Visual Pathway(Jaras Penglihatan)Adib RahmanAhmad SetyadiAmelia PratiwiDian Zarina RahmiFirda Nur IslamiKhoirunnisaMikhwanul Jumar

dr. Eva Melinda, Sp. MResponsiOleh :

1 Media RefraksiKornea Kamera okuli anteriorLensaHumor vitreus

Refleks Pupil

Akomodasi pada Lensa

2 RetinaSerabut saraf optikSel gangglionSel amakrinSel bipolarSel horizontalFotoreseptor (sel batang dan kerucut)Epitel berpigmen

http://anatomy.uams.edu/AnatomyHTML/atlas_html/eye_38.html1.Nervus optikus 2.Ciasma optikus3.Traktus optikus4.Nukleus genikulatum Lateral 5.Radiasi optik6.Korteks visual 7.Colliculus superior8.Putamen 10.Pulvinar talamus 11.Fissura Kalkarina

Serabut Nervus optikTerdiri dari 6 lapisan1-2 lapisan Magnocellular 3-6 Parvocellular layers

(lapisan 2,3,5 berasal dari ipsilateral, dan 1,4,6 dari kontralateral)http://www.physics.utoledo.edu/~lsa/_color/17_eye.htm

Jaras penglihatan klasikNervus optikus dan traktus optikusNukleus genikulatum lateralKorteks visual primer

Beberapa akson tidak menuju nukleus genikulatum latelal tapi berhenti di colliculus superiorKemudian ke pulvinarPulvinar efferents berakhir di korteks visual selain visual primer (V1)

Beberapa akson traktus optikus berakhir di area pretektal

Lesi pada Jaras Penglihatan

Terima Kasih

***The pupillary reflex is induced by suddenexposure of the retina to light (!p. 350). Thesignal is relayed to the pretectal region; fromhere, a parasympathetic signal flows via theEdingerWestphal nucleus, the ciliary ganglionand the oculomotor nerve, and inducesnarrowing of the pupils (miosis) within lessthan 1 s. Since both pupils respond simultaneouslyeven if the light stimulus is unilateral,this is called a consensual light response.Meiosis also occurs when the eyes adjust fornear vision (near-vision response !p. 360).****LGN at #4; fibers from LGN go thru the optic radiation to reach primary visual cortex in occipital lobe (AKA striate cortex, V1, shown in #6)1.Optic nerve 2.Optic chiasma 3.Optic tract 4.Lateral geniculate body 5.Optic radiation 6.Visual cortex 7.Superior colliculus of the midbrain 8.Putamen 9.Long association bundle - inferior occipitofrontal fasciculus 10.Pulvinar of the thalamus 11.Calcarine fissure 12.Posteroinferior horn of the lateral ventricle *80% of optic tract axons synapse in LGN, has 6 layers; ipsilateral fibers of optic nerve go to layers 2, 3, 5; contralateral fibers terminate in layers 1, 4, 6Axons leaving the LGN remain divided according to magnocellular and parvocellular origins and synapse in different layers of the visual cortexThe neurons of all layersthen project further through the optic radiation(arranged also retinotopically) to the primaryvisual cortex (V1) and, after decussating,to further areas of the visual cortex (V25) includingpathways to the parietal and temporalcortex. Magnocellular input reaches theparietal cortex also via the superior colliculi(see below) and the pulvinar.

**Lesions of the left optic nerve for instance cause deficitsin the entire left visual field (!B, a), whereas lesionsof the left optic tract produce deficits in theright halves of both visual fields (!B, c). Damage tothe median optic chiasm results in bilateral temporaldeficits, i.e., bitemporal hemianopia (!B, b).The primary visual cortex (V1) is divided depth-wise(x-axis) into six retinotopic layers numbered I to VI(!p. 333 A). Cells of the primary visual cortex are arrangedas three-dimensional modular hypercolumns(3!1!1mm) representing modules foranalysis of all sensory information from correspondingareas of both retinas (!p. 360). Adjacent hypercolumnsrepresent neighboring retinal regions. Hypercolumnscontain ocular dominance columns (yaxis),orientation columns (z-axis), and cylinders (xaxis).The dominance columns receive alternatinginput from the right and left eye, orientationcolumns process direction of stimulus movementand cylinders receive information of colors.**