Determining the hemispheric dominance of spatial attention: A comparison between fTCD and fMRI

Abstract

Human brain mapping allows the systematic assessment of interindividual differences in functional brain anatomy. Functional transcranial Doppler sonography (fTCD) is an imaging tool that allows for fast and mobile assessment of hemispheric lateralization of task-related brain activation. It is ideal to screen large cohorts of subjects. The goal of the present study was to investigate whether fTCD and functional magnetic resonance imaging (fMRI) determine hemispheric lateralization of brain activation related to visuospatial attention concordantly. Used together, fMRI and fTCD may then open up a wide range of potential applications in neuroscience. Fifteen subjects were examined both with fTCD and fMRI while they judged accuracy of line bisections (Landmark task). For fTCD, the maximal mean difference in stimulus-related relative cerebral blood flow velocity changes in the left and right middle cerebral arteries was assessed as the lateralization index LI(fTCD). For fMRI, two approaches were used to determine hemispheric dominance. First, we measured brain activity as the extent of the activated region, i.e., the number of activated voxels above a statistical threshold. Second, we calculated the magnitude of the fMRI signal change between the activation and the control task within a region of interest. Results of fTCD and fMRI were concordant in every single case. Therefore, scanning large cohorts with fTCD for hemispheric dominance during Landmark task will provide results consistent with fMRI. FMRI can then be used for in depth assessment of the specific patterns of activation.

Visual half-field experiments are a good measure of cerebral language dominance if used properly: Evidence from fMRI

“…The degree of laterality expressed in the LIs is dependant on the chosen statistical threshold and should therefore be treated with caution. The approach itself, however, has been shown to produce LIs which are not significantly different from LIs calculated via other means and which correlate well with LIs calculated from Wada and fTCD measurements (e.g., Chelbus et al, 2007;Jansen et al, 2004). In our study, laterality for those participants who were strongly left dominant and those who were strongly right dominant was exceptionally clear, regardless of cut off p-values chosen.…”

Callosal tracts and patterns of hemispheric dominance: A combined fMRI and DTI study

“…Although there has been some question as to the reliability of fMRI-based laterality measures (Jansen et al, 2006), classification of language lateralization based on this task has yielded results consistent with the Wada test, which is thought to be the "gold standard" for measuring hemispheric dominance (Woermann et al, 2003;Yetkin et al, 1998), and also yield results consistent with functional transcranial Doppler sonography (Jansen et al, 2004). Moreover, the test-retest reliability of lateralization has been shown to be high (Adcock et al, 2003;Fernandez et al, 2003).…”

Atypical Hemispheric Dominance for Attention: Functional MRI Topography

“…Hemispheric dominance for language and spatial attention was originally assessed by fTCD (see below), and confirmed by fMRI Jansen et al, 2004a). (Lezak, 1995).…”

“…In a previous study on healthy subjects, we investigated whether functional transcranial Doppler sonography (fTCD) and functional magnetic resonance imaging (fMRI) determine hemispheric dominance of brain activation related to visuospatial attention concordantly (Jansen et al, 2004a). In this study, we identified three subjects who were lefthemisphere lateralized for spatial attention and right-hemisphere dominant for language and two subjects who were right-hemisphere dominant for both language and spatial attention.…”