NEUR531 - Visual field Flashcards
Describe the laminar organization of the retina
- Photoreceptors
- Bipolar receptors
- ## (ganglion cells) produce APs
Describe the basic structure of rod and cone photoreceptors, and the
regional differences in distribution and connectivity of these
receptors across the retina.
- Outer segment
- Inner segment
- Cell body
- Synaptic terminal
Give a detailed account of the process of phototransduction in rods
and cones.
Describe how the receptive fields of ON and OFF bipolar cells are
formed by inputs from photoreceptors and horizontal cells.
Describe the centre-surround organization of receptive fields of
ganglion cells.
Explain how populations of ganglion cells give rise to enhanced border
detection in the retina.
Describe the different types of ganglion cells, and their distinctive
stimulus-response characteristics.
Explain what is meant by colour-opponency in ganglion cell receptive
fields.
Distinguish between the receptive fields of “simple” cells and
“complex” cells in striate cortex
Discuss the neurobiological theories of visual perception.
What does a retina do?
- Comprises photoreceptors: converts light energy into neural activity
- Detects differences in intensity of light
What does the lateral genicular nucleus (LGN) do?
- First synpatic relay in the primary visual pathway
What wavelength in nm do humans perceive?
400 - 700nm
Which is lower energy wavelengths in nm?
a. 400
b. 700
700
Which is lower energy wavelengths in nm?
a. 400
b. 700
700
Where do horizontal cells receive input?
Photoreceptors and bipolar cells
Layers of the retinal cell layers
What photoreceptor has more discs, rods or cones?
cone
How many times are rods more sensitive to light than cones?
1000
How many times are rods more sensitive to light than cones?
1000
Which photoreceptor is specific to colour, rods or cones?
cones
What photoreceptor has a higher ratio in the peripheral retina?
Rods
What area of the retina is more sensitive to low light?
Peripheral retina
REgional differences in retinal structure
What area of the retina has a 1:1 convergence with bipolar cells, enabling higher acuity vision?
Fovea centralis cones
What area of the eye has the most visual acuity?
Fovea
Are photoreceptors depolarized or hyperpolarized in the light?
Hyperpolarized
Does the cGMP-gated sodium channel also allow Ca2+ into the the channel?
Yes
Is G-protein (transducin) active or inactive during the day (light)?
Active
Is G-protein (transducin) active or inactive during the day (light)?
Active
What does activating g-protein transducin do?
- reduce cGMP to GMP via phosphodiesterase
What happens when cGMP channels open?
What are the only cells that fire action potentions within the retinal processing?
- ganglion cells
Other retinal neurons produce GRADED membrane potentials
What are Receptive fields?
Area of retina where
light changes
neuron’s firing rate
What are ‘off bipolar’ (rod) cells depolarized by?
The dark
What neurotransmitter do neurotransmitter release in the dark?
Glutamate
Are ‘on bipolar’ cells hyperpolarized or depolarized by the dark?
Hyperpolarized (inhibitory)
Are ‘on bipolar cells ‘depolarized or hyperpolarized by the light?
- Depolarized by the light
Learn
Learn
2 types of retinal ganglion cells - learn
M = magnocellular layer
P = Parvocellular layers of the lateral geniculate nucleus
