Schizophrenic

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Michael E Moseley - One of the best experts on this subject based on the ideXlab platform.

  • Brain gray and white matter transverse relaxation time in schizophrenia.
    Psychiatry Research-neuroimaging, 1999
    Co-Authors: Adolf Pfefferbaum, Hedehus, Edith V Sullivan, Michael E Moseley
    Abstract:

    Recent in vivo diffusion brain imaging studies of Schizophrenic patients have revealed microstructural abnormalities, with low diffusion anisotropy present throughout much of cortical white matter. Brain anisotropy is produced when proton movement reflects physically restricted water movement, for example, by myelin sheaths. Conditions that increase self-diffusion, such as edema, may also alter the longitudinal and transverse relaxation time of protons, and it is possible that such changes could explain the observed anisotropy diminution seen in schizophrenia. To test this possibility, we calculated pixel-by-pixel transverse relaxation time (T2) and proton density (PD) maps for gray matter and white matter across eight 5-mm-thick axial slices of fast spin echo MRI in 10 control men (age 30–57 years) and 10 men with schizophrenia (age 32–64 years). Schizophrenics had significantly longer mean white matter T2 (84.0 vs. 81.9 ms, P

  • brain gray and white matter transverse relaxation time in schizophrenia
    Psychiatry Research-neuroimaging, 1999
    Co-Authors: Adolf Pfefferbaum, Maj Hedehus, Edith V Sullivan, Michael E Moseley
    Abstract:

    Recent in vivo diffusion brain imaging studies of Schizophrenic patients have revealed microstructural abnormalities, with low diffusion anisotropy present throughout much of cortical white matter. Brain anisotropy is produced when proton movement reflects physically restricted water movement, for example, by myelin sheaths. Conditions that increase self-diffusion, such as edema, may also alter the longitudinal and transverse relaxation time of protons, and it is possible that such changes could explain the observed anisotropy diminution seen in schizophrenia. To test this possibility, we calculated pixel-by-pixel transverse relaxation time (T2) and proton density (PD) maps for gray matter and white matter across eight 5-mm-thick axial slices of fast spin echo MRI in 10 control men (age 30–57 years) and 10 men with schizophrenia (age 32–64 years). Schizophrenics had significantly longer mean white matter T2 (84.0 vs. 81.9 ms, P<0.03) and gray matter T2 (95.1 vs. 92.2, P=0.003); their mean white and gray matter PD values were not significantly different from those of controls. Correlations were not significant between anisotropy and T2 in either grey or white matter but were significant between anisotropy and PD in white matter. T2 relaxation times are longer in Schizophrenics than in controls in both gray and white matter whereas anisotropy reduction is restricted to white matter. Taken together, these results suggest that the process producing prolonged T2 does not fully account for the abnormally low anisotropy observed selectively in white matter in this group of Schizophrenic patients.

Adolf Pfefferbaum - One of the best experts on this subject based on the ideXlab platform.

  • Brain gray and white matter transverse relaxation time in schizophrenia.
    Psychiatry Research-neuroimaging, 1999
    Co-Authors: Adolf Pfefferbaum, Hedehus, Edith V Sullivan, Michael E Moseley
    Abstract:

    Recent in vivo diffusion brain imaging studies of Schizophrenic patients have revealed microstructural abnormalities, with low diffusion anisotropy present throughout much of cortical white matter. Brain anisotropy is produced when proton movement reflects physically restricted water movement, for example, by myelin sheaths. Conditions that increase self-diffusion, such as edema, may also alter the longitudinal and transverse relaxation time of protons, and it is possible that such changes could explain the observed anisotropy diminution seen in schizophrenia. To test this possibility, we calculated pixel-by-pixel transverse relaxation time (T2) and proton density (PD) maps for gray matter and white matter across eight 5-mm-thick axial slices of fast spin echo MRI in 10 control men (age 30–57 years) and 10 men with schizophrenia (age 32–64 years). Schizophrenics had significantly longer mean white matter T2 (84.0 vs. 81.9 ms, P

  • brain gray and white matter transverse relaxation time in schizophrenia
    Psychiatry Research-neuroimaging, 1999
    Co-Authors: Adolf Pfefferbaum, Maj Hedehus, Edith V Sullivan, Michael E Moseley
    Abstract:

    Recent in vivo diffusion brain imaging studies of Schizophrenic patients have revealed microstructural abnormalities, with low diffusion anisotropy present throughout much of cortical white matter. Brain anisotropy is produced when proton movement reflects physically restricted water movement, for example, by myelin sheaths. Conditions that increase self-diffusion, such as edema, may also alter the longitudinal and transverse relaxation time of protons, and it is possible that such changes could explain the observed anisotropy diminution seen in schizophrenia. To test this possibility, we calculated pixel-by-pixel transverse relaxation time (T2) and proton density (PD) maps for gray matter and white matter across eight 5-mm-thick axial slices of fast spin echo MRI in 10 control men (age 30–57 years) and 10 men with schizophrenia (age 32–64 years). Schizophrenics had significantly longer mean white matter T2 (84.0 vs. 81.9 ms, P<0.03) and gray matter T2 (95.1 vs. 92.2, P=0.003); their mean white and gray matter PD values were not significantly different from those of controls. Correlations were not significant between anisotropy and T2 in either grey or white matter but were significant between anisotropy and PD in white matter. T2 relaxation times are longer in Schizophrenics than in controls in both gray and white matter whereas anisotropy reduction is restricted to white matter. Taken together, these results suggest that the process producing prolonged T2 does not fully account for the abnormally low anisotropy observed selectively in white matter in this group of Schizophrenic patients.

Edith V Sullivan - One of the best experts on this subject based on the ideXlab platform.

  • Brain gray and white matter transverse relaxation time in schizophrenia.
    Psychiatry Research-neuroimaging, 1999
    Co-Authors: Adolf Pfefferbaum, Hedehus, Edith V Sullivan, Michael E Moseley
    Abstract:

    Recent in vivo diffusion brain imaging studies of Schizophrenic patients have revealed microstructural abnormalities, with low diffusion anisotropy present throughout much of cortical white matter. Brain anisotropy is produced when proton movement reflects physically restricted water movement, for example, by myelin sheaths. Conditions that increase self-diffusion, such as edema, may also alter the longitudinal and transverse relaxation time of protons, and it is possible that such changes could explain the observed anisotropy diminution seen in schizophrenia. To test this possibility, we calculated pixel-by-pixel transverse relaxation time (T2) and proton density (PD) maps for gray matter and white matter across eight 5-mm-thick axial slices of fast spin echo MRI in 10 control men (age 30–57 years) and 10 men with schizophrenia (age 32–64 years). Schizophrenics had significantly longer mean white matter T2 (84.0 vs. 81.9 ms, P

  • brain gray and white matter transverse relaxation time in schizophrenia
    Psychiatry Research-neuroimaging, 1999
    Co-Authors: Adolf Pfefferbaum, Maj Hedehus, Edith V Sullivan, Michael E Moseley
    Abstract:

    Recent in vivo diffusion brain imaging studies of Schizophrenic patients have revealed microstructural abnormalities, with low diffusion anisotropy present throughout much of cortical white matter. Brain anisotropy is produced when proton movement reflects physically restricted water movement, for example, by myelin sheaths. Conditions that increase self-diffusion, such as edema, may also alter the longitudinal and transverse relaxation time of protons, and it is possible that such changes could explain the observed anisotropy diminution seen in schizophrenia. To test this possibility, we calculated pixel-by-pixel transverse relaxation time (T2) and proton density (PD) maps for gray matter and white matter across eight 5-mm-thick axial slices of fast spin echo MRI in 10 control men (age 30–57 years) and 10 men with schizophrenia (age 32–64 years). Schizophrenics had significantly longer mean white matter T2 (84.0 vs. 81.9 ms, P<0.03) and gray matter T2 (95.1 vs. 92.2, P=0.003); their mean white and gray matter PD values were not significantly different from those of controls. Correlations were not significant between anisotropy and T2 in either grey or white matter but were significant between anisotropy and PD in white matter. T2 relaxation times are longer in Schizophrenics than in controls in both gray and white matter whereas anisotropy reduction is restricted to white matter. Taken together, these results suggest that the process producing prolonged T2 does not fully account for the abnormally low anisotropy observed selectively in white matter in this group of Schizophrenic patients.

Mark A Geyer - One of the best experts on this subject based on the ideXlab platform.

  • assessing the validity of an animal model of deficient sensorimotor gating in Schizophrenic patients
    Archives of General Psychiatry, 1994
    Co-Authors: Neal R Swerdlow, David L Braff, Navid Taaid, Mark A Geyer
    Abstract:

    Psychiatric researchers need specific animal models to better understand the neurobiology of schizophrenia. Prepulse inhibition (PPI), the reduction in startle produced by a prepulse stimulus, is diminished in Schizophrenic patients. Theoretically, deficient PPI in Schizophrenic patients reflects a loss of sensorimotor gating that may lead to sensory flooding and cognitive fragmentation. In rats, PPI is disrupted by systemic administration of dopamine agonists or by manipulations of neural circuitry linking the limbic cortex, striatum, pallidum, and pontine reticular formation. This loss of PPI in rats may be a useful model for studying the neurobiology of impaired sensorimotor gating in Schizophrenic patients. We assessed the face, predictive, and construct validity of this animal model. Face validity was supported: stimulus manipulations produced parallel changes in PPI in humans and rats, and the dopamine agonist apomorphine disrupted PPI in rats, mimicking PPI deficits in Schizophrenics. Predictive validity was supported: the ability of antipsychotics to restore PPI in apomorphine-treated rats correlated with clinical antipsychotic potency ( r s =.991) and D 2 -receptor affinity ( r s =.893). Antipsychotics that restore PPI in apomorphine-treated rats include "typical" antipsychotics and the "atypical" antipsychotic clozapine. Construct validity was supported: PPI was disrupted in rats when dopamine was infused into the nucleus accumbens; this effect was blocked by haloperidol. The loss of PPI in dopamine-activated rats may be a valid animal model of sensorimotor gating deficits in Schizophrenic patients. This model may help us understand the neurobiology of cognitive deficits in Schizophrenic patients.

Maj Hedehus - One of the best experts on this subject based on the ideXlab platform.

  • brain gray and white matter transverse relaxation time in schizophrenia
    Psychiatry Research-neuroimaging, 1999
    Co-Authors: Adolf Pfefferbaum, Maj Hedehus, Edith V Sullivan, Michael E Moseley
    Abstract:

    Recent in vivo diffusion brain imaging studies of Schizophrenic patients have revealed microstructural abnormalities, with low diffusion anisotropy present throughout much of cortical white matter. Brain anisotropy is produced when proton movement reflects physically restricted water movement, for example, by myelin sheaths. Conditions that increase self-diffusion, such as edema, may also alter the longitudinal and transverse relaxation time of protons, and it is possible that such changes could explain the observed anisotropy diminution seen in schizophrenia. To test this possibility, we calculated pixel-by-pixel transverse relaxation time (T2) and proton density (PD) maps for gray matter and white matter across eight 5-mm-thick axial slices of fast spin echo MRI in 10 control men (age 30–57 years) and 10 men with schizophrenia (age 32–64 years). Schizophrenics had significantly longer mean white matter T2 (84.0 vs. 81.9 ms, P<0.03) and gray matter T2 (95.1 vs. 92.2, P=0.003); their mean white and gray matter PD values were not significantly different from those of controls. Correlations were not significant between anisotropy and T2 in either grey or white matter but were significant between anisotropy and PD in white matter. T2 relaxation times are longer in Schizophrenics than in controls in both gray and white matter whereas anisotropy reduction is restricted to white matter. Taken together, these results suggest that the process producing prolonged T2 does not fully account for the abnormally low anisotropy observed selectively in white matter in this group of Schizophrenic patients.