“I want to try to understand consciousness from a neuroanatomy and neuro-function standpoint. What would consciousness look like in a brain scanner and other types of imaging? What are we looking for, in a sense, and could I predict from basically the architecture and the anatomy, that this could be conscious, and this would not be able to be conscious?”

 

– Dr. Jay Giedd, Developmental Neuropsychiatrist, UCSD School of Medicine, Rady Children’s Hospital, and Johns Hopkins

                                                                                              …

How do we define consciousness? What does that term mean? Where do we even start?

Neuroscientist David Edelman and Developmental Neuropsychiatrist Jay Giedd, Professor of Psychiatry at UCSD School of Medicine and Director of Child & Adolescent Psychiatry at Rady Children’s Hospital talk candidly about our understanding of the complex – and often tantalizing – nature of consciousness.

In the context of the developing human brain, how can we understand consciousness? To many of us, consciousness seems like a simple, commonsense notion. When we’re awake, we all know that we are, more often than not, aware—of the world, of our thoughts and emotions, of our feeling states (i.e., hunger, thirst, pain, etc.), among others. When we fall into a deep, dreamless sleep, that awareness slips away.

But, this notion is actually quite confounding—particularly when one considers that there must be a specific moment during development when the brain transitions from a small, non-conscious organ comprising a few dozen cells to a complex, 86 billion-cell nexus of conscious feelings, emotions, and thoughts.

When, precisely, does that moment occur? In the womb? When we are just a few weeks old? These are the key questions that David Edelman and developmental neuropsychiatrist Jay Giedd ponder in this podcast.

A lively back-and-forth ensues as the two neuroscientists bring their respective backgrounds to bear on the emergence and nature of consciousness during development.

Along the way, David and Jay reinforce the notion that memory is a sine qua non of conscious states. As they learn to negotiate the world, very young infants experience the world with their developing senses, remember certain experiences, and then modify their behaviors accordingly.

But, when do the first substantive memories actually form? There is certainly a Rubicon that is crossed; we just haven’t figured out when it happens or what that passage looks like. Memory is a ubiquitous faculty across the animal kingdom; even relatively simple animals like the humble marine snail Aplysia can learn and remember at a fundamental level.

“There’s a kind of a commonplace notion of what consciousness is. Nearly everyone sort of knows what we mean when we invoke the term. But when it comes to the actual hard-nosed scientific aspect, we really haven’t arrived at any sort of consensus; at least as far as I know, there’s no real consensus.”

– David Edelman, PhD, Visiting Scholar in the Department of Psychological and Brain Sciences at Dartmouth College

Are the different developmental stages of memory in growing infants comparable to the increasingly sophisticated memory faculties found in the nervous systems of ever more complex organisms?

Towards the end of their conversation, David and Jay consider the transition from wakefulness to deep non-REM sleep and its signal importance as a transition between conscious and non-conscious states during which changes in brain activity occur that we can actually study—and that provides clues as to the nature of consciousness.

Talking Points

• 0:03 – Opening lines by David Edelman.
• 0:58 – Jay Giedd introduces himself, his background in psychiatry, robotics, and reproductive medicine, and how all of it ties together as he studies brain development.
• 1:52 – David Edelman opens the conversation by asking about Jay Giedd’s idea of
  consciousness.
• 2:15 – Jay Giedd looks at consciousness from the perspective of the developing brain in a fetus, particularly at what point does consciousness arise and how would that be detectable through a brain scanner.
• 3:14 – Edelman makes a connection between Giedd’s outlook on consciousness with that of the brain’s behavior during a sleeping state.
• 6:02 – Jay Giedd points out that a memory appears to be essential for the rise of consciousness, and how sleep, a process which no animal escaped from evolutionarily, is essential for proper memory formation.
• 8:57 – David Edelman describes what happens in the brain while a person is asleep and proposes the idea that consciousness may have a variety of forms and that a brain’s sleeping state may be one of several.
• 10:11 – Giedd brings up the role of dreams and our vague understanding of them.

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.