Vision Flashcards
Where does the Optic Nerve carry information to?
Thalamus
What happens to the information in the Thalamus?
Processed and denoised
Where is light detected?
In the Retina, in specialized cells called Photoreceptors
What are the two types of photoreceptors? What are they responsible for?
Rods - seeing in low level light
Cones - colour and seeing in normal lighting
Which are greater in number, Rods or Cones?
Rods
Which more sensitive, Rods or Cones?
Rods
Different cells will be stimulated depending on an objects _______ and _______ in the visual field.
Position and orientation
What two factors affect firing rate in the visual Cortex
Position and orientation
Signals go from the rods and cones to the Ganglion cells via which cells?
Bipolar
Rods/Cones —-> Bipolor —-> Ganglion
What is a receptive field?
The receptive field is part of a sensory neuron, it is responsible for triggering that neuron after some stimuli.
Given the equation;
R = Ro + sum(w . I)
Explain the (w . I) term
W_ij = particular part of the receptive field
I_ij = illumination at a particular point in the field
Dotting W and I will give you the neuron activity for a given location in the viusal field.
What qualities make a good feature?
1 - Sparseness
2 - Small reconstruction error
There are 10 dots that positioned vertically.
Why is it easier to identify the vertical line opposed to identifying each dot?
Using the vertical line as a feature will mean less neurons are active.
1 neuron active to identify/code vertical line
10 neurons active to identify/code each dot
How is the quality of a feature determined?
Using an error function.
E = reconstruction error + f(sparseness)
The f(sparseness) is a penalty function, where E incurs a penalty proportional to the information required for the feature (penalty for not being sparse).
The more accurate and sparse the better!
