Unit 7 Vision Flashcards
What is The basic definition of visible light
Visible light is defined as the range of the electromagnetic (EM) spectrum that can be detected by the human eye.
What is The anatomy and function of the eye
The anatomy consists of the cornea, pupil, lens, ciliary muscles, retina, fovea, optic nerve, iris.
The eye controls the quantity and focus of light hitting the retina
The structure and organization of the retina
Primary cell types of the retina: photoreceptor cells (rods and cones), bipolar cells, retinal ganglion cells, amacrine cells, horizontal cells
Sensory transduction for light in the dark
Rhodopsin is inactive, Na+ channels are open, photoreceptors are depolarized, neurotransmitter release is high. Glutamate is highly released.
The differences between rods and cones
Rods Only one opsin, More sensitive than cones, Lower acuity than cones, Lots of convergence, Part of the scotopic system
Cones have 3 opsins therefore different response to different wavelengths of light, Low sensitivity, High acuity, Little/no convergence, Part of the photopic system
The relationship between retinal organization, structure and visual acuity
Section of the retina with the highest visual acuity = fovea:
1.Highest density of cone photoreceptors
2.Little convergence
3.Obstruction is reduced
The journey of visual information to and through the brain
Visual information flows along the optic nerve like a river of electricity. At the optic chiasm, the signals split such that images from the left visual field head to the right brain, and images from the right visual field head to the left brain
What is The receptive fields of bipolar and retinal ganglion cells
The bipolar field is the retinal area which when exposed to light produces a response in the bipolar cell
The ganglion cell is the region of the visual field in which light stimuli evoke responses in the ganglion cell.
What is The receptive fields of V1 neurons
It contributes to our perception of edges and shapes
What is The roles of the dorsal and ventral streams in visual processing
the ventral ‘perceptual’ stream computes a detailed map of the world from visual input
the dorsal ‘action’ stream transforms incoming visual information to the requisite egocentric coordinate system for skilled motor planning
What is The trichromatic theory
A proposed theory that the human eye has three types of receptors, each one maximally sensitive to a different wavelength.
The opponent-process theory (and spectrally-opponent cells)
the mind can only register the presence of one color of a pair at a time because the two colors oppose one another
What is Colour constancy
It is our ability to perceive colors as relatively constant over varying illuminations
What is sensory transduction in the light
Rhodopsin is active, Na+ channels close, cells are hyperpolarized, neurotransmitter release is low. Less glutamate is released
