e. males in visuo-spatial tasks and females in verbal and emotional intelligence tasks. However, in spite of the long research tradition, the functional and structural foundation this website of the neural efficiency phenomenon remains largely unclear. The findings of this study suggest that neural efficiency in men may be associated with more FA accompanied by lower RD (higher degree of myelination). Interestingly, Huster, Westerhausen, and Herrmann (2010) reported that interindividual variations in callosal morphology are associated with electrophysiological and behavioral performance measures. Large middle and posterior subregions of the CC were correlated with low reaction times

and low stop-related P300. This is in line with our assumption that more FA in higher intelligent males may actually be associated with more efficient brain functioning by reducing inter-hemispheric transfer time. Although neural efficiency has been shown repeatedly when working on verbal tasks in the female brain (Neubauer et al., 2002 and Neubauer et al., 2005), we observed no relationship between intelligence and white matter microstructure for females.

Thus, efficient processing ABT-199 purchase in women might be more related to gray matter differences (cf. Burgaleta et al., 2012). Gray matter (cell bodies, dendrites and short protrusions) is important for regional information processing (Gur et al., 1999). Yan et al. (2011) hypothesize that a higher percentage of GM in smaller brains increases the proportion of tissue available for computational processes, which further support high local network efficiency. This result was found for women by Yan et al. (2011). The corpus callosum, together with the cingulum, the corticospinal tract, and the inferior fronto-occipital fasciculus, has been related to intelligence (Li et al., 2009). The corpus callosum, as the largest white matter tract in the human brain, plays an important role in higher cognition (cf. Hinkley et al., 2012). As the corpus callosum allows for functional

interactions Farnesyltransferase both within each hemisphere and between the two hemispheres, regions within the frontal, parietal, and occipital cortices that are implicated in cognitive domains are affected (Hinkley et al., 2012). Previous studies suggest that weakened integrity of the corpus callosum directly impairs cognitive function in aging adults (Voineskos et al., 2012 and Zahr et al., 2009) whereas increased callosal thickness correlates positively with intelligence (Luders et al., 2007, Luders et al., 2011 and Yu et al., 2008), processing speed (Penke et al., 2010), and problem solving abilities (van Eimeren, Niogi, McCandliss, Holloway, & Ansari, 2009). The corpus callosum, as part of the intelligence network (cf. Li et al., 2009), was found to differ between men and women with respect to white matter microstructure (Menzler et al., 2011).