question about amphetamine and cocaine

Shamim Khaliq shamim at khaliq.intensive.co.uk
Tue Jan 9 17:56:15 EST 2001


thank you for your answer. as for your questions, your guess is as good as
mine (well better) because my lecturer hasn't answered my queries yet (and
may never judging from past experience). i only have my lecture notes and
his powerpoint slides to go on, and i wrote down everything they say below.
but i believe you must be right, because i have absolute faith in the
competence of this lecturer. the former experiment must refer to cocaine
being available concurrently with the ICSS, and the textbook experiment
refers to the behaviour of rats during ICSS after cocaine has aleady been
administered.

there's a reference in my lecturers powerpoint slides, but it's not in our
library: Maldonado-Irizarry, C.S., J.R. Stellar, and A.E. Kelley. (1994).
Effects of cocaine and GBR-12909 on brain stimulation reward. Pharmacology,
Biochemistry, and Behavior , 48, 915-20.i have just e-mailed one of the
authors with the query (again e-mail address found using an internet
search), but am not holding my breath.

thank you for answering, because your confirmation of what the textbook said
gives me the faith to quote those results in the exam, and without further
knowledge about what my lecturer was referring to i shall not quote his.


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/
> > *******************************************************
> >
> >
>
>







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