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Bernal S D_2010.pdf - University of Plymouth

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2.3. ILLUSORY AND OCCLUDED CONTOURS<br />

a ^<br />

TMJ<br />

Bound»f¥ [ 1 _,<br />

r*pra»«ntatton V y<br />

Sllmulua<br />

b<br />

Bound iry<br />

rapreHnUHon<br />

stimuli!* C<br />

m?<br />

^<br />

Figure 2.IS: Bipole impiemenlalion by kaizuduand Grossberg (2001), Ovuls represent pyramidal<br />

cells located in layer 2/3 wiih collinear and co-oriented receptive fields.<br />

They arc connected lo each other via excitatory long-range hori/.onlul synapses.<br />

These conticclions also excite a pool <strong>of</strong> inhihilury interneuroiis (black circles)<br />

connected via short range synapses to the pyramidal cell, a) Input froin jusl one<br />

side is insullicient lo elicit a response in the larget pyramidal cell. This is ihe<br />

result <strong>of</strong> exciiaiion also targeting the inhihiiory neurons whicli balance out Ihe<br />

excitation, h) When inpui arrives from collinearly aligned inducers on either<br />

side, the bipole property arises due to the circuits' exciiaiory/inhibitory balance,<br />

leading to coniour completion. The target neuron summates inducing excitation<br />

arising from neurons at both sides. Additionally, this excitation falls onto the<br />

shared pool <strong>of</strong> inhibitory intcrneurons, which also inhibii each other, normalizing<br />

Ihe lolal amount <strong>of</strong> inhibition .sent to the larget pyramidal neuron.<br />

58

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