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Schulte T, Sullivan EV, Muller-Oehring EM, et al. Corpus callosal microstructural integrity influences interhemispheric processing: a diffusion tensor imaging study

Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States
Cerebral Cortex (Impact Factor: 8.67). 09/2005; 15(9):1384-92. DOI: 10.1093/cercor/bhi020
Source: PubMed

ABSTRACT

Normal aging and chronic alcoholism result in disruption of brain white matter microstructure that does not typically cause complete lesions but may underlie degradation of functions requiring interhemispheric information transfer. We examined whether the microstructural integrity of the corpus callosum assessed with diffusion tensor imaging (DTI) would relate to interhemispheric processing speed. DTI yields estimates of fractional anisotropy (FA), a measure of orientation and intravoxel coherence of water diffusion usually in white matter fibers, and diffusivity ( ), a measure of the amount of intracellular and extracellular fluid diffusion. We tested the hypothesis that FA and would be correlated with (i) the crossed-uncrossed difference (CUD), testing visuomotor interhemispheric transfer; and (ii) the redundant targets effect (RTE), testing parallel processing of visual information presented to each cerebral hemisphere. FA was lower and higher in alcoholics than in controls. In controls but not alcoholics, large CUDs correlated with low FA and high in total corpus callosum and regionally in the genu and splenium. In alcoholics but not controls, small RTEs, elicited with equiluminant stimuli, correlated with low FA in genu and splenium and high in the callosal body. The results provide in vivo evidence for disruption of corpus callosum microstructure in normal aging and alcoholism that has functional ramifications for efficiency in interhemispheric processing.

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    • "FA measures the directionality of water diffusion. Decreased FA indicates the loss of water directionality likely due to damage of the structural organization of the tissue [41]. MD is a measure of the average motion of water diffusion, independent of tissue directionality. "
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    ABSTRACT: Corpus callosum (CC) abnormalities may cause cognitive and neuropsychiatric complications due to reduced hemispheric integration. Over a one-year period, we investigated whether the CC structure of 20 patients with mild Alzheimer's disease (AD) was linked to the evolution of cognitive and neuropsychiatric symptoms. We also investigated whether this anatomical-clinical relationship was localized topographically on the CC by combining voxel-based morphometry and diffusion tensor imaging approaches. We assessed patients' global cognitive deterioration and neuropsychiatric symptoms with the Mini-Mental State Examination and the Neuropsychiatric Inventory. Increased global cognitive deterioration during the early course of AD was significantly related to reduced white matter density (p = 0.004) and fractional anisotropy (FA) (p = 0.012) and increased mean diffusivity (MD) (p = 0.017) at the level of the CC isthmus/splenium. Further, increased depression severity was significantly related to reduced FA (p = 0.008) and increased MD (p = 0.018) at the level of the CC rostrum. These results indicate that changes in early myelinated CC fibers, which subserve the lateral temporal and parietal cortices and are less vulnerable to damage, may be related to cognitive impairment. Furthermore, changes in late myelinated CC fibers, which connect the orbitofrontal cortices and are more vulnerable to damage, may be related to the earliest neuropsychiatric symptoms of AD, such as depression.
    Full-text · Article · Feb 2015 · Journal of Alzheimer's disease: JAD
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    • "FA measures the directionality of water diffusion. Decreased FA indicates the loss of water directionality likely due to damage of the structural organization of the tissue [41]. MD is a measure of the average motion of water diffusion, independent of tissue directionality. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Corpus callosum (CC) abnormalities may cause cognitive and neuropsychiatric complications due to reduced hemi-spheric integration. Over a one-year period, we investigated whether the CC structure of 20 patients with mild Alzheimer's disease (AD) was linked to the evolution of cognitive and neuropsychiatric symptoms. We also investigated whether this anatomical-clinical relationship was localized topographically on the CC by combining voxel-based morphometry and diffusion tensor imaging approaches. We assessed patients' global cognitive deterioration and neuropsychiatric symptoms with the Mini-Mental State Examination and the Neuropsychiatric Inventory. Increased global cognitive deterioration during the early course of AD was significantly related to reduced white matter density (p = 0.004) and fractional anisotropy (FA) (p = 0.012) and increased mean diffusivity (MD) (p = 0.017) at the level of the CC isthmus/splenium. Further, increased depression severity was significantly related to reduced FA (p = 0.008) and increased MD (p = 0.018) at the level of the CC rostrum. These results indicate that changes in early myelinated CC fibers, which subserve the lateral temporal and parietal cortices and are less vulnerable to damage, may be related to cognitive impairment. Furthermore, changes in late myelinated CC fibers, which connect the orbitofrontal cortices and are more vulnerable to damage, may be related to the earliest neuropsychiatric symptoms of AD, such as depression.
    Full-text · Chapter · Jan 2015
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    • "Chronic alcohol consumption is associated with subtle but significant compromise in the integrity of whitematter fibers, for example of the corpus callosum, a thick band of white-matter fiber connecting the two cerebral hemispheres (Pfefferbaum et al., 2010). Subtle interhemispheric fiber degradation in alcoholism can restrict interhemispheric information transfer and integration (Schulte et al., 2005b, 2010) and also affect attention, emotion, and cognition (Schulte et al., 2006; Mü ller- Oehring et al., 2013). To study how such fiber degradation in alcoholism may affect visual bottom-up processes, Schulte and colleagues (2010) used a behavioral paradigm that compared a visual display of paired with single targets presented to one or both visual hemifields. "
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    ABSTRACT: Deficits of attention, emotion, and cognition occur in individuals with alcohol abuse and addiction. This review elucidates the concepts of attention, emotion, and cognition and references research on the underlying neural networks and their compromise in alcohol use disorder. Neuroimaging research on adolescents with family history of alcoholism contributes to the understanding of pre-existing brain structural conditions and characterization of cognition and attention processes in high-risk individuals. Attention and cognition interact with other brain functions, including perceptual selection, salience, emotion, reward, and memory, through interconnected neural networks. Recent research reports compromised microstructural and functional network connectivity in alcoholism, which can have an effect on the dynamic tuning between brain systems, e.g., the frontally based executive control system, the limbic emotion system, and the midbrain-striatal reward system, thereby impeding cognitive flexibility and behavioral adaptation to changing environments. Finally, we introduce concepts of functional compensation, the capacity to generate attentional resources for performance enhancement, and brain structure recovery with abstinence. An understanding of the neural mechanisms of attention, emotion, and cognition will likely provide the basis for better treatment strategies for developing skills that enhance alcoholism therapy adherence and quality of life, and reduce the propensity for relapse.
    Full-text · Article · Oct 2014 · Handbook of Clinical Neurology
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