Pages closed - under construction (October- December 1999)
Easy Consciousness Problems (Chalmers)
|
the ability to discriminate, categorize, and react to environmental stimuli; |
|
the integration of information by a cognitive system; |
|
the reportability of mental states; |
|
the ability of a system to access its own internal states; |
|
the focus of attention; |
|
the deliberate control of behavior; |
|
the difference between wakefulness and sleep |
Neural Correlates of consciousness (from Chalmers)
|
40-hertz oscillations in the cerebral cortex (Crick and Koch 1990) |
|
Intralaminar nuclei in the thalamus (Bogen 1995) |
|
Re-entrant loops in thalamocortical systems (Edelman 1989) |
|
40-hertz rhythmic activity in thalamocortical systems (Llinas et al 1994) |
|
Extended reticular-thalamic activation system (Newman and Baars 1993) |
|
Neural assemblies bound by NMDA (Flohr 1995) |
|
Certain neurochemical levels of activation (Hobson 1997) |
|
Certain neurons in inferior temporal cortex (Sheinberg and Logothetis 1997) |
|
Neurons in extrastriate visual cortex projecting to prefrontal areas (Crick and Koch 1995) |
|
Visual processing within the ventral stream (Milner and Goodale 1995) |
The Hard Problem of Consciousness (Chalmers)
"The really hard problem of consciousness is the problem of experience. When
we think and perceive, there is a whir of information-processing, but there is also a
subjective aspect. As Nagel (1974) has put it, there is something it is like to be
a conscious organism. This subjective aspect is experience. When we see, for example, we experience
visual sensations: the felt quality of redness, the experience of dark and light, the
quality of depth in a visual field. Other experiences go along with perception in
different modalities: the sound of a clarinet, the smell of mothballs. Then there are
bodily sensations, from pains to orgasms; mental images that are conjured up internally;
the felt quality of emotion, and the experience of a stream of conscious thought. What
unites all of these states is that there is something it is like to be in them. All of
them are states of experience. ...
If any problem qualifies as the problem of consciousness, it is this one. In this central sense of "consciousness", an organism is conscious if there is something it is like to be that organism, and a mental state is conscious if there is something it is like to be in that state. Sometimes terms such as "phenomenal consciousness" and "qualia" are also used here ..."
|
Nagel, T. 1974. What is it like to be a bat? Philosophical Review 4:435-50. |
Chalmers (1995)
Francis Crick & Christof Kock
"We assume that when people talk about "consciousness," there is something
to be explained. While most neuroscientists acknowledge that consciousness exists, and
that at present it is something of a mystery, most of them do not attempt to study it,
mainly for one of two reasons:
(1) They consider it to be a philosophical problem, and so best left to philosophers.
(2) They concede that it is a scientific problem, but think it is premature to study it now.
We have taken exactly the opposite point of view. We think that most of the philosophical aspects of the problem should, for the moment, be left on one side, and that the time to start the scientific attack is now.
We can state bluntly the major question that neuroscience must first answer: It is probable that at any moment some active neuronal processes in your head correlate with consciousness, while others do not; what is the difference between them? In particular, are the neurons involved of any particular neuronal type? What is special (if anything) about their connections? And what is special (if anything)about their way of firing? The neuronal correlate of consciousness if often referred to as the NCC. Whenever some information is represented in the NCC it is represented in consciousness."
Crick & Kock (1998)
Cross-cultural, historical, comparative, ....