Lateral Inhibition: How does it work Lateral Inhibition: How does it work? Each receptor (R) actives 1 bipolar (B) & 1 horizontal (H) cell. Each horizontal cell inhibits its own bipolar and each neighboring bipolar cell. The “net” output of the bipolar cell to the ganglion cell (G) determines the signal to the brain. R R R R R R R R H H H H H H H H ADD THE EXCITATION AND INHIBITION TO GET THE NET RESULT B B B B B B B B G G G G G G G G -1 +0 -2 +5 -3 +5 -1

EQUAL LIGHT STIMULATION Lateral Inhibition: Rules: Excitation (+5) is greater than inhibition (-1). EQUAL LIGHT STIMULATION R R R R R R R R H H H H H H H H ADD THE EXCITATION AND INHIBITION TO GET THE NET RESULT B B B B B B B B G G G G G G G G -1 +0 -2 +5 -3 +5 -1

EQUAL LIGHT STIMULATION Lateral Inhibition: Calculate the inhibitory and excitatory inputs to the bipolar cells in the boxes at the bottom. EQUAL LIGHT STIMULATION R R R R R R R R H H H H H H H H ADD THE EXCITATION AND INHIBITION TO GET THE NET RESULT B B B B B B B B G G G G G G G G -1 +0 -2 +5 -3 +5 - 0 1 -1 +0 -2 +5 -3 +5 -3 +5 -2 +5 -1 +0

EQUAL LIGHT STIMULATION Lateral Inhibition: The net output to the ganglion cells has an enhanced signal at the borders. EQUAL LIGHT STIMULATION R R R R R R R R H H H H H H H H ADD THE EXCITATION AND INHIBITION TO GET THE NET RESULT B B B B B B B B G G G G G G G G -1 +0 -2 +5 -3 +5 -1 -1 +0 -2 +5 -3 +5 - 0 1 -1 3 2 2 3 -1

Lateral Inhibition: Try it yourself: Try different patterns and intensities of light activation. -1 +0 -2 +5 -3 +5 -1 ADD THE EXCITATION AND INHIBITION TO GET THE NET RESULT