Vision Flashcards
Cones
Cones are responsive to bright light. They are responsible for color vision and our ability to see fine detail. There are 3 kinds (blue, green, and red)
Rods
Rods are more numerous than cones and are more sensitive to dim light. They are mainly used for night vision. There is only one kind of rod
Horizontal cells
Between photo receptors and bipolar cells
Amacrine cell
Between bipolar cells and ganglion cells
Geniculostriate system
Optic nerve —-> Lateral geniculate nucleus (found inside the thalamus) —-> Striate cortex (primary visual cortex) —-> Other visual cortical areas
Tectopulvinar system
Optic nerve —-> Superior colliculus —-> Pulvinar —-> Other visual cortical areas
Primary “x” cortex
Gets its information directly from the switchboard (thalamus)
What is the boundary between the eyes and CNS?
The optic chiasm
Parvocellular layers
Top 4 layers (3-6) receive from cones
Magnocellular layers
Bottom 2 layers (1-2) receive from rods
Ventral stream
“what” Identifying objects (what am i seeing)
Dorsal stream
“how” Plan movement (How do i react to what im seeing)
sensation
registration of physical stimuli from the environment by the sensory organs.
perception
subjective interpretation of sensations by the brain.
blindsight
subject can not identify objects in his blind area but could very accurately “guess” if a light had blinked on there and even where the light was located.
How is receptor density related to sensitivity?
Sensitivity is directly proportional to receptor density. “Denser receptors enable smaller receptive fields – so sensory neurons can be more specific.”
neural relay
Our sensory neurons connect to the cortex through a sequence of 3 or 4 intervening neurons. These stages comprise a neural relay, which can be modified at any level
Generally, how do sensory neurons encode information?
Increasing or decreasing the frequency of action potentials
lens & cornea
The cornea and lens of the eye, like the lens of a camera, focus light rays to project a backward, inverted image on a light-receptive surface.
pupil
As light enters the eye, it is bent first by the cornea, travels through the pupil, and is then bent again by the lens. The curvature of the cornea is fixed, whereas small muscles adjust the curvature of the lens to focus nearby or far away.
retina
Light-sensitive surface at the back of the eye consisting of neurons and photoreceptor cells.
fovea
Region at the center of the retina that is specialized for high acuity; its receptive fields are at the center of the eye’s visual field.
optic disk
“blind spot” Region of the retina where axons forming the optic nerve leave the eye and where blood vessels enter and leave; has no photoreceptors and is thus “blind”
- Located laterally from the fovea in each eye
