The middle temporal area of the extrastriate visual cortex (area MT) is integral to motion perception and is thought to play a key role in the perceptual learning of motion tasks.We have previously found,however,that perceptual learning of a motion discrimination task is possible even when the training stimulus contains locally balanced,motion opponent signals that putatively suppress the response of MT.Assuming at least partial suppression of MT,possible explanations for this learning are that 1) training made MT more responsive by reducing motion opponency,or 2) MT remained suppressed and alternative visual areas such as V1 enabled learning.Here we used fMRI to test these two possibilities.We first confirmed that the motion opponent stimulus did indeed suppress the BOLD response within hMT+ compared to an almost identical stimulus without locally balanced motion signals.We then trained participants on motion opponent or non-opponent stimuli.Training reduced the BOLD response within hMT+ when participants were trained with the motion opponent stimulus and the suppressive effect of motion opponency was increased.In contrast,no changes at hMT+ were detected for the group trained on the non-opponent motion stimulus despite pronounced learning,and no changes occurred at V1 for either group.As the average response of many cells within MT to motion opponent stimuli is the same as their response to non-directional flickering noise,the reduced activation of hMT+ we observed after training may reflect noise attenuation.