On January 22 I attended a lecture sponsored by the Center for the Explanation of Consciousness at Stanford University. John Bickle, who holds positions at both Mississippi State University and the University of Mississippi Medical Center, presented a talk titled “Molecules, Mechanisms, and (Aspects of) Consciousness.” Many scholars believe that the most important discoveries about consciousness will be made at the systems level, understanding the way complex systems within the brain constitute conscious experiences. But Dr. Bickle explained how amazing progress is being made way down at the molecular level.
Here’s an example: By altering brain molecules in laboratory animals, scientists have shown that two key aspects of consciousness depend upon different sets of neurons. One of these aspects is on/off awareness, the difference between waking consciousness and dreamless sleep. Another aspect is level of arousal.
In these experiments with mice, scientists targeted a very specific subunit of an important neurotransmitter system called the GABA-sub-A receptor. They altered this system in two different ways which I’ll call intervention-1 and intervention-2. Intervention-1 changed their patterns of arousal, so that after being dosed with an anesthetic (etomidate) the mice almost immediately regained normal arousal levels after waking up. Their untreated kinfolk were groggy for some time, as you and I would be after receiving a general anesthetic. So with intervention-1, the anesthetic knocked them out as quickly as it did before their brains were altered, but when they woke up they were alert right away instead of spacey. By contrast, mice that received intervention-2 didn’t go to sleep at all when dosed with etomidate. The anesthetic was no longer effective.
Careful analysis of these findings suggests that these changes in two different parts of a neurotransmitter system change two different aspects of consciousness, being aroused and being awake. This backs up the notion that consciousness is not a single phenomenon, but a combination of several features of the mind and/or the brain.
In my posts on December 1 and 14, 2014 I discussed the search for the elusive NCC, the neural correlates of consciousness. This is an incredibly difficult quest, but the data reported by Bickle are certainly encouraging.
For more information, see Engineering the Next Revolution in Neuroscience: The New Science of Experiment Planning, by Alcino J. Silva, Anthony Landreth, and John Bickle:
Roger Christan Schriner