Right Hemisphere: Role in Recovery

By

Emily Seidman & Peter Peloquin

RH To The RESCUE

RH

LH

Figure 1: Location of the Language Areas of the Brain

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