Lectures and seminars Rick Adams: Assessing cortical excitatory/inhibitory imbalance and hippocampal-prefrontal dysconnectivity in schizophrenia using M/EEG
Abstract: Here I will present both empirical and modelling M/EEG work on two fundamental neurobiological changes in schizophrenia. The first is an increase in the ratio of excitatory/inhibitory transmission in cortical circuits, hypothesised to be due to a loss of function of inhibitory interneurons. We assessed the ‘excitability’ of district cortical areas using dynamic causal modelling of a simpleoddball task (the mismatch negativity) in subjects with a diagnosis of schizophrenia (Scz), their relatives and controls. We found evidence for an increase in excitability in prefrontal cortex in both Scz and their relatives. Modelling resting state EEG changes also supports this hypothesis. In a second study, we assessed connectivity (1-8 Hz phase coupling) between hippocampal and prefrontal cortex in Scz using MEG. We found a loss of this phase coupling in Scz, specific to the 1-8 Hz range, relevant to performance, most prominent in those off antipsychotic medication, and not explained by movement, cannabis use, or changes in 1-8 Hz power. This supports recent genetic mouse model evidence of a specific HC-mPFC 1-8 Hz phase coupling deficit causing cognitive dysfunction in Scz (Sigurdsson et al., 2010, Nature).