The visual brain Flashcards
Refractive structures of the eye
Cornea and lens
Problems with focusing the light through the cornea and lens
Cataract, myopia, presbyopia
Myopia
Near-sightedness
Presbyopia
Age-related far-sightedness
Anatomy of an eye
Pupil, Macula lutea, Fovea centralis, Optic disc, Optic nerve
Macula lutea
Yellow spot, central area of the retina where the light rays are focused
Fovea centralis
The center of the macula, responsible for the highest visual acuity and colour
Optic disc
Axons of retinal ganglion cells leave the eye at the optic disc and form the optic nerve
Retinal organization - neurons
Retinal ganglion cells, interneurons, photoreceptors
Retinal ganglion cells
Receive information from the photoreceptors via the interneurons, the only retinal neurons whose axons leave the brain
Photoreceptors
Rods and cones, respond to reflected light and convert it into a neural signal
Rods
Ca. 120 million, very sensitive to light (night vision), multiple rods converge on the same interneuron
Cones
Ca. 6 million, less sensitive to light (day vision), 3 types of cones (red, green, blue), one-to-one convergence with an interneuron
Saccades
Rapid eye movement to shift visual fixation from one point to another
Microsaccades
A type of fixational eye movement produced during visual fixation
Left visual hemifield
Seen by the nasal left retina and temporal right retina
Right visual hemifield
Seen by the nasal right retina and temporal left retina
Visual pathways
Optic nerve, optic chiasm, optic tract, thalamus (LGN) and optic radiaton (Geniculocortical pathway)
Optic nerve
Splits into temporal and nasal branch
Optic chiasm
Crossover of optic nerve branches