Understanding the central control of bladder perception is important to comprehend the neurophysiological mechanism behind bladder sensation and lower urinary tract dysfunction. Here we design a sensation-driven functional magnetic resonance imaging (fMRI) during repetitive bladder filling and examine brain activation related to the first desire to void (FDV) and strong desire to void (SDV) sensations. These sensations are subjective and can be transient, making their study particularly challenging and insightful. To prevent constant engagement of the viscerosensory cortex and to add a layer of complexity, a diversion continuous performance task (CPT) was randomly presented. We modelled and analysed the data given the recorded responses and assessed the validity and reliability of our paradigm. Brain activation was then compared to the canonical functional networks to understand how the brain responded to the transition between CPT and the desire to void. Our approach improved reliability metrics and revealed that SDV triggered more pronounced brain activation than FDV. This underscores a robust relationship between urinary urge intensity and signal intensity. We also pinpointed several brainstem structures linked to the desire to void. Ultimately, our findings demonstrated dynamic interaction among brain functional networks during the transition between goal-driven tasks and reorienting to salient stimuli.