The contribution of noise to contrast invariance of orientation tuning in cat visual cortex.

@article{Anderson2000TheCO,
  title={The contribution of noise to contrast invariance of orientation tuning in cat visual cortex.},
  author={J. Anderson and I. Lampl and D. C. Gillespie and D. Ferster},
  journal={Science},
  year={2000},
  volume={290 5498},
  pages={
          1968-72
        }
}
Feedforward models of visual cortex appear to be inconsistent with a well-known property of cortical cells: contrast invariance of orientation tuning. The models' fixed threshold broadens orientation tuning as contrast increases, whereas in real cells tuning width is invariant with contrast. We have compared the orientation tuning of spike and membrane potential responses in single cells. Both are contrast invariant, yet a threshold-linear relation applied to the membrane potential accurately… Expand
How Noise Contributes to Contrast Invariance of Orientation Tuning in Cat Visual Cortex
TLDR
It is shown that the noise transmutes the threshold nonlinearity of the input–output relationships into an approximate power law without a threshold within some firing rate range, which implies that, under certain conditions, the tuning of the neuron output is approximately contrast invariant. Expand
Contrast invariance of orientation tuning in cat primary visual cortex neurons depends on stimulus size
TLDR
It is shown here that contrast invariance actually depends on stimulus size such that large stimuli extending beyond the neuron's receptive field engage circuits that promote invariance, whereas optimally sized, smaller stimuli result in contrast variance that is more in line with the classical orientation tuning model. Expand
The Emergence of Contrast-Invariant Orientation Tuning in Simple Cells of Cat Visual Cortex
TLDR
High-contrast, orthogonally oriented stimuli that evoke significant depolarizations evoke few spikes, and these mechanisms, without lateral inhibition, can account for contrast-invariant stimulus selectivity. Expand
Effects of inhibitory gain and conductance fluctuations in a simple model for contrast-invariant orientation tuning in cat V1.
TLDR
Inhibition comparable to or stronger than excitation appears necessary to suppress spiking responses to nonpreferred orientations to the extent seen in vivo and to allow the emergence of a tuned mean voltage response. Expand
Comparison of mechanisms for contrast-invariance of orientation selectivity in simple cells
TLDR
The results suggest unequal contributions of these feedforward mechanisms with thalamic synaptic noise widening tuning widths for low contrasts, synaptic depression counteracting a small component of the offset and synaptic inhibition completely removing the remaining offset to produce contrast-invariant orientation tuning. Expand
Broadening of Inhibitory Tuning Underlies Contrast-Dependent Sharpening of Orientation Selectivity in Mouse Visual Cortex
TLDR
Modulation of synaptic inhibition in the mouse V1 cortical circuit preserves the sharpness of response selectivity during changes of stimulus strength, as suggested by in vivo loose-patch recordings. Expand
Variable Discharge Pattern and Contrast Invariant Orientation Tuning of a Simple Cell: A Modeling Study
The orientation tuning width of the spike response of neuron in V1 does not change with the contrast of input signals. It is also known that cortical neurons exhibit tremendous irregularity in theirExpand
Contrast Adaptation Contributes to Contrast-Invariance of Orientation Tuning of Primate V1 Cells
TLDR
Orientation tuning does not appear to be contrast- Invariant when briefly flashed stimuli vary in both contrast and orientation, but contrast adaptation partially restores contrast-invariance of orientation tuning. Expand
Contrast invariance of functional maps in cat primary visual cortex.
TLDR
It is suggested that contrast is represented uniformly over the surface of cat V1, and changes in contrast do not affect maps of orientation preference. Expand
Origins of cross-orientation suppression in the visual cortex.
TLDR
The recovery time course of COS is found to be too rapid to be explained by synaptic depression, and contrast saturation is a consistent property of LGN neurons, which can account for most of the COS that is observed in the visual cortex. Expand
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