Brain Network Dysfunction as a Model for Schizophrenia: Connectivity Alterations Using Ketamine and Pharmacological Magnetic Resonance Imaging

Alterations of functional brain networks have been frequently demonstrated in schizophrenia, although the exact underlying molecular mechanisms remain unrevealed. Ketamine is known to exert its schizophrenia-like effects through modulation of the glutamatergic system, thus facilitating the investigation of the impact of this specific transmitter system on resting state functional brain networks. The aim of the study is therefore to use pharmacological functional Magnetic Resonance Imaging (phMRI) to examine changes in brain networks involved in schizophrenia in response to ketamine application compared to placebo. 30 healthy subjects (15 females) will be examined twice using a double-blind, placebo-controlled, randomized, crossover, counterbalanced-order design. Resting state fMRI will be investigated before, during and after either placebo or ketamine intravenous infusion for 20 minutes. Prior to the main trial 10 additional participants will be included in an open pilot trial.

Hypothesis: Ketamine application will induce changes in resting state networks previously associated with schizophrenia and in the connectivity of relevant brain regions such as the striatum, thalamus, caudate, hippocampus and amygdala. Furthermore, the application of ketamine will provoke changes in the BOLD-activation in three fMRI paradigms each performed before and after ketamine infusion.