Resting-State Functional Connectivity in Individuals with Down Syndrome and Williams Syndrome Compared with Typically Developing Controls - PubMed (original) (raw)

Resting-State Functional Connectivity in Individuals with Down Syndrome and Williams Syndrome Compared with Typically Developing Controls

Jennifer N Vega et al. Brain Connect. 2015 Oct.

Abstract

The emergence of resting-state functional connectivity (rsFC) analysis, which examines temporal correlations of low-frequency (<0.1 Hz) blood oxygen level-dependent signal fluctuations between brain regions, has dramatically improved our understanding of the functional architecture of the typically developing (TD) human brain. This study examined rsFC in Down syndrome (DS) compared with another neurodevelopmental disorder, Williams syndrome (WS), and TD. Ten subjects with DS, 18 subjects with WS, and 40 subjects with TD each participated in a 3-Tesla MRI scan. We tested for group differences (DS vs. TD, DS vs. WS, and WS vs. TD) in between- and within-network rsFC connectivity for seven functional networks. For the DS group, we also examined associations between rsFC and other cognitive and genetic risk factors. In DS compared with TD, we observed higher levels of between-network connectivity in 6 out 21 network pairs but no differences in within-network connectivity. Participants with WS showed lower levels of within-network connectivity and no significant differences in between-network connectivity relative to DS. Finally, our comparison between WS and TD controls revealed lower within-network connectivity in multiple networks and higher between-network connectivity in one network pair relative to TD controls. While preliminary due to modest sample sizes, our findings suggest a global difference in between-network connectivity in individuals with neurodevelopmental disorders compared with controls and that such a difference is exacerbated across many brain regions in DS. However, this alteration in DS does not appear to extend to within-network connections, and therefore, the altered between-network connectivity must be interpreted within the framework of an intact intra-network pattern of activity. In contrast, WS shows markedly lower levels of within-network connectivity in the default mode network and somatomotor network relative to controls. These findings warrant further investigation using a task-based procedure that may help disentangle the relationship between brain function and cognitive performance across the spectrum of neurodevelopmental disorders.

Keywords: APOE; Down syndrome; Williams syndrome; fMRI; resting state functional connectivity.

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Figures

**FIG. 1.

Visualization of the approximate anatomical location of between-network pairs whose interconnectivity was significantly different for DS versus TD (a–f), and WS versus TD (g). No between-network pairs were significantly different for DS versus WS. DAN, dorsal attention network; DMN, default mode network; DS, Down syndrome; TD, typically developing; WS, Williams syndrome.

**FIG. 2.

For the purpose of visualization, the presence (ɛ4+) or absence (ɛ4−) of APOE ɛ4 alleles is plotted in relationship to within-DAN connectivity across the DS (blue) and TD (green) groups. The solid line indicates the mean for within-DAN connectivity value for the ɛ4− group, and the dashed line indicates the mean within-DAN connectivity value for the ɛ4+ group. A two-sample _t_-test showed APOE ɛ4 carrier status to be associated with connectivity within the DAN; however, a larger sample size will be needed to accurately estimate this effect.

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Resting-State Functional Connectivity in Individuals with Down Syndrome and Williams Syndrome Compared with Typically Developing Controls - PubMed (original) (raw)