Title: The role of predictive processes in altered states of consciousness
Abstract: A much-debated question in the search for the neural underpinnings of consciousness is whether prefrontal cortex actively shapes conscious experience or, alternatively, serves only complementary functions such as evaluating and acting on the contents of perception.
In the first part of the talk, I will present data from three experiments that investigated the role of prefrontal cortex in perceptual bistability. Human participants reported periodic changes in conscious experience that were induced by conflicting sensory information. Two functional magnetic resonance imaging experiments showed that prefrontal brain activity in inferior frontal cortex signals the conflict between conscious experience and available sensory information.
In a third experiment, inhibitory transcranial magnetic stimulation revealed that a disruption of neural activity in inferior frontal cortex leads to a decrease of conflict-driven changes in conscious experience. These results suggest that inferior frontal cortex plays a critical role in both the detection and the resolution of perceptual conflicts, pointing to a causal influence of prefrontal brain activity on the dynamic unfolding of conscious experience.
In the second part of the talk, I will present data from three studies that investigated the role of predictive processes for altered states of consciousness in healthy observers and patients suffering from paranoid schizophrenia. Two studies revealed ongoing changes in perceptual decision-making that lead to prolonged intervals of reduced and enhanced sensitivity to conflicting sensory information. A third case-control study between patients suffering from paranoid schizophrenia differ and healthy controls suggested that patients were more sensitive to perceptual conflicts. Importantly, the patients' sensitivity to perceptual conflict correlated positively with the severity of hallucinations.
I will conclude by discussing how model-based imaging and non-invasive brain stimulation of prefrontal cortex may advance the search for a therapeutic modulation of altered states of consciousness.