[Neuroscience] Re: head stage

Bill via neur-sci%40net.bio.net (by connelly.bill from gmail.com)
Thu Jun 17 02:55:15 EST 2010


Hi Ana,

The best thing to use as a ground is a silver chloride pellet. But a
silver chloride wire is pretty good. (made by submerging a piece of
bare silver wire in a sodium chloride solution, and connecting it to
the negative pole of a 9V battery. The complete the circuit with
another wire into the saline. Personally, I place the ground above the
surface of the cerebellum, and "cement" it in place with 1% Saline
agar.

Generally speaking, it doesn't matter if you plug the ground into the
port on the headstage or into the amp; but most people just plug it
into the headstage.

To get rid of the noise (depending on what it looks like), firstly,
you will need to use the low pass filter setting on the amp. Depending
on what you are recording, the 2, 5 or 10kHz settings will probably be
fine.

Secondly, you probably should set up your anesthetic rig inside a
Faraday cage. That is, a large metal shield, to protect your
recordings from electric fields. Of course, the cage needs to be
connected to the ground of the preamp.
(-would look something like this http://www.autom8.com/images_product/table_faraday_cage.jpg
You can test if this will work by setting up a temporary shield out of
aluminum foil. Connecting the input of your headstage to the ground
via a low resistance connection, and then connecting the aluminum
shield to ground

Finally, the amplitude of your noise will be highly dependent on the
resistance of the circuit from your headstage back to your pre-amp
ground. So you need to check the resistance of your electrodes is
appropriate, and as low as reasonably possible.

Hope this helps.



On Jun 17, 9:03 am, Ana Cervera Ferri <Ana.Cervera-Fe... from uv.es> wrote:
> Hi all,
>
> We have just acquired a head stage from A-M systems attached to a 1600  
> Neuroprobe amplifier for extracellular single recording in  
> anesthetized rats. Has any of you used it?
>
> We still have a lot of noise in the signal, and I am not sure of how  
> to use it: what should I use as a ground? should I connect a ground  
> wire to the headstage or directly to the amplifier? any advice to  
> obtain better recordings?
>
> I'd qould appreciate any comment
>
> Ana
>
> .
> El 16/06/2010, a las 19:04, neur-sci-requ... from oat.bio.indiana.edu  
> escribi :
>
>
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> > Today's Topics:
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> >   1. Re: Different reversal potential or just poor space-clamp?
> >      (jonesmat)
> >   2. Last call for applications ----- NWG-Course:  Analysis and
> >      Models in Neurophysiology, Freiburg, Germany (Janina Kirsch)
>
> > ----------------------------------------------------------------------
>
> > Message: 1
> > Date: Tue, 15 Jun 2010 13:56:41 -0700 (PDT)
> > From: jonesmat <jones... from physiology.wisc.edu>
> > Subject: [Neuroscience] Re: Different reversal potential or just poor
> >    space-clamp?
> > To: neur-... from net.bio.net
> > Message-ID:
> >    <944dff09-c0a5-4309-b94a-f7b1edc7f... from c10g2000yqi.googlegroups.com>
> > Content-Type: text/plain; charset=ISO-8859-1
>
> > On Jun 5, 12:25 am, Bill <connelly.b... from gmail.com> wrote:
> >> Hi,
> >> So I'm using whole-cell voltage clamp to record from a cell that has
> >> two classes of inhibitory inputs. One to the soma, and one (largely)
> >> to the dendrites, which I can activate independently. I/V plots show
> >> me that the apparent reversal potential of the dendritic input is  
> >> 10mV
> >> lower than the somatic input. This could be due to the fact that a)
> >> there is active Cl- homeostatis in the dendrites, which means that  
> >> the
> >> reversal potential truly is lower there, or b) I have poor space
> >> clamp, and hence I have to drive the somatic voltage below the actual
> >> reversal potential to get the potential at the dendrite to the
> >> reversal potential. (or I suppose both). There is plenty of evidence
> >> that I don't have proper voltage clamp of the dendritic events  
> >> (slower
> >> rise and decay time).
>
> >> Is there any way to figure out whether this effect is solely due to
> >> cable filtering of my command voltage?
>
> > Hi Bill,
>
> > There is a way to estimate the electrotonic attenuation between your
> > headstage and the synapse, though it's a little involved. It relies on
> > giving voltage jumps at a series of times leading up to, and
> > following, stimulation of the synapse.
>
> > The method is thoroughly described here, with real data and
> > simulations to test its accuracy:
>
> > Estimating the time course of the excitatory synaptic conductance in
> > neocortical pyramidal cells using a novel voltage jump method.
> > H usser M, Roth A.
> > J Neurosci. 1997 Oct 15;17(20):7606-25.
>
> > Cheers,
>
> > Matt
>
> > ------------------------------
>
> > Message: 2
> > Date: Wed, 16 Jun 2010 13:30:50 +0200
> > From: "Janina Kirsch" <kir... from bcf.uni-freiburg.de>
> > Subject: [Neuroscience] Last call for applications ----- NWG-Course:
> >    Analysis and Models in Neurophysiology, Freiburg, Germany
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> > Organisation and teaching:
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