[Neuroscience] Re: LTP measurement

Bill via neur-sci%40net.bio.net (by connelly.bill from gmail.com)
Tue May 29 15:52:44 EST 2007


So I assume you're recording the fEPSP and not the population spike? a
1-1.5mV fEPSP is not too bad. Variations between slices is not a big
deal, and is to be expected, normalize to a baseline period, i.e
basline is always 100%. The lack of stability is a worry though, if
you are seeing run down in the amplitude, possible your stimulating
electrode is getting oxidized (try biphasic pulses). Possible your
stimulating or recording electrodes are moving, i.e. lack of physical
stability.

If you're getting run up the the amplitude of your fEPSP, make sure
you're giving your slices some time (>10min) for the tissue to
recuperate after you stick the recording electrode into it.

Make sure you aren't stimulating at too high a frequency too. 0.1Hz or
less should be fast enough. Also, if your bath depth is not stable,
you will get varying amplitudes, i.e. as the bath height gets higher
your field events will get smaller.

Also, make sure you're putting your electrodes in the same place
everytime, i.e. in the middle of stratum radiatum, and not up towards
the pyramidal layer sometime, and down towards the dentate other
times. I like to always stimulate on the CA3 side, though I know you
can get perfectly reasonable EPSPs stimulating antidromically as it
were.

Getting an I/O curve is easy. Just start at 1 volt, and turn up the
amplitude, 1, 5, 10, 15, etc.... (or microAmps if you're that way
inclined)

On May 27, 2:56 am, blueocea... from tom.com wrote:
> Hi,I am doing field recording on CA1 areaof hippocampus( stimulate
> schaffer collateral) . I try to measure LTP change before and after
> some treatment. I find there is large variation between slices and It
> not easy to get stable base line. The maximal baseline response I get
> is about 1-1.5mv. Can anybody give me some suggestions on recording
> techniques concering the placing location of stimulate electrode and
> recording electrode and how to make the input-output curve? Any
> suggestion of concern good measurement of LTP is greatly appreciated!
> Ni




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