This study investigates by molecular dynamics the response of model metallic glasses to artificial atom displacements at increasing deformation degrees. Glasses are shown to contain unstable regions that spontaneously rearrange under deformation. The relative stability of such regions was measured by the length of artificial atomic displacements inducing a rearrangement. Such length scales with the amplitude of atomic thermal vibrations, which suggests for deformation-induced rearrangements a thermal activation mechanism. (C) 2010 Elsevier B.V. All rights reserved.