**Shared properties of the fly olfactory system and the monkey human face patch neurons**

Perhaps unexpectedly, two quite different types of brain systems – the fruit fly olfactory system and the monkey inferotemporal face patches responding to human faces – share a number of properties. In both cases, the systems represent stimuli (odors and faces) by points and a high-dimensional space, one that is 50- dimensional for the fly and larger than 100-dimenstinal for the monkey. Also in both species, the mean number of neurons used to represent the stimuli is the same for every stimulus. Finally, for every stimulus, the probability distribution function of firing rates is an exponential distribution. Exponential distributions that have the same mean firing rate for every stimulus are known as ones that have a maximum entropy which means that they will encode the most stimuli with the smallest number of total neurons.