CONSCIOUSNESS

96 2. Neuroscience
112 Neurocognitive Theories of Consciousness: a Critical Overview Sid Kouider
(Département d’Etudes Cognitiv, CNRS & Ecole Normale
Supérieure, Paris, France)
The two last decades have given rise to a large number of scientific theories of consciousness.
I will provide a critical overview of the most influential cognitive and neurobiological
accounts of consciousness. I will first introduce the difficulty of constructing a scientific
theory of consciousness, and the problem of relying on neural ‘correlates’ rather than ‘bases’
of consciousness. I will then present several influential neurobiological theories, depicting
them from the most globalists to the most localist accounts of the link between brain structures
and conscious contents (e.g., The Re-entrant Dynamic Core theory of Edelman & Tononi,
the Global Neuronal Workspace theory of Dehaene, the Coalition model of Crick and Koch,
the Duplex Vision theory of Milner & Goodale, the Local Recurrence theory of Lamme, the
Micro-Consciousness theory of Zeki, etc). I will contrast these theories according to their
functionality and explanatory power. I will also discuss how these theories deal with important
issues, such as the existence of a hard problem, the distinction between access and
phenomenal consciousness, the link between attention and consciousness, the dissociation
between primary and self-consciousness, and the crucial problem of measuring consciousness
in a scientific manner. PL9
113 Brain Dark Energy and Default Mode Networks Marcus E. Raichle
(Department of Radiology, Washington University School of
Medicine, St. Louis, MO)
“Whilst part of what we perceive comes through our senses from the object
before us, another part (and it may be the larger part) always comes out of our
own head”. William James (1890)
This prescient comment by William James, to be found in Volume 2 (page 103) of his
monumental work Principles of Psychology captures the essence of a debate ongoing in the
19th century and possibly earlier surrounding two views of brain function. One view, pioneered
by the work of Sir Charles Sherrington posits that the brain is primarily reflexive,
driven by the momentary demands of the environment. The other view is that the brain’s
operations are mainly intrinsic involving the acquisition and maintenance of information for
interpreting, responding to and even predicting environmental demands, a view espoused by
one of Sherrington’s disciples T. Graham Brown.
The view that the brain is primarily reflexive has motivated most neuroscience research
including that with functional neuroimaging. This is not surprising because experiments designed
to measure brain responses to controlled stimuli and carefully designed tasks can be
rigorously controlled, whereas evaluating the behavioral relevance of intrinsic activity (i.e.,
ongoing neural and metabolic activity which is not directly associated with subjects’ performance
of a task) can be an elusive enterprise. Unfortunately, the success of studying evoked
activity has caused us to lose sight of the possibility that our experiments reveal only a small
fraction of the actual functional activity performed by our brain. PL2