Slower theta activity over the midfrontal cortex in schizophrenic patients

Disturbances of the topographical distribution of theta activity in the EEG spectra before and during voluntary movements were investigated in 31 neuroleptic-treated and in 13 untreated schizophrenics and matched controls as well as in 15 normals medicated with haloperidol. All 4 groups demonstrated similar topographical distribution of theta mean power density, with highest values over the midfrontal region. In the center frequency of the theta band, however, treated and untreated schizophrenics had lower values over the midfrontal region than at parietal electrodes. In controls and normals medicated with haloperidol, this frontoparietal "gradient" demonstrated the inverse picture, with highest values at the frontal midline electrode. Patients and controls differed significantly in this gradient. The slower theta activity over the midfrontal cortex in the schizophrenic patients is related to the hypofrontality hypothesis.