Anyone know the method for marking (steel) electrode site electrochemically (Prussian Blue?)?

[Brian Scott]

In article <Dn8wBB.Ln4 at utcc.utoronto.ca> bscott at spine.med.utoronto.ca (Brian Scott) writes:
>In article <4gkmfc$t9f at bigblue.oit.unc.edu>,
>David Parsons  <dparsons at med.unc.edu> wrote:
>>Howdy/g'day,
>>
>>I want to mark an extracellular recording site at the end of an experiment
>> via 
>>elctrochemical deposition of Fe ions from the tip of the elctrode (a fine 
>>stainless-steel).  
>
>[stuff deleted]
>
>>colour (was it with K ferricyanide?, a Prussion blue reaction I think).   
>
>We've done electrical stimulation in rat through chronically implanted
>stainless steel electrodes and lesioned with about 400 - 800 uA for 10 sec.
>This is probably much higher than you'd like to use though.  To see the
>placement we used a solution of K-Ferrocyanide, K-Ferricyanide and some
>kind of acid.

Check out _Electrical Stimulation Research Techniques_, Academic Press, 1981
Michael M. Patterson & Raymond P. Kesner, eds., p. 159.

3% (by weight) potassium ferrocyanide
3% potassium ferricyanide
0.5% trichloroacetic acid

mixed with perfusate (10% formalin) in our case.  We usually let the whole
brain sit in it for a while too.

>This was added to the perfusate (formalin) and simply perfused
>intra-cardially.  The site shows up as a bright blue-green dot.  It's pretty
>nifty.  We used to have trouble locating lesion sites near the edge of the
>brain even at such high currents but this made it much easier.  
>
>>Also, can it be done in both whole mounts (cleared or not) and sections? 
>
>I believe it could easily be done in both.
>
>Brian
>
>
>Brian Scott                   | "They are in you and in me; they created us,
>bscott at spine.med.utoronto.ca  |  body and mind; and their preservation is
>Department of Physiology      |  the ultimate rationale for our existence."
>University of Toronto, Canada |         - Richard Dawkins (The Selfish Gene)
>
>


-- 
Brian Scott                   | "They are in you and in me; they created us,
Department of Psychology      |  body and mind; and their preservation is
University of Toronto, Canada |  the ultimate rationale for our existence."
scott at psych.utoronto.ca       |         - Richard Dawkins (The Selfish Gene)