Fig. 4: Redundant and synergistic in the spontaneous psychotic brain.

The redundant and synergistic information was measured using integrated information decomposition based on partial information decomposition (PID). The basic principle of PID is illustrated in the diagram in panel A. The redundant and synergistic functional connectomes between intrinsic brain domains were estimated across NC, SZ, and BP. It was observed that redundant information decreased within communities and increased between communities. Meanwhile, synergistic information gradually decreased in the psychotic brain compared to the NC. Furthermore, the correlation between psychotic redundancy/synergy and NC redundancy/synergy was labeled in the title of each psychotic matrix, respectively. The functional connectogram within the psychotic brain is shown in B, depicting the redundant and synergistic connections across NC, SZ, and BP. The intensity of connections is represented by the color spectrum, with red indicating the strongest redundant and synergistic connections, and blue representing the weakest information linkages. Notably, redundant information connections primarily occurred within brain network communities in NC, whereas in SZ and BP, these connections increased between communities but decreased within communities. Additionally, a discernible pattern emerged where redundant information connections between specific brain regions were elevated, particularly between the HC and SM networks. In contrast, a reduction in redundant connections was observed between other regions, notably between the CB and TP. This intricate network analysis revealed that synergistic connections also diminished both within and between brain network communities, potentially explaining the decline in information integration observed in SZ and BP. Upon integrating both redundant and synergistic functional connectograms, our analysis suggested that the psychotic brain faces challenges in both information integration and segregation. As a result, the organization of information between brain regions appeared to adopt highly unstable or random states. The associations between functional connectivity strength, derived from both redundancy and synergy measures, and Positive and Negative Syndrome Scale (PANSS) scores were examined. As shown in C, these measures revealed distinct patterns of connectivity significantly related to symptom severity, suggesting that redundant and synergistic interactions may differentially contribute to the clinical profile of individuals.