Vision Flashcards
Where in the retina is the upper visual field projected?
The lower (inferior) retina
Where in the retina is the temporal or lateral visual field projected?
The nasal (inner) retina
What is the fovea?
It is where light from the center of gaze falls on, it is specialized for high-acuity daylight vision.
What is the macula?
it is a ircular irregularly-pigmented area, yellowish in the center and lightly pigmented on the edges
What is the organization of retinal–>visual cortex?
Photoreceptors sense incoming photons of light and transduce this light signal via a biochemical cascade into a change in nt release at synapses they make with bipolar cells.
Bipolar cells integrate info from multiple photoreceptors in a passive way and make synapses on ganglion cells.
Ganglion cells are influenced by bipolar cell synapses to either increase or decrease their firing rates in response to a given light signal.
The ganglion cells send axons (optic nerve) out of the eye to synapse in the LGN of the thalamus.
Secondary neurons in the LGN project to the primary visual cortex.
What are horizontal cells?
They connect photoreceptor cell nerve terminals together laterally
What are amacrine cells?
They connect some bipolar cell nerve terminals together
Why might the organization of the retinal layers be the way it is?
The photoreceptor outer segments are imbedded in the pigmented epithelium that lines the back of he eye and provides fresh photopigment (retinal) and nutrients to the photoreceptor cells as they continually sense light.
What is the blind spot?
a place without rods or cones, it is in the are of the optic nerve head
What is phototopic?
what vision in moderate to high light levels is called
What is scotopic?
night vision
What are the optic radiations?
Nerve fibers spread out almost immediately after they leave the lateral geniculate body and pass near the cerebral peduncles. Fibers carrying information from inferior retina (superior visual field) loop down into temporal lobe (meyer’s loop). Superior fibers (inferior visual field) pass up into the parietal lobe.
Fibers carying corresponding info from the points of the visual field of each eye are not yet adjacent. Partial lesions of the temporal or parietal lobes cause different visual field defects in each eye.
