Table 1.
Demographic and Clinical Characteristics of HDI and Control Groups.
Table 2.
Details on the brain regions in the DMN map (P<0.01, FDR corrected) from the control and HDIs.
Fig 1.
Group-level analyses of the DMN.
A: DMN in the HDI (T> 3.16, P < 0.01, FDR corrected). B: DMN in the Control (T>4.23, P < 0.01, FDR corrected). C: Contrast between the DMN in HDI and controls (| T | >2.7, P < 0.05, FDR corrected). T values, cluster size, and Talairach coordinates of all significant clusters are reported in Table 2.
Fig 2.
Example of DTI fiber tractography on one control (A) and one HDI (B).
Only three fiber bundles connecting the PCC/PCUN and MPFC, bilateral PHGs were detected in all the subjects. The color-coding of the obtained fibers is based on the standard RGB (Red, Green, Blue) code applied to the vector at every segment of each fiber. Red indicates the medio-lateral plane. Green indicates the dorsoventral orientation. Blue indicates the rostro-caudal direction. DTI = diffusion tensor imaging; HDI = heroin dependent individual; PCC/PCUN = posterior cingulated cortex/precuneus; MPFC = medial prefrontal cortex; PHG = parahippocampalgyrus.
Fig 3.
Comparison of structural and functional connectivity between HDIs and Controls.
Compared to the Controls, HDIs show both decreased FA and increased MD between the PCC/PCUN to right PHG, decreased FA and track count between the PCC/PCUN and MPFC, and decreased functional connectivity between the PCC/PCUN and bilateral PHG, and MPFC. For each connection, differences are setting at the significant level of corrected P<0.05(marked with star symbol) with Bonferroni correction. Error bars represent the standard deviation of the measurements. HDI = heroin-dependent individuals; PCC/PCUN = posterior cingulate cortex/precuneus; PHG = parahippocampalgyrus; MPFC = medial prefrontal cortex; FA = fractional anisotropy; MD = mean diffusivity.
Fig 4.
Functional connectivity within the DMN in Controls and HDIs.
Averaged temporal correlation coefficient r (Red) across all subjects in the Controls (A) and in the HDIs (B). Compared with Controls, HDIs show decreased temporal correlation coefficients between the PCC/PCUN and the MPFC, as well as between the PCC/PCUN and the bilateral PHG. MPFC is color-coded Blue, PCC/PCUN color-coded Green, the left PHG color-coded Pink, the right PHG color-coded Red. DMN = default mode network; HDI = heroin-dependent individuals. PCC/PCUN = posterior cingulate cortex/precuneus; MPFC = medial prefrontal cortex; PHG = parahippocampalgyrus.
Fig 5.
Correlationbetweenthe structural/functional indices and clinical markers of HDIs.
Pearson correlation results reveal that in HDIs, the FA values of the tracts connecting PCC/PCUN to the MPFC (A), and connecting PCC/PCUN to the right PHG (B)negatively correlate to the duration of heroin use, the temporal correlation coefficients between PCC/PCUN and the MPFC (C), and the FA values of the tracts connecting PCC/PCUN to the MPFC (D) show positive correlation to the IGT performance (P<0.05, Bonferroni corrected). HDI = heroin dependent individuals; FA = fractional anisotropy; PCC/PCUN = posterior cingulate cortex/precuneus; PHG = parahippocampal gyrus; MPFC = medial prefrontal cortex; IGT = Iowa gambling task.