Stimulus recognition Flashcards
What is the relay station before signals reach the primary visual cortex?
Lateral geniculate nucleus
How many layers are there?
6 layers of grey matter
What are layers 1 + 2?
Magnocellular layers
- Receive from rods
- Depth, movement, light change
What are layers 3-6?
Parvocellular
- Cones (long & medium wavelengths)
- Colour and fine detail
- Response slow and sustained
What does monocular input mean?
Receives input from ganglion cells in 1 eye only
What kind of organisation is there in the LGN?
Retinotopic
What do parvocellular cells sample?
HIgh resolution
Magnocellular?
Motion and object position
What is the LGN also callled?
Thalamic relay system
What makes 1:1 connections?
Ganglion cell axons ==> projection neurons
Where does info go after LGN?
V1 cortex
What is the ventral stream pathway?
Pganglion==>LGN==>V1==>V2==>V4==>inferior temporal cortex
What occurs if there are lesions in the inferior temporal cortex?
Decreases the ability to recognise objects
What do occular dominance columns receive input from
just 1 eye
How can occular dominance columns be shown experimentally?
Inject radioactive proline and its is eventually accepted into cortex and you get striated picture
What do orientation columns do?
Respond to particular oritentation
What do blob columns do?
process and discriminate info about colour
What do blob columns recieve input from?
Parvocellular layers of the LGN
What do simple cells respond to?
Respond to bar orientated in certain direction
Where are simple cells located?
layers 4+6
What are the receptive fields like for simple cells?
Elongated
What is the difference between a complex cell and a simple cell?
A complex cell responds to a bar in a certain orientation positioned anywhere in the receptive field
Which layers are complex cells located?
2, 3, 5
What may complex cells receive input from?
Many simple cells
How does a hypercomplex cell work?
Respond to certain orientation of bar if the stimulus goes away from the receptive field the cell stops responding. But if the bar changes orientation outside of receptive field it starts responding again
Where are simple cells located and where do they send signals?
4+6 and send info to 2+3
What do inferior temporal lobe neurons respond to?
faces
What is the jennifer aniston neuron?
Idea that an object is represented by a large population of cells - population coding model
How is the info bottleneck of the optic nerve dealt with?
Retina rejects unimportant info
In darkness, what will be the state of on-bipolar cells in the fovea, and which receptors mediate this?
hyperpolarised, metabotropic glutamate receptors
What is the difference between type I afferents and type II afferents from the cochlea?
A type II afferents turn basally to innervate high frequency outer hair cells
What can be said of neurons further along the object recognition pathway?
receptive fields grow and responses become more complex
