The origin of auditory hallucinations and how they influence our memory for events.

• Applicant: Dr. Franziska Knolle
• Subject Area: Human Cognitive and Systems Neuroscience ; Biological Psychology and Cognitive Neuroscience
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 530371040

Have you ever heard someone calling your name and then realised that there was nobody there? This is a common phenomenon most people experience at some point in their life, but for some this is a recurring event. They have sensory experiences that are created by their own mind, without external stimulation. These so-called auditory hallucinations are often linked to psychiatric or neurological disorders, such as schizophrenia or dementia, or can be linked to medication/drug use. Importantly, auditory hallucinations also occur in up to 13% of the population independent of illness or medication/drug use. Surprisingly little is known about the causes of these hallucinations. This project sets out to investigate whether hallucinations might be a by-product of how our brain processes and remembers incoming information. We seem to have a better memory for events that are unusual or different, which “stick in our mind”. For example, if we meet the actor Tom Hanks in our local shop we will remember this event for a long time, while all the other times we have been in that shop are long forgotten. This effect is driven by the comparison of what we expect compared to what we actually encounter, which is described as a prediction error in many theories of learning. One theory explaining this phenomenon is Predictive Coding, which assumes we continuously generate expectations about our environment and then update those predictions whenever they are wrong, i.e., when a prediction error occurs. Importantly, accurate predictions enable us to fill in missing information where needed, e.g., when a loud noise drowns a part of a conversation, we are usually still able to understand the other person. In this project, we investigate whether imbalances in Predictive Coding might lead to auditory hallucinations in healthy individuals who report increased psychotic-like experiences possibly because they are overly relying on internally generated predictions, which might evoke the illusion of a sensory perception and may be the origin of a hallucination. We will test this hypothesis in two sets of experiments. Each set will consist of a larger online study to establish the behavioural effect using a novel predictive language paradigm in combination with three verbal episodic memory tasks (i.e. recall, recognition, item memory). This is followed by focused EEG studies to elucidate the neural substrate of the effect. Our overall goal in this project is to better understand what drives hallucinations in non-clinical populations and explain how hallucinations could affect memory functions under everyday circumstances, which might also have important implications for clinical populations.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Cooperation Partner: Dr. Andrea Greve