fMRI of language lateralisation

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Abstracts / Psychiat~ Research: Neuroimaging68 (1997) 155-184

fMR1 is a promising technique to investigate brain activation on different processing levels. Increased attention has been drawn to the non-motor higher order functions of the cerebellum. We studied the activation of the auditory cortex and cerebellum during music as a highly complex pattern of auditory stimulation. Functional imaging was performed using a gradient echo multislice EPI pulse sequence at 1.5 T. (TR 1.8 ms, flip angle 90 °, FOV 210 ram, matrix interpolation 128, voxel size 3.13 x 3.13 x 4 mm, 15 slices) and Z-statistic evaluation. In all subjects (n = 5) superior temporal gyrus and transverse gyrus were activated. Activation of the cerebellum was observed consistently. An intersubject heterogeneity in localization in dentate and cerebellar hemispheric activation pattern appeared. The present study revealed activation of the cerebellum during music listening as a novel finding. Yet it remains to be clarified which aspects are processed in the dentate and cerebellar hemispheres during music listening. fMRI of language lateralisation D. Khorram-Sefat, S. Herminghaus, H. Hacker

Department of Ne,lroradiology, University Hospital Frankfnrt/ Main, Germany The first clinical application of fMRI might be the pre-surgical localization of language areas in patients prior to ressective neurosurgical treatment. Three activation conditions were investigated consisting of covert word generation to an auditory given letter, verb generation to a visually presented noun and listening to a text in patients with left hemispheric lesions (n = 15) and healthy controls (n = 10). Functional imaging was performed using a G E EPI pulse sequence at 1.5 T. (TR 1.8 ms, flip angle 90 °, FOV 220/250 tra/sag, matrix 128, voxel size 3. 13 × 3, 13 × 4 mm, 15 slices) and Z-statistics. Lateralisation was most pronounced during word and verb generation. In patients lateralisation was less clear or even absent. Signal increases were also observed adjacent or inside the lesion reflecting high desoxyhemoglobin content in tumor vessels, or localization of function. In the view of the clinical lesion studies of eloquent areas, further studies are promising for understanding the language functions of the right hemisphere and neuronal plasticity changes and should include specific linguistic task designs adequate for patients. Electrical brain activity reflecting semantic memory access in normal volunteers and schizophrenic patients: evidence from indirect semantic priming M. Kiefer, I. Kern, M. Weisbrod, S. Maier, M. Spitzer

Psychiatric Hospital University of Heidelberg, Germany Event-related potentials (ERPs) are a powerful tool for monitoring the working brain on-line. Furthermore, with dense electrode sampling (i.e. 64 channels or more) inferences about the neural generators are possible. The goal of this study was to investigate the time course and the topography of ERPs in a semantic priming paradigm in controls and schizophrenic

patients. ERPs were collected with 64 electrodes while subjects performed a lexical decision task. Subjects were presented with a prime and subsequently with a target (50~,: words, 50% non-words). Primes and target-words were differently semantically related: directly related (hen-egg), indirectly related (lemon-sweet) and non-related words (sofa-wing). As shown in our recent studies, patients and controls differed in the N400 component. In addition, an earlier left frontal effcct was found. This frontal effect confirms findings of other functional neuroimaging studies (PET, fMRI) and may reflect semantic memory activation. Spatial EEG configuration of dementia patients A. Kinoshita ~. M. Shigeta b, T. Yagyu a'c, N. Saito a, T. Hirota ~, M. Saito a

aDepartrnentof Neuropo'chiatry, Kansai Medical UniL~ersi(v,O~a~, Japan. bDepartment of Psychiatry, Jikei University School of Medicine, Tokyo, Japan. CDepartment of PsychiauT, University Hospital Ziirich, Ziirich, Switzerland Spontaneous multichannel (21 channels) brain electric field (EEG) map series of 54 geriatric patients (18 dementia patients of Alzheimer type, 19 patients with objective memory disturbance, and 17 patients with subjective memory disturbance) and 16 age-matched controls were segmented into microstates of quasi-constant landscape but varying duration. Spatial landscapes consisted of the six microstate variables which were specific window size, duration, orientation, distance between windows, location of center of gravity on the anterior-posterior axis and location of center of gravity on the left-right axis. There were no statistically significant differences among the three groups: objective memory disturbance, subjective memory disturbancc, and normal controls. In comparison to controls, the dementia patients showed an anteriorization of the center of gravity along the anterior-posterior axis. This group also showed a decrease of the distance betwccn windows variables. The results indicate that gravity of brain activity of dementia patients shifts to the antero-superior direction, and are in agreement with neuropathological findings of dementia patients whose brain atrophies have originated from the parieto-occipital region. Microstate segmentation appears to be a useful method for physiologically meaningful reduction of multichannel brain electric field data. Different striatal D2 dopamine receptor binding of typical and atypical neuroleptics in schizophrenic patients visualized by means of 123I-IBZM SPECT E. Klemm a, S. Ruhrmann b, C. Menzel a, A. Stippel b, F. Grfinwald ~, H.-J. M611er I', M. Meier h, H.-J. Biersack a

~'Department of Nuclear Medicine, Universityof Bonn, Germany. bDepartment of Psychiatry, Universityof Bonn, Germany The raclopride derivative 1231-1BZM (iodobenzamide) has been introduced as a highly selective ligand to visualize striatal D2 dopamine receptors. (I) To compare the striatal binding of typical neuroleptics to that of the atypical neu-