A deviant EEG brain microstate in acute, neuroleptic-naive schizophrenics at rest

Momentary brain electric field configurations are manifestations of momenta ry global functional states of the brain. Field configurations tend to pers ist over some time in the sub-second range ("microstates") and concentrate within few classes of configurations. Accordingly, brain field data can be reduced efficiently into sequences of re-occurring classes of brain microst ates, not overlapping in time. Different configurations must have been caus ed by different active neural ensembles, and thus different microstates ass umedly implement different functions. The question arises whether the aberr ant schizophrenic mentation is associated with specific changes in the repe rtory of microstates. Continuous sequences of brain electric field maps (mu ltichannel EEG resting data) from 9 neuroleptic-naive, first-episode, acute schizophrenics and from 18 matched controls were analyzed. The map series were assigned to four individual microstate classes; these were tested for differences between groups. One microstate class displayed significantly di fferent field configurations and shorter durations in patients than control s; degree of shortening correlated with severity of paranoid symptomatology . The three other microstate classes showed no group differences related to psychopathology. Schizophrenic thinking apparently is not a continuous bia s in brain functions, but consists of intermittent occurrences of inappropr iate brain microstates that open access to inadequate processing strategies and context information.