A large-scale scientific collaboration has compared two major theories about consciousness. The study, published in
Nature, involved researchers from around the world for seven years. The theories in question, Integrated Information Theory (IIT) and Global Neuronal Workspace Theory (GNWT), offer distinct visions of how consciousness emerges.
The results suggest that visual areas located at the back of the brain play a crucial role in consciousness. This discovery challenges the idea that the prefrontal cortex would be the main seat of our consciousness. The connections between neurons in visual areas and frontal regions appear essential.
The study involved 256 participants, a record number for this type of research. Scientists used three different methods to measure brain activity. This methodological approach provided robust and comparable data.
The medical implications of these findings are significant. They could help identify signs of consciousness in vegetative state patients. About one quarter of these patients show 'hidden consciousness,' according to a study published in the
New England Journal of Medicine.
What is Integrated Information Theory (IIT)?
IIT proposes that consciousness emerges when information in the brain is highly integrated and unified. This theory suggests that the degree of consciousness depends on a system's ability to integrate information.
IIT stands out for its mathematical approach to quantifying consciousness. It uses a measure called 'phi' to assess the level of information integration. The higher the phi value, the more conscious the system is considered to be.
This theory has profound implications for understanding altered states of consciousness. It could also apply to artificial systems, raising questions about the possibility of artificial consciousness.
Despite its originality, IIT remains controversial. Some critics point out the difficulty of objectively measuring consciousness and applying the theory to non-biological systems.
How does Global Neuronal Workspace Theory (GNWT) work?
GNWT postulates that consciousness results from the broadcasting of information across a network of brain regions. According to this theory, certain information is 'brought into the light' and becomes accessible to various parts of the brain.
This broadcasting allows flexible integration of information, essential for complex tasks. GNWT emphasizes the role of the prefrontal cortex in this process, considered the conductor of consciousness.
The theory explains how information can transition from unconscious to conscious. It provides a framework for understanding phenomena like attention and working memory.
However, GNWT still needs to explain exactly how information is selected for broadcasting. The precise mechanisms of this selection remain an active research topic.