Person:
Tohen, Mauricio

Profile Picture

Email Address

AA Acceptance Date

Birth Date

Research Projects

Organizational Units

Job Title

Last Name

Tohen

First Name

Mauricio

Name

Tohen, Mauricio

Filters

19983

Settings

Author's Publications: search.filters.isAuthorOfPublication.392106a7-6576-432f-885d-003b2f1c57bd

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    First-Episode Schizophrenic Psychosis Differs From First-Episode Affective Psychosis and Controls in P300 Amplitude Over Left Temporal Lobe
    (American Medical Association (AMA), 1998) Salisbury, Dean F.; Shenton, Martha; Sherwood, Andrea R.; Fischer, Iris A.; Yurgelun-Todd, Deborah; Tohen, Mauricio; McCarley, Robert William
    Background: Schizophrenia is associated with central (sagittal) midline reductions of the P300 cognitive event-related potential and topographic asymmetry of P300, with reduced left temporal voltage. This P300 asymmetry is, in turn, linked to tissue volume asymmetry in the posterior superior temporal gyrus. However, it is unknown whether P300 asymmetry is specific to schizophrenia and whether central and lateral P300 abnormalities are due to chronic morbidity, neuroleptic medication, and/or hospitalization, or whether they are present at the onset of illness. Methods: P300 was recorded in first-episode schizophrenia, first-episode affective psychosis, and control subjects (n=14 per group). Subjects silently counted rare (15%) target tones (1.5 kHz) among trains of standard tones (1.0 kHz). Averages were constructed from brain responses to target tones. Results: Peak amplitude of P300 and integrated voltage over 300 to 400 milliseconds were significantly different between first-episode schizophrenics and controls over the posterior sagittal midline of the head. First-episode schizophrenics displayed smaller amplitudes over the left temporal lobe than first-episode affective psychotics and controls, but the groups showed no differences over the right temporal lobe. Conclusions: Left-sided P300 abnormality in first-episode schizophrenia relative to first-episode affective psychosis and controls suggests that P300 asymmetry is specific to schizophrenic psychosis and present at initial hospitalization. This P300 asymmetry suggests left temporal lobe dysfunction at the onset of schizophrenia.
  • Thumbnail Image
    Publication
    MRI Study of Cavum Septi Pellucidi in Schizophrenia, Affective Disorder, and Schizotypal Personality Disorder
    (American Psychiatric Publishing, 1998) Kwon, Jun Soo; Shenton, Martha; Hirayasu, Yoshio; Salisbury, Dean F.; Fischer, Iris A.; Dickey, Chandlee; Yurgelun-Todd, Deborah; Tohen, Mauricio; Kikinis, Ron; Jolesz, Ferenc; McCarley, Robert William
    Objective: A cavum between the septi pellucidi may reflect neurodevelopmental anomalies in midline structures of the brain. The authors examined cavum septi pellucidi in subjects with schizophrenia, affective disorder, and schizotypal personality disorder and in normal subjects. Method: Thirty schizophrenic patients (15 chronic, 15 first-episode), 16 patients with affective disorder (first-episode), 21 patients with schizotypal personality disorder, and 46 normal subjects were evaluated with magnetic resonance imaging. Cavum septi pellucidi was assessed by counting the number of 1.5-mm slices containing cavum septi pellucidi. Results: The presence or absence of cavum septi pellucidi did not differentiate among groups. However, the prevalence of abnormal cavum septi pellucidi (i.e., cavum septi pellucidi contained on four or more slices) was 30.4% for schizophrenic patients (36.4% for chronic, 25.0% for first-episode), 20.0% for patients with affective disorder, 18.8% for patients with schizotypal personality disorder, and 10.3% for normal subjects. When the authors used the Nopoulos et al. criteria for rating cavum septi pellucidi, which omitted borderline cases with cavum septi pellucidi on three slices, the prevalence of abnormal cavum septi pellucidi increased to 35.0% for schizophrenia (40.0% for chronic, 30.0% for first-episode), 25.0% for affective disorder, 27.3% for schizotypal personality disorder, and 13.0% for normal subjects. There was a statistically significant difference in ratings between schizophrenic and normal subjects. Conclusions: The results suggest that alterations in midline structures during the course of neurodevelopment may play a role in the pathogenesis of schizophrenia.
  • Thumbnail Image
    Publication
    Lower Left Temporal Lobe MRI Volumes in Patients With First-Episode Schizophrenia Compared With Psychotic Patients With First-Episode Affective Disorder and Normal Subjects
    (American Psychiatric Publishing, 1998) Hirayasu, Yoshio; Shenton, Martha; Salisbury, Dean F.; Dickey, Chandlee; Fischer, Iris A.; Mazzoni, Paola; Kisler, Tanya; Arakaki, Hajime; Kwon, Jun Soo; Anderson, Jane E.; Yurgelun-Todd, Deborah; Tohen, Mauricio; McCarley, Robert William
    Objective:Magnetic resonance imaging (MRI) studies of schizophrenic patients have revealed structural brain abnormalities, with low volumes of gray matter in the left posterior superior temporal gyrus and in medial temporal lobe structures. However, the specificity to schizophrenia and the roles of chronic morbidity and neuroleptic treatment in these abnormalities remain unclear. Method:Magnetic resonance (1.5-T) scans were obtained from 33 patients with first-episode psychosis and 18 age-matched normal comparison subjects, all right-handed. Sixteen of the patients were diagnosed with affective disorder and 17 with schizophrenia. Results:Quantitative volumetric analysis showed that the patients with first-episode schizophrenia had significantly smaller gray matter volume in the left posterior superior temporal gyrus than did the patients with first-episode affective psychosis or the comparison subjects, with a significant left-less-than-right asymmetry. The schizophrenic patients also showed a smaller gray matter volume of the left posterior amygdala-hippocampal complex than the comparison subjects. Both the patients with schizophrenia and those with affective psychosis had significant left-less-than-right asymmetry of the posterior amygdala-hippocampal complex.Conclusions:These findings suggest that temporal lobe abnormalities are present at the first hospitalization for schizophrenia and that low volume of the left posterior superior temporal gyrus gray matter is specific to schizophrenia compared with affective disorder.