Twenty-two participants, genotyped for the COMT val158met polymorphism, performed verbal and spatial fluid intelligence (Gf) items, classified according to their cognitive complexity, as estimated from the loadings on g (see ref
57). These researchers were particularly interested in the analysis of the frontoparietal network related to fluid intelligence (the lateral prefrontal cortex, the presupplementary motor area/anterior cingulate cortex, and the intraparietal sulcus). Findings revealed a positive effect of COMT val allele load upon the BOLD Inhibitors,research,lifescience,medical signal in regions belonging to this brain network when items showing distinguishable cognitive complexity were compared. This result suggests that the COMT val158met polymorphism impacts on the neural network supporting fluid intelligence. Inhibitors,research,lifescience,medical The finding is a demonstration that the effect of single genes can impact blood oxygen level dependent signal as assessed by fMRI. Further evidence linking catecholamine modulation within the identified network may help explain individual differences in the neural response to
high levels of cognitive complexity, irrespective of the content domain (verbal or nonverbal). Inhibitors,research,lifescience,medical White I-BET151 cell line matter The relationship between human intelligence and the integrity of white matter has been much less investigated, although this trend is changing rapidly. Diffusion tensor imaging (DTI) is based on the diffusion of water molecules in the brain and provides information about the size, orientation, Inhibitors,research,lifescience,medical and geometry of
myelinated axons. DTI can produce measures that include fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RA), and axial diffusivity (AD), which allow for the assessment of myelin and axonal integrity (see Figure 7). Figure 7. DTI is useful for fine-grained deterministic and probabilistic tractography to capture underlying cortical connectivity patterns. This can be used for the quantitative analysis of local and global network properties using graph-theoretical approaches (eg, analysis of small-world properties).58,59 Using DTI, Schmithorst et al60 Inhibitors,research,lifescience,medical analyzed the relationship between intelligence and white matter structure. The sample these comprised 47 children and adolescents (age range 5 to 18). White matter structure was studied using fractional anisotropy (FA) and mean diffusivity (MD) indices. These indices were correlated with intelligence scores obtained from the Wechsler scales. These researchers found positive correlations bilaterally for FA in white matter association areas (frontal and parietooccipital areas). These correlations were thought to reflect a positive relationship between fiber organization-density and intelligence. Also using a DTI approach, Yu et al61 computed correlations between the integrity of several tracts (corpus callosum, cingulum, uncinate fasciculus, optic radiation, and corticospinal tract) and intelligence.