The Dehaene–Changeux model (DCM), also known as the global neuronal workspace, or global cognitive workspace model, is a part of

Bernard Baars Bernard J. Baars (born 1946 in Amsterdam, the Netherlands) is a former Senior Fellow in Theoretical Neurobiology at the Neurosciences Institute in San Diego, US. He is currently an Affiliated Fellow there. He is best known as the originator of ...

's global workspace model for consciousness. It is a

computer model Computer simulation is the running of a mathematical model on a computer, the model being designed to represent the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determin ...

of the

neural correlates of consciousness The neural correlates of consciousness (NCC) are the minimal set of neuronal events and mechanisms sufficient for the occurrence of the mental states to which they are related. Neuroscientists use empirical approaches to discover neural correla ...

programmed as a

neural network A neural network is a group of interconnected units called neurons that send signals to one another. Neurons can be either biological cells or signal pathways. While individual neurons are simple, many of them together in a network can perfor ...

. It attempts to reproduce the

swarm behaviour Swarm behaviour, or swarming, is a collective behaviour exhibited by entities, particularly animals, of similar size which aggregate together, perhaps milling about the same spot or perhaps moving ''en masse'' or migrating in some direction. ...

of the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

's ''higher cognitive functions'' such as

consciousness Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, an ...

decision-making In psychology, decision-making (also spelled decision making and decisionmaking) is regarded as the Cognition, cognitive process resulting in the selection of a belief or a course of action among several possible alternative options. It could be ...

and the central

executive functions In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that support goal-directed behavior, by regulating thoughts and actions thro ...

. It was developed by cognitive neuroscientists

Stanislas Dehaene Stanislas Dehaene (born May 12, 1965) is a French author and cognitive neuroscientist whose research centers on a number of topics, including numerical cognition, the neural basis of reading and the neural correlates of consciousness. As of 201 ...

and

Jean-Pierre Changeux Jean-Pierre Changeux (; born 6 April 1936) is a French neuroscientist known for his research in several fields of biology, from the structure and function of proteins (with a focus on the allosteric proteins), to the early development of the ner ...

beginning in 1986. It has been used to provide a predictive framework to the study of

inattentional blindness Inattentional blindness or perceptual blindness (rarely called ''inattentive blindness'') occurs when an individual fails to perceive an unexpected stimulus in plain sight, purely as a result of a lack of attention rather than any vision defects o ...

and the solving of the

Tower of London test The Tower of London test is a test used in applied clinical neuropsychology for the assessment of executive functioning specifically to detect deficits in planning, which may occur due to a variety of medical and neuropsychiatric conditions. It ...

History

The Dehaene–Changeux model was initially established as a

spin glass In condensed matter physics, a spin glass is a magnetic state characterized by randomness, besides cooperative behavior in freezing of spins at a temperature called the "freezing temperature," ''T''f. In ferromagnetic solids, component atoms' ...

neural network attempting to represent

learning Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, Attitude (psychology), attitudes, and preferences. The ability to learn is possessed by humans, non-human animals, and ...

and to then provide a stepping stone towards artificial learning among other objectives. It would later be used to predict observable reaction times within the priming paradigm and in inattentional blindness.

Structure

General structure

The Dehaene–Changeux model is a meta neural network (i.e. a network of neural networks) composed of a very large number of

integrate-and-fire Biological neuron models, also known as spiking neuron models, are mathematical descriptions of the conduction of electrical signals in neurons. Neurons (or nerve cells) are electrically excitable cells within the nervous system, able to fire ...

neuron A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural net ...

s programmed in either a

stochastic Stochastic (; ) is the property of being well-described by a random probability distribution. ''Stochasticity'' and ''randomness'' are technically distinct concepts: the former refers to a modeling approach, while the latter describes phenomena; i ...

or deterministic way. The neurons are organised in complex thalamo-cortical columns with long-range connexions and a critical role played by the interaction between von Economo's areas. Each thalamo-cortical column is composed of

pyramidal cell Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal cells are the primary excitation units of the mammalian prefrontal cort ...

s and inhibitory interneurons receiving a long-distance excitatory

neuromodulation Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a sec ...

which could represent

noradrenergic Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as a hormone, neurotransmitter and neuromodulator. The name "noradrenaline" (from L ...

input.

A swarm and a multi-agent system composed of neural networks

Among others Cohen &

Hudson Hudson may refer to: People * Hudson (given name) * Hudson (surname) * Hudson (footballer, born 1986), Hudson Fernando Tobias de Carvalho, Brazilian football right-back * Hudson (footballer, born 1988), Hudson Rodrigues dos Santos, Brazilian f ...

(2002) had already used "meta neural networks as intelligent agents for diagnosis". Similarly to Cohen & Hudson, Dehaene & Changeux have established their model as an interaction of meta-neural networks (thalamocortical columns) themselves programmed in the manner of a "hierarchy of neural networks that together act as an intelligent agent", in order to use them as a system composed of a large scale of inter-connected intelligent agents for predicting the self-organized behaviour of the neural correlates of consciousness. Jain et al. (2002) had already clearly identified

spiking neuron Spiking neural networks (SNNs) are artificial neural networks (ANN) that mimic natural neural networks. These models leverage timing of discrete spikes as the main information carrier. In addition to neuronal and synaptic state, SNNs incorpor ...

s as intelligent agents since the lower bound for computational power of networks of spiking neurons is the capacity to simulate in real-time for boolean-valued inputs any

Turing machine A Turing machine is a mathematical model of computation describing an abstract machine that manipulates symbols on a strip of tape according to a table of rules. Despite the model's simplicity, it is capable of implementing any computer algori ...

. The DCM being composed of a very large number of interacting sub-networks which are themselves intelligent agents, it is formally a

multi-agent system A multi-agent system (MAS or "self-organized system") is a computerized system composed of multiple interacting intelligent agents.H. Pan; M. Zahmatkesh; F. Rekabi-Bana; F. Arvin; J. HuT-STAR: Time-Optimal Swarm Trajectory Planning for Quadroto ...

programmed as a swarm or neural networks and ''a fortiori'' of spiking neurons.

Behavior

The DCM exhibits several surcritical emergent behaviors such as

multistability In a dynamical system, multistability is the property of having multiple Stability theory, stable equilibrium points in the vector space spanned by the states in the system. By mathematical necessity, there must also be unstable equilibrium points ...

and a

Hopf bifurcation In the mathematics of dynamical systems and differential equations, a Hopf bifurcation is said to occur when varying a parameter of the system causes the set of solutions (trajectories) to change from being attracted to (or repelled by) a fixed ...

between two very different regimes which may represent either

sleep Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...

arousal Arousal is the physiology, physiological and psychology, psychological state of being awoken or of Five senses, sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the hu ...

with a various

all-or-none All or none (AON) is a finance term used in investment banking or securities transactions that refers to "an order to buy or sell a stock that must be executed in its entirety, or not executed at all". Partial execution is not acceptable; the ord ...

behaviors which Dehaene et al. use to determine a testable taxonomy between different states of consciousness.

Scholarly reception

Self-organized criticality

The Dehaene–Changeux model contributed to the study of

nonlinearity In mathematics and science, a nonlinear system (or a non-linear system) is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathe ...

and

self-organized criticality Self-organized criticality (SOC) is a property of dynamical systems that have a critical point as an attractor. Their macroscopic behavior thus displays the spatial or temporal scale-invariance characteristic of the critical point of a phas ...

in particular as an explanatory model of the brain's emergent behaviors, including consciousness. Studying the brain's phase-locking and large-scale synchronization, Kitzbichler et al. (2011a) confirmed that criticality is a property of human brain functional network organization at all frequency intervals in the brain's physiological bandwidth. Furthermore, exploring the neural dynamics of cognitive efforts after, ''inter alia'', the Dehaene–Changeux model, Kitzbichler et al. (2011b) demonstrated how cognitive effort breaks the

modularity of mind Modularity of mind is the notion that a mind may, at least in part, be composed of innate neural structures or mental modules which have distinct, established, and evolutionarily developed functions. However, different definitions of "module" have ...

to make human brain functional networks transiently adopt a more efficient but less economical configuration. Werner (2007a) used the Dehaene–Changeux global neuronal workspace to defend the use of statistical physics approaches for exploring phase transitions, scaling and universality properties of the so-called "Dynamic Core" of the brain, with relevance to the macroscopic electrical activity in

EEG Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The bio signals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neoc ...

and EMG. Furthermore, building from the Dehaene–Changeux model, Werner (2007b) proposed that the application of the twin concepts of scaling and universality of the theory of non-equilibrium phase transitions can serve as an informative approach for elucidating the nature of underlying neural-mechanisms, with emphasis on the dynamics of recursively reentrant activity flow in intracortical and cortico-subcortical neuronal loops.

Friston Friston is a village and civil parish in the East Suffolk (district), East Suffolk district, in the county of Suffolk, England. It is southeast of Saxmundham, its post town, and northwest of Aldeburgh. The River Alde bounds the village on ...

(2000) also claimed that "the nonlinear nature of asynchronous coupling enables the rich, context-sensitive interactions that characterize real brain dynamics, suggesting that it plays a role in functional integration that may be as important as synchronous interactions".

States of consciousness and phenomenology

It contributed to the study of phase transition in the brain under sedation, and notably GABA-ergic sedation such as that induced by propofol (Murphy et al. 2011, Stamatakis et al. 2010). The Dehaene–Changeux model was contrasted and cited in the study of

collective consciousness Collective consciousness, collective conscience, or collective conscious () is the set of shared beliefs, ideas, and moral attitudes which operate as a unifying force within society.''Collins Dictionary of Sociology'', p93. In general, it doe ...

and its pathologies (Wallace et al. 2007). Boly et al. (2007) used the model for a reverse somatotopic study, demonstrating a correlation between baseline brain activity and somatosensory perception in humans. Boly et al. (2008) also used the DCM in a study of the baseline state of consciousness of the human brain's

default network In neuroscience, the default mode network (DMN), also known as the default network, default state network, or anatomically the medial frontoparietal network (M-FPN), is a large-scale brain network primarily composed of the dorsal medial prefro ...

Adversarial collaboration to test the Dehaene–Changeux model and integrated information theory

In 2019, the

Templeton Foundation The John Templeton Foundation (Templeton Foundation) is a philanthropic organization founded by John Templeton in 1987. Templeton became wealthy as a contrarian investor, and wanted to support progress in religious and spiritual knowledge, espec ...

announced funding in excess of $6,000,000 to test opposing empirical predictions of Dehaene–Changeux model and a rival theory (

integrated information theory Integrated information theory (IIT) proposes a mathematical model for the consciousness of a system. It comprises a framework ultimately intended to explain why some physical systems (such as human brains) are conscious, and to be capable of pr ...

, or IIT). The originators of both theories signed off on experimental protocols and data analyses as well as the exact conditions that satisfy if their championed theory correctly predicted the outcome or not. Initial results were revealed in June 2023. None of the Dehaene–Changeux model predictions passed what was agreed upon pre-registration while two out of three of IIT's predictions passed that threshold.

Publications

* Rialle, V and Stip, E. (May 1994). "Cognitive modeling in psychiatry: from symbolic models to parallel and distributed models". ''J Psychiatry Neurosci''. 19(3): 178–192. * Zigmond, Michael J. (1999). ''Fundamental neuroscience''. Academic Press, p1551. * Dehaene, Stanislas (2001). ''The cognitive neuroscience of consciousness''. MIT Press, p. 13. * Ravi Prakash, Om Prakash, Shashi Prakash, Priyadarshi Abhishek, and Sachin Gandotra (2008). "Global workspace model of consciousness and its electromagnetic correlates". ''Ann Indian Acad Neurol''. Jul–Sep; 11(3): 146–153. * Gazzaniga, Michael S. (2004). ''The cognitive neurosciences''. MIT Press, p. 1146. * Laureys, Steven; et al. (2006). ''The boundaries of consciousness: neurobiology and neuropathology''. Volume 150 of ''Progress in Brain Research''. Elsevier, p. 45. * Naccache, L. (March 2007). "Cognitive aging considered from the point of view of cognitive neurosciences of consciousness". ''Psychologie & NeuroPsychiatrie du vieillissement''. Volume 5, Number 1, 17–21. * Hans Liljenström, Peter Århem (2008). ''Consciousness transitions: phylogenetic, ontogenetic, and physiological aspects''. Elsevier, p. 126. * Tim Bayne, Axel Cleeremans, Patrick Wilken (2009). ''The Oxford companion to consciousness''. Oxford University Press, p. 332. * Bernard J. Baars, Nicole M. Gage (2010). ''Cognition, brain, and consciousness: introduction to cognitive neuroscience''. Academic Press, p. 287. * Carlos Hernández, Ricardo Sanz, Jaime Gómez-Ramirez, Leslie S. Smith, Amir Hussain, Antonio Chella, Igor Aleksander (2011). ''From Brains to Systems: Brain-Inspired Cognitive Systems''. Volume 718 of ''Advances in Experimental Medicine and Biology Series''. Springer, p. 230.

References

External links

"Selected publications of Stanislas Dehaene"

INSERM-CEA Cognitive Neuroimaging Unit
{{DEFAULTSORT:Dehaene-Changeux model Consciousness Cognition Cognitive architecture Cognitive modeling Artificial neural networks Machine learning algorithms Computational neuroscience Cognitive neuroscience