However, after the performance increase saturated, brain activation in V1 decreased to the level observed before training, whereas the high performance was retained. In that case, no systematic activity change particularly in the region or hemisphere corresponding to the trained location was observed in any other brain area. This rules out the possibility that top-down influence or feedback from a higher cortical area(s) modulates V1 activation changes (see sidebar Do Response Changes in a Brain Area Shown afterTraining Always IndicateThat PlasticityHas Occurred inThis Area?).