During presentation of a stimulus, positive BOLD responses are generally attributed to local increases in neuronal activity. Sustained negative BOLD responses are also frequently observed, but their underlying neurovascular coupling mechanisms are less well understood. Here, we studied the negative BOLD response (both intra- and cross-modal) to contrast-varying visual stimuli. In grey matter, negative responses consistently decreased with increasing stimulus contrast in both visual and auditory regions. Although of larger amplitude, responses observed in draining veins tended to be less contrast-dependent.