Right Hemisphere: Role in Recovery By Emily Seidman & Peter Peloquin
RH To The RESCUE RH LH
Barlow Case Study • 1877 Thomas Barlow, London physician, published a case of “functional speech recovery” following brain damage. • The case involved a ten year old boy who had lost his speech, regained it, and then lost it again. • Post-mortem studies of brain revealed morphological changes in brain volume in Broca’s increases in calcified brain nodules in the left facial motor area • These morphological changes also were seen in the right hemisphere. • Barlow’s case provoked subsequent investigations on the possible “takeover” functions of the right hemisphere.
New Procedures and Tests • Only recently has the role of the right hemisphere in language processing been studied thoroughly (Finger 2003). • New neurological procedures and scans have enabled researchers to study speech after unilateral and bilateral brain lesions. • One of the first tests, The Wada test, involves injecting a barbiturate into the carotid artery that leads to one side of the brain. • An injection of carotid into the left side of the brain carotid results in severely impaired speech production in 97% of the population. • However, a right-sided carotid injection was found to inhibit speech in patients with left-hemisphere damage extending into Broca’s area.
Role of RH • It has been hypothesized that although the right hemisphere plays a small role in speech production, the right hemisphere acquires the ability to regulate speech more effectively when the language areas of the left-hemisphere are damaged. • A case of functional recovery: The role of right frontal activation • Finger et al. 2003 reported additional evidence for the increased speech production capabilities of the right hemisphere after left hemispheric damage. The study consisted one non-fluent aphasiac, who had most of the damage in the left frontal cortex near Broca’s area. • His aphasia was labeled “incomplete” because he continued to do well on word generation tasks which normally activate the area he had sustained damage to, the frontal cortex.
Figure 2: A case of functional recovery; The role of right frontal activation • (a) (b) (c) • Part (a) of represents PET-scans of the coronal sections of a healthy • individual performing a speech production task. • Part (b) shows a structural MRI of a lesion to the frontal region (Broca’s • Area) of a patient who has suffered a stroke. • Part (c) shows a PET scan of the same patient during a speech production • task. • The right frontal activation is prominent in the patient post-stroke. • Researchers believe that right frontal activation could be one of many • mechanisms accounting for speech recovery.
Conclusions • In patients with LH lesions, PET-scans revealed abnormally high activation of the right frontal brain regions. • This evidence indicates that the patient’s preserved word generation abilities may be due to the recruitment of right-frontal regions. • Other studies also have shown increased right-frontal activation during word generation tasks six months to one year after stroke. • The right frontal activation is pronounced in the patient post-stroke. Therefore, researchers believe that right frontal activation may play a critical role in speech recovery in patients with LH lesions.
NO Speech & Hearing Center • Primarily autistic children • Currently 4000 patients • Treat patients autism, down syndrome, Broca’s aphasia, Wernicke’s aphasia, minor and major speech impediments, pronounciation. • 8-12 speech therapists