Brain mechanisms of conscious processing, from correlates to signatures

Introduction

When we are awake, part of the information processed by our brain becomes conscious, so that we can acknowledge and report it. Despite important advances, there is no consensus on what brain mechanisms underlie this phenomenon.

Theoretical Models

According to some models, we become conscious of a stimulus when information gets integrated across different sensory areas. For others, conscious processing only arises when sensory representations are made available to the executive system.

Research Objective

With this project, I explore a third possibility: that the core mechanisms of conscious processing can actually be distinguished both from sensory and executive processes. Such experimental dissection is made possible by two new approaches developed by my team.

Methodology

1. First Approach: This approach allows detecting brain dynamics that are characteristic of conscious processing, independently of whether a task is required on the stimulus or not, thus dissociating conscious processing from executive functions.

2. Second Approach: This builds upon the “retro-perception” phenomenon, in which we trigger conscious access at an arbitrary latency after the disappearance of a stimulus, thus desynchronizing conscious access from sensory processing.

Techniques

I will jointly leverage these two approaches through a wide range of complementary techniques, including:

• Experimental psychology
• Functional MRI
• Electro and magnetoencephalography
• Human intracranial recordings

Expected Outcomes

Experimentation will go hand in hand with the development of a major update to current neuro-computational models of conscious processing, to explore the computational properties of such a core system for conscious processing.

Finally, this research should reveal much longed-for neural signatures of conscious processing. I will aim at operationalizing these signatures for the diagnosis of conscious access in non-communicating patients and for starting the exploration of how a conscious stream emerges from these moment-to-moment conscious access events.