What part of the brain is conscious?

[hypnagogue]

All in all, I think there must be some organizing force acting simultaneously on the whole brain; it's the only thing that can explain how billions of neurons can work together without creating absolute chaos. As far as I can tell, electromagnetic radiation is the most likely candidate, since we already know neurons respond too slowly to electrical impulses. It's a hypothesis that is very difficult to investigate, but it can certainly be entertained by amateur neuroscientists.

There are several general mechanisms by which the brain's activation patterns are coordinated and organized. Regular pulses of neural signals sent widely across the brain (I believe originating from the brain stem) act as a sort of timing device that helps keep individual neurons and neuron groups coordinated. The brain also features rich re-entrant feedback loops which help to stabilize, magnify, and propogate certain neural signals. There may be other such mechanisms; without looking up any specific information, this is the best I can offer right now, off the top of my head.

 

[zoobyshoe]

I don't think there's any mystery concerning the source of electrical signals in our scalp. What nobody seems to know is what those signals mean. At least that is what two neurologists told me after taking my EEG. They basically said something like, "we measure this stuff and we know certain patterns are associated with certain conditions, but we have no clue why".

The average neurologist may not be up on this research, but I bet if you looked through medical journals you'd find they have all kinds of good leads.

(Any neurologist who is in the process of treating you is probably the worst person to ask general questions about neurology. They don't have time to give any explanations that take more than a couple sentences, and will avoid going into it.)

"that is a fine explanation Dr. Persinger, but when someone is having the experience of being abducted by an alien, who do you think is waving the flashlight?"

Whatever bright star or airplane the person became fixated on would serve as the flashlight. The article I read in Omni magazine many years ago said he got the "Alien Abduction" scenario simply by suggesting to the subject that he was staring at a bright light in the sky (no flashlight used).

In any case, 15 Hz is too low a frequency to be used for inter-neuron communication so it isn't really what I had in mind.

Why is 15 hz too low a frequency?

It would be interesting to know if neurons emit EM signals whose frequency is high enough to propagate across the brain or even beyond the skull.

The frequency would have little to do with it. It's the strength of the signal that determines how far it can propagate. The strength of the signal is the product of how many neurons are firing at the same time. As I mentioned earlier, it takes about a million neurons firing at once to be picked up through the scull by a surface electrode, and these have to be firing more or less on the surface of the brain.

The EM wave produced by a firing neuron in unbelievably weak. During seizures, as I mentioned in an earlier post, an individual neuron fires more strongly than otherwise. In this case it can cause surrounding neurons (ones right next to it) to go off by mere induction, and things can cascade from there. This is different than one neuron setting the next one off by neurotransmitters across the synapses.

Persinger's solenoids are almost certainly setting neurons off by induction, and there is probably secondary neurotransmitter communication from there.

Over what distance are neuronal EM waves effective? Can the left hemisphere of a split brain patient pick up what is going on in the right hemisphere by induction? There doesn't seem to be any indication that it can. Persinger's solenoids give off an extremely strong EM signal compared to anything the brain itself can produce, which probably accounts for the large-scale effects they can have.

Anyway, the stroke patients who don't seem to realize they are half paralyzed aren't suffering from "blocks" that can be bridged in the way Q-Goest was speculating. The parts of their brain which might process the information into knowledge they are paralyzed are receiving contradictory imput which it seems to be resolving by "trusting" the feeling that the paralyzed limbs are still moving and active over the visual information that they aren't. Information isn't being blocked by any physical damage to connections here. Certain circuits are electing to go to sleep, so to speak, and not process it, in order to keep the whole picture more or less coherent.

 

[Q_Goest]

You mean microtubules as in Roger Penrose's microtubules? There's a whole debate on that already, although the focus is on quantum mechanics, not electromagnetism.

Actually, I believe we have to give Stuart Hameroff the credit for coming up with that one.

Yes, his idea regards quantum mechanical processes in the brain, but let's disregard that possibility for a moment. The concept may or may not be proven. What I was suggesting was the possibility that microtubules could act as transmitter/recievers for neurons like miniture radio stations. If this were true, that might predict there are electromagnetic fields within the brain that correspond to the information about which we are consciously aware. The neurons might be calculating things across synaptic gaps, but the neuron might have a secondary reaction to the electromagnetic field which might serve as a 'canvas' of information we are aware of.

Would it be possible that the brain processes information in more than one way, and the way in which the information is processed results in either conscious or subconscious awareness of that information? I think the unique idea here is that perhaps there are two methods of interpreting information by the brain.

 

[Q_Goest]

It's certainly not the case that only NCCs 'vote.'

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?

 

[Q_Goest]

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

Thanks for the clarification. I'll have to look into neurotransmitters a bit more now.

 

[hypnagogue]

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.

 

[somasimple]

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 traveling action potential) rejects an electrical explanation

There is so many balloneys/contradictions about neurons.

 

[somasimple]

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.

 

[zoobyshoe]

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.

 

[somasimple]

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.

 

[selfAdjoint]

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.

 

[somasimple]

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.