Orientation selectivity of network responses to more weakly tuned inputs.

<p><b>(A)</b> Simulations of the network in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#pcbi.1004307.g002" target="_blank">Fig 2</a> (before learning) are repeated with the following changes in the parameters: <i>s</i>_<i>b</i> (see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#pcbi.1004307.e007" target="_blank">Eq 2</a> in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#sec011" target="_blank">Materials and Methods</a>) is scaled by a connectivity factor (<i>C</i> = 1, 2, 4), which emulates an effective increase in connectivity. The relative modulation of the feedforward input to excitatory neurons, <i>μ</i>_exc (<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#pcbi.1004307.e007" target="_blank">Eq 2</a>), is reduced by a factor <math><mrow><mn>1</mn><mo>/</mo><msqrt><mi>C</mi></msqrt></mrow></math>. Finally, to keep the absolute size of modulation the same, feedforward synaptic strength is scaled by a factor <math><mrow><mn>1</mn><mo>/</mo><msqrt><mi>C</mi></msqrt></mrow></math>. The output tuning curve of the sample neuron in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#pcbi.1004307.g002" target="_blank">Fig 2A</a> for the three different values of <i>C</i> is then plotted. <b>(B)</b> Same as (A) for the network after learning. <b>(C)</b> Average tuning curves of all the cells in the network (extracted similarly to <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#pcbi.1004307.g002" target="_blank">Fig 2C</a>) are plotted for different values of <i>C</i>, along with the OSI computed for each average tuning curve. <b>(D)</b> Same as (C) for the network after learning. <b>(E, F)</b> Distribution of OSI of individual tuning curves (similar to Fig <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#pcbi.1004307.g002" target="_blank">2E</a> and <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004307#pcbi.1004307.g002" target="_blank">2F</a>) for the networks before and after learning, respectively.