Quantitative Analysis of the Responses of V1 Neurons to Horizontal Disparity in Dynamic Random-Dot Stereograms

2002 ◽  
Vol 87 (1) ◽  
pp. 191-208 ◽  
Author(s):  
S.J.D. Prince ◽  
A. D. Pointon ◽  
B. G. Cumming ◽  
A. J. Parker
Keyword(s):  
Spatial Frequency ◽  
Tuning Curve ◽  
Ocular Dominance ◽  
Large Population ◽  
Gaussian Function ◽  
Energy Model ◽  
Horizontal Disparity ◽  
Orientation Preference ◽  
Tuning Curves ◽  
Random Dot Stereograms

Horizontal disparity tuning for dynamic random-dot stereograms was investigated for a large population of neurons ( n = 787) in V1 of the awake macaque. Disparity sensitivity was quantified using a measure of the discriminability of the maximum and minimum points on the disparity tuning curve. This measure and others revealed a continuum of selectivity rather than separate populations of disparity- and nondisparity-sensitive neurons. Although disparity sensitivity was correlated with the degree of direction tuning, it was not correlated with other significant neuronal properties, including preferred orientation and ocular dominance. In accordance with the Gabor energy model, tuning curves for horizontal disparity were adequately described by Gabor functions when the neuron's orientation preference was near vertical. For neurons with orientation preferences near to horizontal, a Gaussian function was more frequently sufficient. The spatial frequency of the Gabor function that described the disparity tuning was weakly correlated with measurements of the spatial frequency and orientation preference of the neuron for drifting sinusoidal gratings. Energy models make several predictions about the relationship between the response rates to monocular and binocular dot patterns. Few of the predictions were fulfilled exactly, although the observations can be reconciled with the energy model by simple modifications. These same modifications also provide an account of the observed continuum in strength of disparity selectivity. A weak correlation between the disparity sensitivity of simultaneously recorded single- and multiunit data were revealed as well as a weak tendency to show similar disparity preferences. This is compatible with a degree of local clustering for disparity sensitivity in V1, although this is much weaker than that reported in area MT.

Encoding of both vertical and horizontal disparity in random-dot stereograms by Wulst neurons of awake barn owls

2001 ◽  
Vol 18 (4) ◽  
pp. 541-547 ◽  
Author(s):  
ANDREAS NIEDER ◽  
HERMANN WAGNER
Keyword(s):  
Lateral Displacement ◽  
Two Dimensions ◽  
Orientation Tuning ◽  
Main Peak ◽  
Horizontal Disparity ◽  
Vertical Disparity ◽  
Tuning Curves ◽  
Random Dot Stereograms ◽  
Barn Owls ◽  
Stimulus Offset

In binocular vision, the lateral displacement of the eyes gives rise to both horizontal and vertical disparities between the images projected onto the left and right retinae. While it is well known that horizontal disparity is exploited by the binocular visual system of birds and mammals to enable depth perception, the role of vertical disparity is still largely unclear. In this study, neuronal activity in the visual forebrain (visual Wulst) of behaving barn owls to vertical disparity was investigated. Single-unit responses to global random-dot stereograms (RDS) were recorded with chronically implanted electrodes and transmitted via radiotelemetry. Nearly half of the cells investigated (44%, 16/36) varied the discharge as a function of vertical disparity. Like horizontal-disparity tuning profiles, vertical-disparity tuning curves typically exhibited periodic modulation with side peaks flanking a prominent main peak, and thus, could be fitted well with a Gabor function. This indicates that tuning to vertical disparity was not caused by disrupting horizontal-disparity tuning via vertical stimulus offset, but by classical disparity detectors whose orientation tuning was tilted. When tested with horizontal in addition to vertical disparity, almost all cells investigated (92%, 12/13) were tuned to both kinds of disparity. The emergence of disparity detectors sensitive in two dimensions (horizontal and vertical) is discussed within the framework of the disparity energy model.

scholarly journals Ocular Dominance Predicts Neither Strength Nor Class of Disparity Selectivity With Random-Dot Stimuli in Primate V1

2004 ◽  
Vol 91 (3) ◽  
pp. 1271-1281 ◽  
Author(s):  
Jenny C. A. Read ◽  
Bruce G. Cumming
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Binocular Disparity ◽  
Tuning Curve ◽  
Ocular Dominance ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Tuning Curves ◽  
Inhibitory Type ◽  
Random Dot Patterns

We address two unresolved issues concerning the coding of binocular disparity in primary visual cortex. Experimental studies and theoretical models have suggested a relationship between a cell's ocular dominance, assessed with monocular stimuli, and its tuning to binocular disparity. First, the disparity energy model of disparity selectivity suggests that there should be a correlation between ocular dominance and the strength of disparity tuning. Second, several studies have reported a relationship between ocular dominance and the shape of the disparity tuning curve, with cells dominated by one eye more likely to have disparity tuning of the tuned-inhibitory type. We investigated both of these relationships in single neurons recorded from the primary visual cortex of awake fixating macaques, using dynamic random-dot patterns as a stimulus. To classify disparity tuning curves quantitatively, we develop a new measure of symmetry, which can be applied to any function. We find no evidence for any correlation between ocular dominance and the nature of disparity tuning. This places constraints on the circuitry underlying disparity tuning.

Coding of Horizontal Disparity and Velocity by MT Neurons in the Alert Macaque

2003 ◽  
Vol 89 (2) ◽  
pp. 1094-1111 ◽  
Author(s):  
Gregory C. DeAngelis ◽  
Takanori Uka
Keyword(s):  
Large Scale ◽  
Signal To Noise Ratio ◽  
Response Modulation ◽  
Horizontal Disparity ◽  
Tuning Curves ◽  
Mt Neurons ◽  
V1 Neurons ◽  
Area V4 ◽  
Random Dot Stereograms ◽  
Direction Tuning

We performed the first large-scale ( n = 501), quantitative study of horizontal disparity tuning in the middle temporal (MT) visual area of alert, fixating macaque monkeys. Using random-dot stereograms, we quantified the direction tuning, speed tuning, horizontal disparity tuning, and size tuning of each neuron. The vast majority (93%) of MT neurons were significantly tuned for horizontal disparity. Although disparity tuning was generally quite robust, the average disparity sensitivity of MT neurons was significantly weaker than their direction or speed sensitivity as quantified using both an index of response modulation and an index of signal-to-noise ratio. Disparity tuning was not correlated with direction or size tuning but tended to be broader and weaker for neurons that preferred faster speeds of motion. By comparison with recent studies, we find that disparity selectivity in MT is substantially stronger than that seen in either primary visual cortex (V1) or area V4. In addition, MT neurons are more broadly tuned for disparity than V1 neurons at comparable eccentricities. Disparity tuning curves are very well described by Gabor functions for >80% of MT neurons. The distribution of Gabor phases shows clear bimodality, indicating that MT neurons tend to have odd-symmetric disparity tuning (unlike neurons in V1). The preferred disparities were more strongly correlated with the phase parameter of the Gabor function than with the positional offset parameter. In fact, for neurons with preferred disparities close to zero, the positional offset tended to oppose the phase shift in specifying the disparity preference. We suggest that this result reflects a strategy used to finely distribute the disparity preferences of MT neurons, given the predominance of odd-symmetry and broad tuning.

scholarly journals Statistical assessment of the stability of neural movement representations

2011 ◽  
Vol 106 (2) ◽  
pp. 764-774 ◽  
Author(s):  
Ian H. Stevenson ◽  
Anil Cherian ◽  
Brian M. London ◽  
Nicholas A. Sachs ◽  
Eric Lindberg ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Tuning Curve ◽  
Modulation Depth ◽  
Measurement Noise ◽  
Neural Representation ◽  
Experimental Conditions ◽  
Sensory Stimuli ◽  
Tuning Curves ◽  
Dynamic Tuning ◽  
Preferred Direction

In systems neuroscience, neural activity that represents movements or sensory stimuli is often characterized by spatial tuning curves that may change in response to training, attention, altered mechanics, or the passage of time. A vital step in determining whether tuning curves change is accounting for estimation uncertainty due to measurement noise. In this study, we address the issue of tuning curve stability using methods that take uncertainty directly into account. We analyze data recorded from neurons in primary motor cortex using chronically implanted, multielectrode arrays in four monkeys performing center-out reaching. With the use of simulations, we demonstrate that under typical experimental conditions, the effect of neuronal noise on estimated preferred direction can be quite large and is affected by both the amount of data and the modulation depth of the neurons. In experimental data, we find that after taking uncertainty into account using bootstrapping techniques, the majority of neurons appears to be very stable on a timescale of minutes to hours. Lastly, we introduce adaptive filtering methods to explicitly model dynamic tuning curves. In contrast to several previous findings suggesting that tuning curves may be in constant flux, we conclude that the neural representation of limb movement is, on average, quite stable and that impressions to the contrary may be largely the result of measurement noise.

The Study of Spatial Frequency Channels for Human Visual System

2019 ◽  
Vol 33 (06) ◽  
pp. 1955007
Author(s):  
Xiangyang Xu ◽  
Qiao Chen ◽  
Ruixin Xu
Keyword(s):  
Receptive Field ◽  
Spatial Frequency ◽  
Visual System ◽  
Human Visual System ◽  
Frequency Tuning ◽  
Tuning Curve ◽  
Vision System ◽  
Human Vision ◽  
Psychophysical Experiment ◽  
Human Vision System

Similar to auditory perception of sound system, color perception of the human visual system also presents a multi-frequency channel property. In order to study the multi-frequency channel mechanism of how the human visual system processes color information, the paper proposed a psychophysical experiment to measure the contrast sensitivities based on 17 color samples of 16 spatial frequencies on CIELAB opponent color space. Correlation analysis was carried out on the psychophysical experiment data, and the results show obvious linear correlations of observations for different spatial frequencies of different observers, which indicates that a linear model can be used to model how human visual system processes spatial frequency information. The results of solving the model based on the experiment data of color samples show that 9 spatial frequency tuning curves can exist in human visual system with each lightness, R–G and Y–B color channel and each channel can be represented by 3 tuning curves, which reflect the “center-around” form of the human visual receptive field. It is concluded that there are 9 spatial frequency channels in human vision system. The low frequency tuning curve of a narrow-frequency bandwidth shows the characteristics of lower level receptive field for human vision system, the medium frequency tuning curve shows a low pass property of the change of medium frequent colors and the high frequency tuning curve of a width-frequency bandwidth, which has a feedback effect on the low and medium frequency channels and shows the characteristics of higher level receptive field for human vision system, which represents the discrimination of details.

Inferior colliculus. II. Development of tuning characteristics and tonotopic organization in central nucleus of the neonatal cat

1975 ◽  
Vol 38 (5) ◽  
pp. 1208-1216 ◽  
Author(s):  
L. M. Aitkin ◽  
D. R. Moore
Keyword(s):  
Inferior Colliculus ◽  
Tuning Curve ◽  
External Auditory Meatus ◽  
Auditory Pathway ◽  
Central Nucleus ◽  
Synaptic Density ◽  
Tonotopic Organization ◽  
Tuning Curves ◽  
Sharp Form ◽  
Cochlear Development

Tuning curves were measured for 65 units in the inferior colliculus of seven anesthetized kittens aged from 6 to 28 days. At 2 days of age the inferior colliculus was divisible into central, pericentral, and external nuclei. Evidence was found for broader tuning curves to occur in the pericentral nucleus compared with the central nucleus, as has been observed in the adult. The middle ear was filled with serous fluid to 6 days, while the external auditory meatus remained collapsed until 10 days. Central nucleus tuning curves in kittens were relatively flat with high thresholds. Best-frequency thresholds diminished from a mean of near 100 dB SPL at 6-11 days to near 50 dB in the adult. The marked drop in thresholds between days 22 and 21 led to the adoption of the sharp form of tuning curve common for adults. Tonotopic organization of the central nucleus was clear at day 11. Speculations were advanced about the dependence of central auditory maturations on cochlear development, axon myelination in the auditory pathway, and changes in synaptic density as a function of age.

Perceived Speed of Moving Cyclopean Corrugations Increases with Increasing Disparity Amplitude

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 195-195
Author(s):  
A M Johns ◽  
B J Rogers ◽  
R A Eagle
Keyword(s):  
Spatial Frequency ◽  
Feature Tracking ◽  
Temporal Frequency ◽  
Reference Stimulus ◽  
Experimental Control ◽  
The Poor ◽  
Random Dot Stereograms ◽  
Matching Performance ◽  
Perceived Speed ◽  
Central Fixation

In order to investigate how cyclopean motion is coded by the visual system, the points of subjective equality (PSEs) were measured for (i) speed, (ii) spatial frequency (SF), and (iii) temporal frequency (TF) as a function of peak-to-trough disparity amplitude for cyclopean corrugations. Two panels (3.0 deg × 7.0 deg) of dynamic random-dot stereograms were located 0.5 deg on either side of a central fixation spot. Each panel contained a horizontally oriented sinusoidal cyclopean corrugation whose SF, TF, and disparity amplitude were under experimental control. On each trial, the cyclopean corrugations were displaced vertically in opposite directions. Subjects judged which panel contained the higher SF, TF, or speed depending on condition. The reference stimulus was a sinusoidal corrugation with SF=0.4 cycles deg−1, TF=0.8 Hz, speed of 2.0 deg s−1, and peak-to-trough disparity amplitude of 8 min arc around fixation. We found that, as the peak-to-trough disparity amplitude of the test stimulus increased from 2 min arc to 32 min arc, the PSE for speed decreased from 2.21 deg s−1 to 1.67 deg s−1, compared to a reference speed of 2.00 deg s−1. However, across the same levels of disparity amplitude, the PSE for SF remained constant and the PSE for TF varied but with no consistent pattern. Thus, perceived speed increases with increased disparity amplitude. As all levels of disparity amplitude were above threshold, cyclopean speed cannot be detected by a purely ‘feature-tracking’ mechanism. These metamers and the poor TF matching performance suggest that cyclopean speed is coded by a sparse number of temporal mechanisms.

Disparity Modulation Sensitivity for Narrow-Band-Filtered Stereograms Viewed out of the Plane of Fixation

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 94-94
Author(s):  
B Lee ◽  
B J Rogers
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Significant Interaction ◽  
Narrow Band ◽  
Low Frequency ◽  
Frequency Pattern ◽  
Spatial Frequencies ◽  
Size Disparity ◽  
Random Dot Stereograms

Narrow-band-filtered random-dot stereograms were used to determine stereo thresholds for detecting sinusoidal disparity modulations. These stereograms were designed to stimulate selectively channels tuned to luminance and corrugation spatial frequencies (Schumer and Ganz, 1979 Vision Research19 1303 – 1314). Thresholds were determined for corrugation frequencies ranging from 0.125 to 1 cycle deg−1, luminance centre spatial frequencies ranging from 1 to 8 cycles deg−1 and disparity pedestal sizes ranging from −32 to +32 min arc. For small disparity pedestals, lowest modulation thresholds were found around 0.5 cycle deg−1 corrugation frequency and 4 cycles deg−1 luminance centre spatial frequency. For large disparity pedestals (±32 arc min), lowest thresholds were shifted towards the lower corrugation frequencies (0.125 cycle deg−1) and lower luminance frequencies (2 cycles deg−1). There was a significant interaction between luminance spatial frequency and disparity pedestal size. For small pedestals, lowest thresholds were found with the highest luminance frequency pattern (4 cycles deg−1). For large pedestals, best performance shifted towards the low-frequency patterns (1 cycle deg−1). This effect demonstrates a massive reduction in stereo-efficiency for high-frequency patterns in the luminance domain at large disparity pedestals which is consistent with the ‘size-disparity relation’ proposed by previous researchers.

Spontaneous activity and frequency selectivity of acoustically responsive vestibular afferents in the cat

1995 ◽  
Vol 74 (4) ◽  
pp. 1563-1572 ◽  
Author(s):  
M. P. McCue ◽  
J. J. Guinan
Keyword(s):  
Spontaneous Activity ◽  
Tuning Curve ◽  
Strong Relationship ◽  
Frequency Selectivity ◽  
Vestibulocochlear Nerve ◽  
Acoustic Frequency ◽  
Tuning Curves ◽  
Vestibular Afferents ◽  
Acoustic Reflexes ◽  
Inferior Vestibular Nerve

1. Recordings were made from single afferent fibers in the inferior vestibular nerve. Firing rates of a substantial portion of the afferents with irregular background activity increased in response to moderately intense tone bursts. 2. Spontaneous activity from acoustically responsive vestibular afferents was statistically analyzed and compared with data from a more widespread sampling of primary afferents in the cat's vestibulocochlear nerve. Acoustically responsive vestibular afferents had interspike interval histograms with modes > 10 ms, coefficients of variation > 0.15, and skews > 0.88. On the basis of spontaneous activity, these afferents were easily distinguishable from cochlear afferents and regular vestibular afferents, but no obvious features differentiated them from other irregular vestibular afferents. 3. The distributions of spike intervals in the spontaneous activity of acoustically responsive vestibular afferents were fitted by Erlang probability density functions describing the second-order interarrival times of a Poisson process initiated after a finite delay (refractory period). 4. Acoustically responsive vestibular afferents had broad, V-shaped tuning curves with best frequencies between 500 and 1,000 Hz, thresholds of > or = 90 dB SPL, and shapes comparable with the tuning-curve “tails” of cochlear afferents. In contrast to cochlear-nerve afferents, acoustically responsive vestibular afferents did not show a strong relationship between spontaneous rate and threshold. 5. We compare the acoustic frequency selectivity of vestibular and cochlear afferents in terms of their functional and evolutionary relationships. Our data and those of others indicate that acoustically responsive vestibular afferents are likely to provide an input to the acoustic activation of the sternocleidomastoid muscle in humans, and they may provide an input to other acoustic reflexes such as the middle-ear-muscle reflexes.

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