The Visual System Flashcards
(8 cards)
Simple cells
Antagonistic on and off regions with straight borders
Responds best to bars of light in a specific orientation at a specific location in the visual field - edge/line detectors
High level feature
Complex cells
More common
Respond to a particular straight-edge stimulus of a particular orientation regardless of its position within the receptive field
Some respond optimally to movement of the bar in a specific direction - some like the stimulus to move
Cortical organisation
Space mapping of the visual cortex
Separation of the lines
Orientation of these lines
Whether they’re moving or not (a cue for depth perception)
Ventral stream
Travels to temporal lobe (memory and speech are here)
Involved in scene analysis and object identification (what stream)
Knowing what a thing is (able to recognise and identify it) and all the info associated with it
Recognition, analysis, identification
Dorsal stream
Travels to parietal lobe
Processes spatial locations (where stream)
Spatial and (to some extent) movement info
Understanding where body is in space and being able to move around and navigate space
Retino-tectal projection
Gaze shift - foveation (evoked eye movements being events onto the fovea)
Away or to sudden visual events
Neurons are sensitive to luminance change - appear, disappear, move
Access to reinforcement learning mechanisms
Retino-geniculate-striate pathway
Spatially organised retinotopjc projection - each relay within the system is organised according to a spatial map of the retina
2 stimuli presented to adjacent regions of retina excite adjacent neurons at all levels of the system
How is a neural model of the visual world constructed?
Elemental features construct a neural model of the visual world through perceptual processing which enhances the features critical for survival
- Contrast enhancement - object detection
- Luminance change - movement detection
What’s importance for survival? Change and contrast
