Individual Differences in Verbal Abilities Associated with Regional Blurring of the Left Gray and White Matter Boundary

Abstract

Blurring of the cortical gray and white matter border on MRI is associated with normal aging, pathological aging, and the presence of focal cortical dysplasia. However, it remains unclear whether normal variations in signal intensity contrast at the gray and white matter junction reflect the functional integrity of subjacent tissue. This study explores the relationship between verbal abilities and gray and white matter contrast (GWC) in healthy human adults. Participants were scanned at 3 T MRI and administered standardized measures of verbal expression and verbal working memory. GWC was estimated by calculating the non-normalized T1 image intensity contrast above and below the cortical gray/white matter interface. Spherical averaging and whole-brain correlational analyses were performed. Sulcal regions exhibited higher contrast compared to gyral regions. We found a strongly lateralized and regionally specific profile with reduced verbal expression abilities associated with blurring in left hemisphere inferior frontal cortex and temporal pole. Reduced verbal working memory was associated with blurring in widespread left frontal and temporal cortices. Such lateralized and focal results provide support for GWC as a measure of regional functional integrity and highlight its potential role in probing the neuroanatomical substrates of cognition in healthy and diseased populations.

Decoding the Neuroanatomical Basis of Reading Ability: A Multivoxel Morphometric Study

“…Not surprisingly, the regions that are predictive of this ability, particularly the hippocampus, have been consistently implicated in language learning and general memory tasks. For example, the hippocampus has also been implicated in learning new lexicons (Breitenstein et al, 2005;Davis et al, 2009), and the integrity of the hippocampus and surrounding white matter is correlated with language training success in aphasia (Meinzer et al, 2010). On the other hand, studies on patients with hippocampal lesions (e.g., patient HM Corkin, 2002) and neuroimaging studies on healthy participants (Schacter and Wagner, 1999;Eldridge et al, 2000;Greicius et al, 2002;Zeineh et al, 2003) have all emphasized the role of the hippocampus in memory encoding and retrieval.…”

“…Compared with functional imaging, the anatomical approach requires less participant cooperation, and is most cost-effective and less contaminated by performance differences, providing an ideal tool for a largescale study of participants with various ages and reading abilities. This method has been widely used to examine the neural basis of reading difficulties (Vinckenbosch et al, 2005;Hoeft et al, 2007;Frye et al, 2010;Welcome et al, 2011;Richlan et al, 2013), and also the neural basis of individual differences in reading ability among typical adults (Blackmon et al, , 2011Zhang et al, 2013).…”

Prefrontal lobe structural integrity and trail making test, part B: converging findings from surface-based cortical thickness and voxel-based lesion symptom analyses

“…In healthy young to middle age adults, decreased CT is associated with a performance advantage across a range of cognitive domains, including attention (Westlye et al 2011), word-reading (Blackmon et al 2011), and expert chess-playing (Hänggi et al 2014). When cognitive domain-specific performance discrepancies are observed, a verbal over visuospatial advantage is associated with decreased CT in bilateral occipito-temporal and frontal regions; whereas, a visuospatial over verbal advantage is associated with increased CT in the same regions (Margolis et al 2013).…”

“…CT was calculated at every vertex as the shortest distance between the two surfaces (Fischl and Dale 2000). Major components of the applied procedure were described in detail in recent publications (Blackmon et al 2010, 2011; Butler et al 2012). In brief, MRI data were registered to Talairach space, intensity normalized and the skull was automatically removed (Dale et al 1999; Ségonne et al 2004).…”

“…The introduction of qMRI methods allows for precise measurement of cortical thickness (CT) and for statistical comparison between individual brains, which increases sensitivity to more subtle variations in brain morphology (Fischl and Dale 2000; Jones et al 2000). This has launched several investigations of the relationship between morphological aberrations and cognition or behavior in healthy individuals with visually normal MRI scans (Bermudez et al 2009; Blackmon et al 2010, 2011). This work has also been extended to those with neurological disease, with evidence of a relationship between CT abnormalities and cognitive impairments in temporal lobe epilepsy (Dabbs et al 2009).…”