[Alok Mishra (OP)]

Does the magnetic field of one conducting neuron affects neighbouring neuron? I think there should be some mutual induction.

[Ians Daddy]

I would say yes. I have, in my tool box, a really cool gadget. It's two magnets held together with a rubber-band. You strap it onto a screw driver and by morning it's magnetized to hold screws on it's tip. So, I would say that magnetic fields do affect their surroundings. But, as always, I'm somewhat guessing. Correct me if I'm wrong.

[Ylide]

You need a decent amount of current or charge separation to generate a magnetic field of any significant strength.  I don't see how the current travelling a neural pathway could generate enough of a field to affect any of the others.  

Ians Daddy:  Induced magnetic fields via current is a bit different from the magnetic fields of ferromagnetic substances.  Your screwdriver is being magnetized because the field inherent in the two magnets is polarizing the metal in the screwdriver.  Polarized ferrous material = ferromagnet.  That's how they make permanent magnets....they expose the metal to a VERY strong field for a day or two, so that the entire object is as polarized as it can get.  If you play with magnets quite a bit, you'll find out that you can ruin the polarity of one magnet by keeping it in close proximity with another oppositely polarized stronger magnet for too long.  Magnets are fun.  



This message brought to you by The Council of People Who Are Sick of Seeing More People

[chris]

You can indeed induce activity within neurones with the aid of a magnetic field. Transcranial magnetic stimulation (TCMS) involves placing an extremely powerful electromagnet against the skull and can be used to activate regions of the brain including, for instance, elliciting movements by recruiting neurones in the brain's motor strip (cortical area 4). However the field strength required to do this is huge, and certainly way beyond that produced by an individual neurone relative to its neighbour.

That said, the electrical activity of the brain does produce measurable skin potentials which can be read with scalp electrodes. This is the basis of an EEG (electroencephalogram) which, quite literally, measures 'brain waves' - the electrical ebb and flow of the functioning brain. The EEG is a useful, though insensitive, tool for the diagnosis of a variety of brain conditions including epilepsy, prion diseases (sporadic CJD), and, when measured in the context of evoked-activity, multiple sclerosis (MS).

On a lighter note, team of Australians came up with an idea for a "thinking cap" which placed a series of magnets over the right side of the brain - thought to be your more "creative" hemisphere - and apparently boosted the wearer's capacity for abstract thought ! We did a piece on it for radio, here's the link - it's at the bottom of the summary blocks, and in full in the "full length text"

http://www.nakedscientists.com/html/shows/2002.06.16.htm

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[tweener]

A faster to way to make a magnet is to heat the metal being magnetized while it is in a strong magnetic field.  The annealing process loosens the molecules and allows them to polarize more effectively.

I can't wait to get home and lookup more on the "Thinking Cap".  I really need a brain stimulant!


----
John

[nilmot]

If magnetic field can induce the activity of neurons. Can magnetic field also alter the activity of the neron like messing it up or change the direction of the impulse?

Tom

[chris]

The Action potential - the wave of depolarisation that propagates along a neurone to convey information - can travel along the cell in any direction. Electrical stimulation of the axon (the long thin extension of the cell that carries the action potential) will result in depolarisation spreading away from the point of stimulus in both directions.

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx