Underactivate

Wood and Flowers (1999) demonstrated with Positron Emission Tomography (PET) that the same brain regions that underactivate in dyslexia also underactivate in the inattentive subtype of attention deficit hyperactivity disorder.

In contrast, struggling readers underactivate the reading systems in the back of the brain and overactivate the system in the front of the brain.

An important discovery over the last ten years comes from studies that parametrically varied working memory load to establish that, compared to younger adults, older adults tend to overactivate PFC regions at lower loads, and to underactivate at higher loads, where performance also drops off.