Spontaneous pupil fluctuations during rest offer a non-invasive, low-cost index of central arousal dynamics. This review synthesizes evidence on the resting-state pupil-brain system, focusing on central neuromodulatory circuits and large-scale cortical networks. It examines the relationship between pupil fluctuations and the ascending arousal system, including noradrenergic, cholinergic, serotonergic, and dopaminergic nuclei, and details coupling with intrinsic functional networks—default mode, salience, and sensorimotor systems. Converging evidence from animal and human neuroimaging studies reveals robust spatiotemporal and spectral coupling between pupil fluctuations and neural activity across micro- and macro-scales. The findings support a systems-level framework where pupil fluctuations serve as integrative markers linking subcortical neuromodulation with large-scale cortical dynamics, with potential utility as biomarkers for neuropsychiatric conditions and altered states of consciousness.
Auditory verbal hallucinations occur along a continuum from the general population to patients with psychosis, yet how sensory feedback processing and attention control interact along this continuum is unclear. By manipulating self-voice quality (from neutral to angry) and measuring brain activity with electroencephalography, the study found that hallucination proneness (HP) modulated the N100 and P200 suppression effects regardless of voice quality. Individuals with high HP showed an increased N100 response to self-generated voices and an increased P200 response to externally-generated voices, suggesting heightened error awareness and attention allocation during self-voice production due to altered sensory feedback processing and attentional control. These findings indicate that altered sensory feedback processing in self-voice production is a fundamental characteristic of the HP continuum, independent of clinical status.