Correlation of Brain White Matter Diffusion Anisotropy and Mean Diffusivity with Reaction Time in an Oddball Task

Abstract

Background: Reaction time (RT) is a frequently used measure of information processing speed, but the underlying physiological and anatomical conditions are not yet fully understood. A correlation between measures of white matter (WM) ultrastructural properties and RT is expected – particularly for those WM tracts that are involved in the attentional system of the brain. Methods: Diffusion tensor imaging data were acquired in 43 unrelated healthy subjects (age: 22.7 ± 1.8 years), and RT was measured during an attention-requiring visual oddball task in the same scanning session. Voxel-by-voxel and region of interest analyses were performed for the large association tracts. A linear regression model was used to correlate fractional anisotropy (FA) and mean diffusivity (MD) values with mean RT. Results: Our analyses revealed significant positive correlations between RT and MD in several WM association tracts, predominantly in the right hemisphere. To a lesser extent, significant negative correlations were found between RT and FA in right temporal WM. Conclusion: These findings suggest that subcortical ultrastructural properties of the dorsal and ventral visual stream are relevant with regard to information processing speed. Furthermore, MD appears to be more sensitive than FA in detecting functionally relevant ultrastructural variations in WM tracts.

Linking Brain Connectivity Across Different Time Scales with Electroencephalogram, Functional Magnetic Resonance Imaging, and Diffusion Tensor Imaging

“…Thus, taken together, there seems to be a physiological association between blood flow, BOLD signal fluctuations, and EEG features in the alpha band (IAF and power) in networks relevant for specific tasks involving attention and working memory. Further support of the view of an association to task performance is provided by studies that demonstrated a relation of FA (within association fascicles) with reaction time (Konrad et al, 2009), cognitive performance (Madden et al, 2009;Moseley et al, 2002;Sasson et al, 2010), and mental disorders (Begre et al, 2008). Our results of the present study, together with previous work, indicate that transient activity of FCNs is related to baseline activity of the same FCNs, and structural connectivity within those FCNs.…”

Brain microstructural correlates of visuospatial choice reaction time in children

“…However, in the TBSS effect-size map (Fig. 5), some clusters exhibiting an apparent relationship with choice RT are present in regions similar to those found in adults (Konrad et al, 2009;Tuch et al, 2005), suggesting that regions supporting visuospatial attention may also be related to children's performance on the present task. Future studies are necessary to address this in more detail.…”

“…Alternatively, the variability in motor system MD may reflect individual differences in the architecture of the motor system (perhaps differences in the underlying connectivity) that emerge earlier during brain development and remain stable in spite of superimposed biological changes associated with maturation. This is plausible since individual differences in behavioural performance have been associated with MD variability in adults (Konrad et al, 2009;Piras et al, 2010) as well as children.…”

“…Previous studies of young adults examining relationships between choice RT and white matter microstructure generally employed more complex choice RT tasks that also placed high demands on visual discrimination, response inhibition, and/or working memory (Konrad et al, 2009;Madden et al, 2004;Tuch et al, 2005). These studies mainly focused on regions outside the motor system and found effects in pathways supporting visuospatial attention.…”

“…Increasing speed of processing can involve a wide range of sensory, cognitive and motor functions, and has been studied at the behavioural level with many different choice reaction time (RT) tasks (Konrad et al, 2009;Madden et al, 2004;Miller and Low, 2001). In this study, we wished to clarify whether choice RT on a simple behavioural task was correlated with microstructure within the motor network.…”