The figure is based on an experiment performed by our research group, in which the images shown to participants were similar to those shown here (see ref. 137 for the actual images and ref. 138 for more examples). The raster plots indicate the action potentials fired by the neuron in response to the image above the raster. Each line represents a separate repetition. Below the raster plots, we show a post-stimulus time histogram (PSTH) aligned to the stimulus onset, showing the average activity of the neuron as a function of time. The activity of this neuron increased in response to three different images of former president Bill Clinton and not to other faces or other stimuli. The neuron showed a remarkable degree of selectivity and tolerance to transformations (92, 137). Image credit (tiger photo): www.freedigitalphotos.net.