Monday, August 04, 2014

Stanislas Dehaene - Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts

Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts

Stanislas Dehaene: Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts (2014); $27.95 hardcover, $20.93 at Amazon.

Publisher's ad-copy:
A breathtaking look at the new science that can track consciousness deep in the brain

How does our brain generate a conscious thought? And why does so much of our knowledge remain unconscious? Thanks to clever psychological and brain-imaging experiments, scientists are closer to cracking this mystery than ever before.

In this lively book, Stanislas Dehaene describes the pioneering work his lab and the labs of other cognitive neuroscientists worldwide have accomplished in defining, testing, and explaining the brain events behind a conscious state. We can now pin down the neurons that fire when a person reports becoming aware of a piece of information and understand the crucial role unconscious computations play in how we make decisions. The emerging theory enables a test of consciousness in animals, babies, and those with severe brain injuries.

A joyous exploration of the mind and its thrilling complexities, Consciousness and the Brain will excite anyone interested in cutting-edge science and technology and the vast philosophical, personal, and ethical implications of finally quantifying consciousness.
Table of Contents:

Introduction: The Stuff of Thought
Ch. 1: Consciousness Enters the Lab
Ch. 2: Fathoming Unconscious Depths
Ch. 3: What Is Consciousness Good For?
Ch. 4: The Signatures of a Conscious Thought
Ch. 5: Theorizing Consciousness
Ch. 6: The Ultimate Test
Ch. 7: The Future of Consciousness
Global Workspace Theory

Global Workspace Theory (GWT) is a model of "cognitive architecture" proposed by Bernard Baars (1988, 1997, 2002) that seeks to account for a large set of matched pairs of conscious (declarative memory) and unconscious processes (procedural memory).

GWT expands the concept of Working Memory - a "momentarily active, subjectively experienced" event — the "inner domain in which we can rehearse telephone numbers to ourselves or in which we carry on the narrative of our lives. It is usually thought to include inner speech and visual imagery" (in Baars, 1997: In the Theater of Consciousness).

Global Neuronal Workspace Theory

Cognitive neuroscientists Stanislas Dehaene and Jean-Pierre Changeux developed this model beginning in 1986, and it was originally known by the acronym DCM. In essence, this a meta neural network (i.e. a network of neural networks) composed of a very large number of integrate-and-fire neurons.

Dehaene's model became a part of Baars' GWT, developing his broader idea, which operates at the level of neural circuits, down to the neuronal level.

In his new book, Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts (2014), Dehaene sets out his computational model of neural correlates of consciousness in a book friendly to non-experts and in prose that is engaging without simplifying the ideas.

Here is a brief encapsulation of his model:
Its main postulate is that conscious access is global information availability (see Baars 1989): what we subjectively experience as conscious access is the selection, amplification and global broadcasting, to many distant areas, of a single piece of information selected for its salience or relevance to current goals. (Dehaene, Changeux, and Naccache, 2001)
Dehaene offers a very simple (simplistic?) definition of consciousness: "Consciousness is brain-wide information sharing." Compare that definition with Dan Siegel's definition of mind: "The mind can be defined as an embodied and relational process that regulates the flow of energy and information." The key word here, which I have emphasized, is information.

When information enters the system (whether visual, auditory, tactile, and so on, including interoceptive information) it's all equal in terms of how the brain processes it, whether it becomes conscious or remains unconscious. However, if there is sufficient interference from earlier or newer stimuli, the response diminishes as it moves through the brain's modules, where it still can assert subliminal influence on behavior. If the information remains preconscious, the subject cannot offer a verbal report of the experience.

For Dehaene, that last point is crucial. His research into how and why some information becomes conscious (enters the global neuronal workspace) or remains unconscious depends on first-person, subjective accounts of whether they register a piece of information in conscious or do not.

The experiments developed and used to test the threshold of conscious awareness are ingenious and provide an intriguing and entertaining narrative.

The two serious issue I have with Dehaene are (1) his reliance on computational models of neural processing (the brain is so much more complex than anything that can be modeled on a computer), and (2) that his equivocations on free will is similar to those of Daniel Dennett:
“Our belief in free will expresses the idea that, under the right circumstances, we have the ability to guide our decisions by our higher-level thoughts, beliefs, values, and past experiences, and to exert control over our undesired lower-level impulses. Whenever we make an autonomous decision, we exercise our free will by considering all the available options, pondering them, and choosing the one that we favor. Some degree of chance may enter in a voluntary choice, but this is not an essential feature. Most of the time our willful acts are anything but random: they consist in a careful review of our options, followed by the deliberate selection of the one we favor.” 264
Like Dennett, he suggests that the only free will that matters is the free will we believe that we have.

These are small issues, really, for what is a great introduction to one of the leading theories of how our brains process information. I would highly recommend this book for masters level therapists who more than likely received little (if any) education on the brain and how consciousness becomes an emergent property of brain processes.


Dehaene, S, Changeux, JP, and Naccache, L. (2011). The Global Neuronal Workspace Model of Conscious Access: From Neuronal Architectures to Clinical Applications. S. Dehaene and Y. Christen (eds.), Characterizing Consciousness: From Cognition to the Clinic? Research and Perspectives in Neurosciences. Berlin Heidelberg: Springer-Verlag.

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