NSCI 175 PT. 6 CENTRAL VISUAL
SYSTEM 2 EXAM QUESTIONS AND
ANSWERS GRADED A+ 2025/2026
*Predict the site of a lesion in the retinofugal pathway based upon the visual field deficit*
How can sites of damage be located? - ANS Because unique deficits result from lesions at
different sites, neuro ophthalmologist and neurologist can locate sites of damage by assessing
visual field deficits.
*Predict the site of a lesion in the retinofugal pathway based upon the visual field deficit*
Two points to remember - ANS -Left visual field is imaged on the nasal retina of the left eye
and the temporal retina of the right eye
-Right visual field is imaged on the nasal retina of the right eye and the temporal retina of the
left eye
*Predict the site of a lesion in the retinofugal pathway based upon the visual field deficit*
Affects of cutting the optic nerve, optic tract, and optic chiasm - ANS -If the optic nerve on
the left side is cut, vision will be lost completely in the left eye. Note that the resultant blindness
is only in the monocular portion of the left hemifield because the right eye still sees most of the
left visual field.
-If the optic tract on the left side is cut, vision will be lost in the right visual field of each eye.
-If the optic chiasm is split down the middle, only the crossing fibers will be damaged, and the
peripheral vision will be lost in both eyes.
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,*Describe the organization of retinal inputs to the LGN*
LGN Defintion - ANS Lateral Geniculate Nucleus (LGN of thalamus) gateway to visual cortex
"like a little knee". LGN is part of the thalamus
-Input from the eyes is segregated! And Input from different cells is segregated
*Describe the organization of retinal inputs to the LGN*
6 Distinct cell layers. And what targets it mainly? - ANS It is a major target of optic tracts
1 contralateral eye input
2 ipsilateral
3 Ipsilateral
4 Contralateral
5 Ipsilateral
6 Contralateral
Most ventral layer is 1
*Describe the organization of retinal inputs to the LGN*
Function of the geniculate nuclei? And why are the layers numbered 1-6? - ANS The right and
left lateral geniculate nuclei, located in the dorsal thalamus, are the major targets of the two
optic tracts. Viewed in cross section, each LGN appears to be arranged in 6 distinct layers of
cells.
By convention the layers are numbered 1 through 6, starting with the most ventral layer, layer 1.
In three dimensions, the layers of the LGN are arranged like a stack of six pancakes, one on top
of the other. They bend around the optic tract like a knee joint. The LGN is the gateway to the
visual cortex and therefore, to conscious visual perception
*Describe the organization of retinal inputs to the LGN*
What are the three types of ganglion cells? What do they all do? - ANS M-Type
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, P-Type
Non-M/Non-P type
-M and P-type ganglion cells process different types of information
-M and P ganglion cells carry different kinds of information to the LGN from the retina.
*Describe the organization of retinal inputs to the LGN*
LGN Organized by? - ANS LGN Organized by GC input: Different types of ganglion cells appear
to play different roles in visual perception.
*Describe the organization of retinal inputs to the LGN*
Compare and contrast P-Type and M-Types ganglion cells
-5% of the ganglion cell population
-90% of the ganglion cell population
-Color opponent cells (red versus green and blue versus yellow)
-Conduct AP more rapidly
-Respond to stimulation of their receptive fields with a transient BURST of APs - ANS -5% of
the ganglion cell population: M-Types
-90% of the ganglion cell population: P-Type
-Color opponent cells (red versus green and blue versus yellow): P-Type
-Conduct AP more rapidly: M-type
-Respond to stimulation of their receptive fields with a transient BURST of APs: M-Type
*Describe the organization of retinal inputs to the LGN*
Compare and contrast P-Type and M-Types ganglion cells
3 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
SYSTEM 2 EXAM QUESTIONS AND
ANSWERS GRADED A+ 2025/2026
*Predict the site of a lesion in the retinofugal pathway based upon the visual field deficit*
How can sites of damage be located? - ANS Because unique deficits result from lesions at
different sites, neuro ophthalmologist and neurologist can locate sites of damage by assessing
visual field deficits.
*Predict the site of a lesion in the retinofugal pathway based upon the visual field deficit*
Two points to remember - ANS -Left visual field is imaged on the nasal retina of the left eye
and the temporal retina of the right eye
-Right visual field is imaged on the nasal retina of the right eye and the temporal retina of the
left eye
*Predict the site of a lesion in the retinofugal pathway based upon the visual field deficit*
Affects of cutting the optic nerve, optic tract, and optic chiasm - ANS -If the optic nerve on
the left side is cut, vision will be lost completely in the left eye. Note that the resultant blindness
is only in the monocular portion of the left hemifield because the right eye still sees most of the
left visual field.
-If the optic tract on the left side is cut, vision will be lost in the right visual field of each eye.
-If the optic chiasm is split down the middle, only the crossing fibers will be damaged, and the
peripheral vision will be lost in both eyes.
1 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
,*Describe the organization of retinal inputs to the LGN*
LGN Defintion - ANS Lateral Geniculate Nucleus (LGN of thalamus) gateway to visual cortex
"like a little knee". LGN is part of the thalamus
-Input from the eyes is segregated! And Input from different cells is segregated
*Describe the organization of retinal inputs to the LGN*
6 Distinct cell layers. And what targets it mainly? - ANS It is a major target of optic tracts
1 contralateral eye input
2 ipsilateral
3 Ipsilateral
4 Contralateral
5 Ipsilateral
6 Contralateral
Most ventral layer is 1
*Describe the organization of retinal inputs to the LGN*
Function of the geniculate nuclei? And why are the layers numbered 1-6? - ANS The right and
left lateral geniculate nuclei, located in the dorsal thalamus, are the major targets of the two
optic tracts. Viewed in cross section, each LGN appears to be arranged in 6 distinct layers of
cells.
By convention the layers are numbered 1 through 6, starting with the most ventral layer, layer 1.
In three dimensions, the layers of the LGN are arranged like a stack of six pancakes, one on top
of the other. They bend around the optic tract like a knee joint. The LGN is the gateway to the
visual cortex and therefore, to conscious visual perception
*Describe the organization of retinal inputs to the LGN*
What are the three types of ganglion cells? What do they all do? - ANS M-Type
2 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
, P-Type
Non-M/Non-P type
-M and P-type ganglion cells process different types of information
-M and P ganglion cells carry different kinds of information to the LGN from the retina.
*Describe the organization of retinal inputs to the LGN*
LGN Organized by? - ANS LGN Organized by GC input: Different types of ganglion cells appear
to play different roles in visual perception.
*Describe the organization of retinal inputs to the LGN*
Compare and contrast P-Type and M-Types ganglion cells
-5% of the ganglion cell population
-90% of the ganglion cell population
-Color opponent cells (red versus green and blue versus yellow)
-Conduct AP more rapidly
-Respond to stimulation of their receptive fields with a transient BURST of APs - ANS -5% of
the ganglion cell population: M-Types
-90% of the ganglion cell population: P-Type
-Color opponent cells (red versus green and blue versus yellow): P-Type
-Conduct AP more rapidly: M-type
-Respond to stimulation of their receptive fields with a transient BURST of APs: M-Type
*Describe the organization of retinal inputs to the LGN*
Compare and contrast P-Type and M-Types ganglion cells
3 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
