
Contrast Sensitivity ◽  
Striate Cortex ◽  
Signal To Noise Ratio ◽  
High Spatial Frequency ◽  
Sensitivity Training ◽  
Spatial Frequencies ◽  
Cortex Area ◽  
Adult Cats

Abstract It is well known that, in humans, contrast sensitivity training at high spatial frequency (SF) not only leads to contrast sensitivity improvement, but also results in an improvement in visual acuity as assessed with gratings (direct effect) or letters (transfer effect). However, the underlying neural mechanisms of this high spatial frequency training improvement remain to be elucidated. In the present study, we examined four properties of neurons in primary visual cortex (area 17) of adult cats that exhibited significantly improved acuity after contrast sensitivity training with a high spatial frequency grating and those of untrained control cats. We found no difference in neuronal contrast sensitivity or tuning width (Width) between the trained and untrained cats. However, the trained cats showed a displacement of the cells’ optimal spatial frequency (OSF) to higher spatial frequencies as well as a larger neuronal signal-to-noise ratio (SNR). Furthermore, both the neuronal differences in OSF and SNR were significantly correlated with the improvement of acuity measured behaviorally. These results suggest that striate neurons might mediate the perceptual learning-induced improvement for high spatial frequency stimuli by an alteration in their spatial frequency representation and by an increased SNR.

Acuity and contrast sensitivity of the bluegill sunfish and how they change during optic nerve regeneration

2007 ◽  
Vol 24 (3) ◽  
pp. 319-331 ◽  
Author(s):  
D.P.M. NORTHMORE ◽  
D.-J. OH ◽  
M.A. CELENZA
Keyword(s):  
Optic Nerve ◽  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Cutoff Frequency ◽  
Lepomis Macrochirus ◽  
High Spatial Frequency ◽  
Contrast Threshold ◽  
Bluegill Sunfish ◽  
Sensitivity Functions ◽  
Spatial Frequencies

Spatial vision was studied in the bluegill sunfish, Lepomis macrochirus (9.5–14 cm standard length) to assess the limitations imposed by the optics of the eye, the retinal receptor spacing and the retinotectal projection during regeneration. Examination of images formed by the dioptric elements of the eye showed that spatial frequencies up to 29 c/° could be imaged on the retina. Cone spacing was measured in the retina of fresh, intact eyes. The spacing of rows of double cones predicted 3.4 c/° as the cutoff spatial frequency; the spacing between rows of single and double cones predicted 6.7 c/°. Contrast sensitivity functions were obtained psychophysically in normals and fish with one regenerating optic nerve. Fish were trained to orient to gratings (mean luminance = 25 cd/m2) presented to either eye. In normals, contrast sensitivity functions were similar in shape and bandwidth to those of other species, peaking at 0.4 c/° with a minimum contrast threshold of 0.03 and a cutoff at about 5 c/°, which was within the range predicted by cone spacing. Given that the optical cutoff frequency exceeds that predicted by cone spacing, it is possible that gratings could be detected by aliasing with the bluegill's regular cone mosaic. However, tests with high contrast gratings up to 15 c/° found no evidence of such detection. After crushing one optic nerve in three trained sunfish, recovery of visual avoidance, dorsal light reflex and orienting to gratings, were monitored over 315 days. At 64–69 days postcrush, responses to gratings reappeared, and within 2–5 days contrast sensitivity at low (0.15 c/°) and medium (1.0 c/°) spatial frequencies had returned to normal. At a high spatial frequency (2.93 c/°) recovery was much slower, and complete only in one fish.

scholarly journals Contrast Sensitivity after Zyoptix Tissue Saving LASIK and Standard LASIK for Myopia with 6-Month Followup

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Li-Quan Zhao ◽  
Huang Zhu
Keyword(s):  
Spatial Frequency ◽  
Comparative Study ◽  
Contrast Sensitivity ◽  
High Myopia ◽  
High Spatial Frequency ◽  
High Group ◽  
Spatial Frequencies ◽  
Group A

This control-matched comparative study evaluated changes in contrast sensitivity after Zyoptix tissue-saving (TS) LASIK and Planoscan standard LASIK (Technolas 217z, Bausch & Lomb) for myopia 6 months postoperatively. 102 TS LASIK-treated eyes were matched with 102 standard LASIK-treated eyes (divided into low, moderate, and high groups). There were no significant differences in refraction outcomes between the groups postoperatively. In high group, a significant reduction in contrast sensitivity after TS LASIK was found at high spatial frequencies (P<.05) under photopic conditions and at middle to high spatial frequencies (P<.05) under mesopic conditions. And significant reduction was also found in standard LASIK at high spatial frequency (P<.05) under mesopic conditions. The reduction was significantly lower in TS LASIK than that in standard LASIK at high spatial frequencies (P<.05) under mesopic conditions. TS LASIK was prone to reduce mesopic contrast sensitivity of high myopia at high spatial frequencies.

scholarly journals Sharpening coarse-to-fine stereo vision by perceptual learning: asymmetric transfer across the spatial frequency spectrum

2016 ◽  
Vol 3 (1) ◽  
pp. 150523 ◽  
Author(s):  
Roger W. Li ◽  
Truyet T. Tran ◽  
Ashley P. Craven ◽  
Tsz-Wing Leung ◽  
Sandy W. Chat ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Perceptual Learning ◽  
Frequency Spectrum ◽  
Three Dimensional ◽  
High Spatial Frequency ◽  
Visual Image ◽  
Spatial Frequencies ◽  
Early Visual Cortex ◽  
Coarse To Fine ◽  
Spatial Frequency Spectrum

Neurons in the early visual cortex are finely tuned to different low-level visual features, forming a multi-channel system analysing the visual image formed on the retina in a parallel manner. However, little is known about the potential ‘cross-talk’ among these channels. Here, we systematically investigated whether stereoacuity, over a large range of target spatial frequencies, can be enhanced by perceptual learning. Using narrow-band visual stimuli, we found that practice with coarse (low spatial frequency) targets substantially improves performance, and that the improvement spreads from coarse to fine (high spatial frequency) three-dimensional perception, generalizing broadly across untrained spatial frequencies and orientations. Notably, we observed an asymmetric transfer of learning across the spatial frequency spectrum. The bandwidth of transfer was broader when training was at a high spatial frequency than at a low spatial frequency. Stereoacuity training is most beneficial when trained with fine targets. This broad transfer of stereoacuity learning contrasts with the highly specific learning reported for other basic visual functions. We also revealed strategies to boost learning outcomes ‘beyond-the-plateau’. Our investigations contribute to understanding the functional properties of the network subserving stereovision. The ability to generalize may provide a key principle for restoring impaired binocular vision in clinical situations.

Extrageniculostriate vision in the monkey. VII. Contrast sensitivity functions

1980 ◽  
Vol 43 (6) ◽  
pp. 1510-1526 ◽  
Author(s):  
M. Miller ◽  
P. Pasik ◽  
T. Pasik
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Striate Cortex ◽  
Pattern Discrimination ◽  
Sensitivity Threshold ◽  
Sinusoidal Grating ◽  
Frequency Detection ◽  
Spatial Frequencies ◽  
The Mean ◽  
Method Of Constant Stimuli

1. Psychophysical and electrophysiological experiments have indicated the importance of spatial frequency components and their respective contrasts and orientations for the recognition of patterns. It is in the striate cortex where these types of information first converge, a fact that lends support to the accepted crucial role of this structure in pattern discrimination. 2. Monkeys with total bilateral ablation of the striate cortex, however, retain a residual capacity for pattern discrimination and also can differentiate between a vertical and an oblique luminous bar. The present study explores their capacity for spatial frequency detection both as a function of contrast and, by extrapolation, at maximum contrast (visual acuity measure). 3. Monkeys were presented with a forced choice between a homogeneous target and a vertically oriented sinusoidal grating in a pulling-in apparatus. Stimuli were produced by the transillumination of transparencies at spatial frequencies of 0.5, 1.0, 2.0, 4.0, 8.0, 16, and 32 cycles/deg, in 0.1-log unit steps of contrast from 0.79 to 0.006. The stimuli subtended 8 degrees of visual angle and were matched for mean luminance at 20 cd/m2. After mastering the discrimination of one spatial frequency at the highest contrast, contrast thresholds were first estimated by a staircase technique, and then determined by the method of constant stimuli. The procedure was repeated for each spatial frequency before and after histologically verified total bilateral removal of striate cortex and partial damage to circumstriate cortices. 4. Discrimination at all spatial frequencies was mastered by all normal monkeys. Postoperatively, they could solve only problems with frequencies between 0.5 and 4.0 cycles/deg. 5. Contrast sensitivity (threshold-1) functions for normal and destriated monkeys have the characteristic inverted J shape. The high- and low-frequency limbs are related exponentially to spatial frequency, and the peak of the curve is about 2.0 cycles/deg. The dimensions of the functions, however, change significantly following the ablation. Sensitivity is depressed at all spatial frequencies. The mean “visuogram” indicates a 26-dB flat loss. 6. The mean high-frequency cutoff point is 43 cycle/deg preoperatively and 12 cycles/deg postoperatively, equivalent to 0.7' and 2.5' of arc, respectively. The latter value is not worse than 20/80 on the Snellen chart. 7. The variability of the response at each spatial frequency in the staircase method and the slope of the psychometric function derived from the method of constant stimuli provide a measure of “instability” and “precision,” respectively, which are inversely related. Preoperatively, precision is significantly greater at high than at low spatial frequencies. Postoperatively, it is similar at all frequencies, and the values are lower than those determined preoperatively. 8. The results demonstrate that destriated monkeys can detect gratings, although to a lesser degree than normal animals…

Organisation and Interrelationships of Functional Maps in Cat and Monkey Striate Cortex

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 356-356
Author(s):  
D Shoham ◽  
M Hübener ◽  
T Bonhoeffer ◽  
A Grinvald
Keyword(s):  
Spatial Frequency ◽  
Cytochrome Oxidase ◽  
Striate Cortex ◽  
Temporal Frequency ◽  
Activity Patterns ◽  
Ocular Dominance ◽  
High Spatial Frequency ◽  
Spatial Frequencies ◽  
Frequency Domains

Optical imaging of intrinsic signals allows mapping of the cortical functional architecture in vivo at high spatial resolution. The ability to image activity patterns evoked by many different stimuli in the same piece of cortex can provide information on the spatial relationships between different functional maps. Our findings on the organisation of multiple functional maps in cat and monkey striate cortex are reviewed. The main focus is on the recent finding in cat of two subsystems differing in their response to spatiotemporal aspects of the stimulus. We used grating stimuli of different spatial frequencies in an attempt to verify the existence of spatial frequency columns in cat area 17. Rather than observing a map of continuously changing spatial frequency across the cortical surface we found two distinct sets of domains, one preferring low and one preferring high spatial frequencies. By using different drift velocities we also found that the low-spatial-frequency domains preferred higher speeds than the high-spatial-frequency domains. Comparison of these spatiotemporal frequency domains with the cytochrome oxidase staining pattern revealed that the cytochrome oxidase blobs in cat striate cortex coincide with domains devoted to the processing of the low-spatial-frequency and high-temporal-frequency contents of the visual scene. Together with recent anatomical results these data suggest that spatiotemporal frequency domains are the manifestation of parallel streams in cat visual cortex with distinct patterns of thalamic inputs and extrastriate projections. In the same experiments we also imaged the orientation preference and ocular dominance maps. We investigated the relationships between these three columnar systems, and compared them to an earlier study of orientation, ocular dominance, and blobs in macaque striate cortex. We found systematic relationships between the three systems. While some of these relationships were much weaker than those found in monkey, the organisational principles are similar.

Behavioral determination of the spatial selectivity of contrast adaptation in cats: Some evidence for a common plan in the mammmlian visual system

1990 ◽  
Vol 4 (05) ◽  
pp. 413-426 ◽  
Author(s):  
M.A. Berkley
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Striate Cortex ◽  
Frequency Tuning ◽  
Spatial Vision ◽  
Adaptation Effect ◽  
Test Grating ◽  
Contrast Adaptation ◽  
Visual Systems ◽  
Spatial Frequencies

AbstractAn aftereffects paradigm was used to behaviorally measure contrast sensitivity of cats to gratings of three different test spatial frequencies after adaptation to gratings of various spatial frequencies, contrasts, and durations. Post-adaptation reductions in sensitivity occurred even after short periods of adaptation (&lt;7 s) and could be as large as 1.0 log unit under some conditions. The magnitude of the adaptation effect varied monotonically with (1) adaptation grating contrast, (2) duration, and (3) the contrast sensitivity for the test grating. Average half-width (at half-height) of the spatial-frequency tuning curves constructed from the data was 1.4 octaves, and was not dependent upon the level of adaptation or the spatial frequency of the test grating. Post-adaptation psychometric functions of the cats showed reduced slopes and maxima suggesting that, unlike humans, in cats apparent contrast grows more slowly with increases in physical contrast after contrast adaptation. All of the characteristics observed are in excellent agreement with electrophysiologically measured properties of neurons in striate cortex of cats. In addition, there was a remarkable similarity of the cat tuning functions, both in shape and bandpass, to those measured in man with a similar paradigm suggesting that (1) the two visual systems are sufficiently similar to make the cat a useful spatial vision model and (2) there is a common functional plan to all mammalian visual systems despite significant anatomical differences between species.

Afferent bases of spatial- and temporal-frequency processing by neurons in the cat's posteromedial lateral suprasylvian cortex: effects of removing areas 17, 18, and 19

1990 ◽  
Vol 64 (5) ◽  
pp. 1636-1651 ◽  
Author(s):  
W. Guido ◽  
L. Tong ◽  
P. D. Spear
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Temporal Frequency ◽  
Direction Selectivity ◽  
Response Amplitude ◽  
Response Threshold ◽  
Cortical Areas ◽  
Spatial Frequencies ◽  
Adult Cats ◽  
Frequency Processing

1. We investigated whether spatial- and temporal-frequency processing by neurons in the cat's posteromedial lateral suprasylvian (PMLS) extrastriate cortex depends on inputs from ipsilateral areas 17, 18, and 19 (visual cortex; VC) or occurs in parallel with those cortical areas. 2. Single neurons were recorded in PMLS cortex of normal adult cats and adult cats that had ipsilateral VC removed within 24 h before recording. Receptive-field properties were characterized, and responses to sine-wave gratings of different spatial frequencies, contrasts, and temporal frequencies were measured and Fourier analyzed. 3. As in previous studies, removing inputs from VC led to a reduction in the proportion of direction-selective PMLS cells. In addition there were statistically significant reductions in response amplitude and variability, although signal-to-noise ratios were unchanged. Contrast sensitivity also was reduced at all spatial frequencies. Spatial resolution was reduced slightly; however, this reduction appears to be secondary to the overall reduction in response amplitude and sensitivity. 4. The shape of the spatial-frequency contrast-sensitivity functions and the distribution of optimal spatial frequencies were unaffected by removing inputs from VC. In addition, once response threshold was reached, the slope of the contrast-response function (contrast gain) at the optimal spatial frequency was similar for PMLS cells in normal cats and cats with a VC lesion. 5. When tested at the optimal spatial frequency, temporal-frequency bandwidths, high and low temporal-frequency cutoffs, and optimal temporal frequencies were similar for PMLS cells in normal cats and cats with VC removed. 6. The results thus indicate that inputs from VC are important for the elaboration of direction selectivity and affect response amplitude and contrast sensitivity among PMLS neurons. However, visual-cortical inputs have little or no influence on spatial- and temporal-frequency processing by PMLS neurons. These properties depend on inputs from other cortical areas or the thalamus and are processed in parallel with areas 17, 18, and 19.

Harmonic basis functions for spatial coding in the cat striate cortex

1989 ◽  
Vol 3 (4) ◽  
pp. 351-363 ◽  
Author(s):  
V. D. Glezer ◽  
V. V. Yakovlev ◽  
V. E. Gauzelman
Keyword(s):  
Spatial Frequency ◽  
Striate Cortex ◽  
Weighting Function ◽  
Discrete Distribution ◽  
Basis Functions ◽  
Spatial Coding ◽  
Central Visual Field ◽  
Spatial Frequencies ◽  
The Absolute ◽  
Number Of Cycles

AbstractThe number of subregions in the activity profiles of simple cells varies in different cells from 2–8; that is, the number of cycles in the weighting function varies from 1–4. The distribution of receptive-field (RF) sizes at eccentricities of 0-6 deg are clustered at half-octave intervals and form a discrete distribution with maxima at 0.62, 0.9, 1.24, 1.8, 2.48, and 3.4 deg. The spatial frequencies to which the cells are tuned are also clustered at half-octave intervals, forming a discrete distribution peaking at 0.45, 0.69, 0.9, 1.35, 1.88, 2.7, 3.8, and 5.6 cycles/deg. If we divide the RF sizes by the size of the period of the subregions, then the average indices of complexity (really existing) or the number of cycles in the weighting function form (after normalization) the sequences: 1, 1.41, 2.0, 2.9, 4.15.The relation between the bandwidth of the spatial-frequency characteristic and the optimal spatial frequency is in accordance with predictions of the Fourier hypothesis. The absolute bandwidth does not change with the number of cycles/module. This means that inside the module the absolute bandwidth does not change with the number of the harmonic. The results allow us to suggest the following. A module of the striate cortex, which is a group of cells with RFs of equal size projected onto the same area of central visual field, accounts for the Fourier description of the image. The basis functions of the module are composed of four harmonics only, irrespective of size and position of the module.Besides linear cells (sinusoidal and cosinusoidal elements), the module contains nonlinear cells, performing a nonlinear summation of the responses of sinusoidal and cosinusoidal elements. Such cells are characterized by an index of complexity which is more than the number of cycles in the weighting function and by marked overlap of ON and OFF zones. The analysis of organization suggests that the cells can measure the amplitude and phase of the stimulus.

Effects of strabismus on responsivity, spatial resolution, and contrast sensitivity of cat lateral geniculate neurons

1984 ◽  
Vol 52 (3) ◽  
pp. 538-552 ◽  
Author(s):  
K. R. Jones ◽  
R. E. Kalil ◽  
P. D. Spear
Keyword(s):  
Contrast Sensitivity ◽  
Spatial Resolution ◽  
Striate Cortex ◽  
Receptive Fields ◽  
Orienting Response ◽  
Lateral Geniculate ◽  
Spatial Frequencies ◽  
Area Centralis ◽  
X Cells ◽  
Y Cells

Rearing cats with esotropia is known to cause a number of deficits in visual behavior tested through the deviated eye. These include a loss of orienting response to stimuli presented in the nasal visual field of the deviated eye, a reduction in visual acuity, and a general reduction in contrast sensitivity at all spatial frequencies. To assess the involvement of the lateral geniculate nucleus (LGN) in these deficits, we measured the following: 1) the visual responsiveness of lamina A1 cells with peripheral (more than 10 degrees from area centralis) receptive fields in three esotropic and three normal cats and 2) the spatial resolution and contrast sensitivity of lamina A X-cells with central (within 5 degrees of the area centralis) receptive fields in six esotropic and six normal cats. For comparison, we also measured LGN X-cell spatial resolutions in four exotropic cats and in two cats raised with an esotropia in one eye and the lids of the other eye sutured shut (MD-estropes). Recordings from the lateral portion of lamina A1 in esotropic cats yielded similar numbers of visually responsive cells with far nasal receptive fields as were seen in normal animals. Peak and mean response rates to a flashing spot also were normal. In addition, no differences were found between esotropes and normals in the percentages of X- and Y-cells encountered. These results suggest that the loss of orienting response to stimuli presented in the nasal field (12, 20) is not due to a loss of neural responses in the LGN of esotropic cats. In addition, they suggest that decreases in cell size in lamina A1 of esotropic cats (13, 36; R. E. Kalil, unpublished observations) are not accompanied by marked functional abnormalities of the cells and that cortical abnormalities ipsilateral to the deviated eye (22) are likely to have their origin within striate cortex itself. Recordings from lamina A cells with receptive fields near area centralis revealed that the average X-cell spatial resolution in esotropes (2.1 cycles/deg) was significantly lower than that in normal cats (3.1 cycles/deg). This reduction was seen in all esotropic cats tested and was due both to an increase in the proportion of X-cells with very low spatial resolution and to a loss of X-cells responding to high spatial frequencies (greater than 3.25 cycles/deg). The average spatial resolution of X-cells driven by the deviated eye in MD-esotropes fell midway between those of esotropes and normals. In exotropes, mean X-cell spatial resolution was normal.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Contrast thresholds reveal different visual masking functions in humans and praying mantises

2017 ◽  
Author(s):  
Ghaith Tarawneh ◽  
Vivek Nityananda ◽  
Ronny Rosner ◽  
Steven Errington ◽  
William Herbert ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Motion Detection ◽  
Visual Masking ◽  
High Spatial Frequency ◽  
Visual Noise ◽  
Frequency Noise ◽  
Detection Systems ◽  
Spatial Frequencies ◽  
Summary Statement ◽  
Contrast Thresholds

AbstractRecently, we showed a novel property of the Hassenstein-Reichardt detector: namely, that insect motion detection can be masked by “invisible” noise, i.e. visual noise presented at spatial frequencies to which the animals do not respond when presented as a signal. While this study compared the effect of noise on human and insect motion perception, it used different ways of quantifying masking in two species. This was because the human studies measured contrast thresholds, which were too time-consuming to acquire in the insect given the large number of stimulus parameters examined. Here, we run longer experiments in which we obtained contrast thresholds at just two signal and two noise frequencies. We examine the increase in threshold produced by noise at either the same frequency as the signal, or a different frequency. We do this in both humans and praying mantises (Sphodromantis lineola), enabling us to compare these species directly in the same paradigm. Our results confirm our earlier finding: whereas in humans, visual noise masks much more effectively when presented at the signal spatial frequency, in insects, noise is roughly equivalently effective whether presented at the same frequency or a lower frequency. In both species, visual noise presented at a higher spatial frequency is a less effective mask.Summary StatementWe here show that despite having similar motion detection systems, insects and humans differ in the effect of low and high spatial frequency noise on their contrast thresholds.

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