Distinct Hierarchical Alterations of Intrinsic Neural Timescales Account for Different Manifestations of Psychosis

Summary

Hallucinations and delusions in schizophrenia may arise from distinct alterations in how the brain integrates information over time across different levels of sensory processing hierarchies. Using resting-state fMRI to measure intrinsic neural timescale (INT), which reflects the time window of neural integration, researchers found that hallucinations were linked to altered INT in lower auditory and somatosensory regions, while delusions were associated with changes in higher hierarchical areas. Computer simulations suggested that local imbalances between excitation and inhibition at different hierarchical levels could underlie these patterns. The findings support hierarchical perceptual-inference models of psychosis and demonstrate INT as a useful tool for studying brain hierarchies.

Study at a glance

Abstract

Hierarchical perceptual-inference models of psychosis may provide a holistic framework for understanding psychosis in schizophrenia including heterogeneity in clinical presentations. Particularly, hypothesized alterations at distinct levels of the perceptual-inference hierarchy may explain why hallucinations and delusions tend to cluster together yet sometimes manifest in isolation. To test this, we used a recently developed resting-state fMRI measure of intrinsic neural timescale (INT), which reflects the time window of neural integration and captures hierarchical brain gradients. In analyses examining extended sensory hierarchies that we first validated, we found distinct hierarchical INT alterations for hallucinations versus delusions in the auditory and somatosensory systems, thus providing support for hierarchical perceptual-inference models of psychosis. Simulations using a large-scale biophysical model suggested local elevations of excitation-inhibition ratio at different hierarchical levels as a potential mechanism. More generally, our work highlights the robustness and utility of INT for studying hierarchical processes relevant to basic and clinical neuroscience.