The RF algorithm identified 29 DMN connections, representing all frequency bands, as significantly important to classify AUD individuals from the unaffected controls. The predominant pattern across these DMN connections was hyperconnectivity (i.e., increased FC magnitude in 25 of 29 connections, p < 0.05) (Figure 5, panels a–e). Among these important 29 connections, 12 connections satisfied a higher threshold of significance (p ≤ 0.001) (Figure 6). Interestingly, 11 of these highly significant connections showed hyperconnectivity in AUD. It was interesting to find that this pattern of predominant hyperactivity was not restricted to any specific frequency band(s) nor any region-specific DMN seeds. In other words, the hyperactivity was a ubiquitous pattern ranging all frequencies and all 12 DMN seed regions. Broadly, these findings may indicate an aberrant network functioning during resting state in AUD individuals. It is likely that resting state hyperconnectivity across DMN connections may be suggestive of neural hyperexcitability and disinhibition in AUD individuals [108,109,110,111,112], possibly modulated by GABAergic and glutamatergic mechanisms underlying neural excitability reflected in EEG and acute and chronic effects of alcohol in the brain [113,114,115,116,117]. While
