Tissue density increases with the increased presence of unspecific cellular structures (i.e., capillaries, synapses, spines, and macromolecular proteins); the properties of myelin, neuronal membranes, and axons; the shape of neurons and glia; and enhanced tissue organization (Beaulieu, 2002; Sagi et al., 2012).
The majority of these tissue differences are thought to affect neural plasticity.
Although studies with smaller sample sizes have generated inconsistent results, they generally show a relation between low family SES and decreased brain volume (Hanson et al., 2011; Lawson et al., 2013; Luby et al., 2013). doi: 10.1080/14622200802323274 Pub Med Abstract | Cross Ref Full Text | Google Scholar Takeuchi, H., and Kawashima, R. Neural mechanisms and children’s intellectual development: multiple impacts of environmental factors. doi: 10.1177/1073858415610294 Pub Med Abstract | Cross Ref Full Text | Google Scholar Takeuchi, H., Taki, Y., Hashizume, H., Asano, K., Asano, M., Sassa, Y., et al. Impact of videogame play on the brain’s microstructural properties: cross-sectional and longitudinal analyses.
Another study involving a diverse sample of 1082 children and adolescents aged between 3 and 21 years showed that a higher family income is related to higher fractional anisotropy (FA) (which reflects the structural properties of white matter) in and near the hippocampus and frontal cortex (Ursache and Noble, 2016b).
A neuroimaging study with 1099 typically developing individuals aged between 3 and 20 years showed that parents’ educational qualifications and the family income were positively correlated with the total brain surface area (Hurt and Betancourt, 2015).
Another study involving 389 typically developing children showed an association between a higher family SES and a greater total gray matter volume (Hair et al., 2015). doi: 10.1038/mp.2015.193 Pub Med Abstract | Cross Ref Full Text | Google Scholar Takeuchi, H., Taki, Y., Sekiguchi, A., Nouchi, R., Kotozaki, Y., Nakagawa, S., et al. Differences in gray matter structure correlated to nationalism and patriotism.
Mean diffusivity (MD) is measured by diffusion tensor imaging (DTI) (Beaulieu, 2002) and used to measure the microstructural properties of gray and white matter. Delay discounting and smoking: association with the fagerström test for nicotine dependence but not cigarettes smoked per day.
As we summarized previously (Takeuchi et al., 2016a), lower MD is sensitive to greater tissue density of the brain parenchyma (though is not strictly a measure of it).
Therefore, MD is supposed to provide characteristic information regarding neural plasticity (though, it is obviously not limited to be a measure of neural plasticity); indeed, MD measurements served as a characteristic and sensitive tool to study neural plasticity and development (Sagi et al., 2012; Takeuchi et al., 2015a, 2016a).
As described, family SES is an important factor that affects cognitive, socioemotional, neural, and health development. Threshold-free cluster enhancement: addressing problems of smoothing, threshold dependence and localisation in cluster inference. doi: 10.1016/j.neuroimage.20 Pub Med Abstract | Cross Ref Full Text | Google Scholar Sweitzer, M.