Central Visual Pathways Flashcards
What are the 3 interneurons in the retina
Bipolar, amacrine, and horizontal
What are the only projection neurons int he retina
Retinal ganglion cells
What is meant by the horizontal and vertical organization of the retina
Horizontal is inhibitory and vertical is cone, bipolar, retinal ganglion cells
What vessels supply the inner and outer portions of the retina
Central artery of the retina=inner and choroidal arteries=outer
What are the major refractory structures of the eye
The cornea and the lens
What is the difference between the optic nerve and optic tract
In the optic nerve the axons are from one eye only. Int he optic tract there are axons from parts of both eyes
What are the 4 main central targets of RGC axons
- Lateral geniculate nucleus
- Superior colliculus
- Pretectum
- Hypothalamus
How is the lataral geniculate nucleus (LGN) involved in the visual pathway
It relays to the cortex for conscious proprioception of vision
How is the superior colliculus involved in the visual pathways
It generates eye movements, visual reflexes, and is part of an indirect pathway for the relay of information to the cortex
How is the pretectum involved in the visual pathway
It is an area of the midbrain involved in the pupillary light reflex
How is the hypothalamus involved in the visual pathway
It is involved in circadian rhythms
Where does the LGN lie
In the posterior and lateral part of the thalamus
What does each LGN process
Information from he contralateral hemifield of vision
What vessels supply the LGN
The anterior choroidal artery and small branches ft he posterior cerebral artery
Where do the LGN neurons project
To area 17 via the geniculo-calcarine tract as OPTIC RADIATIONS of the posterior limb of the internal capsule
Where do axons coming out of the medial part of the LGN travel
They course dorsally over the lateral ventricle, to the internal capsule, and enter the cuneus gurus of the calcarine cortex
Where do axons coming out of the lateral portion of the LGN course
Rostral around the Meyers loop, enter the internal capsule, and project to the lingual gyrus of the calcarine cortex
What is the blood supply to the geniculo-calcarine tract
Deep perforating branches of the middle and posterior cerebral arteries, but mainly the middle cerebral artery
Optic radiations represent what visually
The contralateral hemifield
After entering area 17, area 17 projects to what
Extrastriate visual areas=higher order visual cortical areas int he occipital, temporal, and parietal lobes
In order to identify “what” and object is, area 17 projects to where
Extrastriate visual areas of the occipital and temporal lobes
In order to identify “where” an object is, area 17 projects to what areas of the brain
Extrastriate visual areas of the occipital and parietal lobes
Once RGC’s project to the superior colliculus what are some of the roles it plays with vision
- Orienting to moving stimuli and directing gaze
2. Relaying information to the cortex via the pulvinar
Describe the pathway involving the superior colliculus to the pulvinar from RGC’s
And what is something unique about this pathway
RGC’s–> Superior Colliculus–>Pulvinar(thalamus)–>extrastriate visual cortex
It does not pass through area 17, it goes straight to the extrastriate visual cortex
