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Shawn
post Mar 21, 2004, 07:57 PM
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we can't leave out structured synchronous neural activity as a neural correlate of consciousness (NCC), though such an NCC is not very satisfactory, even if the relation is shown to be partially true.
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Guest_sprinklehopper_*
post Mar 20, 2006, 05:59 PM
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QUOTE(Shawn @ Mar 21, 07:57 PM) *

we can't leave out structured synchronous neural activity as a neural correlate of consciousness (NCC), though such an NCC is not very satisfactory, even if the relation is shown to be partially true.


Thats an understatement, if i ever heard it. Synchrony deserves more possibility than this. Also what do you mean by "structured" neuronal synchrony ? I was surprised to discover that EEG originated from white matter, myself. Women have more white matter than men (on average) and also greater degrees of self awareness. Another term could be self -conscious.

The white matter doesnt appear to have any kind of "three dimensional" structure. That is look at the corpus callosum from the top. It has a very tight structure. Look at it from the side and the wiring looks random.

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Neural
post Mar 20, 2006, 06:47 PM
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the EEG signal originates from current sources in both gray matter and white matter. What do you mean by the corpus callosum looking random when viewed from the side? The fibers are largely parallel to each other at that orientation. Also, white matter consists of fibers that arborize and are oriented in 3D.

Also, synchrony as an NCC does not seem plausible to me because it does not explain anything. There's more to the story than synchrony. The "structured synchrony" probably references our variegated experience.
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Guest_sprinklehopper_*
post Mar 20, 2006, 09:08 PM
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QUOTE(Neural @ Mar 20, 06:47 PM) *

the EEG signal originates from current sources in both gray matter and white matter. What do you mean by the corpus callosum looking random when viewed from the side? The fibers are largely parallel to each other at that orientation. Also, white matter consists of fibers that arborize and are oriented in 3D.

Also, synchrony as an NCC does not seem plausible to me because it does not explain anything. There's more to the story than synchrony. The "structured synchrony" probably references our variegated experience.


cool good reply.

http://www.csit.fsu.edu/~yagi/project/

That looks random or disordered to me. Ok i admit, its all the white matter. If you could see all the neurons in all the various bits of the brain at one time, they would not look that disordered, as they tend to orientate coherently outwards.

The sync component which is essentially what you read in EEG originates from white matter. It is expressed and readable within the grey matter.

Everything biological could be said to be orientated in 3d. The flow of the axon signal itself can be defined within two dimensions. There is more than synchrony.

My point if its even original, is :put female biased synchrony together (which does seem to be a reference system) with the hard to define male biased sensory processing and another take for consciousness will arise.

I will try to express this better another time when less tired.

















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Neural
post Mar 20, 2006, 11:38 PM
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bear in mind sprinklehopper that the link you posted is for fiber tracts constructed using Diffusion Tensor Imaging (DTI). DTI has poor resolution, and when you learn the details behind how they do it, you'll become even more skeptical. Look at some myelin stains to get a better idea of white matter organization. Granted, it'll be in 2D and not 3D (like DTI generates), but it will be much better quality.
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post Mar 22, 2006, 04:42 AM
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QUOTE(Neural @ Mar 20, 11:38 PM) *

bear in mind sprinklehopper that the link you posted is for fiber tracts constructed using Diffusion Tensor Imaging (DTI). DTI has poor resolution, and when you learn the details behind how they do it, you'll become even more skeptical. Look at some myelin stains to get a better idea of white matter organization. Granted, it'll be in 2D and not 3D (like DTI generates), but it will be much better quality.



Dti is good enough for illustrating big fibers, which are the most vital anyway. The Dti fiber results are almost identical to real brain dissections of white matter fiber. its a good image to look at the overall wiring of the whole brain system. I think its quite a strinking image. it brings together what would previousy have needed three or four dissections.
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Guest_sprinklehopper_*
post Mar 22, 2006, 04:43 AM
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a strinking image ? Strinking ?

To strink...

A strinkling





Strinkle
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Neural
post Mar 22, 2006, 05:01 AM
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QUOTE(Guest_sprinklehopper_* @ Mar 22, 04:42 AM) *

Dti is good enough for illustrating big fibers, which are the most vital anyway.


I disagree. The fine fiber networks carry modulatory, behavioral, and contextual information and cannot be resolved with DTI. Also, DTI cannot deal with bifurcating fibers, which are common in the CNS. DTI, at best, can only provide rough agreement with gross dissections of the white matter, but has nothing to say about the microscopic level since that is far below its resolution. Each axon is about one thousand times finer in width than what DTI is capable of resolving (one micron versus one millimeter), which means that each "fiber bundle" in DTI really amounts to 1000*1000 (or a million) real axons. And this means that DTI is only showing you, at best, 0.00001 % (or 1/1000000) of the white matter picture. Do you really think that the other 99.99999% of the information about axon fibers that DTI is incapable of resolving and in effect throws away is not vital?

Btw, the person posted a pdf of their dissertation over DTI at http://www.csit.fsu.edu/~yagi/project/report.pdf

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Guest_sprinklehopper_*
post Mar 22, 2006, 07:29 PM
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QUOTE(Neural @ Mar 22, 05:01 AM) *

QUOTE(Guest_sprinklehopper_* @ Mar 22, 04:42 AM) *

Dti is good enough for illustrating big fibers, which are the most vital anyway.


I disagree. The fine fiber networks carry modulatory, behavioral, and contextual information and cannot be resolved with DTI. Also, DTI cannot deal with bifurcating fibers, which are common in the CNS. DTI, at best, can only provide rough agreement with gross dissections of the white matter, but has nothing to say about the microscopic level since that is far below its resolution. Each axon is about one thousand times finer in width than what DTI is capable of resolving (one micron versus one millimeter), which means that each "fiber bundle" in DTI really amounts to 1000*1000 (or a million) real axons. And this means that DTI is only showing you, at best, 0.00001 % (or 1/1000000) of the white matter picture. Do you really think that the other 99.99999% of the information about axon fibers that DTI is incapable of resolving and in effect throws away is not vital?

Btw, the person posted a pdf of their dissertation over DTI at http://www.csit.fsu.edu/~yagi/project/report.pdf



The tensor images are a good replacement for dissections. I'm sure we can agree on that much. do you have links for modulation and information carriage along axons.

the bifurcating fibers ? are those when the axons hit the grey matter ?




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