What part of the brain is conscious?

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  • #76
hypnagogue
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Q_Goest said:
Thanks for the clarification. I was always under the assumption that all neurons have some threshold, below which they don't 'fire' and above which they do. Is that a correct way of percieving a neuron's function? How could that be better explained?

Yes, that is quite true. Neurons normally have a resting potential, such that the interior of the neuron is negatively charged with respect to the exterior. A neuron's potential can be be made either more or less negative by inputs it receives from other neurons at its dendrites. If the inputs a neuron receives raise its potential above a certain threshold, then the action potential (process of neural firing) is automatically triggered. (Actually, neurons normally fire spontaneously at some rate; inputs from other neurons can make a given neuron fire more or less rapidly, though.) Here are some good links that go into further detail:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/ExcitableCells.html
http://www.everything2.com/index.pl?node=neuron

However, the threshold of a neuron's action potential is just about the mechanics of individual neurons. This threshold is not to be confused with e.g. some notion of a threshold that might obtain between neural events that find expression in consciousness and those that don't. All neurons function in the same basic manner with voltage thresholds and action potentials and the like, but of course, not all neurons directly contribute to conscious experience.
 
  • #77
somasimple
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HI,

Actually, neurons commuicate across the synaptic gap by means of neurotransmitters, not ions.

It is certainly true for a little population of peripheral neurons but false for 80% of brain ones that use gap junctions. A gap junction is a direct connection that transmit a ion flow from a neuron to another.

The transmission of action potential is not electrical but ionic since ions cross the membrane through ion channels. If it was electrical you will have a huge problem to solve: the soliton wave (the travelling action potential) rejects an electrical explanation

There is so many balloneys/contradictions about neurons.
 
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  • #78
somasimple
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About NCC, it seems that it is an old thing located in the brainsteem for some scientist (Damasio) and thalamus for some other.

Do not forget that cortices are projections of older sites and may override their behaviours.
 
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  • #79
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somasimple said:
The transmission of action potential is not electrical but ionic since ions cross the membrane through ion channels.
Yes, this is important to realize. Terms like "the electrical activity of the brain" have mislead people into assuming too many incorrect comparisons with elecrical circuits.
 
  • #80
somasimple
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Yes, this is important to realize. Terms like "the electrical activity of the brain" have mislead people into assuming too many incorrect comparisons with elecrical circuits.

I would like that neuroscientists and neurophysiologists heard this. They are glued with a 75 year old cable theory and push their researches in the wrong direction. Neuron is a fabulous and simple cell.
 
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somasimple said:
I would like that neuroscientists and neurophysiologists heard this. They are glued with a 75 year old cable theory and push their researches in the wrong direction. Neuron is a fabulous and simple cell.

Actually models derived from cable theory work pretty well in predicting the responses of the dendrites, those often overlooked "other processes" of the neuron. It's not just all about axons.
 
  • #82
somasimple
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Hi,

A mathematical model is just a mathematical model that mimics Nature. But it remains only a curve fitting IMHO. The cable model isn't reliable for:

ions that cross membrane
continuity
travelling wave
latency time
refractory period
saltatory conduction
amplification of AP seen in dendrites
acceleration AP seen in "trees"

Well, quite 99% of a neuron functioning. :surprised
 

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