The mushroom bodies (MBs) are involved in the visual cognitive behavior of Drosophila,such as context generalization and decision-making facing conflicting cues.Here we report that MBs mediate the salience-based orientation behavior in object fixation-tracking paradigms in the flight simulator that resemble attention behavior in primates.We found that the fixation-tracking ability of flies without MBs was significantly reduced not only at low contrast levels but also in certain noise backgrounds.In the fixation-tracking selection among multiple objects,only wild type fries discriminated the strong contrast stimulus to track,while MB-deficient flies could not.Furthermore,we also found that the MBs not only inhibit visual background noise,but also inhibit olfactory background noise in salience-based fixation-tracking behavior.However,all flies including the MB mutants showed improved fixation-tracking performance when the visual/olfactory signal was synchronous presented with an olfactory/ visual hint,which suggest that MBs are not involved in crossmodal synergetic integration between olfactory and visual signals in fixation-tracking behavior.Our findings suggest that the MBs are the brain center implementing a gating mechanism that pass and amplify the salient signals and filter out background noise or unrelated signals.