Draining the pond and catching the fish: Uncovering the ecosystem of auditory verbal hallucinations

Publication date: Available online 21 September 2018Source: NeuroImage: ClinicalAuthor(s): Jasper Looijestijn, Jan Dirk Blom, Hans W. Hoek, Remco Renken, Edith Liemburg, Iris E.C. Sommer, André Aleman, Rutger GoekoopAbstractThe various models proposed for the mediation of auditory verbal hallucinations (AVH) implicate a considerable number of brain areas and mechanisms. To establish which of those mechanisms are actually involved in the mediation of AVH, we developed a novel method to analyze functional MRI data, which allows for the detection of the full network of mutually interacting brain states, and the identification of those states that are relevant to the mediation of AVH, while applying a minimum number of preconceived assumptions. This method is comparable to the draining of a pond to lay bare the full ecosystem that affects the presence of a particular fish species. We used this model to analyze the fMRI data of 85 psychotic patients experiencing AVH. The data were decomposed into 98 independent components (ICs) representing all major functions active in the brain during scanning. ICs involved in mediating AVH were identified by associating their time series with the hallucination time series as provided by subjects within the scanner. Using graph theory, a network of interacting ICs was created, which was clustered into IC modules. We used causal reasoning software to determine the direction of links in this network, and discover the chain of events that leads to...
Source: NeuroImage: Clinical - Category: Radiology Source Type: research