Studies in primate physiology and human functional neuroimaging have convincingly shown that the area of the brain termed MT/V5+-which includes the middle temporal visual area MT/V5 along with adjacent motion-sensitive areas such as MST-is involved in the processing of motion information. Tootell et al.  showed that the blood oxygenation level dependent (BOLD) signal measured by functional magnetic resonance imaging (fMRI) in the human MT/V5+ seemingly correlates with the strength of perceived motion aftereffect (MAE), the illusory motion of a stationary pattern that one sees after adapting to a moving pattern. The signal in MT/V5+ decayed slowly during the period when the MAE was seen. It is possible that this slow decrease in MT/V5+ activity was unrelated to the perceptual experience of motion. After replicating Tootell et al.'s experiment, a modified version of the experiment was concluded in which a blank period was inserted between the adapting motion stimulus and the stationary testing pattern. The results demonstrated that MT/V5+ activity indeed decayed more slowly after an effective unidirectional motion adaptation than after bidirectional adaptation, without corresponding perception of MAE. Nevertheless, in a more conclusive experiment, we adapted observers to a unidirectional motion for a very long period and showed that the activity in MT/V5+ changed in synchrony with the presence and absence of perceived MAE, simply as a result of presenting a stationary visual stimulus in and out of the adapted retinal region.