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Brain-viscera interactions underlie subjectivity

Periodic Reporting for period 3 - BRAVIUS (Brain-viscera interactions underlie subjectivity)

Reporting period: 2018-12-01 to 2020-05-31

Subjectivity defines the subject who is perceiving, feeling, thinking, acting, and is essential to understand the conscious mind from the inside. In its simplest form, subjectivity is the first-person perspective inherent to conscious mental life. The BRAVIUS project proposes a biological mechanism to generate first-person perspective and tests it experimentally. Two vital organs that generate their own rhythmic electrical activity, the stomach and the heart, constantly send information up to the neocortex, even in the absence of bodily change. Cortical responses to those visceral organs would define the organism as an entity at the neural level, and create a subject-centered reference frame from which first-person perspective can develop. The results of the BRAVIUS project are important to understand the nature of human consciousness, but also to offer experimental tools to probe for the existence of consciousness in non-communicating patients. In a more distant future, the framework developed in BRAVIUS might prove important to probe for consciousness in animals or artificial-intelligence based systems.
The BRAVIUS projects tackles two main questions. The first one is mechanistic: how are visceral organs such as the stomach represented in the brain? We revealed the existence of a synchronization between the stomach and a number of brain regions, many of them known to be involved with limb or body surface representation. The coupling between the stomach rhythm and brain rhythm follows the same mathematical rule than coupling between brain areas. The second question pertains to the functional relevance of the neural monitoring of visceral inputs: is this neural monitoring related to the self? We showed that two different dimensions of the self, the agentive or experiencing 'I', and the reflective 'Me' (when reflecting upon oneself) are revealed by neural responses to heartbeats, in two different brain areas.
BRAVIUS will test with magneto-encephalography (MEG) the role of neural responses to ascending visceral signals in generating subjectivity by cutting across domains of cognitive sciences and exploring diverse paradigms where subjectivity is engaged. Beyond perceptual consciousness and self-consciousness, we will also test emotions and preference-based decision making. BRAVIUS will further explore how cardiac and gastric ascending signals shape the temporal (MEG) and spatial (fMRI) organization of spontaneous brain activity and how the neural monitoring of visceral signals interacts with external information processing. The project outcome is a detailed mechanistic neural account of the most private part of the human mind, and a unified concept of subjectivity across cognitive domains.