Animal models for the assessment of hallucinations and their related biological mechanisms

Abstract

Hallucinations represent a transdiagnostic phenomenon observed in multiple neuropsychiatric disorders, including schizophrenia, substance use disorder and substance-induced psychotic conditions. Despite their clinical prevalence, objective assessment remains challenging due to its subjective nature, underscoring the critical need for validated translational models. The present study explores the biological mechanisms underlying hallucinations, evaluates the animal models developed to date, and discusses methods for analyzing these models along specific pathways. Hallucinations are primarily mediated through glutamatergic and/or serotonergic pathways. Numerous animal models for assessing hallucinations have been extensively reported; however, these models have mainly been designed to investigate specific neurotransmitter mechanisms, rather than encompassing all relevant pathways. Therefore, this study systematically examines currently established animal models based on the aforementioned neurotransmitter mechanisms and proposes future directions for developing universal animal models capable of comprehensively evaluating hallucinatory phenomena. The present study aims to provide deeper insights for future research involving animal models of hallucination.