51 Vision II Flashcards
State the flow of the reticulogeniculate pathway for vision.
optic nerve > optic chiasm > optic tract > lateral geniculate body > optic radiation > primary visual cortex
What is monocular field and binocular visual field?
Monocular: 1/3 (not overlapping)
Bonocular visual field: 2/3 (overlapping)
The fixation point that will be projected to the macula is made up by the intersections of?
Vertical median and horizontal median
lines passing vertically/horizontally through the fovea centralis
Nasal retina perceives ___________ visual field.
Temporal
The optic tract is at the _________ surface of the diencephalon. It contains axons from both eyes representing opposite visual field.
lateral
The optic tract is divided into? Where are their destinations?
Lateral root > lateral geniculate nucleus (90%);
Medial root:
1. pretectal area
>to both EW nucleus for pupillary light reflex
2. superior colliculus
> 2.1 pulvinar: to visual association cortex (extrageniculate pathway) for blindsight
2.2 PPRF for autonomic scanning (saccadic eye movement)
- RF for arousal
- Suprachiasmatic nucleus in hypothalamus for circadian rhythm
Neurons in each layer of the lateral geniculate layer receives inputs from ________ eye(s).
1
Name which side of the retinal input does the LGN receive from from layers 1-6.
CIICIC
What are the different cell types of LGN in different layers? What are their functions respectively?
Layers 1-2: Magnocellular layer (Y-cell: movement perception)
Layers 3-6: Parvocellular layer (X-cell: visual detail and color)
Any defect that occurs before the optic chiasm is on the ________ side.
same (stays on the same side)
e.g. left optic nerve lesion > left visual field defect
Any defect occurs at/beyond the optic chiasm involves ______ eyes with ___________defect.
both; ventral meridian
In what defect that the peripheral visual field in the right eye is lost?
Right optic neuropathy e.g. glaucoma, optic neuritis
__________________ happens when there is complete lesion of the optic chiasm.
Bitemporal hemianopia
e.g. tumor
What is left homonymous hemianopia?
Give 3 examples of when it will happen
Left visual hemifield of both eyes are lost.
- Lesion of the right optic tract
- Lesion of right optic radiation
- Right occipital lobe (visual cortex) defect
If there is lesion at the upper right optic radiations, what will happen to the visual fields?
Left homonymous superior quadrantonopia
Axons from _________ hemiretina cross the midline (thus contralateral)
While those from _____________ hemiretina go to the optic tract on the same side (ipsilateral)
nasal;
temporal
___________ enter retro-lentiform part of the internal capsule (behind posterior limb) and run alongside the posterior horn of the lateral ventricle.
Optic radiation
The optic radiation run alongside the posterior horn of the lateral ventricle and turn _____________ to enter the occipital cortex.
medially
What is the Meyer’s loop?
Axons carrying image from the contralateral superior quadrant, runs lateral to temporal horn of the lateral ventricle
What happen when there is damage to Meyer’s loop?
- Medial sector are anterior most fibers > lost earliest in temporal lobectomy
- superolateral field cut: pie in the sky
In retinotopic map, ________ region is over-represented than _________ regions.
Central; peripheral
The primary cortex projects the ____________________ visual field __________(orientation) in the retinotopic map.
contralateral visual hemifield ; upside down
Information from the upper quadrant of the left visual fields projects to the __________________ of the retina, the travels to the ______LGN then to the ________ visual cortex above/below the calcimine sulcus.
lower right quadrant;
right;
right
In the primary visual cortex, afferents terminate mostly at layer ______, also named as ____________.
4C; line of Gennari (white colour, = striae cortex)
What does it mean by ocular dominance columns?
info coming from the left and
the right eye (already segregated in LGN) is kept separate in layer IV of the visual cortex
- binocular cells in layers superficial to layer 4
How spatial information is obtained from the visual field to the primary visual cortex?
- Left cortex: right visual field
- Upper half of visual view > lower part of visual cortex
- Macula: posterior of primary visual cortex
- Peripheral: anterior in primary visual cortex
How to define area of projection in the primary visual cortex?
proportional to the number of photoreceptors in the retina
State the route, functions, destination of the what pathway .
Route:
P-ganglion cell > parvocellular LGN (layers 3-6) > V1 > V2 > V4 (area 19) > Inferior Temporal Cortex
Functions: color, form, face (area 37)
Jm9 = what??
V1-2-4 (area 19)
Inferior temporal cortex (inf:濕鳩)
V4: colour and form (fusiform gyrus, at inferotemporal cortex)
V1 = area ? V2,V3 = area? V4 = ? V5 = ?
17;
18, 19;
anteromedial area 19, what pathway, fusiform gyrus;
anterolateral area 19; where pathway, middle temporal gyrus
State the route, functions, destination of the where pathway.
M-ganglion cell > Magnocellular layer in LGN (layers 1-2) > V1 > V2 > V3 > V5 (middle temporal gyrus) > Posterior Parietal cortex (where)
Functions: movement perception, attention center, stereopsis (depth perception)
地方咁大= magno
V1-2-3-5 (area 17,18, 19)七上八下 (movement)
Easy to go parietal (側邊)
What will happen when damage to V4?
V4 = anteromedial area 19, fusiform gyrus;
Visual agnosia: cannot recognise or interpret visual information;
acquired colour blindness (form and color)
Damage in V5?
Motion blindness, spatial neglect
Site for visual memory?
Visual association cortices/ extrastriae visual cortex (V2-5/ Area 18-19)
____________ hypothesis means that each neuron at the bottom level is specialised in detecting certain properties,
e.g. line, movement, colour
> Combined in neurons at higher layer
Hierarchical coding
____________ hypothesis means simultaneous activation of defining properties; co-occurrence of characteristics.
Ensemble-coding
