Evoked Potential Connection Problem

Thomas R. Gregg greggt at brahms.udel.edu
Sun Nov 20 15:17:49 EST 1994


In article <94315.113331U12615 at uicvm.uic.edu>,
Michael Davis  <U12615 at uicvm.uic.edu> wrote:
>I'm going to be recording evoked potentials from the skull surface of
>rats.  I have a question concerning the connection between the
>electrodes (stainless steel screws) and the amplifiers.  I can do it
>by soldering the pins of a connector plug to the screws and cementing
>in place, however I was wondering if anyone knew of a way a connection
>can be made without the need to solder during surgery.  Is there any
>specialized electrode/connector apparatus currently being marketed
>for small animal EPs, if so does anyone know the name of it and
>the company I could contact?   Thanks for your help.  Mike Davis

Before surgery:
1) Use single stranded (solid) wire with a thin layer of insulation.  
California Fine Wire company-- .01 inch diam I think.  Cut a piece of wire
2-3 cm long.  Scrape  4 mm insulation off each end.

2) Solder the underside of the screw head to the length of wire without
getting solder on the threads or the top of the screw head- this takes
practice. 

3) trim the wire to length and crimp an Amphenol male goldplated
connector pin on the free end.  Use a special crimping tool for this.

During surgery:
1) install screw in skull.  Wire and pin will be stick up from skull.
For acute recording, you are done.

2) (For chronic recording.)  Use plastic Cannon connector housing.  Snap the
pins
for active and indifferent electrodes up into the housing using needlenose
pliers.  Cement to rat's head.  

For chronic recording:
Use female Amphenol pins and Cannon housing to connect
rat to amp.  Put a long screw into one of the holes intended for Amphenol
pins, to hold the housings together firmly.

More than you wanted to know.
Tom Gregg
grad student



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