“I think a feature, like Bernie mentioned, of sleeping is that we’re not attending to things in our sensory environment in the same way. Maybe we’re dreaming, maybe we don’t have any awareness of what’s going on, but our brain doesn’t just stop working.“
– Alea Skwara, postdoctoral scholar at the UC Davis Center for Mind and Brain and Global Migration Center
In Episode 18 of our podcast On Consciousness with Bernard Baars, the third in a three-part series on GWT Origins & Evidence, we continue to explore the links between cutting edge brain evidence and how that supports or updates our understanding of consciousness and the Global Workspace Theory.
After some quick introductions and a summary of the previous two episodes by Ilian, the trio delves right into the main subject of the conversation, namely what can sleep tell us about the conscious mind. Bernie explains that in everyday life, sleep is the most natural absence of consciousness and that it can serve as a comparison to moments of awareness.
Next, Alea introduces the work of Marcello Massimini M.D., Ph.D., a professor in the Department of Biomedical and Clinical Sciences at the University of Milan, Italy, whose papers are the central topic of discussion in this episode. She points out that Massimini’s research is devoted to understanding changes in thalamocortical networks when consciousness fades and recovers, such as when we sleep and reawaken. The organ of consciousness inside the brain is a system that includes the cortex, and an egg-shaped structure inside the cortex, called thalamus. They work closely together and we call it the corticothalamic (CT) system. Alea emphasizes that in addition to neurophysiology, Massimini is interested in the theoretical and philosophical implications of the neuroscience of consciousness.
Bernie, Alea, and Ilian describe the stages and the mechanisms of the sleep cycle, namely the REM and non-REM phases. The trio also define some of the terminology used in this conversation, focusing on neuronal oscillation, or the electrical patterns of activity in the central nervous system. When examined with an EEG, oscillations throughout the brain display which regions are active during a particular state.
Enjoy a brief excerpt from the episode:
Alea Skwara:
Bernie — tell us a little bit about why are we talking about sleep today? How is that relevant to consciousness? What are we going to learn here?
Bernard Baars:
I guess because, first of all, this is the most prominent example of an unconscious state, or what appears to be an unconscious state. And I think pretty much every single culture in human history has words for waking and sleep, and lots of other words, of course, for mental processes, you’re like “Wake up, you lazy bum, it’s time to do some work or it’s time to milk the cow and get the eggs from the chickens.” Anyway, we always, I think as scientists, we tend to forget the ordinary human experience, which is all about consciousness and something more of course, about dreams and about the imaginary world that every single culture creates and updates and follows.
So those three domains, I think of waking consciousness, which is reality-based. Freud was right on the reality function of consciousness. It is at least one of the functions. And then there are these two domains of fantasy, dreams being one of them. And of course, waking fantasies, which turn into myths and narratives and enormously important things, right? That the popular view is that these things are projected onto reality by people. And so they reflect people. Anyway, all of those states are crucial for human beings. And so, waking has clearly evolved with coping with reality because if you’re a hunter-gatherer and you’re a child and you’re not awake when the tribe is going off to the hunt in the morning, you’re not going to be happy and nobody else is going to be happy about you either. So consciousness is something that we all talk about. We call it attention, right? And attention brings about consciousness whatever it is we want people to pay attention to.
Alea Skwara:
Thank you, Bernie. So yeah, it’s these kinds of different states that we all cycle through in our day. And as Bernie alluded to there’s waking, or we’re kind of processing all of this external information and then there’s everything that happens during sleep, including dreaming, which I don’t think we’re going to get into too deeply today, but we are going to talk about our different phases of sleep and what goes on in our brain.
I think a feature, like Bernie mentioned, of sleeping is that we’re not attending to things in our sensory environment in the same way. Maybe we’re dreaming, maybe we don’t have any awareness of what’s going on, but our brain doesn’t just stop working. So historically, there are philosophers thought that maybe the brain went to sleep, that it became less active during sleep. Is that right Bernie? Am I kind of getting my history of philosophy and science right?
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Talking Points:
- 0:00 – Intro and Recap of Episodes 17 & 18 (Parts I & II)
- 6:40 – A Discussion on Sleep, Dreaming, Waking, and Consciousness
- 10:35 – Summary of Marcello Massimini’s Research
- 18:35 – The Stages of Human Sleep
- 24:26 – What Are Neuronal Oscillations?
- 35:58 – Summary of Paper #1: The Sleep Slow Oscillation as a Traveling Wave (Massimini et al., 2004)
- 50:34 – How GWT is Related to the Findings of Paper #1: Massimini et al. (2004)
- 57:10 – Summary of Paper #2: Breakdown of Cortical Effective Connectivity During Sleep (Massimini et al., 2005)
- 1:03:43 – Discussion of Findings in Paper #2: Massimini et al. (2005)
- 1:20:34 – What Does Effective Connectivity Tell Us About Consciousness?
- 1:30:03 – Does the Evidence Support a Grand Hypothesis?
Cited Papers
Massimini, M., Ferrarelli, F., Huber, R., Esser, S. K., Singh, H., & Tononi, G. (2005, September 30). Breakdown of cortical effective connectivity during sleep. Science. https://www.science.org/doi/10.1126/science.1117256
Massimini, M., Huber, R., Ferrarelli, F., Hill, S., & Tononi, G. (2004, August 4). The sleep slow oscillation as a traveling wave. Journal of Neuroscience. https://www.jneurosci.org/content/24/31/6862
Bios
Bernard J. Baars: a former Senior Fellow in Theoretical Neurobiology at The Neurosciences Institute in La Jolla, CA, Bernie is best known as the originator of the global workspace theory and global workspace dynamics, a theory of human cognitive architecture, the cortex and consciousness. Bernie’s many acclaimed books include A Cognitive Theory of Consciousness; The Cognitive Revolution in Psychology; In the Theater of Consciousness: The Workspace of the Mind; Fundamentals of Cognitive Neuroscience. Winner of the 2019 Hermann von Helmholtz Life Contribution Award by the International Neural Network Society, which recognizes work in perception proven to be paradigm changing and long-lasting.
Alea Skwara is now a postdoctoral scholar at the UC Davis Center for Mind and Brain and Global Migration Center. Her research explores the neurocognitive bases of compassion and adaptive responses to suffering, and how we can bridge basic research and urgent real-world issues to create a more just society for all.
Ilian Daskalov is a senior undergraduate student at University of California, Irvine where he studies Cognitive Science. His research interests include sleep, psychedelics, and artificial intelligence and he is passionate about communicating science and promoting critical thinking.
Global Workspace Theory (GWT) began with this question: “How does a serial, integrated and very limited stream of consciousness emerge from a nervous system that is mostly unconscious, distributed, parallel and of enormous capacity?”
GWT is a widely used framework for the role of conscious and unconscious experiences in the functioning of the brain, as Baars first suggested in 1983.
A set of explicit assumptions that can be tested, as many of them have been. These updated works by Bernie Baars, the recipient of the 2019 Hermann von Helmholtz Life Contribution Award by International Neural Network Society form a coherent effort to organize a large and growing body of scientific evidence about conscious brains.
