ILAV   21219
INSTITUTO DE INVESTIGACION EN LUZ, AMBIENTE Y VISION
Unidad Ejecutora - UE
artículos
Título:
Luminance and chromatic signals interact differently with melanopsin activation to control the pupil light response
Autor/es:
CAO, DINGCAI; BARRIONUEVO, PABLO A.
Revista:
JOURNAL OF VISION
Editorial:
ASSOC RESEARCH VISION OPHTHALMOLOGY INC
Referencias:
Lugar: Rockville, MD 20852; Año: 2016
ISSN:
1534-7362
Resumen:
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin. These cells receive afferent inputs from rods and cones, which provide inputs to the post-receptoral visual pathways. It is unknown, however, how melanopsin activation is integrated with post-receptoral signals to control the pupillary light reflex. This study reports human flicker pupillary responses measured using stimuli generated with a five-primary photostimulator that selectively modulated melanopsin, rod, S-, M- and L-cone excitations in isolation, or in combination to produce post-receptoral signals. We first analyzed the light adaptation behavior of melanopsin activation and rod and cones signals. Second, we determined how melanopsin is integrated with post-receptoral signals by testing with cone luminance, chromatic blue-yellow, and chromatic red-green stimuli that were processed by magnocellular (MC), koniocellular (KC) and parvocellular (PC) pathways, respectively. A combined rod and melanopsin response was also measured. The relative phase of the post-receptoral signals was varied with respect to the melanopsin phase. The results showed that light adaptation behavior for all conditions were weaker than typical Weber adaptation. Melanopsin activation combined linearly with luminance, S-cone and rod inputs, suggesting the locus of integration with MC and KC signals was retinal. The melanopsin contribution to phasic pupil responses was lower than luminance contributions, but much higher than S-cone contributions. Chromatic red-green modulation interacted with melanopsin activation non-linearly as described by a ?winner-takes-all? process, suggesting the integration with PC signals might be mediated by a post-retinal site.