322. Diffusion tensor imaging in schizophrenia and schizophrenia spectrum disorders

322. Diffusion tensor imaging in schizophrenia and schizophrenia spectrum disorders

Friday Abstracts tions. Much of the past imaging literature has involved the external induction of emotions via presented stimuli. This usually resul...

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Friday Abstracts

tions. Much of the past imaging literature has involved the external induction of emotions via presented stimuli. This usually results in an activation of the anterior cingulate and limbic structures. The paradigm of this study involves the self-generation of emotions of loss without external stimuli. The paradigm is as follows, five 4-minute neutral periods interspersed with increasing periods of loss induction (2, 3, 4, and 5 minutes). Eight healthy adults (4 males and 4 females) participated. A Siemens Magnetom Vision MR scanner was used. An echo-planer imaging (EPI) sequence was used for the emotional fMRI sequence (TE ⫽ 168, TR ⫽ 64, TD ⫽ 0, flip angle ⫽ 90°, 16 slices, 5mm thick, 1mm gap, matrix ⫽ 64 ⫻ 128, FOV ⫽ 220). Males exhibited bilateral mean signal activation in the amygdala that correlated with the emotional paradigm (r ⫽ 0.5). Female subjects demonstrated more activation in right retrosplenial, posterior limbic structures and parietal cortex. No significant activation was seen in the anterior cingulate in either group, suggesting that its role in emotional processing is linked to external stimuli. Although the subjective nature of the subject’s perception and induction of arousal place limitations on the validity of the paradigm, this study demonstrates the utility of fMRI in the study of emotion. Studies of emotion in non-clinical samples help in the understanding of psychiatric populations, particularly mood disorders.

322. DIFFUSION TENSOR IMAGING IN SCHIZOPHRENIA AND SCHIZOPHRENIA SPECTRUM DISORDERS L. Shihabuddin (1,2), M.S. Buchsbaum (1), C. Tang (1), A.M. Brickman (1,2), M. Fleischman (1), A.S. New (1,2), L.J. Siever (1,2) (1) Mount Sinai School of Medicine, New York, NY 10029 (2) Bronx VA Medical Center, Bronx, NY 10468 Cortico-striatal circuitry abnormalities have been proposed in schizophrenia based on indirect evidence from psychopharmacology studies and animal circuitry studies. Different structural and functional imaging techniques have been implemented in the study of these abnormalities. Diffusion tensor imaging is a new magnetic resonance imaging sequence designed to assess white matter tract integrity. This technique allows the direct assessment of large axons stretching from the prefrontal cortex to the striatum. This is done through the quantification of the directionality of restricted diffusion (anisotropy, a physical aspect of water in closely pact bundles of parallel axons in the white matter tracts). Diffusion tensor imaging and structural magnetic imaging sequences were obtained on 65 patients with schizophrenia, 11 patients with schizotypal personality disorder (SPD), and 35 age- and sex-matched normal controls. Preliminary analysis showed decreased anisotropy in the frontal-striatal white matter, implying diminished fronto-striatal connectivity in schizophrenia compared to normal controls. These findings suggest that cortico-striatal circuitry interruptions are a part of the disease process in schizophrenia. Further analysis including the SPD sample is being performed. Implications of these findings in the neuropathology of schizophrenia and schizophrenia spectrum disorders will be discussed.

BIOL PSYCHIATRY 2000;47:1S–173S

97S

323. CAN INTERLEAVED TMS AND fMRI DEMONSTRATE CHANGES IN AN ACTIVATED CIRCUIT? M. Lomarev (1,4), A. Shastri (1), U. Ziemann (5), E.M. Wassermann (5), K.A. McConnell (1), Z. Nahas (2), J.P. Lorberbaum (2), Diana J. Vincent (1), M.S. George (1,2,3), D.E. Bohning (1) Functional Neuroimaging Research Division, Departments of (1) Radiology, (2) Psychiatry, and (3) Neurology, MUSC, Charleston, South Carolina; (4) Institute of the Human Brain, St. Petersburg, Russia, (5) Intramural Research Program, NINDS, Bethesda, MD TMS, combined with fMRI, offers the potential for demonstrating functional brain circuits, as well as the changes induced by direct non-invasive stimulation (TMS). Recent human electrophysiological and imaging studies have found that 1 Hz TMS has local and remote inhibitory effects in different time domains. To test whether this inhibition occurs at time domains of several seconds and is visible with interleaved TMS/fMRI, we performed TMS within an fMRI scanner and measured blood flow. Within a 1.5 T MRI scanner, five adults were stimulated with a figure eight TMS coil over the left motor cortex. Subjects alternated between rest and a sequential finger opposition task in their left hand. On alternating movement trials, TMS was applied either at 120% motor threshold or 10% of stimulator output (below threshold for movement). Over seconds, TMS did not inhibit local or remote BOLD response during the movement. In fact, TMS over the left hemisphere caused a local 1.5% increase in blood flow in addition to the 2.5% activation caused by the complex movement. Of note, thin deactivation clusters underlying areas of activation were associated with BOLD response to motor activity and the acoustical effects of TMS. Such clusters were revealed in the motor cortex contralateral to the coil, SMA, temporal cortex. These data differ from previous reports of the inhibitory nature of 1 Hz TMS. The differing lengths of stimulation may account for this discrepancy. Interleaved TMS/fMRI appears to be a useful tool for imaging activated circuits and how these circuits are modified by direct, noninvasive cortical stimulation.

324. ACTIVATING BRAIN REGIONS INVOLVED IN SOCIAL ATTACHMENT J.P. Lorberbaum (1,2), J.D. Newman (2), A.R. Horwitz (1), J.R. Dubno (1), M.B. Hamner (1,2), D.E. Bohning (1), A. Shastri (1), J.C. Ballenger (1), R.B. Lydiard (1), M.S. George (1,2) (1) Medical University of South Carolina, Charleston, SC 29425; (2) Ralph H. Johnson VA Medical Center, Charleston, SC 29425 An understanding of the brain basis of social attachment may not only be important in understanding normal emotions such as love, separation, and grief but also important in understanding abnormal behavior such as depression, autism, and child maltreatment in which social bonding deficits may exist. Mammalian lesion data suggests that the thamocingulate circuit—a brain region including the cingulate and anterior thalamus—may play an important role in both maternal behavior and infant crying which are well-known mammalian social attachment behaviors. In humans, we have previously reported on a small pilot study