Schulte T, Sullivan EV, Muller-Oehring EM, et al. Corpus callosal microstructural integrity influences interhemispheric processing: a diffusion tensor imaging study
Neuroscience Program, SRI International, Menlo Park, CA 94025, USA.Cerebral Cortex (Impact Factor: 8.67). 09/2005; 15(9):1384-92. DOI: 10.1093/cercor/bhi020
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.
- "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. "
Article: Cognition, emotion, and attention[Show abstract] [Hide abstract]
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.Handbook of Clinical Neurology 10/2014; 125C:341-354. DOI:10.1016/B978-0-444-62619-6.00020-3
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- "Patients who have undergone partial or complete callosotomy demonstrate significant bimanual coordination deficits (Eliassen et al. 2000; Serrien et al. 2001; Kennerley et al. 2002; Sternad et al. 2007). In patients with multiple sclerosis who have damage to the CC, white matter organization of the anterior callosal portions has been correlated with impairments of bimanual coordination (Schulte et al. 2005; Johansen-Berg et al. 2007; Bonzano et al. 2008, 2011a,b; Della-Maggiore et al. 2009; Tomassini et al. 2011). However, these studies only examined short-term motor performance. "
ABSTRACT: The corpus callosum (CC) is the largest white matter tract in the brain. It enables interhemispheric communication, particularly with respect to bimanual coordination. Here, we use diffusion tensor imaging (DTI) in healthy humans to determine the extent to which structural organization of subregions within the CC would predict how well subjects learn a novel bimanual task. A single DTI scan was taken prior to training. Participants then practiced a bimanual visuomotor task over the course of 2 wk, consisting of multiple coordination patterns. Findings revealed that the predictive power of fractional anisotropy (FA) was a function of CC subregion and practice. That is, FA of the anterior CC, which projects to the prefrontal cortex, predicted bimanual learning rather than the middle CC regions, which connect primary motor cortex. This correlation was specific in that FA correlated significantly with performance of the most difficult frequency ratios tested and not the innately preferred, isochronous frequency ratio. Moreover, the effect was only evident after training and not at initiation of practice. This is the first DTI study in healthy adults which demonstrates that white matter organization of the interhemispheric connections between the prefrontal structures is strongly correlated with motor learning capability.Learning & memory (Cold Spring Harbor, N.Y.) 07/2012; 19(8):351-7. DOI:10.1101/lm.026534.112 · 3.66 Impact Factor
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- "While FA may have a number of determinants, even in healthy subjects, the principle factors are myelination and tissue architecture , with the inference that higher FA represents more “efficient” white matter organisation. This inference is supported by correlations of FA with conduction speed , . These gender differences may thus be informative about function. "
ABSTRACT: Sexual dimorphism in human brain structure is well recognised, but little is known about gender differences in white matter microstructure. We used diffusion tensor imaging to explore differences in fractional anisotropy (FA), an index of microstructural integrity. A whole brain analysis of 135 matched subjects (90 men and 45 women) using a 1.5 T scanner. A region of interest (ROI) analysis was used to confirm those results where proximity to CSF raised the possibility of partial-volume artefact. Men had higher fractional anisotropy (FA) in cerebellar white matter and in the left superior longitudinal fasciculus; women had higher FA in the corpus callosum, confirmed by ROI. The size of the differences was substantial--of the same order as that attributed to some pathology--suggesting gender may be a potentially significant confound in unbalanced clinical studies. There are several previous reports of difference in the corpus callosum, though they disagree on the direction of difference; our findings in the cerebellum and the superior longitudinal fasciculus have not previously been noted. The higher FA in women may reflect greater efficiency of a smaller corpus callosum. The relatively increased superior longitudinal fasciculus and cerebellar FA in men may reflect their increased language lateralisation and enhanced motor development, respectively.PLoS ONE 06/2012; 7(6):e38272. DOI:10.1371/journal.pone.0038272 · 3.23 Impact Factor
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