EEG coherence during hemispheric activation in schizophrenics

Abstract

We studied the change of EEG alpha-band coherence between resting and motor performance ("reactivity of EEG coherence") in 18 chronic schizophrenics and 30 normal controls, examining differences between left and right hemisphere tasks. Three coherences were examined for each hemisphere. The central-parietal coherence in normals increased on the left for left hemisphere tasks, and decreased on the right for right hemisphere tasks, whereas the patients showed a decrease of both measures, more on the left side. Thus, the interhemispheric difference of central-parietal coherence reactivity was reversed for the schizophrenics (P less than 0.06) and suggested a left-sided deviation. The lateral-percentral and precentral-central coherences showed no left-right deviations of reactivity in the patients. Since coherence increase is considered to be a sign of the coupled function between the studied regions, our findings suggest a defective coordination of left central-parietal regions during a task in schizophrenics.

Parametric manipulations of auditory stimuli differentially affect P3 amplitude in schizophrenics and controls

“…Schizophrenics also show left-sided temporal area electro-physiological abnormalities, both in electroencephalograms (e.g., alpha coherence [Michelogiannis, Paritsis, & Trikas, 1991]) and P3 voltage (e.g., Morstyn, Duffy, & McCarley, 1983). Recent experiments in our lab have replicated this left temporal scalp area deficit in P3 in schizophrenics, with smaller amplitudes at electrode sites overlying left temporal lobe relative to those on the right (Faux, Shenton, McCarley, Torello, & Duffy, 1988a;Faux, Torello, McCarley, Shenton, & Duffy, 1988b;Faux et al, 1990).…”

NMDA receptor antagonist effects, cortical glutamatergic function, and schizophrenia: toward a paradigm shift in medication development

“…These postmortem studies are paralleled by in vivo structural neuroimaging findings indicating reduced cortical volumes (Lim et al 1996;Weinberger et al 1992;Wible et al 1995), magnetic resonance spectroscopy studies consistent with reduced neuropil volume or viability (Bertolino and Weinberger 1999;Steel et al 2001), and diffusion tensor imaging studies suggesting that cortical connectivity is disturbed (Buchsbaum et al 1998;Kubicki et al 2002;Lim et al 1999). These synaptic deficits appear to interfere with the coherent activity of cortical networks (Hoffman et al 1991;Koenig et al 2001;Lawrie et al 2002;MeyerLindenberg et al 2001;Michelogiannis et al 1991;Tauscher et al 1998;Winterer et al 2001), but may in some cases and using some research paradigms produce excessive coherence of regional brain activity (Mann et al 1997;Wada et al 1998). Consistent with these disturbances in cortical network functions, schizophrenic In each figure, dendritic spines are the lollipop-like blebs that protrude from the dendrites.…”

Aberrant Functional Organization in Schizophrenia: Analysis of EEG Coherence during Rest and Photic Stimulation in Drug-Naive Patients

“…These findings are consistent with those of Shaw et al [35], who reported that the EEG coherence of schizophrenic patients decreased when they performed visual imagery tasks, in contrast to the increase observed in neurotic patients. Similarly, Michelogiannis et al [36] reported that chronic schizophrenic inpatients failed to show an increase in coherence (particularly in the left hemisphere) when performing hemisphere activation tasks (i.e., finger movements). In accordance with these data on coherence, earlier EEG studies reported that schizophrenic patients generally showed reduced EEG changes in response to external stimuli [2].…”