Föreläsningar och seminarier Cognitive Neuroscience Club: "A tale of two symptoms: Computational and neural mechanisms underlying hallucinations and delusions"

Sammanfattning (på engelska)

Hallucinations—false percepts occurring without external stimuli—and delusions—fixed, idiosyncratic beliefs resistant to change—are hallmark features of psychotic disorders such as schizophrenia. For decades, these symptoms have been treated as two sides of the same coin, given their frequent co-occurrence and shared response to dopamine D2 receptor-blocking medications. However, emerging theoretical and clinical evidence calls for a more nuanced understanding. In this talk, I will advocate for a refined perspective on psychosis through the lens of computational psychiatry.

In the first part, I will focus on auditory hallucinations. I will present a study in which we used a conditioned hallucination paradigm to show that patients prone to hearing voices exhibit heightened susceptibility to this effect, likely driven by overly strong perceptual priors. Notably, the strength of these priors was negatively correlated with glutamate levels in the left anterior insula, providing a link between pathophysiological (glutamate hypofunction) and computational (strong priors) theories of hallucinations.

In the second part, I will shift to paranoia. I will describe a series of studies demonstrating that paranoid ideation and delusions arise from distinct impairments in domain-general inference mechanisms—specifically, an exaggerated expectation of environmental volatility.

Finally, I will briefly discuss passivity delusions and propose ideas toward a unifying computational framework for understanding psychotic symptoms.