Functional exploration of Non-Executive Forms of Consciousness – NonExCo

Human nature cannot be restricted to our daily activities – to eat, sleep, reproduce, earn and spend money. We know that we act, we can communicate how we feel, we can plan, reason and deliberate. In other words, we are conscious beings. Consciousness has long been studied by philosophers only, but twenty years ago scientific studies of consciousness begun to emerge. Experimental psychology and cognitive neuroscience methods were successfully applied to this difficult issue, helping distinguish between different forms of consciousness and establishing a series of important processing steps for a stimulus to reach consciousness. This line of research has concentrated on explaining the cognitive abilities that often come together with consciousness: I am conscious of the stimulus I attend to, I can report a stimulus I have memorized, I can chose between two options after conscious deliberation. However, in the last years, it appeared that attention, control and memory can take place unconsciously. We showed that at the neural level, visual awareness and spatial attention can be implemented independently. All those recent results show that consciousness cannot be reduced to its accompanying cognitive functions. By trying to understand consciousness through the prism of cognitive functions only, we may be missing an important part of the story: the most private part of consciousness that pertains to subjective experience, the fact that seeing a given object evokes a feeling as well as an ability to act appropriately, remains unexplained.
The brain-as-a-computer metaphor has been very successful to account for a wide range of cognitive abilities. However it may not be well suited to account for subjective experience: we all agree that a computer, however smart, is not conscious. Our proposal is that for a stimulus to be subjectively experienced, to be incorporated into our private inner life, it must not only be processed by the brain but also integrated into the brain-body schema, even if this stimulus has no emotional content. In other words, the conscious mind may require not only a brain, but also a body to emerge. Taking advantage of encouraging preliminary results, we will test this hypothesis in three experimental tasks. In the first one, we will examine to what extent subjective experience and cognitive performance can be distinguished, at both the behavioral and neural level. In the second and third tasks, we will test the hypothesis that re-entry, a concept central to all theories of consciousness because it is considered as a way the mind can "speak to itself", extends to two major brain-body loops, the heart-brain loop (task 2), and the loop between the central nervous system and the enteric (or gastrointestinal) nervous system (task 3). The latter, although often overlooked in cognitive neuroscience, is a complex system comprising several hundred millions of neurons. It is suspected to play an important role in emotion and cognition, although this remains to be demonstrated.
Our results should shed new light on the participation of brain-body loops to the emergence of consciousness. Better understanding consciousness remains a central issue because it fundamentally relates to the definition of human nature. It also has practical implications. Defining new objective tools to measure consciousness can be crucial for those patients who are conscious but behaviorally unresponsive. Such situations occur following severe brain injury, that may leave the patient conscious but unable to communicate, or in patients transiently regaining consciousness during surgery despite anesthesia, who can be left with traumatic memories. More generally, our results could open new venues for the study of brain-body interactions, that are suspected to play an important role in cognitive, emotional but also immune functions, such as in the placebo effect.