BS545 - Visual System
Terms
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- Give the pathway from the nasal hemiretinae to visual cortex. Name fiber pathways and synapses by name.
- Retina -> optic nerve -> decussation at optic chiasm -> optic tract -> synapse in lateral geniculate nuclei -> optic radiation -> synapse in visual cortex
- Give the pathway from the temporal hemiretinae to visual cortex. Name fiber pathways and synapses by name.
- Retina -> optic nerve -> optic chiasm -> optic tract -> synapse in ipsilateral lateral geniculate nuclei -> optic radiation -> synapse in visual cortex.
- What are the five main types of cells in the retina?
-
cone/rod photoreceptor
bi-polar
ganglion
horizontal
amacrine - What is the name of the yellowish central area of the retina that is heavily populated in cones?
- macula
- What is the name of the depression located at the center of the macula? What is special about its contents?
-
Fovea.
This contains only elongated cones and is specialized for vision of the highest acuity. - Identify the "projection" cells of the retina.
-
Ganglion cells
Melanopsin cells - Predict the effect of light and dark on a photoreceptor's release in neurotransmitter, glutamate.
-
Light -> hyperpolarization -> decrease in glutamate.
Dark -> depolarization -> increase in release of glutamate. -
Describe the concept of "center-surround receptive field". Keep it simple.
Why have it? -
Start with a center cell. Suppose no light on it. Now suppose there is light on adjacent cells. These cells will couple to the center cell via an inhibitory interneuron thus turning it off even more.
The contrast is increased via this scheme. - What cells in the retina are able to generate APs?
-
Ganglion cells
Melanopsin cells -
How many layers are there in the lateral geniculate nucleus?
What are the names of these? -
Six layers
Two magnocellular and four parvocellular. -
What layers of the LGN are used by the magnocellular pathway?
What is the function of the magnocellular pathway? -
One and two.
The magnocellular pathway deals with ganglion cells which are sensitive to movement and contrast. -
What layers of the LGN are used by the parvocellular pathway?
What is the function of the parvocellular pathway? -
3,4,5,6
The parvocellular pathway deals with ganlion cells which are sensitive to color and form. - Identify which layers of the LGN receive information from the ipsilateral versus the contralateral eye.
-
Layers 1,4,6 deal with info from the contralateral eye.
Layers 2,3,5 deal with info from the ipsilateral eye. - Distinguish between the dorsal and ventral pathways ("streams") for processing different aspects of the visual stimuli. Use the terms parvocellular and magnocellular.
-
The parvocellular system (color, detailed form) projects to more ventral portions of the extrastriate cortex.
THe magnocellular system (location, movement) projects to more dorsal portions. - What is the term for a reduction in visual acuity or blindness in one or both eyes?
- anopsia (anopia)
-
Map each numbered area into the visual cortex.
Label as: left or right, superior or inferior, and most posterior, middle, most anterior. -
1: Right, inferior, posterior
2: Right, superior, posterior
3: Left, inferior, posterior
4: Left, superior, posterior
5: Right, inferior, middle
6: Right, superior, middle
7: left, inferior, middle
8: left, superior, middle
9: right, inferior, anterior
10: right, superior, anterior
11: left, inferior, anterior
12: left, superior, anterior - What is the name for a reduction in visual acuity in half of the visual field?
- hemianopsia (hemianopia)
- What is the name for a reduction in visual acuity for the lateral (temporal) half of the visual field of each eye?
- bitemporal hemianopsia (hemiaonopia)
- What is the name for a reduction in visual acuity for the nasal visual field of one eye and the lateral visual field of the other eye?
- homonymous hemianopsia (hemianopia)
-
What is the name for a reduction in visual acuity for 1/4 of the superior visual lateral field in one eye and and 1/4 of the superior visual lateral field in the other eye?
What is a simple name for this?
What portion of the visual -
contralateral homonymous superior quadrant anopsia hemianopia)
"Pie in the sky"
Meyer's loop - What is the name for a reduction of visual acuity in the area surrounding the macula?
- Foveal (macula) sparing
- What nucleus is a relay in the primary vision pathway?
- lateral geniculate nucleus.
- What nucleus is a relay in the pupillary light reflex pathway?
- Pretectal nuclei
- What structure is involved with coordination of the visual grasp reflex?
- superior colliculus
- The nuclei is associated with Circadian rhythms?
- suprachiasmatic nuclei
- What is it called when somone has an impaired ability to recognize familiar faces?
- prosopagnosia