How Do Efficient Coding Strategies Depend on Origins of Noise in Neural Circuits?
Fig 5
Optimal nonlinearities for a circuit with two parallel pathways, found by minimizing mean squared error (MSE) of a linear estimator.
A: Optimal nonlinearities for circuits in which pathways are of opposite polarity. Each row corresponds to a case in which one particular noise source is dominant. The dominant noise source is indicated by the highlighted source in the schematics at the center of the figure. As in Fig 2, solid curves are the optimal sigmoidal nonlinearities and colored dashed curves are optimal nonlinearities obtained analytically. The gray dashed curves represent the stimulus distribution. Shaded regions represent the range of sigmoidal nonlinearities that perform within 1% of the mean squared error of the optimal sigmoidal nonlinearities. B: Same as A but for pathways of the same polarity. We address the relative coding efficiency of the different polarities in the section “Globally optimal strategies.”