Bacterial Microprocessing

To someone trying to understand the brain, the bacterium Escherichia coli must be an awesome beast. Its talents are legion, but its size is miniscule. E. coli is a cylindrical organism less than 1 μm in diameter by 2 μm long—20 would fit end-to-end in a single rod cell of the human retina or some 3000 in that of a frog. Yet, it is adept at counting molecules of specific sugars, amino acids, or dipeptides; at integration of similar or dissimilar sensory inputs over space and time; at comparing counts taken over the recent and the not so recent past; at triggering an all-or-nothing response; at swimming in a viscous medium; and as we shall see, even at pattern formation.