Fig. 2.

Constraints on the combinatorial face code. (A) The mean firing rate of active neurons (ordinate) as a function of face number (abscissa). The white line represents the grand mean firing rate of 9.7 Hz calculated across the 2,000 individual mean rates. (B) Cumulative probability distribution of AM neuron rates. The abscissa gives the firing rate for each AM neuron, and the ordinate is the cumulative probability. The distribution functions for 2,000 faces are superimposed (black band), and an exponential distribution with a mean of 9.7 Hz (thin white line) and the average across all 2,000 observed distribution functions (thicker white line) are superimposed.