Final answer:
The sensation that may precede the onset of a migraine is called an aura. It includes visual disturbances and sensory changes that serve as a warning sign.
Step-by-step explanation:
The sensation that may precede the onset of a migraine is called an aura. An aura is a group of symptoms that can include visual disturbances such as seeing flashing lights or zigzag lines, as well as sensory changes like tingling or numbness in the face or hands. These symptoms typically last for about 15-30 minutes and serve as a warning sign that a migraine headache is about to occur.