A BOLD Assumption.

Abstract

Interpreting fMRI data relies on the assumption that hemodynamic responses reflect neuronal activity. Some recently reported results seem to suggest that this assumption might be less robust than what has been thought so far. Data by Schummers et al. (2008) suggest that hemodynamic responses depend on functional properties of astrocytes as mediators of neuronal activity to blood vessels, and therefore reflect neuronal tuning properties only indirectly. The question is how much the final outcome differs from a linear integration of the local neuronal responses.