Medical Do neurons communicate with magnetism ?

[ketchup king]

Magnetic effects on the brain are well known, as are magnetic brain scans, but I'm having difficulty finding anything to say magnetism has a function within the brain. I can find electrical communication, but not magnetic.

Am I missing something ?

Folk, do say if so.

 

[DiracPool]

Transcranial magnetic stimulation (TMS) is a noninvasive method to cause depolarization or hyperpolarization in the neurons of the brain. TMS uses electromagnetic induction to induce weak electric currents using a rapidly changing magnetic field;

http://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation

You can induce action potential trains artificially using TMS. As far as natural communication between cells, we usually model these as electrochemical interactions. So, although magnetism always goes along with the territory when speaking of these actions, we typically do not invoke it a causal agent in natural brain function.

 

[ketchup king]

Thanks for the reply. OK there are charges moving around in the brain, so there should be magnetic fields even at the molecular level, but not so that it is involved in neuron-neuron communication in itself that has been found yet - that I can find.

So, as it was recently found that http://www.caltech.edu/content/neurobiologists-find-weak-electrical-fields-brain-help-neurons-fire-together, I was wondering wether there was potential for findings of a similar nature regarding magnetic fields ?

 

[DiracPool]

So, as it was recently found that http://www.caltech.edu/content/neurobiologists-find-weak-electrical-fields-brain-help-neurons-fire-together, I was wondering wether there was potential for findings of a similar nature regarding magnetic fields ?

From the article you posted:

"while active neurons give rise to extracellular fields, the same fields feed back to the neurons and alter their behavior,"

What happens is that weak, plentiful, and disparate signal afferents arriving in any given cytoarchitectoniaclly defined cortical region set up a collective pattern of activity, a gestalt, if you will, that places that region onto a basin of attraction through which all of the neurons in that region couple via an order parameter. This coupling is typically in the gamma range locally and in the alpha-theta range globally. You can measure the spatial signature of the coupling through topographic maps generated by the summed dendritic currents across the local expanse. It is the establishment of that order parameter that provides the nonlinear feedback referred to in that article.

I don't know why you are so hung up on the magnetic aspect, though, unless you have some reason you are not mentioning. The local potential fields that arise from the actions I describe above make up the fields that the EEG ("electro"-encephalagram) pick up as well as the MEG ("magneto"-encephalagram). The activity is electro-magnetic, so both are involved in an inextricable way. The question of whether the magnetic potential/fields produced play a significant causal role in this coupling is one that I have not encountered, and it seems as if you have not either by your comment in your original post:

I'm having difficulty finding anything to say magnetism has a function within the brain.

So, if you find something, let me know, I'd be interested

 

[ketchup king]

I'll let you know, aye.

 

[atyy]

Neurons do not communicate with magentism. They communicate with current flows (spatially propagating potential differences across the cell membrane) and chemicals (release of neurotransmitter from a chemical synapse). The current flows give rise to magnetic effects in 2 ways.

The time-varying current generates an electromagnetic field, which can be sensed quite far from the neurons as in electroencephalography (EEG) and magnetoencephalography (MEG). For reasons that are probably well known (but not to me without googling), MEG is preferred over EEG for recording auditory cortical responses.

In functional magnetic resonance imaging (fMRI), the magnetism of the heme in blood is an indicator of blood oxygenation, which is an indicator of neural activity.

Both of these provide less detailed information than if one could record electrically from individual neurons. They lack either spatial or temporal resolution. But they are important because one can't always cut a hole in the brain and insert an electrode.

 

[ketchup king]

Hmmm, I'd much rather see "Neurons do not communicate with magentism, so far as we know yet.", because they were saying that neurons don't communicate with electrical fields, but of course it turns out they do. A bit like the once established fact that the brain does not regenerate it's cells once damaged - but now neuroplasticity is a hot topic.

But OK, just because someone asserts a scientific finality doesn't mean they necessarily think that a question is closed - it's a habit that is so prevalent it is hard to shake.

Do you think its a closed question - whether there is neuron to neuron communication via magnetism ?

I got thinking about this because I was compiling a list of ways neurons communicate, and realized I didn't really know.

So far my list would be

1. Neurotransmitters
2. Hormones (not quite sure whether to categorise this as direct neuron-neron communication)
3. Electric current (electrical synapse, dendrite current)
4. Electric Field (ephaptic coupling)
5. Biophotons - ? established ?

What have I missed ?

 

[DiracPool]

What have I missed ?

I wouldn't be so worried about missing anything, but more worried about overthinking the issue. If I were you, I'd be wary of straying off into that fringe neuroscience of "alternate communication" models of cortical interactions. Two of the more famous of these are the "glial cells do much of the information processing in the brain" theories, and Hameroff's "consciousness is created through the quantum coupling of microtubules."

In my opinion, these alternative models surface when progress on understanding brain function stalls and researchers get frustrated because they can't see the end of the tunnel. However, these models have a vanishingly small probability of having any significant contribution to cortical function. The danger is that you can waste a lot of time before you realize this is the case. So my advice is stick to the electrochemical model. But it's up to you. Tread carefully

 

[ketchup king]

I could sense that lurking in the background. I'm not bothered about whether I'm straying from orthodoxy or not, I've got no scientific reputation to defend, no one is going to deny me funding or employment, I'm just curious, so don't worry about steering me to safe ground. Safe ground is always shifting anyway. I've already mentioned two orthodox views that have gone. Time will tell what happens next to other orthodoxies. No particular reason for me to stick to any particular model, electrochemical or otherwise, I just wanted to know about whether there is any role for communication via magnetic fields within the brain. As far as I can make out this is an open question - maybe there is, maybe there isn't - at the moment I can't see much by way of evidence just from web searches.

What other forces or energies have we got that may turn out to be involved ?
There's a paper on biophotons whose title asserts biophotonic communication, but the body of the text only seems to be suggestive, not conclusive.

Is there any evidence that neurons communicate physically, by contracting and expanding and tugging on their neighbours, stuff like that ?

 

[DiracPool]

Is there any evidence that neurons communicate physically, by contracting and expanding and tugging on their neighbours, stuff like that ?

Absolutely, this is how memories are formed and motor skills are learned. One model is that co-active neuronal assemblies secret nerve growth factors that cause dendrites to spread out and strengthen connections within the network. These are called "cell-assemblies," a term coined by D.O. Hebb. There are also direct connections between some neuron types called "gap junctions," which bypass the traditional chemical synapse. This type of connection transfers pulse energy directly and electrically from one neuron to another, I do not believe magnetism per se plays a significant role here either.

 

[ketchup king]

OK, but could that sort of growth factor stimulated growth be called communication ? The transmission of growth factor could, I suppose, be a communication that it's time to grow, but the growth itself ?
I was thinking more like a neuron that tugs or beats on another neuron and so on - mechanical transmission of signal would be an apt term I think.

Also, could we think that it would be a waste for the brain not to be using magnetic fields - if that energy is available would it not be efficient for it to have evolved a use somehow ?

 

[atyy]

Hmmm, I'd much rather see "Neurons do not communicate with magentism, so far as we know yet.", because they were saying that neurons don't communicate with electrical fields, but of course it turns out they do. A bit like the once established fact that the brain does not regenerate it's cells once damaged - but now neuroplasticity is a hot topic.

But OK, just because someone asserts a scientific finality doesn't mean they necessarily think that a question is closed - it's a habit that is so prevalent it is hard to shake.

Do you think its a closed question - whether there is neuron to neuron communication via magnetism ?

I got thinking about this because I was compiling a list of ways neurons communicate, and realized I didn't really know.

So far my list would be

1. Neurotransmitters
2. Hormones (not quite sure whether to categorise this as direct neuron-neron communication)
3. Electric current (electrical synapse, dendrite current)
4. Electric Field (ephaptic coupling)
5. Biophotons - ? established ?

What have I missed ?

Well, obviously. I just didn't want to be pedantic.

 

[ketchup king]

That's one point of pedantry I don't mind. Some of the terrible things scientists say...
Like - "the brain is the most complicated object in the universe". I just keep hearing this repeated by by every scientist who is running short of things to amaze the public with and it just makes me wince.

Think about it, we live on a 6 billion year old planet, the history of which we are largely ignorant, and which still remains partially unexplored, one of many planets - billions - trillions - and we're stuck in one little galaxy of a humungus universe the extent of which we don't truly know, of which we only recently realized we are only seeing 15% even with our best instruments, and Brian Cox thinks he can just up and claim he knows what the most complicated object is in all of of that ?!

Been and looked round it all have you Brian ?

 

[DiracPool]

...and Brian Cox thinks he can just up and claim he knows what the most complicated object is in all of of that ?!

Been and looked round it all have you Brian ?

Lol. I like your passion. But hey, slow down on the ketchup. A little makes you mellow, but take too much and you start having delusions of grandeur, just ask Garrison Keillor. I definitely don't agree with everything Brain Cox has to say, but it's arguably correct that the human brain is the most complicated object we know of. Give me an example of something you think might be more complicated, and things like the entire universe or a galaxy don't count. Something on the size scale of the brain. I'll hold off on a discussion as to whether we need to more clearly define "complicated" until I see if you come up with something compelling.

 

[ketchup king]

Got to entertain yourself sometimes. Really though, its not the claim that its the most complicated thing we know of, but that exists. It's funny how people make these assertions.

Example of something more complicated ? The human body inc. head ? A decapitated head with some vessels still attached to give it that .01% greater complexity ?
The definitions of a thing are a bit meaningless, but it all sounds good on science documentaries so it will keep coming up - gives the impression that we've really Arrived Somewhere in our Great Quest for Knowledge.

Here we go - see what I mean ?
http://www.bbc.co.uk/news/uk-scotland-18233409
""We won't be able to understand the brain. It is the most complex thing in the universe," says Professor Sir Robin Murray, one of the UK's leading psychiatrists."

Boy, that guy must really have some stamps on his passport for **that** amount of travel, someone should write him and ask him what the crab nebula looks like up close.

More musings - "I just read the book The Evolving Brain, by R. Grant Steen, 2007. The main thing I took away from the experience was two astounding numbers. The number of neurons in the human brain: 100 billion, and the number of synapses each can make: 10,000. Upon reading this, it is easy to accept Steen’s conclusion that the human brain is likely the most complex thing in the universe."

No it's not, it is very daft to accept Steen's conclusion.

More daftness - "Consider the human brain," says physicist Sir Roger Penrose. "If you look at the entire physical cosmos, our brains are a tiny, tiny part of it. But they're the most perfectly organized part. Compared to the complexity of a brain, a galaxy is just an inert lump."

He's seen it all and come to the conclusion that he's found the most perfectly organised part. Wow, he must have been hitch hiking UFO's with the earlier professor.

A video example of omniscience - - man with gadget on head - "Our brain is the most complex thing in the universe." - those galactic neuroscience fact finding trips are really popular.

Discover magazine shows it doesn't really understand the nature of scientific discovery -http://discovermagazine.com/2007/aug/unsolved-brain-mysteries -
"Of all the objects in the universe, the human brain is the most complex: There are as many neurons in the brain as there are stars in the Milky Way galaxy.

and it goes on...

So that's a leading psychiatrist, a world famous physics professor, a leading popular science mag - took me five minutes of googling. Big fail for science culture.

And finally, couldn't resist it, I knew seen him saying it too, Dawkins

"As Richard Dawkins marvels at a human brain he says; “This is arguably the most complex thing in the universe ... there are perhaps 100 billion nerves (neurons) in there and maybe 200 trillion connections between them.” (From the TV series “Brave New World with Stephen Hawking” from the episode on Health)"

Yeah ? What argument is that then ?

 

[ketchup king]

So, ahem, after that, back to my original question, what about other forces - gravity, strong and weak force - any chance at all that they play any part (apart from the obvious one of bonding) in brain activity ?

And biophotons, has the research got any further than a somewhat inconclusive paper ?

And just to round it off and push the question somewhat close to the possibly unacceptable fringe, any chance of a dark matter or even anti matter role in brain biochemistry ?

 

[Borek]

You do know that per the forum rules PF is not a place for idle speculation?

 

[ketchup king]

That's right, those forum rules I just read. Those are perfectly decent rules.
Is there a good place for idle speculation about such things that you would recommend ?

 

[berkeman]

That's right, those forum rules I just read. Those are perfectly decent rules.
Is there a good place for idle speculation about such things that you would recommend ?

Certainly not here at the PF. This thread is closed.