Diffusion properties of cortical and pericortical tissue: regional variations, reliability and methodological issues

Kang, Xiaojian; Herron, Timothy J.; Turken, U.; Woods, David L.

doi:10.1016/j.mri.2012.04.004

Cited by 29 publications

(31 citation statements)

References 53 publications

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“…First, the spatial resolution of standard DTI is low relative to the underlying WM structure and the inability of DTI-based fiber tractography to resolve crossing fibers. Second, the measurement of tissue structure is complicated because of partial voluming of WM, GM, and cerebrospinal fluid (CSF) [21]. Third, the standard tensor models diffusion assumes that water molecule diffusion occurs in a free and unrestricted environment with a Gaussian distribution.…”

Section: Discussionmentioning

confidence: 99%

A diffusional kurtosis imaging study of idiopathic generalized epilepsy with unilateral interictal epileptiform discharges in children

Zhang

Gao

Zhou

et al. 2016

Journal of Neuroradiology

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Section: Discussionmentioning

confidence: 99%

A diffusional kurtosis imaging study of idiopathic generalized epilepsy with unilateral interictal epileptiform discharges in children

Zhang

Gao

Zhou

et al. 2016

Journal of Neuroradiology

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“…Fourth, some of the newer measurements described in this study (i.e., cortical and pericortical diffusion measures) are receiving increased attention in the neuroimaging literature given their proposed ability to provide insight into the cytoarchitectonic organization of the human cortex and add to the morphological information provided by T 1 -weighted images (Behrens, Jenkinson, Robson, Smith, & Johansen-Berg, 2006). However, there are methodological issues related to these measurements (Kang et al, 2012). In particular, given the thin and variable nature of the cortex, and the diffusion imaging voxel size of 2.5 mm, MD of cortical regions is likely to be contaminated to some degree by partial voluming with CSF, and pericortical white matter ROIs may be affected by partial voluming with adjacent gray matter.…”

Section: Discussionmentioning

confidence: 99%

“…Microstructural damage within medial and anterior temporal lobe ROIs has also been linked to impaired immediate and delayed memory performances, respectively (Riley et al, 2010), and there is some evidence that DTI measurements are more sensitive than white matter volumes for predicting cognitive impairments in TLE (McDonald et al, 2008a). Beyond the deep white matter, microstructural damage can also be quantified within the cortex and the subadjacent white matter (Govindan, Asano, Juhasz, Jeong, & Chugani, 2013; Kang, Herron, Turken, & Woods, 2012; McNab et al, 2013). These pericortical diffusion measures may add value to the understanding of regional pathology in TLE since white matter proximal to a cortical region preferentially contains afferent and efferent fibers associated with that cortical region; thus, providing insight into the integrity of the region.…”

Section: Introductionmentioning

confidence: 99%

White matter microstructure complements morphometry for predicting verbal memory in epilepsy

McDonald

Leyden

Hagler

et al. 2014

Cortex

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Verbal memory is the most commonly impaired cognitive domain in patients with temporal lobe epilepsy (TLE). Although damage to the hippocampus and adjacent temporal lobe structures is known to contribute to memory impairment, little is known of the relative contributions of white versus gray matter structures, or whether microstructural versus morphometric measures of temporal lobe pathology are stronger predictors of impairment. We evaluate whether measures of temporal lobe pathology derived from diffusion tensor imaging (DTI; microstructural) versus structural MRI (sMRI; morphometric) contribute the most to memory performances in TLE, after controlling for hippocampal volume (HCV). DTI and sMRI were performed on 26 patients with TLE and 35 controls. Verbal memory was measured with the Logical Memory subtest of the Wechsler Memory Scale–III. Hierarchical regression analyses were performed to examine unique contributions of DTI and sMRI measures to verbal memory with HCV entered in block 1. In patients, impaired recall was associated with increased mean diffusivity (MD) of multiple fiber tracts that project through the temporal lobes. In addition, increased MD of the left cortical and bilateral pericortical white matter was associated with impaired recall. After controlling for left HCV, only microstructural measures of white matter pathology contributed to verbal recall. The best predictive model included left HCV and MD of the left inferior longitudinal fasciculus (ILF) and pericortical white matter beneath the left entorhinal cortex. This model explained 60% of the variance in delayed recall and revealed that MD of the left ILF was the strongest predictor. These data reveal that white matter microstructure within the temporal lobe can be used in conjunction with left HCV to enhance the prediction of verbal memory impairment, and speak to the complementary nature of DTI and sMRI for understanding cognitive dysfunction in epilepsy and possibly other memory disorders.

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“…DTI volumes were coregistered with subjects’ anatomical T1-weighted volume using FreeSurfer. FreeSurfer was also used to identify white matter voxels that lie 2 mm below the cortical gray-white boundary (Kang, Herron, Turken, & Woods, 2012). The fractional anisotropy (FA) within each of these voxels was then calculated.…”

Section: Methodsmentioning

confidence: 99%

The Neural Correlates of Speech Motor Sequence Learning

Segawa¹,

Tourville²,

Beal

et al. 2015

Journal of Cognitive Neuroscience

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Speech is perhaps the most sophisticated example of a species-wide movement capability in the animal kingdom, requiring split-second sequencing of approximately 100 muscles in the respiratory, laryngeal, and oral movement systems. Despite the unique role speech plays in human interaction and the debilitating impact of its disruption, little is known about the neural mechanisms underlying speech motor learning. Here, we studied the behavioral and neural correlates of learning new speech motor sequences. Subjects repeatedly produced novel, meaningless syllables comprising illegal consonant clusters (e.g. GVAZF) over two days of practice. Following practice, subjects produced the sequences with fewer errors and shorter durations, indicative of motor learning. Using functional magnetic resonance imaging, we compared brain activity during production of the learned illegal sequences and novel illegal sequences. Greater activity was noted during production of novel sequences in brain regions linked to non-speech motor sequence learning, including the basal ganglia and pre-supplementary motor area. Activity during novel sequence production was also greater in brain regions associated with learning and maintaining speech motor programs, including lateral premotor cortex, frontal operculum, and posterior superior temporal cortex. Measures of learning success correlated positively with activity in left frontal operculum and white matter integrity under left posterior superior temporal sulcus. These findings indicate speech motor sequence learning relies not only on brain areas involved generally in motor sequencing learning but also those associated with feedback-based speech motor learning. Furthermore, learning success is modulated by the integrity of structural connectivity between these motor and sensory brain regions.

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Diffusion properties of cortical and pericortical tissue: regional variations, reliability and methodological issues

Cited by 29 publications

References 53 publications

A diffusional kurtosis imaging study of idiopathic generalized epilepsy with unilateral interictal epileptiform discharges in children

A diffusional kurtosis imaging study of idiopathic generalized epilepsy with unilateral interictal epileptiform discharges in children

White matter microstructure complements morphometry for predicting verbal memory in epilepsy

The Neural Correlates of Speech Motor Sequence Learning

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