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Guillen Fernandez - One of the best experts on this subject based on the ideXlab platform.

  • acute psychological stress reduces working memory related activity in the Dorsolateral Prefrontal Cortex
    Biological Psychiatry, 2009
    Co-Authors: Erno J Hermans, Hein J F Van Marle, Guillen Fernandez
    Abstract:

    BACKGROUND: Acute psychological stress impairs higher-order cognitive function such as working memory (WM). Similar impairments are seen in various psychiatric disorders that are associated with higher susceptibility to stress and with Prefrontal cortical dysfunctions, suggesting that acute stress may play a potential role in such dysfunctions. However, it remains unknown whether acute stress has immediate effects on WM-related Prefrontal activity. METHODS: Using functional magnetic resonance imaging (fMRI), we investigated neural activity of 27 healthy female participants during a blocked WM task (numerical N-back) while moderate psychological stress was induced by viewing strongly aversive (vs. neutral) movie material together with a self-referencing instruction. To assess stress manipulation, autonomic and endocrine, as well as subjective, measurements were acquired throughout the experiment. RESULTS: Successfully induced acute stress resulted in significantly reduced WM-related activity in the Dorsolateral Prefrontal Cortex (DLPFC), and was accompanied by less deactivation in brain regions that are jointly referred to as the default mode network. CONCLUSIONS: This study demonstrates that experimentally induced acute stress in healthy volunteers results in a reduction of WM-related DLPFC activity and reallocation of neural resources away from executive function networks. These effects may be explained by supraoptimal levels of catecholamines potentially in conjunction with elevated levels of cortisol. A similar mechanism involving acute stress as a mediating factor may play an important role in higher-order cognitive deficits and hypofrontality observed in various psychiatric disorders.

  • acute psychological stress reduces working memory related activity in the Dorsolateral Prefrontal Cortex
    Biological Psychiatry, 2009
    Co-Authors: Shaozheng Qin, Erno J Hermans, Hein J F Van Marle, Jing Luo, Guillen Fernandez
    Abstract:

    Background: Acute psychological stress impairs higher-order cognitive function such as working memory (WM). Similar impairments are seen in various psychiatric disorders that are associated with higher susceptibility to stress and with Prefrontal cortical dysfunctions, suggesting that acute stress may play a potential role in such dysfunctions. However, it remains unknown whether acute stress has immediate effects on WM-related Prefrontal activity. Methods: Using functional magnetic resonance imaging (fMRI), we investigated neural activity of 27 healthy female participants during a blocked WM task (numerical N-back) while moderate psychological stress was induced by viewing strongly aversive (vs. neutral) movie material together with a self-referencing instruction. To assess stress manipulation, autonomic and endocrine, as well as subjective, measurements were acquired throughout the experiment. Results: Successfully induced acute stress resulted in significantly reduced WM-related activity in the Dorsolateral Prefrontal Cortex (DLPFC), and was accompanied by less deactivation in brain regions that are jointly referred to as the default mode network. Conclusions: This study demonstrates that experimentally induced acute stress in healthy volunteers results in a reduction of WM-related DLPFC activity and reallocation of neural resources away from executive function networks. These effects may be explained by supraoptimal levels of catecholamines potentially in conjunction with elevated levels of cortisol. A similar mechanism involving acute stress as a mediating factor may play an important role in higher-order cognitive deficits and hypofrontality observed in various psychiatric disorders.

Erno J Hermans - One of the best experts on this subject based on the ideXlab platform.

  • acute psychological stress reduces working memory related activity in the Dorsolateral Prefrontal Cortex
    Biological Psychiatry, 2009
    Co-Authors: Erno J Hermans, Hein J F Van Marle, Guillen Fernandez
    Abstract:

    BACKGROUND: Acute psychological stress impairs higher-order cognitive function such as working memory (WM). Similar impairments are seen in various psychiatric disorders that are associated with higher susceptibility to stress and with Prefrontal cortical dysfunctions, suggesting that acute stress may play a potential role in such dysfunctions. However, it remains unknown whether acute stress has immediate effects on WM-related Prefrontal activity. METHODS: Using functional magnetic resonance imaging (fMRI), we investigated neural activity of 27 healthy female participants during a blocked WM task (numerical N-back) while moderate psychological stress was induced by viewing strongly aversive (vs. neutral) movie material together with a self-referencing instruction. To assess stress manipulation, autonomic and endocrine, as well as subjective, measurements were acquired throughout the experiment. RESULTS: Successfully induced acute stress resulted in significantly reduced WM-related activity in the Dorsolateral Prefrontal Cortex (DLPFC), and was accompanied by less deactivation in brain regions that are jointly referred to as the default mode network. CONCLUSIONS: This study demonstrates that experimentally induced acute stress in healthy volunteers results in a reduction of WM-related DLPFC activity and reallocation of neural resources away from executive function networks. These effects may be explained by supraoptimal levels of catecholamines potentially in conjunction with elevated levels of cortisol. A similar mechanism involving acute stress as a mediating factor may play an important role in higher-order cognitive deficits and hypofrontality observed in various psychiatric disorders.

  • acute psychological stress reduces working memory related activity in the Dorsolateral Prefrontal Cortex
    Biological Psychiatry, 2009
    Co-Authors: Shaozheng Qin, Erno J Hermans, Hein J F Van Marle, Jing Luo, Guillen Fernandez
    Abstract:

    Background: Acute psychological stress impairs higher-order cognitive function such as working memory (WM). Similar impairments are seen in various psychiatric disorders that are associated with higher susceptibility to stress and with Prefrontal cortical dysfunctions, suggesting that acute stress may play a potential role in such dysfunctions. However, it remains unknown whether acute stress has immediate effects on WM-related Prefrontal activity. Methods: Using functional magnetic resonance imaging (fMRI), we investigated neural activity of 27 healthy female participants during a blocked WM task (numerical N-back) while moderate psychological stress was induced by viewing strongly aversive (vs. neutral) movie material together with a self-referencing instruction. To assess stress manipulation, autonomic and endocrine, as well as subjective, measurements were acquired throughout the experiment. Results: Successfully induced acute stress resulted in significantly reduced WM-related activity in the Dorsolateral Prefrontal Cortex (DLPFC), and was accompanied by less deactivation in brain regions that are jointly referred to as the default mode network. Conclusions: This study demonstrates that experimentally induced acute stress in healthy volunteers results in a reduction of WM-related DLPFC activity and reallocation of neural resources away from executive function networks. These effects may be explained by supraoptimal levels of catecholamines potentially in conjunction with elevated levels of cortisol. A similar mechanism involving acute stress as a mediating factor may play an important role in higher-order cognitive deficits and hypofrontality observed in various psychiatric disorders.

Daniel R. Weinberger - One of the best experts on this subject based on the ideXlab platform.

  • effect of metabotropic glutamate receptor 3 genotype on n acetylaspartate measures in the Dorsolateral Prefrontal Cortex
    American Journal of Psychiatry, 2006
    Co-Authors: Stefano Marenco, Michael F Egan, Richard E Straub, Sonya Steele, Terry E Goldberg, Anjail Z Sharrief, Daniel R. Weinberger
    Abstract:

    Objective: This study was carried out to confirm prior evidence of an effect of a single nucleotide polymorphism (SNP) in the metabotropic glutamate receptor 3 (GRM3) gene (a putative risk factor for schizophrenia) on measures of N -acetylaspartate in healthy comparison subjects. Method: Fifty-four carefully screened healthy volunteers genotyped at SNP rs6465084 underwent magnetic resonance spectroscopic imaging (MRSI) at 3 T and selected neuropsychological testing. Results: The A/A genotype group exhibited a significant reduction of N -acetylaspartate/creatine levels in the right Dorsolateral Prefrontal Cortex compared to the G carriers. A tendency in the same direction was seen in the left Dorsolateral Prefrontal Cortex and in the white matter adjacent to the Prefrontal Cortex. Conclusions: These findings provide further evidence that GRM3 affects Prefrontal function and that variation in GRM3, monitored by SNP rs6465084, affects GRM3 function.

  • expression analysis of neuregulin 1 in the Dorsolateral Prefrontal Cortex in schizophrenia
    Molecular Psychiatry, 2004
    Co-Authors: Ryota Hashimoto, Cynthia Shannon Weickert, Richard E Straub, Thomas M Hyde, Joel E Kleinman, Daniel R. Weinberger
    Abstract:

    Genetic linkage and association have implicated neuregulin-1 (NRG-1) as a schizophrenia susceptibility gene. We measured mRNA expression levels of the three major isoforms of NRG-1 (ie type I, type II, and type III) in the postmortem Dorsolateral Prefrontal Cortex (DLPFC) from matched patients and controls using real-time quantitative RT-PCR. Expression levels of three internal controls—GAPDH, cyclophilin, and β-actin—were unchanged in schizophrenia, and there were no changes in the absolute levels of the NRG-1 isoforms. However, type I expression normalized by GAPDH levels was significantly increased in schizophrenia DLPFC (by 23%) and positively correlated with antipsychotic medication dosage. Type II/type I and type II/type III ratios were significantly decreased (18 and 23% respectively). There was no effect on the NRG-1 mRNA levels of genotype at two SNPs previously associated with schizophrenia, suggesting that these alleles are not functionally responsible for abnormal NRG-1 expression patterns in patients. Subtle abnormalities in the expression patterns of NRG-1 mRNA isoforms in DLPFC may be associated with schizophrenia.

  • catechol o methyltransferase comt mrna expression in the Dorsolateral Prefrontal Cortex of patients with schizophrenia
    Neuropsychopharmacology, 2003
    Co-Authors: Mitsuyuki Matsumoto, Daniel R. Weinberger, Cynthia Shannon Weickert, Thomas M Hyde, Mary M Herman, Senda Beltaifa, Bhaskar Kolachana, Jingshan Chen, Joel E Kleinman
    Abstract:

    Human Prefrontal cortical neurons express catechol O-methyltransferase (COMT), an enzyme that inactivates the neurotransmitter dopamine. A functional polymorphism of COMT, Val108/158 Met, affects Prefrontal function, and the high-activity Val allele has been reported to be a genetic risk factor for schizophrenia. We used in situ hybridization histochemistry to measure mRNA levels of COMT in the Dorsolateral Prefrontal Cortex (DLPFC) of patients with schizophrenia (N=14) and of normal controls (N=15). While the groups did not differ in terms of mean level of COMT mRNA, there was a significantly different laminar pattern of COMT mRNA expression in pyramidal neurons (F=2.68, df=4,108, P<0.04); patients with schizophrenia had relatively lower levels in the superficial (II/III) layers and higher levels in the intermediate/deep (IV/V) layers (P<0.01), while in controls, the expression was homogeneous across layers. Neither the mean level nor the laminar distribution of COMT mRNA was related to the Val108/158 Met genotype, suggesting that the feedback regulation of mRNA level is not a compensation for the functional effect of the COMT polymorphism. The disease-related laminar difference of COMT expression may be involved in dysregulation of dopamine signaling circuits in the DLPFC of patients with schizophrenia.

  • abnormal fmri response of the Dorsolateral Prefrontal Cortex in cognitively intact siblings of patients with schizophrenia
    American Journal of Psychiatry, 2003
    Co-Authors: Joseph H Callicott, Michael F Egan, Venkata S Mattay, Alessandro Bertolino, Ashley D Bone, Beth Verchinksi, Daniel R. Weinberger
    Abstract:

    Objective: The identification of neurobiological intermediate phenotypes may hasten the search for susceptibility genes in complex psychiatric disorders such as schizophrenia. Earlier family studies have suggested that deficits in executive cognition and working memory may be related to genetic susceptibility for schizophrenia, but the biological basis for this behavioral phenotype has not been identified. Method: The authors used functional magnetic resonance imaging (fMRI) during performance of the N-back working memory task to assess working memoryrelated cortical physiology in nonschizophrenic, cognitively intact siblings of patients with schizophrenia. They compared 23 unaffected siblings of schizophrenic patients to 18 matched comparison subjects. As a planned replication, they studied another 25 unaffected siblings and 15 comparison subjects. Results: In both cohorts, there were no group differences in working memory performance. Nevertheless, both groups of siblings showed an exaggerated physiological response in the right Dorsolateral Prefrontal Cortex that was qualitatively similar to results of earlier fMRI studies of patients with schizophrenia. Conclusions: These fMRI data provide direct evidence of a primary physiological abnormality in Dorsolateral Prefrontal Cortex function in individuals at greater genetic risk for schizophrenia, even in the absence of a manifest cognitive abnormality. This exaggerated fMRI response implicates inefficient processing of memory information at the level of intrinsic Prefrontal circuitry, similar to earlier findings in patients with schizophrenia. These data predict that inheritance of alleles that contribute to inefficient Prefrontal information processing will increase risk for schizophrenia.

Warren D Taylor - One of the best experts on this subject based on the ideXlab platform.

  • Dorsolateral Prefrontal Cortex and anterior cingulate Cortex white matter alterations in late life depression
    Biological Psychiatry, 2006
    Co-Authors: James R Macfall, Martha E Payne, David C Steffens, Ranga Rama K Krishnan, Jae Nam Bae, Warren D Taylor
    Abstract:

    Background The Dorsolateral Prefrontal Cortex (DLPFC) and anterior cingulate Cortex (ACC) are critical for mood regulation. Alterations in the white matter connections of these regions may impair their role in mood regulation and increase the risk of developing depression. This study used diffusion tensor imaging to examine for white matter microstructural abnormalities of these regions and of central white matter structures in late-life depression. Methods One hundred six elderly depressed subjects and eighty-four elderly nondepressed subjects underwent clinical assessment and diffusion tensor imaging. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in regions of interest placed in the white matter of the DLPFC, ACC, corpus callosum, and internal capsule. Differences between groups were assessed, controlling for age, sex, and total cerebral volume. Results After controlling for covariates, depressed subjects had significantly lower FA values in white matter of the right ACC, bilateral superior frontal gyri, and left middle frontal gyrus. There were no significant differences in ADC values. Conclusions Lower FA, representing lower tissue organization, is observed in depressed elders in the DLPFC and right ACC. These findings support the hypothesis that altered connectivity between brain regions contributes to the risk of depression.

  • late life depression and microstructural abnormalities in Dorsolateral Prefrontal Cortex white matter
    American Journal of Psychiatry, 2004
    Co-Authors: Warren D Taylor, James R Macfall, Martha E Payne, Douglas R Mcquoid, James M Provenzale, David C Steffens, Ranga Rama K Krishnan
    Abstract:

    OBJECTIVE: The purpose of this study was to determine whether microstructural abnormalities in the white matter of the Dorsolateral Prefrontal Cortex are associated with late-life depression. METHOD: Seventeen elderly depressed subjects were compared with 16 elderly subjects who were not depressed. Diffusion tensor imaging was used to measure the fractional anisotropy of the white matter in the Dorsolateral Prefrontal Cortex’s superior and middle frontal gyri bilaterally and in the left occipital lobe as a control region. The authors compared results between groups while controlling for age, sex, and comorbid medical disorders. RESULTS: Even after controlling for age, sex, hypertension, and heart disease, the authors found significantly lower fractional anisotropy values in the right superior frontal gyrus white matter of depressed patients than comparison subjects. CONCLUSIONS: Microstructural changes in the white matter of the right superior frontal gyrus are associated with late-life depression. Furthe...

Ranga Rama K Krishnan - One of the best experts on this subject based on the ideXlab platform.

  • Dorsolateral Prefrontal Cortex and anterior cingulate Cortex white matter alterations in late life depression
    Biological Psychiatry, 2006
    Co-Authors: James R Macfall, Martha E Payne, David C Steffens, Ranga Rama K Krishnan, Jae Nam Bae, Warren D Taylor
    Abstract:

    Background The Dorsolateral Prefrontal Cortex (DLPFC) and anterior cingulate Cortex (ACC) are critical for mood regulation. Alterations in the white matter connections of these regions may impair their role in mood regulation and increase the risk of developing depression. This study used diffusion tensor imaging to examine for white matter microstructural abnormalities of these regions and of central white matter structures in late-life depression. Methods One hundred six elderly depressed subjects and eighty-four elderly nondepressed subjects underwent clinical assessment and diffusion tensor imaging. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in regions of interest placed in the white matter of the DLPFC, ACC, corpus callosum, and internal capsule. Differences between groups were assessed, controlling for age, sex, and total cerebral volume. Results After controlling for covariates, depressed subjects had significantly lower FA values in white matter of the right ACC, bilateral superior frontal gyri, and left middle frontal gyrus. There were no significant differences in ADC values. Conclusions Lower FA, representing lower tissue organization, is observed in depressed elders in the DLPFC and right ACC. These findings support the hypothesis that altered connectivity between brain regions contributes to the risk of depression.

  • late life depression and microstructural abnormalities in Dorsolateral Prefrontal Cortex white matter
    American Journal of Psychiatry, 2004
    Co-Authors: Warren D Taylor, James R Macfall, Martha E Payne, Douglas R Mcquoid, James M Provenzale, David C Steffens, Ranga Rama K Krishnan
    Abstract:

    OBJECTIVE: The purpose of this study was to determine whether microstructural abnormalities in the white matter of the Dorsolateral Prefrontal Cortex are associated with late-life depression. METHOD: Seventeen elderly depressed subjects were compared with 16 elderly subjects who were not depressed. Diffusion tensor imaging was used to measure the fractional anisotropy of the white matter in the Dorsolateral Prefrontal Cortex’s superior and middle frontal gyri bilaterally and in the left occipital lobe as a control region. The authors compared results between groups while controlling for age, sex, and comorbid medical disorders. RESULTS: Even after controlling for age, sex, hypertension, and heart disease, the authors found significantly lower fractional anisotropy values in the right superior frontal gyrus white matter of depressed patients than comparison subjects. CONCLUSIONS: Microstructural changes in the white matter of the right superior frontal gyrus are associated with late-life depression. Furthe...