PSB-2000 Lecture Notes - Lecture 8: Amacrine Cell, Edge Detection, Trichromacy
Document Summary
Light: most light you see is reflected light, wavelength perceived as color, number of photons perceived as brightness. Light enters through cornea pupil lens gets to retina. Cornea- protective outer covering: refracts lights. Pupil- hole in center of iris: controls light entry. Lens- refracts light dynamically: changes to adjust focal distance. Retina- light-sensitive neural tissue: transduces light to electrical signal, sends info to brain via optic. Cells of retina: retinal ganglion cells, amacrine cells, bipolar cells, horizontal cells, cone receptors, rod receptors. Light passes these cells & affects photoreceptors in back of retina. Neural signal travels from back to front of retina. Optic nerve turns back and goes into brain. Lateral connections in the retina modulate visual info. Lateral neural network: when light excites a photoreceptor, the photoreceptor inhibits its neighbors on either side. Photoreceptors are not evenly distributed across retina. Fovea: high acuity, color vision, only cones; no rods.
