Complex sentence: Deep dyslexia is caused by lesions that are often widespread and include much of the left frontal lobe; specifically, research suggests that damage to the left perisylvian region of the frontal lobe causes deep dyslexia.
Split into simpler sentences: Deep dyslexia is caused by lesions that are often widespread and include much of the left frontal lobe. Research suggests that damage to the left perisylvian region of the frontal lobe causes deep dyslexia.