The P300 peek of an evoked potential is hypothesized to index an internal updating of external meaningful events. This peak is particularly relevant to the study of schizophrenia, a disorder characterized by thought disorder and auditory hallucinations. In schizophrenia, a reduction in the auditory P300 has been a robust and consistently reported finding, which is one of the most often replicated biological deficits in this disorder. Converging lines of research point to left greater than right temporal lobe abnormalities in right-handed (RH) schizophrenic males. Furthermore, recent studies have shown that functional asymmetries are linked to handedness; there is a reversal of temporal region asymmetries of P300 topography in left-handed (LH) and RH schizophrenic males. These data suggest that schizophrenic pathology of P300 generators is lateralized according to handedness in males. Furthermore, these results provide evidence that LH and RH schizophrenic males an be dissociated based on left-right voltage asymmetries in P300 topography. These data have implications for theories of functional abnormalities in schizophrenia: electrophysiological deficits may be related to neuroanatomical structure, which are auditory and language related. While the P300 data in schizophrenic males imply that lateralized P300 topographic asymmetries based on handedness may be related to cerebral dominance and related neuroanatomical structures in schizophrenia males, it is important to study these same variables in females to determine whether LH and RH schizophrenic women show similar deficits and lateralized P300 topographic asymmetries. The crucial issue is to see whether there is a relationship between handedness and P300 in schizophrenic females, particularly in light of recent normative findings that suggest a link between handedness, language development, and lateralization. Lateralized P300 asymmetry according to handedness in schizophrenic males could represent a physiological manifestation of a genetic link between handedness and language-related temporal cortex in schizophrenia; we propose to explore whether schizophrenic females also show lateralized asymmetry based on handedness. This proposed study will extend the previous work of schizophrenic males by investigating the relationship between the auditory P300 and handedness in schizophrenic females. The plan of this study is to collect P300 data on 120 female subjects: 30 RH schizophrenic females, 30 RH control females, 30 LH schizophrenic females, and 30 LH control females. A practical consequence of data from this study would be justification for a larger study, which could lead to the discovery of morphological brain markers that correlate with specific anatomical abnormalities and electrophysiological deficits in schizophrenia.
| Holinger, D P; Shenton, M E; Wible, C G et al. (1999) Superior temporal gyrus volume abnormalities and thought disorder in left-handed schizophrenic men. Am J Psychiatry 156:1730-5 |
