Lecture 13 Flashcards
What are the two major types of ganglion cells?
Large M-type ganglion cells
Small P-type ganglion cells
How are ganglion cells categorized? (3 properties)
Appearance
Connectivity
Electrophysiological properties
What is the composition of the population of ganglion cells?
90% P-type
5% M-type
5% non-M non-P ganglion cells
Ganglion cells:
Larger receptive fields, low res vision
M-cells
Ganglion cells:
Conduct action potentials more rapidly
M-cells
Ganglion cells:
More sensitive to low-contrast stimuli
M-cells
Ganglion cells:
Respond to stimulation of their receptive field centers with a transient burst of action potentials
M-cells
M ganglion cells lack color _______ and their responses are __________ specific
opponency
responses are not color specific
Color-opponent cells:
The response to one color in the receptive field center is canceled by showing another color in the receptive field surround
Two types of opponency
red vs green (R+G-, red wavelengths of light are partially absorbed by green cones)
blue vs yellow (B+Y-, little blue light is absorbed in receptive field surround)
What ganglion cell types are sensitive to differences in the wavelength of light?
Some P-cells and non-M, non-P cells
Overall ganglion cell population sends information to the brain about which three spatial comparisons?
Light vs Dark
Red vs Green
Blue vs Yellow
Some blind people appear to synchronize their behavior to ______ ________ in _______.
daily changes in light
Intrinsically photosensitive retinal ganglion cells (ipRGCs); how do they synchronize behaviors
Photoreceptors that depolarize to light, large receptive fields;
Synchronize behaviors to daily changes in light level (circadian rhythms), not used in fine pattern vision
Use melanopsin as a photopigment
ipRGCs
Retina _____ information about _______ in brightness and color
Extracts
differences
Information extracted by the retina is analyzed by what?
Central visual system.
Neural processing results in ________
Perception
Path of conscious visual perception
Originates in retina–> lateral geniculate nucleus–> primary visual cortex and higher order visual areas
Retinofugal Projection
Neural pathway that leaves the eye, beginning with the optic nerve
Retinofugal projection passes three structures before forming synapses in the bain stem
Optic nerve
Optic chiasm
Optic tract
Optic chiasm location
Anterior of pituitary, axons originating in the nasal retinas cross from one side to the other (partial decussation)
Binocular visual field:
Central portion of both visual hemifields is viewed by both retinas
The entire region of space seen with both eyes looking straight ahead
Full visual field
