Article,
How behavioral constraints may determine optimal sensory representations
PLoS Biol, (2006)
Abstract
The sensory-triggered activity of a neuron is typically characterized
in terms of a tuning curve, which describes the neuron's average
response as a function of a parameter that characterizes a physical
stimulus. What determines the shapes of tuning curves in a neuronal
population? Previous theoretical studies and related experiments
suggest that many response characteristics of sensory neurons are
optimal for encoding stimulus-related information. This notion, however,
does not explain the two general types of tuning profiles that are
commonly observed: unimodal and monotonic. Here I quantify the efficacy
of a set of tuning curves according to the possible downstream motor
responses that can be constructed from them. Curves that are optimal
in this sense may have monotonic or nonmonotonic profiles, where
the proportion of monotonic curves and the optimal tuning-curve width
depend on the general properties of the target downstream functions.
This dependence explains intriguing features of visual cells that
are sensitive to binocular disparity and of neurons tuned to echo
delay in bats. The numerical results suggest that optimal sensory
tuning curves are shaped not only by stimulus statistics and signal-to-noise
properties but also according to their impact on downstream neural
circuits and, ultimately, on behavior.
