Evolving columnar circuitry for lateral cortical inhibition

A localized excitatory stimulus applied directly to the cerebral cortex can produce a surrounding peri-stimulus inhibitory zone (“Mexican Hat Pattern”). This has long been viewed as surprising by some because this inhibitory zone appears in regions where the connections are pre-dominantly excitatory. Here we use a genetic algorithm to discover the structure and weights of a neuronal circuit for individual cortical columns without intercolumnar inhibitory connections. This circuit produces a “Mexican Hat Pattern” when an excitatory stimulus is applied. The best circuit produced in this fashion is described and predictions are made about its relation to biological cortical circuitry