“Episodic memory involves conscious experiences being encoded. Same goes for semantic and autobiographical memories. All varieties of memories come in through conscious moments of recall. So, I think that consciousness is the means by which any kinds of memories are established.”
– Bernard Baars, PhD, originator of global workspace theory and former Senior Fellow in Theoretical Neurobiology at the Neurosciences Institute in La Jolla, CA
In this episode of ON CONSCIOUSNESS, co-hosts Bernard Baars and David Edelman are joined by renowned developmental neuropsychiatrist Dr. Jay Giedd to conclude their discussion on the brain areas which are critical for higher brain function, neuroimaging techniques associated with detecting conscious experiences, and the possible existence of consciousness in non-mammalian animals.
Talking Points
- 00:03 – Introduction by David Edelman
- 02:09 – The Role of Thalamus and Cortex in Higher Brain Processing
- 08:08 – Is Memory Fundamental to Consciousness?
- 12:14 – Brain Variations Between Mammals and Other Animals
- 16:22 – Differences Between Sleep and Awake States in the Human Brain
Summary of the Conversation
In this absorbing episode of ‘On Consciousness,’ Bernard Baars, David Edelman, and developmental neuropsychiatrist Dr. Jay Giedd initiate the conversation by considering the functional aspects of the brain that are believed to be absolutely critical to consciousness.
Bernie, Jay, and David ponder the role of cortex and thalamus in higher brain function, including conscious processing. Bernie underlines the problem of considering the linkage between thalamus and cortex as merely a simple feedback loop. From an engineering perspective, this sort of circuit could not possibly work as such an arrangement would inevitably, as Bernie puts it, lead to effective failure of the thalamocortical circuit. Instead, it seems to be the case that the cortex functions in a state of near-criticality. As Jay indicates, this implies that the cortex is always at a tipping point, i.e., close to a phase transition and “always ready to be influenced.”
Elucidating the neurobiology of consciousness has been somewhat hindered by technical hurdles. But, despite the spatial and temporal limitations of current neurophysiological and imaging technologies, David observes that certain aspects of brain anatomy—including cortex and thalamus—have been established as the sine qua non of conscious experience in mammals. In an optimistic vein, Jay offers that new combinations of existing techniques (such as MEG, EEG, and fMRI) may soon yield a much clearer picture.
Next, Edelman, Baars, and Giedd consider the idea that certain higher neural processes are central to consciousness, even though those processes may often function independently of any state of awareness. Memory, which seems to be fundamental to conscious experience, is one such process. While memory and recall figure prominently in conscious experience, it’s certainly the case that some varieties of memory are regularly engaged during non-conscious states and behaviors.
The trio concludes the conversation by reflecting on the prospect of consciousness as a biological phenomenon. Additionally, they consider the possibility of consciousness in animals distant from the mammalian line and as it is the case of the octopus, a creature separated from the vertebrate radiation by more than half a billion years. The octopus as a possible test case for consciousness beyond the realm of vertebrates is particularly tantalizing, given that, unlike mammals, it has neither a cerebral cortex nor a thalamus.
Bios
David Edelman, PhD: a neuroscientist and currently Visiting Scholar in the Department of Psychological and Brain Sciences at Dartmouth College, David has taught neuroscience at the University of San Diego and UCSD. He was Professor of Neuroscience at Bennington College until 2014 and visiting professor in the Dept of Psychology, CUNY Brooklyn College from 2015-2017. He has conducted research in a wide range of areas, including mechanisms of gene regulation, the relationship between mitochondrial transport and brain activity, and visual perception in the octopus. A longstanding interest in the neural basis of consciousness led him to consider the importance—and challenge—of disseminating a more global view of brain function to a broad audience.
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.
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