title: Working memory abnormalities in chronic interictal epileptic psychosis and schizophrenia revealed by magnetoencephalography.
abstract: Working memory (WM) deficits are considered a core cognitive dysfunction in schizophrenia. To determine cognitive abnormalities in chronic interictal psychosis (CIP), and to assess whether these abnormalities are distinguishable from those seen in schizophrenia in terms of WM deficits, we used magnetoencephalography during a WM task performed by patients with CIP, nonpsychotic epilepsy, and schizophrenia and by healthy subjects. Multiple Source Beamformer and Brain-Voyager were used for analysis. In both patients with CIP and those with schizophrenia, we found dorsolateral prefrontal hyperactivation and left inferior temporal hypoactivation, as indicated by alpha event-related desynchronization and synchronization, respectively. Patients with schizophrenia also showed alpha2 event-related desynchronization in the mid-prefrontal cortex relative to healthy controls. Direct comparison of patients with CIP and schizophrenia rendered no difference in source-power changes. Our findings indicate similar functional cognitive abnormalities in CIP and schizophrenia in the prefrontal and left temporal cortex, which supports the possibility that these disorders share common underlying pathophysiological mechanisms.
authors.affiliation: Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Leonides
authors.initials: L
authors.lastname: Canuet
authors.forename: Ryouhei
authors.initials: R
authors.lastname: Ishii
authors.forename: Masao
authors.initials: M
authors.lastname: Iwase
authors.forename: Koji
authors.initials: K
authors.lastname: Ikezawa
authors.forename: Ryu
authors.initials: R
authors.lastname: Kurimoto
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Takahashi
authors.forename: Antonio
authors.initials: A
authors.lastname: Currais
authors.forename: Michiyo
authors.initials: M
authors.lastname: Azechi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakahachi
authors.forename: Ryota
authors.initials: R
authors.lastname: Hashimoto
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Takeda
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D004827:Epilepsy / Q000150:complications* / Q000523:psychology; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis* / Q000209:etiology*; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000150:complications*; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000150:complications*; D013223:Statistics as Topic; D013997:Time Factors; D055815:Young Adult