Chapter 6: Vision Flashcards
Receptors for vision are sensitive to . . .
Light
believed that the brain’s representation of a stimulus resembled the stimulus.
Which is WRONG your brain encodes information in a way that doesn’t resemble what you see
Rene Descartes
held that whatever excites a particular nerve establishes a special kind of energy unique to the nerve.
Johannes Muller
Light enters the eye through an opening in the center of the iris called the
Pupil
Light is focused by the _____ (adjustable)
Lens
Light is focused by the Lens (adjustable) and _____ (not adjustable)
Cornea
_______send messages to the neurons called Bipolar Cells, located closer to the center of the eye.
Visual Reseptors
located closer to the center of the eye, ______send messages to Ganglion Cells,
Bipolar Cells
located still closer to the center of the eye.
The axons _______ join together and travel back to the brain.
Ganglia cells
are additional cells that receive information from Bipolar Cells and send it to other Bipolar, Amacrine, and Ganglion Cells.
cells control the ability of ganglion cells to respond to shapes, movements, or other specific aspects of visual stimuli.
Amacrine Cells
_______are inhibitors, when there is light it stops the inhibiting which causes an action potential to the brain.
Rods and Cones
Formed by ganglion cell axons, the_____ exits through the back of the eye.
Optic Nerve
The point at which the optic nerve leaves (which is also where the blood vessels enter and leaver) is the _______ because it has no receptors.
Blind Spot
Tiny area specialized for acute, detailed vision.
Fovea
The ganglion cells in the fovea of humans and other primates. Each is small and responds to just a single cone.
Midget Ganglion Cells
The vertebrate retina contains two types of receptors
rods and cones
Which are abundant in the periphery of human retina, respond to faint light but are not useful in daylight because bright light bleaches them.
Rods
Which are abundant in and near the fovea, are LESS active in dim light, more useful in bright light, and essential for color vision.
Cones
Chemicals that release energy when struck by light .
Photopigments
Photopigments consist of _____ (a derivative of vitamin A bound to proteins called Opsins
11-cis-retinal
modify the photopigments sensitivity to different wavelengths of light.
Opsins
Light converts 11-cis-retinal to _______l, thus releasing energy that activates second messangers within the cell.
all-trans-retina
The perception of _____ is dependent upon Wavelength of the light.
Color Vision
According to this theory, we perceive color through relative rates of response by three kind of cones, each one maximally sensitive to a different set of wavelengths.
The Trichromatic (Young-Helmholtz) Theory
Why 3?
Helmholtz found that people could match any color by mixing appropriate amounts of just three wavelengths; he concluded that three kinds of receptors (cones) are sufficient to account for human color vision.