Iris A. Fischer

Volumetric Evaluation of the Thalamus in Schizophrenic Male Patients Using Magnetic Resonance Imaging

BACKGROUND The thalamus, an important subcortical brain region connecting limbic and prefrontal cortices, has a significant role in sensory and cortical processing. Although inconsistently, previous studies have demonstrated neuroanatomical abnormalities in the thalamus of schizophrenic patients. METHODS This structural magnetic resonance imaging study, based on segmentation of contiguous coronal 1.5-mm images, compared thalamic brain volumes of 15 chronic, male schizophrenic patients with 15 normal controls matched on age, sex, handedness, and parental socioeconomic status. RESULTS There were no significant differences between patients and controls in thalamic volumes, right or left, adjusted for total brain volume; however, there were significantly different correlations of thalamic volumes with prefrontal white matter and lateral ventricles among patients, but not among controls. Thalamic volumes among patients were also significantly correlated with bizarre behavior, hallucinations, and thought disorder. CONCLUSIONS Findings suggest that connectivity between thalamic nuclei and prefrontal cortical areas are abnormal in chronic male schizophrenic patients. In addition, ventricular enlargement may be, in part, due to subtle reduction in thalamic volume and/or in volume of thalamocortical and corticothalamic fibers secondary to thalamic abnormalities. Finally, correlations with positive symptomatology underscore the role of the thalamus in gating or filtering of sensory information and coordination of cortical processing.

Parcellation of the human prefrontal cortex using MRI

A methodology was developed for dividing prefrontal cortical gray matter into insular, orbital, inferior, middle, superior, cingulate, and frontal pole regions using anatomical criteria. This methodology was developed as a follow-up to one that measured whole prefrontal gray and white matter volumes in schizophrenic and control subjects. This study showed no overall volume differences in prefrontal cortex between schizophrenic and control subjects. The parcellation of prefrontal cortex was done to increase the probability of detecting abnormalities that were circumscribed to a particular portion of the region. A 1.5 Tesla magnet was used to acquire contiguous 1.5-mm coronal slices of the entire brain. Volumes were then measured in a group of right-handed male (n = 15) subjects. Gray matter was parcellated using criteria that were mainly based on gross anatomy, as visualized in 3-dimensional renderings of the brain. Reliability of the parcellation scheme was very high (r(i) = 0.80 and above). This methodology should be useful in the study of cortical pathology in a number of neurological disorders, including schizophrenia.

A quantitative MR measure of the fornix in schizophrenia

Some cognitive disturbances accompanying schizophrenia may be due to abnormalities in the thalamus and components of the limbic system. The fornix is an important white-matter relay pathway connecting these structures and is likely to be affected in schizophrenia as well.Magnetic resonance images of the fornix were analyzed in 15 schizophrenic patients and 15 matched comparison group subjects. Fornix volume was compared between the two groups and was also correlated with the volumes of other neuroanatomical structures, as well as with illness presentation, clinical status, and cognitive/psychological measures. There was no significant difference in fornix volume between the two groups. Of note, fornix volume correlated significantly with the volumes of the hippocampus, parahippocampus, and the superior temporal gyrus in the schizophrenic subjects, but not in the controls. Moreover, the correlation between fornix and parahippocampal gyrus volumes differed significantly between the two groups. No association was found between fornix volume and illness presentation or between fornix and cognitive/clinical measures.Results suggest that there are no marked changes in fornix volume in schizophrenia by MRI. The fornix, however, may be part of a network of structures affected in schizophrenia, as indicated by correlated volumetric changes.

407. Evidence for a selective bias towards strong associates in schizophrenic language

that cigarettesmokingis associatedwith increasedrisk of dyskinesiss, independentof psychiatricdiagnosisor medicationexposure.The enhancementof striatsf dopsrninerelease by nicotineprovides,perhaps, someexplanationfor the relationshipbetweensmokinganddyskinesiss. We nowhave data tbm 2 studiesin whichevidencefor the effects of nicotineon dyskinesisswas observed.In the fmt experiment,12heavy smokerswith schizophreniawere evaluatedduring3 days of smoking abstinencewith trsnsdermalnicotine(22 mgkiay)or placebopatch in counter-brdancedorder. We noted that AIMS score decreasedduring abstinenceplus placebo patch, but increased during abstinenceplus active patch condition.These effects were seen despite steady-state nicotineplasmalevelswhichwerelowerthanthoseachievedbysmoking alone.ElevatedAIMSscoresdidnotappearto persistaftertheendof the experiment.In the secondstudy,10heavysmokerswith schizophrenia smokedad libitomover32 hourswhilewearingactiveor placebopatch in counterbalancedorder. AIMS scores increasedduring jire smoking plusactivepatchcondition.It remainsunclearwhetherthiseffectis seute and self-limited,or persistsif treatmentis sustained.We are nowin the processof collectingdata froma longer-termstudyto examinethe time courseof thisphenomenon: heavysmokerswithschizophreniasmokead libitumwhile wearingdaily, for 2 separate4 week periods,setive or placebo patch in counter-balancedorder. The effects of nicotine on dyskinesiasmayprovidea modelto examinestriataldopaminefunction in schizophrenia.

13. Neuroimaging, structural414 - MRI and ERP abnormalities in first episode schizophrenia and affective psychosis

to 100, reflecting the percentage of the tissue component in every voxel. The study comprised 17 schizophrenic patients and 19 normal healthy volunteers. . Results:.Significantly decreased brain volumes were recorded III the schizophrenic patient group compared to controls. This decrease appeared to be due to white matter volume deficits. The grey/white ratio in schizophrenic patients was 1.31 as compared with I.l7 in the normal healthy volunteers (p<O.OOS). The findings could not be explained by difference in age, height, sex or abuse . Comment: The impairment of the white matter in schizophrenic patients may suggest a defect of the communicative ~o~nection system within the brain in this patient group. Th is ~s III CO?cert with recent findings of impaired fronto-temporal mt~ractlOn during the word fluency task in schizophrenic patients,

675 - Temporal P300 asymmetry in first episode schizophrenia

event-related brain potentials (ERPs) are examined to uncover electrocortical correlates of cognitive or behavioral characteristics in schizophrenic patients. While smaller amplitudes of several ERP-components have been repeatedly reported for schizophrenic patients versus control groups, a larger slow surface-negative potential following the completion of a forewarned (motor or cognitive) response, called postimperative negative variation (PINY), has been reliably found in schizophrenic patients by several authors, but only rarely in healthy subjects. In a series of studies we examined contributions to the PINY by varying task-related features in visual and auditory delayed-matching-to-sample tasks in groups of schizophrenic patients (DSM-II1-R) and healthy controls. While demands on working memory enhanced PINY amplitude primarily in schizophrenic patients, PINV amplitude increased with ambiguity of the matching in controls and schizophrenics alike. Differential effects of ambiguity and performance requirements (Go-NoGo) on PINY amplitude and its scalp distribution suggest that performance uncertainty contributes to PINV generation and that the threshold for performance uncertainty is reduced in schizophrenics. Topographical analyses suggest that the PINY is generated symmetrically in the frontal lobes in schizophrenics, while it shows a right frontal dominance in controls. Research was supported by the Deutsche Forschungsgemeinschaft (Ro 805).