SENSORY CODING IN THE VERTEBRATE RETINA - TOWARDS AN ADAPTIVE-CONTROLOF VISUAL SENSITIVITY

We propose a theoretical framework for the adaptive control of visual sensitivity in the vertebrate retina. The photoreceptor transfer funct ion is modelled with a Michaelis-Menten law instead of a logarithmic f unction. This more plausible function has a biophysical correlate, and it allows consideration of the photoreceptor as the main locus of ret inal adaptation. The retinal model suggests that the function of photo receptors might be to control visual sensitivity, defined as the optim al transcoding of non-stationary visual information. This is done by u sing an adaptive transfer function whose parameters are spatiotemporal ly and locally estimated by the subsequent retinal circuit and fed bac k to the photoreceptors. The proposed model also supports the function al architecture of the vertebrate retina.