question about amphetamine and cocaine

Glen M. Sizemore gmsizemore at triad.rr.com
Tue Jan 9 15:42:46 EST 2001


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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