2009, Meinzer, Marcus, Paul, Isabella, Wienbruch, Christian, Djundja, Daniela, Rockstroh, Brigitte

AIM: Little is known about how treatment affects the neural substrate of language function in stroke sufferers. In the present study authors investigated neuronal correlates of treatment induced recovery of language functions in patients with chronic aphasia. METHODS: In 10 chronic aphasia patients and 10 age- and gender-matched control participants, evoked high-frequency activity (HFA, >20 Hz) was determined from the magnetoencephalogram in an automatic word recognition task, in which content, function, and pseudowords were visually presented at fast rate (350-ms). Recording was repeated after 2 weeks, in aphasics after intensive language training to evaluate training effects, in controls to establish HFA stability. RESULTS: In the first recording, bilateral HFA distribution in controls contrasted right-hemispheric predominance in the patients. After training, this right>left asymmetry in aphasics was reduced to a bilateral pattern similar to controls. While word class did not substantially affect HFA patterns in the two groups, enhanced right-hemispheric HFA in the patients varied with better language function (test performance) prior to training, while after training, left-temporal function- and pseudoword evoked HFA varied with performance in tests of written language. CONCLUSIONS: Results suggest that HFA might serve as a measure in the evaluation of rehabilitation efforts in chronic aphasia: enhanced right-hemispheric HFA might indicate compensatory activation of contralateral language areas, which tends towards patterns comparable to normal subjects after effective language training.

2001, Rockstroh, Brigitte, Kissler, Johanna, Mohr, Bettina, Eulitz, Carsten, Lommen, Ursula, Wienbruch, Christian, Cohen, Rudolf, Elbert, Thomas

Background: A growing body of literature suggests that schizophrenic patients often do not show the normal brain hemispheric asymmetry. We have found this for simple tones presented to the right ear in a previous study. In this study we extended this investigation to left ear stimulation and verbal stimuli. Methods: With a whole-head neuromagnetometer, contra- and ipsilateral auditory-evoked magnetic fields in response to tones (1000 Hz) and to the syllables (ba) delivered to the left and right ears in separate runs were compared between schizophrenic patients (n = 17) and healthy control subjects (n = 15). Results: In response to tones, all control subjects showed the expected asymmetry (contralateral predominance) of the auditory-evoked magnetic N100m (dipole moment). In the patient sample asymmetry was reversed following tones presented to the left ear in 47% and following tones to the right ear in 24%. In response to syllables, the asymmetry was similar between groups. In patients compared with control subjects the N100m was located more anterior without asymmetry between hemispheres. Conclusions: Results suggest that deviation from the normal functional lateralization in schizophrenia appears in a proportion of patients at a basic stage of auditory processing, but may be compensated for at higher levels such as the processing of syllables.

2002, Fernández, Alberto, Maestú, Fernando, Amo, Carlos, Gil, Pedro, Fehr, Thorsten, Wienbruch, Christian, Rockstroh, Brigitte, Elbert, Thomas, Ortiz, Tomás

2000, Rockstroh, Brigitte, Kissler, Johanna, Mohr, Bettina, Eulitz, Carsten, Lommen, Ursula, Wienbruch, Christian, Cohen, Rudolf, Elbert, Thomas

Background: A growing body of literature suggests that schizophrenic patients often do not show the normal brain hemispheric asymmetry. We have found this for simple tones presented to the right ear in a previous study. In this study we extended this investigation to left ear stimulation and verbal stimuli.
Methods: With a whole-head neuromagnetometer, contra- and ipsilateral auditory-evoked magnetic fields in response to tones (1000 Hz) and to the syllables ("ba") delivered to the left and right ears in separate runs were compared between schizophrenic patients (n = 17) and healthy control subjects (n = 15).
Results: In response to tones, all control subjects showed the expected asymmetry (contralateral predominance) of the auditory-evoked magnetic N100m (dipole moment). In the patient sample asymmetry was reversed following tones presented to the left ear in 47% and following tones to the right ear in 24%. In response to syllables, the asymmetry was similar between groups. In patients compared with control subjects the N100m was located more anterior without asymmetry between hemispheres.
Conclusions: Results suggest that deviation from the normal functional lateralization in schizophrenia appears in a proportion of patients at a basic stage of auditory processing, but may be compensated for at higher levels such as the processing of syllables.

2001, Fehr, Thorsten, Kissler, Johanna, Moratti, Stephan, Wienbruch, Christian, Rockstroh, Brigitte, Elbert, Thomas

Background: Schizophrenic patients exhibit more activity
in the electroencephalographic delta and theta frequency
range than do control subjects. Using magnetic source
imaging (MSI) our study aimed to explore this phenomenon
in the magnetoencephalogram (MEG), the distribution
of its sources, and associations between symptom
profiles and sources of low-frequency activity in the brain.
Methods: Whole-head MEG recordings were obtained
from 28 schizophrenic patients and 20 healthy control
subjects during a resting condition. The generators of the
focal magnetic slow waves were located employing a
single moving dipole model. Distributed or multiple delta
and theta sources were captured by the minimum norm
estimate.
Results: Both localization procedures showed slow wave
activity to be enhanced in schizophrenic patients compared
with control subjects. Focal slow wave activity
differed most between groups in frontotemporal and in
posterior regions. Slow wave activity was associated with
symptom characteristics in that positive symptoms varied
with frontal delta and theta activity.
Conclusions: Results indicate that activity in low-frequency
bands in schizophrenic patients exceeds the activity
of control subjects in distinct areas, and that this focal
clustering of neuromagnetic slow waves may be related to psychopathologic characteristics.