Flexibility and neural dynamics of conscious access – FlexConscious

At the heart of our cognition is a very intriguing divide: even when we are awake, our brain can process external stimulation either consciously (“I have perceived it”) or non-consciously (“I have not perceived anything”). In the past forty years, major advances have been made in the identification of the neural correlates of conscious perception: increased sensory activity, implication of fronto-parietal areas, and increased functional connectivity. We are now at a turning point in our knowledge: do we know enough about the neurophysiology of conscious perception to be able to infer consciousness from brain activity alone? The answer is: not yet. We still need to extract the core neural mechanisms of conscious access from the other cognitive functions and neural events that correlate with it but are not directly part of it.

The objective of the present project is to bridge this gap in our knowledge, using as a benchmark of success our ability to read out conscious access from the brain activity of individual human adults. I will use the complementarity of different techniques: experimental psychology, functional MRI, electroencephalography, magnetoencephalography and intracranial recordings. The issue will be tackled from two complementary angles: teasing apart core mechanism of conscious access from initial sensory processing (1), and from task-related decision making (2). The global neuronal workspace model of consciousness will be our theoretical framework for shaping the experimental work. In return, the experimental results will be used to specify and update this model.

My work program will be constructed around two phenomena:
(1) One is the « retro-perception » phenomenon that I have recently revealed, which shows that it is possible to experimentally trigger conscious perception of a past unconscious stimulus by reactivating its sensory trace. This uncovers a flexibility in conscious access relative to sensory processing that was previously unsuspected. This phenomenon, which will be investigated in neuroimaging for the first time in this project, will be instrumental to explore the independence of core conscious access mechanisms from initial sensory processing.
(2) Several studies suggest that conscious access is accompanied by a systematic discontinuous jump in global cerebral activity. This dynamic phenomenon is a very promising signature of consciousness. We will construct a simple protocol that allows detecting this dynamic jump in the EEG activity of healthy volunteers, both in an active session where they report their perception and in an passive session where they have no task to perform on the same external stimulation. With this we will test whether the discontinuous jump can be used to read-out silent consciousness in the passive session.
This will be used a stepping-stone for transferring this test in clinics to diagnose silent consciousness in non-communicating patients in vegetative or minimally conscious state, in collaboration with clinicians.

This project will last 48 months. The main costs will be related to neuroimaging experiments (service delivery) and consolidating my team with one PhD student and one Post-Doc student.

By 2021, we will have produced the following: (i) a description of the core mechanism and cognitive characteristics of conscious access (ii) an update of the global neuronal workspace model of consciousness (iii) a set of neural signatures of conscious access in humans (v) methods to derive them from recordings in each individual and (vi) a procedure to extract this information in patients that can be readily used by clinicians to diagnose consciousness in non communicating patients. This project should produce between 6 and 10 experimental articles, 1 or 2 theoretical articles, and one clinical tool, validated in one clinical service and ready to transfer to our network of other national and international services for testing on a larger cohort.