How have researchers determined that the brain of a dyslexic reader functions differently than the brain of a non-dyslexic reader?

Researchers have compared results from the Jerry Johns Reading Inventory to identify differences in dyslexic readers and non-dyslexic readers.
Researchers have documented the fluency rates of dyslexic readers and non-dyslexic readers.
Researchers have not found that the brains of dyslexic readers and non-dyslexic readers are different.
Researchers have functional Magnetic Resonance Imaging (fMRI) to identify differences in the brain.