Vision II Flashcards
Photoreceptors
- Rods and Cones
- Transmit signals from the Plexiform layer
- Synapse w/ Bipolar and Horizontal cells
Plexiform Layer
Layer of SYNAPTIC connections
The Neurons that make up the Pure ROD Vision
- Rods
- Bipolar Cells
- Amacrine Cells
- Ganglion Cells
How much decussation occurs in the Optic Chiasm?
50%
Amacrine Cells an Neurotransmitters
- 8+ more kinds of NT
- GABA, Glycine, Dopamine, ACh and Indolamine ALL INHIBITORY
Ganglion Cells
- Transmit signals from the retina to the Brain
- Axons make up the OPTIC NERVE
What controls how much of the signal is allowed to Pass to the Cortex?
Lateral Geniculate Nucleus
The Peripheral Retina is more sensitive to what kind of light?
Weak
Bipolar Cells
- Transmit signals from Rods, Cones, and Horizontal cells
- Synapse w/ Amacrine and Ganglion cells
What Geniculate Nucleus Layers receive signals from the LATERAL Half of the opposite retina?
II, III, and V
2, 3, 5
How many layers are in the VISUAL Cortex?
6
Accommodation in CHILDREN
- Refr Power of lens can Increase from 20-34
14 diopters
Axons of the Ganglion Cells
- Make up the OPTIC NERVE
Is the Output of Horizontal Cells inhibitory or Excitatory?
- Inhibitory
Lateral Inhibition
Y Ganglion Cells
- Diameter Size of Axon
- Transmission
- Characteristics
- LARGE Diameter
- 50m/sec (Fast)
- Responds to RAPID changes in Visual Image
Presbyopia
The decrease in ability for the eye to focus on NEAR objects
Horizontal Cells
- Transmit Signals from Rond and Cones to Bipolar cells
- Output is ALWAYS Inhibitory
Lateral Inhibition
T/F: Some Amacrine Cells respond when a Light is turned On or Off
True
Accommodation in OLD Adult
- Lens becomes Large and Thick
- Power decreases to Less than 2 diopters by 45-50yrs
- Power decreases to 0 by age 70
W Ganglion Cells
- Diameter Size of Axon
- Transmission
- Field size
- Small AXON Diameter
- Transmits 8m/Sec (SLOW)
- BROAD Fields
What Retinal cells Transmit signals to the OUTER Plexiform
- Photoreceptors
- Horizontal cells
What is the ONLY retinal cells that transmit AP?
Ganglion Cells
What Dorsal Lateral Geniculate layers Transmit only COLOR?
Layers III -> VI
What Geniculate Nucleus Layers receive signals from the MEDIAL Half of the opposite retina?
I, IV, and VI
1, 4, and 6
Inter-Plexiform Cells
- Transmit from Inner Plexiform Layer to the Outer Plexiform layer (Retrograde)
- Lateral Inhibition
What ganglion cell is responsible for ALL Color Vision?
X Ganglion cells
How many rods converge on a single optic fiber in the peripheral regions of the Retina?
200
Dorsal Lateral Geniculate Nucleus
- Receives Input from the OPTIC Nerves
- Relays information from the Optic tract to the Visual Cortex
X Ganglion Cells
- Diameter Size of Axon
- Transmission
- Field size
- Medium Diameter
- 14m/sec (Medium)
- SMALL Fields
- EVERY X ganglion cell receives an input from at lease One CONE cell *
Three Neurons in the Foveal Region
- Cones
- Bipolar Cells
- Ganglion Cells
What Retinal cells Transmit signals to the Inner Plexiform
- Bipolar cells
- Amacrine cells
What Dorsal Lateral Geniculate layers Transmit only BLACK and WHITE
Layers I and II
How many Ganglion Cells are there? What are they?
- Three types
- W, X, and Y
Layers of the Retina
- Photoreceptors
- Horizontal cells
- Bipolar Cells
- Amacrine Cells
- Ganglion Cells
Most Amacrine cells are what?
- INTERNEURONS
- Help analyze Visula signals BEFORE they leave the retina
Amacrine Cells
- Transmit signals from Bipolar to Ganglion cells
- Transmit signals w/in Inner Plexiform
How Many Layers in the Lateral Geniculate Nucleus?
6
Geniculo-Calcarine Fibers terminate mainly in what Visual Cortex Layer?
Layer IV (4)
Ganglion Cells by percentage.
W: 40%
X: 55%
Y: 5%
