Perception Flashcards
Where is the retina located?
- We have the cornea and the pupil in the front
- And in the back we have the Retina, and in the retina we have 2 types of receptors
What are the two receptors in the retina?
Rods
Cones
What are the properties of Rods?
- Sensitive to light and movement
- 125 million in the retina
- Magnocellular Pathway = sensitive to motion, most input from rods
What are the properties of cones?
- colour vision, sharpness of vision
- 6 million in the outer regions of the retina
- Parvocellular Pathway = sensitive to fine detail, most input comes from cones
What is the pathway from eye to brain step by step?
- Retina
- Optic nerve
- Optic chiasm
- Lateral Geniculate Nucleus
- Cortical area V1
What are the 3 properties of visual neurons?
Receptive fields
Retinopy
Lateral inhibition
What are receptive fields?
every neuron is responsible for a certain region of space
- And it will fire more when when something happens in that space and won’t fire when something happens in another space
What retinopy?
The neurons that are near to each other in space are processed in cells that are physically near to each other
What is Lateral inhibition?
one neuron can inhibit a neighbouring neuron (useful for enhancing contrast at edges of objects)
What is the first stop in the brain before going to the cortex?
Lateral Geniculate nucleus
- Part of the thalamus
- Cells have a centre- surround receptive field
- Maintains a retinotopic map
What is the stop after the lateral geniculate nucleus?
Primary visual cortex (V1)
- Extracts basic information from visual scene
- Sends this info for later stages of processing.
- Maintains retinotopy
What does functional specialisation theory propose?
Different parts of the visual cortex are specialised for different visual functions
What is the function of V1 and V2 according to functional specialisation theory?
Early stage of visual perception
What is the function of V3 and V3a according to functional specialisation theory?
Responsive to form
What is the function of V4 according to functional specialisation theory?
responsive to colour