A novel mechanism of cone photoreceptor adaptation

• DOI: 10.1371/journal.pbio.2001210
• Publication Date: 2017-04-12T13:25:13Z
• Authors: Marcus H. C. Howlett; Robert G. Smith; Maarten Kamermans
• Keywords: Visual phototransduction; Hyperpolarization; Receptor potential

An animal's ability to survive depends on its sensory systems being able adapt a wide range of environmental conditions, by maximizing the information extracted and reducing noise transmitted. The visual system does this adapting luminance contrast. While adaptation can begin at retinal photoreceptors, contrast has been shown start later stages in retina. Photoreceptors changes over multiple time scales ranging from tens milliseconds minutes, with adaptive arising processes within phototransduction cascade. Here we show new form cones that is independent process. Rather, it mediated voltage-gated ion channels cone membrane acts changing frequency response such their responses speed up as potential modulation depth increases slow down decreases. This mechanism effectively activated high-contrast stimuli dominated low frequencies natural stimuli. However, more generally used Gaussian white were not effective since they did modulate same extent. process had constant less than second. A critical component underlying hyperpolarization-activated current, Ih, pharmacologically blocking prevented long- mid- wavelength sensitive photoreceptors (L- M-cones) adapting. Consistent this, short- (S-cones) response, found also lacked prominent Ih. filtering identified here improves flow removing higher-frequency during lower signal-to-noise ratio occurs when levels are low. Although be driven contrast, strictest sense, will argued Discussion.