ion channels - resonance frequency?

Kaushik Ghose kghose at wam.umd.edu
Sun Apr 30 22:47:33 EST 2000


Hi,
This is an interesting idea. Assuming that the electrically operating
channels mentioned refer to voltage gated channels we can approach the
problem this way :

THe voltage gated channels are operated by a voltage difference between
the inside of the neuron and the outside. THis voltage diference typically
has to be of a certain magnitude and also has to exist for a certain time
before the channel can open.

If we consider the brain matter to be a conducting mass
(extracellular medium) filled with semi-insulated strands of wire
(neurons) then passing radio waves through this mass can possibly induce
currents in the strands of wire. 

But radio frequencies are fairly high (in the order of MHz and at least
KHz) and so the cycle of the induced currents (if they existed) would be
too short to set off these channels.

What is done is to use much lower frequencies - actually DC pulses - and
disguise the radio transmitter as a large magnetic coil - and the result
is TMS or transcranial magnetic stimulation with which people are getting
very interesting results. 

But the technique is new, and because it is not very well localised
(stimulating one part of the brain often affects a large region) results
obtained with it are controversial.

thanks

Kaushik Ghose
Graduate Student
Programme in Neurosciences and Cognitive sciences
University of Maryland College Park
                              
On Thu, 20 Apr 2000 kyan1 at hofstra.edu wrote:

> hi group,im thinking that, since ion channels operate electrically,there
> could exist some resonance frequencies of electro-magnetic waves such that
> the channel activity is altered,e.g. forced to open/closed states.  If these
> frequencieshappens to be in the radio range,  then they could beexploited, 
> say,  for use in non-invasive stimulation.has any research been done re this
> topic?	thanks:)kyan1 at hofstra.edu
> 
> 
> Sent via Deja.com http://www.deja.com/
> Before you buy.
> 





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