The neural mechanisms and function of consciousness

How does the collective activity of individual neurons result in a subjective conscious experience of the world? It is one of the core questions in contemporary psychology, cognitive neuroscience and philosophy. Cognitive neuroscientist Simon van Gaal received an ERC grant of 1,5 million euro to bring the answer a little bit closer.

How does something you experience, like a thought or a dream, arise from the electrochemical processes taking place in the brain? To unravel the neural foundations of consciousness, Van Gaal and his team will spend the next five years on a series of studies.

Pharmacological intervention
An important part of the ERC funded project focuses on the molecular processes underlying consciousness. Studies in other animals have shown that the NMDA-receptor might be crucial for recurrent processing, the dynamic information exchange between brain regions. Because recurrent processes are thought to give rise to consciousness, Van Gaal expects NMDA-mediated processes to be essential in becoming aware of a stimulus. To test this, he will do reversible pharmacological interventions in humans in which he temporarily blocks NMDA receptors and measures how this influences the likelihood a subject will consciously perceive a stimulus that is briefly shown.

In order to string the behavioral measures and the molecular intervention together, Van Gaal and his team will use different visualization techniques to keep track of neural activity during the experiments. Specifically, the team is interested in registering to what extent recurrent signaling between different areas in the brain is affected by NMDA blockade.

A potential function of conscious experience
Another part of the project focuses on establishing what purpose consciousness may serve in human functioning. Van Gaal: ‘Consciousness has developed in evolution, possibly because it helps us in some way. But what it is that we gain by having conscious experiences is no yet known.’

It is known that many cognitive and perceptual functions, like processing visual or auditory input or the initiation of motor actions, can operate unconsciously, so these are not the function of consciousness. Van Gaal proposes that consciousness might benefit us by extending the period that information is available in the brain. In order to find out whether this might be true, the research team will measure whether subjects can use unconscious information to base decisions on later in time or whether this retention of information only happens when a stimulus is consciously processed.

Vegetative state
Although Van Gaal is primarily driven by curiosity to understand the fundamental workings of the human brain, in a longer run, he can see these insights resulting in more practical solutions, especially when it concerns insight into the molecular processes involved. Van Gaal: ‘Knowledge of the neurotransmitter-systems implicated in consciousness might eventually help us find ways to treat people who have problems relating to consciousness, patients who are in a vegetative state for example.’

Text: Marieke Buijs