In bipolar disorder, the sense of time's speed is distorted: manic patients experience inner time as too fast and outer time as too slow, while depressed patients experience inner time as too slow and outer time as too fast. This desynchronization between self-time and world-time arises from opposite changes in neuronal variability—specifically, the standard deviation ratio between somatomotor and sensory brain networks. The authors' empirical data show abnormal SD balance in both manic and depressed bipolar patients, as well as in major depressive disorder. These findings suggest that individualized stimulation techniques like TMS or tDCS might normalize the neuronal variability patterns in these networks, potentially correcting the distorted time perception.
Psychosis, involving hallucinations and delusions, arises from a combination of sensory system deficits and overactivity in brain networks linked to internal thought, such as the default-mode network. Hallucinations are tied to transient activation in sensory cortices (e.g., superior temporal gyrus) and increased connectivity in associative areas like the temporoparietal junction. Delusions are linked to hyperactivity in the medial prefrontal cortex. These changes cause internally generated imagery to become as vivid as real perceptions, impairing the ability to distinguish reality from imagination, leading to a loss of contact with the environment.