The right inferior frontal gyrus and poststroke aphasia: a follow-up investigation.

Background And Purpose: Recently, a combined repetitive transcranial magnetic stimulation (rTMS) and activation positron emission tomography (PET) study showed essential language function of the right inferior frontal gyrus (IFG) in some right-handed acute poststroke aphasics. We reexamined these patients in the chronic phase to test whether the right IFG remained essential for language performance.

Methods: We reexamined 9 male right-handed patients, age 41 to 75 years, with aphasia 8 weeks after left hemispheric stroke.

Early electroencephalography in acute ischemic stroke: prediction of a malignant course?

Objective: In patients with large middle cerebral artery (MCA) infarction space occupying brain edema may lead to a malignant course with up to 80% mortality under conservative treatment. As interventional treatment strategies must be started before the deterioration occurs predictors of a malignant course are necessary.

Patients And Methods: This study reports on the results of early electroencephalography (EEG) within 24h after onset of stroke in 25 patients suffering a large MCA infarct (12 patients with a malignant and 13 with a non-malignant course).

From the left to the right: How the brain compensates progressive loss of language function.

In normal right-handed subjects language production usually is a function oft the left brain hemisphere. Patients with aphasia following brain damage to the left hemisphere have a considerable potential to compensate for the loss of this function. Sometimes, but not always, areas of the right hemisphere which are homologous to language areas of the left hemisphere in normal subjects are successfully employed for compensation but this integration process may need time to develop.

Role of the contralateral inferior frontal gyrus in recovery of language function in poststroke aphasia: a combined repetitive transcranial magnetic stimulation and positron emission tomography study.

Background And Purpose: Functional neuroimaging studies have demonstrated right inferior frontal gyrus (IFG) activation in poststroke aphasia. It remains unclear whether this activation is essential for language performance. We tested this hypothesis in a positron emission tomography (PET) activation study during a semantic task with repetitive transcranial magnetic stimulation (rTMS) on right-handed patients experiencing poststroke aphasia and examined whether rTMS stimulation over the right and left IFG would interfere with language performance.

Neuroimaging-guided rTMS of the left inferior frontal gyrus interferes with repetition priming.

Neuroimaging studies of right-handed normal volunteers under semantic word generation tasks have consistently reported left lateralized activation of the anterior inferior frontal gyrus (ifg) which decreased during task repetition. This repetition-related activation decrease has been interpreted as the neurophysiological correlate of repetition priming, a mechanism of implicit memory for initial semantic processing. We interfered with left lateralized ifg activation, as identified by O-15-water PET activation, using repetitive transcranial magnetic stimulation (rTMS) in five right-handed male normal subjects, once using new (unprimed) nouns and once using known (primed) nouns for the procedure.

Essential language function of the right hemisphere in brain tumor patients.

Neuroimaging studies of language networks in patients with brain lesions of the left language-dominant hemisphere have shown activation in the right inferior frontal gyrus (IFG). We tested the functional relevance of right IFG activation using neuroimaging-guided repetitive transcranial magnetic stimulation (rTMS) to disturb language function over bilateral IFG in right-handed patients with brain tumors and controls. All subjects were susceptible to TMS over the left IFG.

Functional imaging in the assessment of capability for recovery after stroke.

After an ischaemic lesion preserved components of a functional network are utilized for recovery from neurological defects. The hierarchy of the individual parts within the damaged network, however, determines the quality of the outcome. This could be clearly demonstrated for the complex network of language ability, for which the left temporal region plays an integrative role: only if the left temporal regions are morphologically preserved and can be reactivated in imaging studies of speech performance was the outcome of poststroke aphasia satisfying.