Hemispheric specialization using SPECT and stimulation tasks in children with dysphasia and dystrophia

Area of Science:

• Neuroscience
• Developmental Psychology
• Speech-Language Pathology

Background:

• Developmental dysphasia is a severe childhood learning disorder linked to hemispheric specialization issues.
• Understanding brain function in dysphasia is crucial for effective interventions.

Purpose of the Study:

• To investigate regional cerebral blood flow (rCBF) in children with developmental dysphasia during specific cognitive tasks.
• To compare brain activity patterns in dysphasia patients with those in children with Duchenne muscular dystrophy and healthy controls.

Main Methods:

• SPECT imaging was used to measure rCBF at rest and during dichotic listening (left hemisphere) and dichaptic palpation (right hemisphere) tasks.
• Eight right-handed boys with expressive dysphasia (8-12 years) were compared to age-matched boys with Duchenne muscular dystrophy and healthy controls.

Main Results:

• Children with dysphasia failed to increase left hemisphere rCBF (Broca's area) during dichotic listening, showing increased right hemisphere activity instead.
• Dichaptic tasks revealed bilateral rCBF increases in dysphasia patients, unlike controls who showed right-hemisphere specific increases.
• Resting state rCBF asymmetry favored the right hemisphere in dysphasia patients, except in Broca's area.

Conclusions:

• Functional specialization of both cerebral hemispheres is impaired in developmental dysphasia.
• Abnormal hemispheric specialization may also underlie learning disabilities observed in Duchenne muscular dystrophy.