# Least Exciting Inputs (LEIs)

Many neurons in macaque V1 and V4 do not merely raise firing for a preferred stimulus; they are excited by one visual feature and suppressed by a distinct one around an elevated baseline. Using functional digital twins, deep networks trained on recorded responses that predict how a neuron will answer new images, researchers identified each neuron's most and least activating images across more than a million natural images, and confirmed that these images sit at the extremes of recorded responses and hold up under independent models. The same bidirectional selectivity appears in mouse V1 and lateral visual areas.

Many neurons in macaque V1 and V4 do not merely raise firing for a preferred stimulus; they are excited by one visual feature and suppressed by a distinct one around an elevated baseline. Using functional digital twins, deep networks trained on recorded responses that predict how a neuron will answer new images, researchers identified each neuron's most and least activating images across more than a million natural images, and confirmed that these images sit at the extremes of recorded responses and hold up under independent models. The same bidirectional selectivity appears in mouse V1 and lateral visual areas.