World/self ambivalence: A shared mechanism in different subsets of psychotic experiences? Linking symptoms with resting-state fMRI.

The psychosis spectrum comprises heterogeneous disorders characterized by both world-related and self-related symptoms. How these symptoms may arise with similar features in spite of the different aetiologies is yet an unsolved question. In behavior narrative review, we compare three conditions characterized by psychotic experiences (schizophrenia, substance-use disorder and sensory-deprivation) searching for links between their phenomenological features and the mechanisms underlying their onset. Clinically, psychotic experiences are characterized by the reciprocal contamination of world- and self-related contents, termed 'world/self ambivalence'. Neuroimaging evidence suggests that the imbalance between stimuli-, self-, and attention-related functional networks (visual/auditory, default-mode, and salience network respectively) assumes central relevance in all the conditions considered. Phenomenology and neurobiology were thus interrelated in light of the reviewed literature, identifying two key neuronal mechanisms which may lead to world/self ambivalence. First, psychotic experiences are associated with the relative dominance of one network over the other (default-mode over auditory/visual networks, or vice-versa), prompting an excess of internal or external pressure to the experienced ambivalence between world and self. Second, an altered salience network resting-state functional connectivity could generate a dysregulation of the attentive fluctuations from self- to world-related activity, thus blurring the boundary between the environment and oneself, labelled the 'world/self boundary'.