p074fig02.23 The equations for a shunting on-center off-surround network.  Shunting terms lead to many beautiful and important properties of these networks, which are found ubiquitously, in one form or another, in all cellular tissues.<BR>||  Shunting on-center off-surround network.<TABLE border="1"><TR><TD>Mass action: </td><TD>d[dt: xi] = </td><TD>-A*xi </td><TD>+(B - xi)*Ii </td><TD>-xi*sum[k≠i: Ik]</td></tr><TR><TD></td><TD></td><TD></td><TD>Turn on unexcited sites</td><TD>Turn off excited sites</td></tr></table>At equilibrium: <BR>0 = d[dt: xi] = -(A + Ii + sum[k≠i: Ik])*xi + B*Ii = -(A + I)*xi + B*Ii<TABLE border="1"><TR><TD>xi = B*Ii/(A + I) = B*θi*I/(A + I) = θi* B*I/(A + I)</td><TD>No saturation!<BR>Infinite dynamical range<BR>Automatic gain control<BR>Compute ratio scale<BR>Weber law</td></tr><TR><TD>x = sum[k-1 to n: xk] = B*I/(A + I) ≤ B </td><TD>Conserve total activity<BR>NORMALIZATION<BR>Limited capacty<BR>Real-time probability</td></tr></table>