What physiological change accompanies increased neuronal activity in an fMRI scan?

The correct answer is associated with the phenomenon known as neurovascular coupling, which describes how an increase in neuronal activity leads to a corresponding increase in blood flow to the active regions of the brain. When neurons become more active, they require more oxygen and nutrients to sustain that activity. To meet this demand, local blood flow increases, which is detected during functional MRI (fMRI) scans.

This increase in blood flow enriches the area with oxygenated blood, allowing the neurons to function more effectively. In fMRI, this is measured through the Blood Oxygen Level Dependent (BOLD) signal, which reflects changes in blood flow and oxygenation levels in the brain. This response is critical for understanding brain function and is the basis for using fMRI as a tool to map brain activity during various tasks or stimuli.

Thus, the correct response highlights the essential relationship between neuronal activity and hemodynamic responses, which is fundamental in the study of brain functions using neuroimaging techniques like fMRI.