Functions of the ON and OFF channels of the visual system.

摘要: In the mammalian eye, ON-centre and OFF-centre retinal ganglion cells form two major pathways projecting to central visual structures from retina. These originate at bipolar cell level: one class of becomes hyperpolarized in response light, as do all photoreceptor cells, other depolarized on exposure thereby inverting receptor signal. It has recently become possible examine functional role ON-pathway vision by selectively blocking it level using glutamate neuro-transmitter analogue 2-amino-4-phosphonobutyrate (APB)1. APB application monkey, cat rabbit retinas abolishes ON responses lateral geniculate nucleus cortex but no effect centre-surround antagonism OFF or orientation direction selec-tivities cortex2–5. related findings6–11 suggest that remain largely separate through cortex, contrary some hypotheses, they are not directly involved mechanisms giving rise selectivities. We have examined roles channels rhesus monkeys trained detection discrimination tasks. report here channel is reversibly blocked injection into vitreous. Detection light increment decrement severely impaired, there a pronounced loss contrast sensitivity. The perception shape, colour, flicker, movement stereo images only mildly longer times required for their discrimination. Our results reasons system both yield equal sensitivity rapid information transfer incremental decremental stimuli facilitate high