question about amphetamine and cocaine

Shamim Khaliq shamim at khaliq.intensive.co.uk
Thu Jan 11 09:30:28 EST 2001


J.R. Stellar, one of the experimenters in the study my lecturer cited, wrote
back to me with:
The cocaine was given just before the ICSS test, but the idea was
the cocaine lasted throughout the test.

The idea is that the rat's THRESHOLD of pulse frequency went
down.  They became more sensitive to ICSS under cocaine.  This is
reflective of the fact that cocaine made ICSS better.  Of course, we
used half-maximal responding as the threshold.  But this does not
change the logic.

The point of the study was a technical one.  Others had shown that
cocaine makes ICSS more rewarding.  We alone showed that the
starting level of ICSS current did not affect the level of shift in half-
maximal threshold of pulse frequency (called Locus of Rise or LOR)
produced by the drug.  Ever since that study, I have not worried
about matching the currents of my rats when I run ICSS and
cocaine studies.

-Jim Stellar

Glen M. Sizemore <gmsizemore at triad.rr.com> wrote in message
news:aJK66.8179$gg.1089512 at typhoon.southeast.rr.com...
> Shamim: My lecturer said, "Cocaine decreased the
> frequency administered for the rate
> free method where rats press a bar for different
> ICSS frequencies. With
> cocaine they don't bar press for electricity as much,
> therefore indicating
> the rewarding properties as cocaine substituted for ICSS."
>
> My textbook says, "the set-reset technique reduces
> current frequency or
> intensity after say 5 presses. At any time the subject
> may press another
> lever to reset the current to its original value.
> Amphetamine decreases the
> reset threshold, implying an increase in the
> rewarding value of the
> stimulation. Another paradigm is curve shifting.
> Holding either current or
> frequency constant and increasing the other
> increases lever pressing up to
> some limit. Amphetamine shifts the curve to the left,
> i.e. they press more
> for a given value"
>
> Do these sources contradict? Or have I understood
> it wrong?
>
> Glen: It is difficult to see from the first paragraph
> what is being done. Can you elaborate? What is the
> "rate-free method?" If the cocaine was simply
> administered response-independently prior to the
> session, the fact that it decreased the rate at which
> ICSS was obtained could hardly be regarded as
> "...indicating the rewarding properties as [sic?]
> cocaine substituted for ICSS."
>
> As the second paragraph indicates, stimulants (and
> other "drugs of abuse" I believe - I'm not really an
> expert) lower the threshold (either intensity or
> frequency or even other parameters) necessary to
> maintain self-stimulation. That is, these drugs shift
> the "intensity-response functions" to the left.
>
> The only thing that I can think of is that your
> lecturer is either mistaken, not knowledgeable about
> the effects of drugs on schedule-controlled behavior,
> or the cocaine was available concurrently with the
> availability of ICSS. That is, it is possible that your
> lecturer is talking about an organism's behavior
> when given a choice between ICSS and drug
> infusion.
>
> Glen
>
>
> "Shamim Khaliq" <shamim at khaliq.intensive.co.uk> wrote in message
> news:3a59940d_3 at news.intensive.net...
> > My lecturer said, "Cocaine decreased the frequency administered for the
> rate
> > free method where rats press a bar for different ICSS frequencies. With
> > cocaine they don't bar press for electricity as much, therefore
indicating
> > the rewarding properties as cocaine substituted for ICSS."
> >
> > My textbook says, "the set-reset technique reduces current frequency or
> > intensity after say 5 presses. At any time the subject may press another
> > lever to reset the current to its original value. Amphetamine decreases
> the
> > reset threshold, implying an increase in the rewarding value of the
> > stimulation. Another paradigm is curve shifting. Holding either current
or
> > frequency constant and increasing the other increases lever pressing up
to
> > some limit. Amphetamine shifts the curve to the left, i.e. they press
more
> > for a given value"
> >
> > Do these sources contradict? Or have I understood it wrong?
> >
> >
> > --
> > *******************************************************
> > Ms. Shamim Khaliq
> > B.Sc. Psychology Undergraduate, London Guildhall University
> > Secondary School Science, Maths & SEN Supply Teacher
> > 217, Richmond Road
> > Hackney
> > London E8 3NJ
> > Tel. 020 8510 9487
> > Fax: 0870 132 4186
> > E-mail: shamimkhaliq at hotmail.com
> > Web page: http://shamimkhaliq.50megs.com/
> > *******************************************************
> >
> >
>
>







More information about the Neur-sci mailing list