- Email: [email protected]
Evidence for multiple distributed cortical map-like representations of language from functional MRI
100
activity between groups. Schizophrenics as a group activated both left FL and TL; qualitatively different from normals. Within group analysis revealed medial FL overactivity confined to RD syndrome. The results suggest abnormal frontotemporal connectivity in schizophrenia, with differences in symptom profile implicating differential frontal lobe activity.
EVIDENCE FOR MULTIPLE DISTRIBUTED CORTICAL MAP-LIKE REPRESENTATIONS OF LANGUAGE FROM FUNCTIONAL MRI M. Spitzer*, M.E. Bellemann, F. Gueckel, G. Brix, U. Kischka, T. Kammer, A. Schwartz, S. Seyyedi, M. Weisbrod
Department of Psychiatry, University of Heidelberg, Voss-Str. 4, 69115 Heidelberg, Germany There is linguistic, electrophysiological, clinical, and neurocomputational evidence that semantic representations are stored in a map-like form. While maplike representations of sensory and motor aspects of the environment are known for decades and have recently been found to be highly dependent upon input characteristics (cf. M.M. Merzenich and K. Sameshima, Curt. Op. Neurol. 3: 187-196, 1993), the existence (let alone input-driven changes) of higher order cognitive representations has not been demonstrated using noninvasive methods. We report a picture-naming study performed in 7 normal subjects, using a conventional 1.5 Tesla MR-system and additional hard- and software for stimulation. In six alternating blocks of 6 min each, subjects had to covertly name 120 animals or furniture items (each displayed for 3 s) per block. Results provide strong evidence for domain-specific lexical regions in the frontal and temporal lobes, and hence, for a map-like organization of high-level language-related representations. This result not only provides a neurophysiological framework for the discussion of thought disorder in terms of spreading activation in semantic maps, but also has implications for future research regarding neuroplasticity and delusional systems.
REGIONAL PROFILES OF CORTICAL GRAY MATTER VOLUME DEFICITS IN SCHIZOPHRENIA AND ALCOHOLISM E.V. Sullivan*, K.O. Lim, A. Pfefferbaum
Department of Psychiatry, D VA and Stanford University School of Medicine, Palo Alto, CA 94304, USA Quantitative MRI studies report that cortical gray matter volume deficits occur in schizophrenia and alcoholism. This study examined whether the profile of regional tissue volume abnormality, in the context of widespread brain dysmorphol-
ogy, distinguished these patient groups. Accordingly, we analyzed MRI-derived volumes of gray matter and white matter of six cortical regions in 80 schizophrenics and 65 alcoholics. The volumes were adjusted for normal variation in head size and age, established from 73 healthy men, and were expressed as Z-scores. Repeated measures analyses of variance showed that schizophrenics had a greater gray matter volume deficit than alcoholics (p<0.015). Furthermore, the two groups had different profiles, revealed by a group-by-region interaction (p<0.0001). Both groups showed widespread gray matter volume deficits compared with controls (p < 0.0001); only the alcoholics had white matter volume deficits. Compared with alcoholics, schizophrenics had greater volume deficits in the prefrontal, frontal-temporal, and temporal-parietal cortical regions. Thus, the cortical tissue volume deficit of schizophrenia is selective to gray matter, is widespread and has a regional pattern of dysmorphology distinct from alcoholism. This pattern is consistent with other reports of brain structure and function that implicate prefrontal and temporal lobe pathology in schizophrenia. Supported by MH 30854, AA 05965, Department of Veterans Affairs.
PET STUDIES OF VOLUNTARY SACCADIC EYE MOVEMENTS AND SPATIAL WORKING MEMORY J.A. Sweeney*, M.A. Mintun, S. Kwee, M.B. Wiseman, D.L. Brown, D.R. Rosenberg, J.R. Carl
Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA Disturbances of spatial working memory and voluntary saccades have been demonstrated in schizophrenic patients and their relatives. In the present study, regional cerebral blood flow (rCBF) was measured with [150]H20 PET in welltrained, healthy adults during visual fixation, visually guided saccades, antisaccades and memory guided saccades. Analyses were performed using both the Statistical Parametric Mapping (SPM) method and MR-aligned images. Performing visually guided saccades led to activations in frontal eye fields (FEF), cerebellum, posterior temporal cortex and posterior thalamus. Compared to visually guided saccades, performing memory guided saccades increased rCBF in FEF, SMA, dorsolateral prefrontal cortex and posterior parietal cortex, paralleling findings from single cell recording studies in monkeys. Similar activations were observed during the antisaccade task. During the antisaccade and memory guided saccade tasks, rCBF was significantly reduced in medial orbital cortex and ventral anterior cingulate cortex. Task-related rCBF changes were highly intercorrelated across regions of interest. These results define a widely distributed neural circuit that subserves the voluntary control of saccades in humans, and therefore provide a model for interpreting oculomotor deficits associated with schizophrenia.
activity between groups. Schizophrenics as a group activated both left FL and TL; qualitatively different from normals. Within group analysis revealed medial FL overactivity confined to RD syndrome. The results suggest abnormal frontotemporal connectivity in schizophrenia, with differences in symptom profile implicating differential frontal lobe activity.
EVIDENCE FOR MULTIPLE DISTRIBUTED CORTICAL MAP-LIKE REPRESENTATIONS OF LANGUAGE FROM FUNCTIONAL MRI M. Spitzer*, M.E. Bellemann, F. Gueckel, G. Brix, U. Kischka, T. Kammer, A. Schwartz, S. Seyyedi, M. Weisbrod
Department of Psychiatry, University of Heidelberg, Voss-Str. 4, 69115 Heidelberg, Germany There is linguistic, electrophysiological, clinical, and neurocomputational evidence that semantic representations are stored in a map-like form. While maplike representations of sensory and motor aspects of the environment are known for decades and have recently been found to be highly dependent upon input characteristics (cf. M.M. Merzenich and K. Sameshima, Curt. Op. Neurol. 3: 187-196, 1993), the existence (let alone input-driven changes) of higher order cognitive representations has not been demonstrated using noninvasive methods. We report a picture-naming study performed in 7 normal subjects, using a conventional 1.5 Tesla MR-system and additional hard- and software for stimulation. In six alternating blocks of 6 min each, subjects had to covertly name 120 animals or furniture items (each displayed for 3 s) per block. Results provide strong evidence for domain-specific lexical regions in the frontal and temporal lobes, and hence, for a map-like organization of high-level language-related representations. This result not only provides a neurophysiological framework for the discussion of thought disorder in terms of spreading activation in semantic maps, but also has implications for future research regarding neuroplasticity and delusional systems.
REGIONAL PROFILES OF CORTICAL GRAY MATTER VOLUME DEFICITS IN SCHIZOPHRENIA AND ALCOHOLISM E.V. Sullivan*, K.O. Lim, A. Pfefferbaum
Department of Psychiatry, D VA and Stanford University School of Medicine, Palo Alto, CA 94304, USA Quantitative MRI studies report that cortical gray matter volume deficits occur in schizophrenia and alcoholism. This study examined whether the profile of regional tissue volume abnormality, in the context of widespread brain dysmorphol-
ogy, distinguished these patient groups. Accordingly, we analyzed MRI-derived volumes of gray matter and white matter of six cortical regions in 80 schizophrenics and 65 alcoholics. The volumes were adjusted for normal variation in head size and age, established from 73 healthy men, and were expressed as Z-scores. Repeated measures analyses of variance showed that schizophrenics had a greater gray matter volume deficit than alcoholics (p<0.015). Furthermore, the two groups had different profiles, revealed by a group-by-region interaction (p<0.0001). Both groups showed widespread gray matter volume deficits compared with controls (p < 0.0001); only the alcoholics had white matter volume deficits. Compared with alcoholics, schizophrenics had greater volume deficits in the prefrontal, frontal-temporal, and temporal-parietal cortical regions. Thus, the cortical tissue volume deficit of schizophrenia is selective to gray matter, is widespread and has a regional pattern of dysmorphology distinct from alcoholism. This pattern is consistent with other reports of brain structure and function that implicate prefrontal and temporal lobe pathology in schizophrenia. Supported by MH 30854, AA 05965, Department of Veterans Affairs.
PET STUDIES OF VOLUNTARY SACCADIC EYE MOVEMENTS AND SPATIAL WORKING MEMORY J.A. Sweeney*, M.A. Mintun, S. Kwee, M.B. Wiseman, D.L. Brown, D.R. Rosenberg, J.R. Carl
Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA Disturbances of spatial working memory and voluntary saccades have been demonstrated in schizophrenic patients and their relatives. In the present study, regional cerebral blood flow (rCBF) was measured with [150]H20 PET in welltrained, healthy adults during visual fixation, visually guided saccades, antisaccades and memory guided saccades. Analyses were performed using both the Statistical Parametric Mapping (SPM) method and MR-aligned images. Performing visually guided saccades led to activations in frontal eye fields (FEF), cerebellum, posterior temporal cortex and posterior thalamus. Compared to visually guided saccades, performing memory guided saccades increased rCBF in FEF, SMA, dorsolateral prefrontal cortex and posterior parietal cortex, paralleling findings from single cell recording studies in monkeys. Similar activations were observed during the antisaccade task. During the antisaccade and memory guided saccade tasks, rCBF was significantly reduced in medial orbital cortex and ventral anterior cingulate cortex. Task-related rCBF changes were highly intercorrelated across regions of interest. These results define a widely distributed neural circuit that subserves the voluntary control of saccades in humans, and therefore provide a model for interpreting oculomotor deficits associated with schizophrenia.