Transcript 3680l10

Center-Surround Receptive Field
Why does black seem so real?
• White on Black
• Black on White
• 50% of Bipolar Cells
invert “Image”
• “ON” - turned on by
light, off by dark
• “OFF” - turned on by
dark, off by light
Lateral Inhibition
• Process by which activity in one cell
influences (negatively) the activity of
neighbouring cells.
• General, common process
• Reflected in center-surround in vision
• In retina is mediated by horizontal cells
Surround is mediated by
Horizontal Cells
Summary: Retinal Neurons
• Photoreceptors (rods & cones)
• Ganglion cells
– Outputs information to visual brain
• Bipolar cells
– Connect photoreceptors to ganglion cells
– 50% invert - “on” and “off”
• Horizontal cells
– Mediate Lateral Inhibition
– Create Receptive Field Surround
On- and Off-Center Ganglion Cells
Retinal Receptive Field Structure
Outer Plexiform Layer Surrounds
Inner Plexiform Layer Connections
Retinal Ganglion Cell Responsivity
Edge-Induced Response
Cortical Receptive Fields
Visual Receptive Fields
Building Cortical Receptive Fields
Cortical Visual Responses
Columnar Organization of Striate Cortex
Laminar Orientation Responses
Next class…
Hierarchical Visual Processing
Normal Visual Development