We used a parametric experimental design to identify the rCBF variations related to a continuous variation of the attention load. The experiment involved goal-directed visual tasks. The length of time during which the subject's attention was engaged toward the external stimulus was taken as the factor of interest. The neural network revealed areas that positively (left cerebellum, bilateral MT/V5 complex and superior parietal lobule, right inferior temporal lobe and dorsolateral prefrontal cortex) or negatively (precuneus, anterior cingulate and medial superior frontal cortex) correlate with the attention load. Results demonstrate that the activity of these areas varies continuously as a function of the variation in the attention load.