Schulte T, Sullivan EV, Muller-Oehring EM, et al. Corpus callosal microstructural integrity influences interhemispheric processing: a diffusion tensor imaging study
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.
- "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 01/2014; 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 · 4.38 Impact Factor
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- "bundle responsible for homotopic and heterotopic interhemispheric connections ( Paul et al . 2007 ) , has also been studied in this syndrome . Fibers of the CC are implicated in a wide range of cognitive abilities , such as binocular coordination skills ( Johansen - Berg et al . 2007 ) , visual attention ( Hines et al . 2002 ) , processing speed ( Schulte et al . 2005 ) , reading and intelligence ( Luders et al . 2007b ) , and comprehension of syntax and linguistic pragmatics ( Paul et al . 2007 ) . Of note , all of these cognitive functions have been found to be affected in WS ( Karmiloff - Smith et al . 2003 ) . Previous studies that have analyzed the CC in WS reported mor - phologic abnormalities "
ABSTRACT: Brain abnormalities in Williams syndrome (WS) have been consistently reported, despite few studies have devoted attention to connectivity between different brain regions in WS. In this study, we evaluated corpus callosum (CC) morphometry: bending angle, length, thickness and curvature of CC using a new shape analysis method in a group of 17 individuals with WS matched with a typically developing group. We used this multimethod approach because we hypothesized that neurodevelopmental abnormalities might result in both volume changes and structure deformation. Overall, we found reduced absolute CC cross-sectional area and volume in WS (mean CC and subsections). In parallel, we observed group differences regarding CC shape and thickness. Specifically, CC of WS is morphologically different, characterized by a larger bending angle and being more curved in the posterior part. Moreover, although CC in WS is shorter, a larger relative thickness of CC was found in all callosal sections. Finally, groups differed regarding the association between CC measures, age, white matter volume and cognitive performance. In conclusions, abnormal patterns of CC morphology and shape may be implicated in WS cognitive and behavioural phenotype.Brain Structure and Function 05/2012; 218(3). DOI:10.1007/s00429-012-0423-4 · 4.57 Impact Factor