@article{StrikDierksFranzeketal.1994,
  author    = {Strik, Werner K. and Dierks, Thomas and Franzek, Ernst and St{\"o}ber, Gerald and Maurer, Konrad},
  title     = {P300 in Schizophrenia: Interactions between Amplitudes and Topography},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-63351},
  year      = {1994},
  abstract  = {Low P300 amplitudes and topographical asymmetries have been reponed in schizophrenic patients, but reference-independent amplitude assessment failed to replicate reduced amplitudes. P300 amplitude is conventially assessed at midline electrodes (PZ), anti asymmetric topography as reported in schizophrenics, may conj'ound this measurement. We lnvestigated the possible Interaction between P300 ropography and assessments of amplitudes. ln 41 clinically stable schizophrenics and 31 normal controls, the generalfinding ofreduced amplitudes at the P'l electrode and topographical asymmetrles in the patient group were replicated. ln both groups, a.symmetries of the P300 field (lateralized peaks) reduced the standard amplitude assessment at the midline parletal electrode, but did not Qjfoct the reference-independent, global amplitude assessment. This shows thal asymmetry per se does not imply reduced field strength. in addition, in schizophreraics. but not in controls, there was a significcmt effect oftlae direction of asymmetry on both amplltude measures, amplitudes belng lower with increasing shift ofthe P300 peak to the right side. Considering also the slightly left-lateralized peaks in the normal controls. this suggests rhat only right lateralized P300 peaks upressfunctional deficits in schizophrenics, whereas left lateralized pealcs fall wlthin the physiological variability of the P3OO field. Tht refonnce-independent amplitude assessment is proposed for unambiguous amplitude assessment in order to better define the clinical, psychological and physiopathological mtaning of the P3OO alterations in schizophrenics.},
  subject      = {Schizophrenie},
  language  = {en}
}
@article{StrikDierksFranzeketal.1994,
  author    = {Strik, Werner K. and Dierks, Thomas and Franzek, Ernst and St{\"o}ber, Gerald and Maurer, Konrad},
  title     = {P 300 asymmetries in schizophrenia revisited with reference-independent methods},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-63372},
  year      = {1994},
  abstract  = {Evidence of hemispheric asymmetries in schizophrenia has been reported from different research areas. Asymmetries in evoked potential P300 topography are still controversial because of inconsistent findings. In the present study. previous results of abnormal lateralization of P300 were replicated in stabilized residual Schizophrenie patients. Auditory P300 was recorded during an odd ball task in which subjeets detected rare target stimuli. Schizophrenie patients had the P300 peak shifted to the right hemisphere and differed signifieantly from age- and sex-matched normal control subjects who had left-lateralized P300 peaks. A comparison of different methods of assessment and analysis of the topographical features of the P300 electric fields showed that the extraction of reference-independent descriptors of P300 topography is a reliable and sensitive method for statistical handling of the maps. The results suggest left hemispheric dysfunction during cognitive tasks in a subgroup of Schizophrenie patients. Inconsistencies between previous sturlies are likely to be due to heterogeneous patient groups, which may have included patients in an acute Schizophrenie episode or patients in clinical remission. lnvestigation of the clinical meaning of P300 alterations requires careful psychopathological definition of the patient groups.},
  subject      = {Schizophrenie},
  language  = {en}
}