Investigation of the Neurite Density in Language Areas

As for the language contrast, Fig. 6(top-left) depicts the group level neurite density map, Fig. 6(top-right) the group level z-scores map stemming from the reading contrast and Fig. 6(bottom) the corresponding group level Dice index map at the cortical area level (using the Destrieux’s parcellation [8]). The language network has been widely studied and has been proven to be left-lateralized in most cases (right and left-handed). Figure 6 shows a high level of activation in the primary auditory cortex, the motor tongue area and more generally the temporal lobe.

Fig. 6 Group level maps for the language contrast: (top-left) neurite density at the vertex level; (top-right) z-scores at the vertex level; (bottom) Dice index results at the cortical area level

As we did for the hand motor tasks, we computed a statistical t-test in order to characterize the significant asymmetrical areas involved in the reading paradigm used. More precisely, we can recognize the Broca’s area, the Wernicke’s area, the inferior parietal lobule and some parts of the primary auditory cortex to be the highest meaningful cortical regions for this paradigm. Thus, the Dice index corroborates the link between the neurite density and the functional activity in those areas.