Visual stimulus recognition Flashcards
What is the hierarchical order of object recognition?
Detection of edges -> Combination of edges and contours -> detection of parts -> detection of objects from a point of view -> view invariant object recognition (e.g a particular person) -> Categorisation
What are the areas in the ventral stream?
p-ganglion cell -> LGN parvocells -> V1 -> V2 -> V4 -> inferior temporal lobe
How does the hierarchical order of object recognition work?
From V1 to inferior temporal lobe, complexity and size of receptive fields increases
What is the Structure of the LGN?
6 layers
monocular input (layers alternate input from each eye)
has P and M ganglion cells
Retinoptically organised - neurones with receptive fields close together in visual space have cell bodies close together in nucleus
What is the Function of the LGN?
Thalamic relay station - ganglion cell axons connect with LGN projection neurones
What are the 3 columns in the cortex?
Occular dominance
Orientation
Blobs
What is the function of the occular dominance column?
Each column responds preferentially to contralateral or ipsilateral eye - important for binocular vision
What is the function of the orientation column?
Contains neurones that responds to different orientations of objects
What is the function of blobs?
Contains neurones that process information about colour
What layers of the cortex are Simple cells present in?
Layers 4 and 6
What layers of the cortex are complex cells present in?
Layers 2,3 and 5
How do simple cells work?
respond to stimuli with specific orientations
have distinct excitatory and inhibitory regions
have summation properties and mutual antagonism properties
How do complex cells work?
Cannot be mapped into excitatory and inhibitory regions
Respond to patterns of light in certain orientations within large receptive field
Receives input from simple cells
