Practice question

Neurovascular coupling links synaptic activity to hemodynamic changes. Heightened neuronal firing raises glutamate cycling and metabolic demand, triggering vasodilation through nitric oxide and astrocyte signaling, increasing regional cerebral blood volume and flow. Oxygen delivery surpasses consumption, reducing capillary and venular deoxyhemoglobin fraction. Functional MRI sensitive to blood-oxygen-level dependent contrast detects this alteration as T2* signal rise. Electroencephalography records electrical potentials directly, PET tracks glucose analogue uptake, computed tomography measures X-ray attenuation, only fMRI relies on oxygenation-level change to infer brain activity.