50 Visual Pathway Flashcards
1
Q
describe the visual pathway
A
- retina converts photo-energy to neural impulses
- the optic nerve transmits neural signals from retina to optic chiasm
- the nasal hemiretinal information decussates, and after the OC, the entire hemifield is represented on the contralateral side in the nervous system
- the optic tract transmits neural signals from OC to LGN and carries contralateral hemifield info.
- LGN = lateral geniculate nucleus of the thalamus
- the optic radiation transmits neural signals from LGN to primary visual cortex
- Meyer’s loop - projection through temporal lobe and represents upper visual field quadrants
- Baum’s loop - projection through parietal lobe and represents lower visual field quadrants
- the primary visual cortex (V1) in the occipital lobe receives signals in layer IV
2
Q
describe Meyer’s loop
A
3
Q
describe Baum’s loop
A
4
Q
describe the location of the primary visual cortex (V1), the Broadmann area and the blood supply
A
- the major portion of V1 is represented on the medial aspect of the brain
- located along the 2 banks (gyri) of the calcarine sulcus, one portion superior and the other portion inferior to the calcarine sulcus
- the primary visual cortex receives its major blood supply from calcarine branches originating from the PCA
5
Q
describe the retnotopic organization of the primary visual cortex
A
6
Q
describe the pathway for depth and motion
A
- the pathway for depth and motion starts with magnocellular neurons (M ganglion cells) in the retina
- these neurons synapse in two out of the six layers of the LGN
- the output from the LGN follows the M pathway along the optic radiation and synapse in layer 4 of the primary visual cortex
- from the primary visual cortex onwards, the M pathway forms the dorsal (parietal) pathway
7
Q
describe the pathway for form and color
A
- the pathway for form and color starts with parvocellular neurons (P ganglion cells) in the retina
- these neurons synapse in layers 3-6 of the LGN
- the output from the LGN follows the P pathway along the optic radiation and synapse in layer 4 of the primary visual cortex
- from the primary visual cortex onwards, the P pathway forms the ventral (inf. temporal) pathway
8
Q
describe cortical color blindness (achromatopsia)
A
- inability to distinguish colors or color hues may be due to cortical lesion in Brodmann’s Areas 18 or 37
-
inf. temporal cortical lesions can cause color blindness
- P pathway
9
Q
describe what can cause this
A
10
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11
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12
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13
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14
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15
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