-
-
LGN- Magnocellular (M) layers
- 1,2
- projections from large (magnocellular) RG cells
- movt, location, contrast
-
LGN- Parvocellular (P) layers
- 3-6
- projections from small (prvocellular) RG cells
- color, form, fine visual detail (incl object recognition)--> facial recognition
-
Projections from primary cortex--> many, including extra-striate cortical segments
- extra-striate cortical segments:
- Ventral (temporal)-parvocellular modalities
- Dorsal (parietal)- magnocellular modalities
-
R optic n lesion
- blind in R eye
- Monocular blindness
-
optic chiasm lesion
- loose temporal vision in both eyes
- Bitemperal hemianopsia
-
R optic tract/LG lesion
- loose L side vision in both eyes
- Contralateral homonymous hemianopsia
-
R Superior radiation lesion
- loose inferior VF on L side in both eyes (L inf quad out)
- Contralateral (homonymous) inferior quadrantanopsia
-
L Inferior radiation lesion
- loose R superior VF in both eyes (R sup quad is out)
- Contralateral (homonymous) superior quadrantanopsia
-
R occiptial cortex
- L VF out in both eyes with macular sparing
- Contalateral homonymous hemianopsia with macular sparing (similar to optic tract lesion)
-
other pathways other than the retino-geniculo-calcarine pathway:
-
• Retino-collicular pathways
- – Projections to the superior
- colliculus
- • Retino-pretectal pathways
- – The pupillary light reflex
- • Retino-hypothalamic pathways
- – Control of circadian rhythms
-
Retino-collicular pathways
- rapid reflex to external stim
- aff: retina, prima visu cortex, somatosens system, auditory sytem, etc
- eff: cervical SC (tectospinal tract), pulvinar, reticular formation, inf colliculus
-
Retino-pretectal pathways
- pupillary reflex, consensual
- retina->pretectum->Edinger-Westphal (pregang parasym, BILATERAL)
-
Retino-hypothalamic pathways
- circadian rhythms
- retina->suprachiasmatic nucl->paraventricular hypoth neurons->intermediolateral (sympathetic) spinal neurons-> cervical ganglion-> pineal glands-> melatonon release
|
|
