PSYCH 454 Lecture Notes - Lecture 9: Ganglion Cell, Edge Detection, Ganglion
24 May 2018
School
Department
Course
Professor
Lecture 9: Eye- On/Off Centers (3)
ON and OFF center Ganglion Cells → which bipolar cells control/predict/provide input to
● Ganglion cells have center-surround receptive fields
● 2 main types of receptive fields (same as bipolar)
○ON-center (and OFF-surround)
○OFF-center (and ON-surround)
●ON-center ganglion cells responds when…
○ Onset of small bright light in center of RF
○ Offset of annulus of light in surround of RF
○ Shine light @ center→ increased response of ganglion cell
■ Shine light on surround→ no response of ganglion cell
●OFF-center ganglion cells responds when…
○ Offset of small bright light in center of RF
○ Onset of annulus of light in surround of RF
○ Shine light @ surround→ increased response of ganglion cell
■ Shine light on center→ no response of ganglion cell
○ Will respond if you take light away from center of RF
● Ganglion cells→ SENSITIVE to contrast (ie light and dark areas)
○ Ganglion cells respond little with change in brightness over large area
○ Good response if light and dark difference (center and surround differences in
light amount)
○ Key role to play in edge detection in our environment
● On center and off center ganglion cells across retina → small individually, but summed
can cover all of visual space
○ Although individual RF =small, piecing them together covers visuals field
○ Ex of fine grain representation
Response characteristics of Ganglion Cells
● ON-center and OFF-center ganglion cells have complementary responses
○ When on-center cell responds well, off-center cell responds poorly
● Ex: OFF-center cell responses
● Vertical lines below- single action
potential
● TOP ROW PANELS:
○ When light is applied across
entire RF of OFF-center→
very few AP
○ When dark @ center→ many
AP
○ When dark @ center AND
surround→ some AP’s
Document Summary
On and off center ganglion cells which bipolar cells control/predict/provide input to. 2 main types of receptive fields (same as bipolar) Onset of small bright light in center of rf. Offset of annulus of light in surround of rf. Shine light @ center increased response of ganglion cell. Shine light on surround no response of ganglion cell. Offset of small bright light in center of rf. Onset of annulus of light in surround of rf. Shine light @ surround increased response of ganglion cell. Shine light on center no response of ganglion cell. Will respond if you take light away from center of rf. Ganglion cells sensitive to contrast (ie light and dark areas) Ganglion cells respond little with change in brightness over large area. Good response if light and dark difference (center and surround differences in light amount) Key role to play in edge detection in our environment.
