fMRI data analyses are often directed to disentangling and understanding the neural processes that occur among brain regions.
Interactions in the brain are expressed, not at the level of hemodynamic responses, but at the neural level. Thus, an intermediate step that estimates the underlying neuronal activity is necessary for such analyses.
These global events are difficult to compensate during data preprocessing (Power et al. (2018)) and can be misinterpreted as neuronally related since their temporal signature can closely resemble the hemodynamic response function (HRF) assumed by the deconvolution model to describe neurovascular coupling.