A possible mechanism of zero-crossing detection using the concept of the extended classical receptive field of retinal ganglion cells

Abstract

The extended classical receptive field (ECRF) of retinal ganglion cells has been modelled as a combination of three zero-mean Gaussians at three different scales that has been shown to be equivalent to a Biharmonic or Bi-Laplacian of Gaussian filter. It has also been shown that the ECRF can be approximated by a combination of Laplacian of Gaussian (LoG) and the Dirac-delta function. Zero-crossings detected with this operator are more informative than those detected by the traditional filters like LoG or Difference of Gaussians (DoG) that had been devised using the classical receptive field of the ganglion cells. We have also explained that such an additional information processing is not in contradiction with the recent experimental findings on the physiology of retinal ganglion cells.

A possible explanation of the low-level brightness–contrast illusions in the light of an extended classical receptive field model of retinal ganglion cells

“…Mammalian ECRF also shows the disinhibitory properties of the retinal cells from the extended field (Ikeda and Wright 1972). Thus to probe whether the explanation of the White effect could have a basis in the retinal physiology, it would be tempting to use the model of ECRF (Ghosh et al 2005) in the simulation of the White effect.…”

“…However, a simplified linear model [vide Eq. 2], approximating some of the properties of ECRF, had been shown (Ghosh et al 2005) to be advantageous in forming a "raw primal sketch" (Marr and Hildreth 1980). We shall now show that this model, which is an alternative and simpler approach to the models known to our knowledge (Blakeslee and McCourt 1999;Ross and Pessoa 2000;Yu et al 2004), is not only able to effectively simulate the perception of various low-level brightness-contrast illusions but is also able to provide explanation to some other illusions, which were generally thought to be the resultants of higher-level perceptual groupings.…”

“…Yu et al (2004) first pointed out that a peripheral effect in this illusion might be due to the disinhibition in the early visual pathway. This tempts us to find out the effects of introducing a disinhibition (Ghosh et al 2005), and see whether it is able to neutralize the effect of inhibition to the extent that the lightness of the peripheral region appears intermediate between the streets and the crossings in Hermann grid.…”

“…Since it is conjectured that some of the brightness contrast illusions are processed at the retinal level and, in all probability, the contribution from ECRF plays a significant role in that processing, we are motivated to incorporate the effect of ECRF in our model. Ghosh et al (2005) have shown that some of the effects of the ECRF may be emulated by modeling a filter as a combination of three zero-mean Gaussians at three different scales. It has been shown that the Gaussians at three different scales may represent the classical center, the classical antagonistic surround and the nonclassical extended disinhibitory surround (mostly contributed by the amacrine cells), respectively, in ascending order of their widths.…”

Early Vision and Image Processing: Evidences Favouring a Dynamic Receptive Field Model

“…Most of the explanations of White effect provided so far are not computational models, except that of Ross and Pessoa [11]. But the White effect can also be explained in the light of a simple modification of the classical DoG model, that takes into consideration a disinhibitory contribution from the amacrine cells [12]. This model is based on the existence of an extended surround beyond the classical receptive field.…”