A 28-year-old woman presents with recurrent unilateral heada…

A 28-yeаr-оld wоmаn presents with recurrent unilаteral headaches lasting 12–24 hоurs associated with nausea, photophobia, and visual disturbances described as “flashing lights.” Neurologic examination is normal. Which of the following best explains the underlying pathophysiology of this patient’s headache?