Term
| What is the role of the macular? |
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Definition
| It is important for recognising faces and reading. The centre is called the fovea. |
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Term
| Describe the pathway of the retinal signal. |
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Definition
| Receptors (rods and cones)- bipolar cells- ganglion cells- optic nerve |
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Term
| What are rods responsible for? |
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Definition
| Scotopic (night time vision) |
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Term
| What are cones responsible for? |
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Definition
| Photopic (daytime vision) |
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Term
| Where are rods and cones distributed? |
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Definition
| Cones in the centre near the fovea. Rods in the periphery. |
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Term
| Which conformational change is most important in phototransduction in cones and what does it result in? |
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Definition
| 11-cis retinal to trans-retinal. This bleaches opsin. |
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Term
| What is retinitis pigmentosa caused by? |
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Definition
| A mutation along the phototransduction chain. It can cause blindness. |
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Term
| What is different about phototransduction in cones? |
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Definition
| There are three types of opsin which respond to different wavelengths of light (short, middle and long). |
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Term
| Which cells are important in colour opponency? |
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Definition
| Amacrine and horizontal cells. |
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Term
| How do you test for colour blindness? |
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Definition
| Pseudoisochromatic plates |
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Term
| Describe the visual field pathway. |
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Definition
| Retina- optic nerve- optic chiasm- optic tract- lateral geniculate body- geniculo-calcarine tract (optic radiations)- striate cortex |
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Term
| Which fibres cross at the optic chiasm? |
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Definition
| Fibres from the nasal retina (which serves the temporal visual fields) cross at the optic chiasm. |
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Term
| Describe the retinotopic map in V1. |
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Definition
| The macular is most posterior and the peripheral field is most anterior |
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Term
| What does a migraine aura tell us about the retinotopic map? |
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Definition
| That 50% of it is devoted to the central 5 degrees (speeding up of movement). |
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Term
|
Definition
| Normal eye but normal connections not developed leading to poor vision in that eye. |
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Term
| What can cause amblyopia? |
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Definition
1) Strabismus
2) Congenital cataracts
3) Unequal refraction |
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Term
| Where does information from the striate cortex feed forward to? |
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Definition
1) Dorsal stream to the parietal cortex
2) Ventral stream to the temporal lobe |
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Term
| What is the parietal cortex involved in? |
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Definition
|
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Term
| What is the temporal lobe involved in? |
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Definition
| Object recognition (visual agnosias) |
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Term
| What is optic ataxia and how is it caused? |
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Definition
| Fixed staring ahead unable to make visually guided eye movements. Dorsal stream damage. |
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Term
|
Definition
1: Left central scitoma
2: Bitemporal hemianopia
3: Left homonymous hemianopia (incongruous)
4: Left homonymous hemianopia (congruous)
5: Left homonymous hemianopia (with macular sparing)
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