Illustration of representation sharpening in L1. (Left) Initial stimulus presentation activated a pattern of activity of the units in L1 that were activated to varying degrees. Darker filled circles indicate higher activity levels. Strengths of connections are indicated by the thickness of lines connecting the units. For clarity, we illustrate reciprocal connections as one line with two arrowheads, indicating two synapses. (Right) With stimulus repetition, connections between strongly activated units were strengthened, and connections from strongly responding units to weakly active units and between weakly active units were weakened and eventually silenced. This resulted in representation sharpening: only the most active units remained in the representation, and weakly responding units were eliminated from the representation of the stimulus.