Retinal Processing Flashcards
What is responsible for creating center-surround receptive fields?
Lateral inhibition of horizontal cells
What are the two functional types of bipolar cells and how do they differ?
On-center - inhibited by glutamate released from photoreceptor
Off-center - excited by glutamate released from the photoreceptor
What type of channel is located on on-center bipolar cells?
Metabotropic glutamate receptor that closes a cation channel which is normally open
Results in depolarization (turned on) in response to light stimulation of the photoreceptor
What type of channel is located on off-center bipolar cells?
Ionotropic glutamate receptors
Results in hyperpolarization (turned off) in response to light stimulation of the photoreceptor
What is the response of on-center bipolar cells to light stimulation in the surround portion of the receptive field? Off-center?
On-center - are inhibited or hyperpolarize
Off-center - are excited or depolarize
What is the function of A2 amacrine cells?
Relay rod bipolar cell output to the cone bipolar cells, and therefore the central nervous system
What is melanoma-associated retinopathy?
Melanoma patients can lose night vision due to the production of an antibody against mGlu6
Can’t use rod system - loss of on-center bipolar cells
What is congential stationary night blindness?
Loss of night vision due to gene alterations affecting on-center bipolar cells
How is the ganglion cell receptive field generated?
A reproduction of the bipolar cell receptive field
On-center ganglion cells are driven by on-center bipolar cells and vice versa
How are retinal ganglion cells best activated in terms of their receptive fields?
They are best activated by large, relative differences in brightness between the antagonistic zones of their receptive fields
E.g. edges
Describe M-type ganglion cells.
5% of all ganglion cells
Large
Fast conduction
Transient response (adapt)
Not sensitive to wavelength differences
Function to detect movement
Describe P-type Ganglion cells
90% of ganglion cells
Small
Slower conduction
Sustained response
Sensitive to different wavelengths
Detect form and fine detail
What are color-opponent ganglion cells?
P-type ganglion cells that are sensitive to different wavelengths of light
Two types: Red-green and Blue-Yellow
