Download to read offline
Perception lesson 2
- 1. Perception lesson 2 Theoptic nerve and the brain
- 2. Learning Objectives • Tolearn about the blind spot • To understand where visual information is used in the brain
- 3. The blind spot •We use the phrase ‘the blind spot’ to mean all sorts of things • I often say I have a blind spot for maths, because I cant see how it works • Drivers use their mirrors to see what is behind them, but there is always a blind spot that the mirrors don’t cover • In your eyeballs there is a small area with no rods or cones, so it is called the blind spot
- 4. Why do wehave a blind spot • Each rod or cone connects to a neurone (a nerve cell), and these leave the eyeball via the optic nerve (the eyeball stalk) • At the point where the optic nerve leaves the retina there are no rods or cones, so nothing can be detected • This is your blind spot
- 5.
- 6. Blind Spot • Youmay wonder why you don’t see a hole in your vision. • This is because the two blind spots don’t overlap, so if you cant see a small area with one eye, you can see it with the other • They ‘fill in’ for each other
- 7. The Optic Chiasma •From the back of the eyeball the optic nerve travels to the back of the brain • About half way back the two optic nerves (one from each eye) cross over at the optic chiasma • At the chiasma, fibres from each eye swap to the other side • This means that information from each eye goes to both sides of the brain
- 8.
- 9. The Visual cortex •The part of the brain that receives and processes information from the eyes is the visual cortex • It is right at the back about half way up (look at the model of the brain) • The visual cortex uses the information from the rods and cones to understand shapes and distances
- 10.