IUBio

Brain clues to attention disorder

Glen M. Sizemore gmsizemore2 at yahoo.com
Sun Dec 21 11:43:08 EST 2003


Whatever meaning might be given to the term "psychomotor stimulant," it is
clear that the term is useless for describing the effects, on complex
behavior in animals, of drugs like cocaine, amphetamine etc. and related
drugs like methylphenidate (Ritalin). It has been noted for some time that,
in laboratory animal operant preparations, such drugs will decrease high
rates of response maintained by food presentation, while increasing low
rates of response, in the same subject within the same experimental session.
This led to the notion that the particular event maintaining responding,
i.e., food, water, shock-termination (usually termination of a stimulus that
is perfectly correlated with shock-occurrence in the absence of responding)
etc. didn't matter in determining the effects of psychomotor stimulants -
what mattered was the ongoing rate of response under non-drug conditions.
Although it is now clear that there are a variety of circumstances in which
the so-called "rate-dependent" effects of psychomotor stimulants do not hold
(such drugs rarely increase the rate of punished responding, for example),
it is still a fact that under a variety of circumstances the effects of
psychomotor stimulants on positively- and negatively-reinforced behavior, in
laboratory animals, is an inverse function of non-drug rate of responding
(and dose, of course; small doses of the drugs tend to increase low rates of
response while having no effect on higher rates; moderate doses will produce
substantial increases in low rates while high-rates will be reduced; high
doses will, of course, decrease both high and low rates).

<orkeltatte at hotmail.com> wrote in message
news:84da9680.0312210247.4030f84b at posting.google.com...
> > >The fact that Ritaline and other similar central stimulating drugs has
> > >the paradoxal effect of normalizing activity and attention in ADDH
> > >conditions ,
> >
> > It is only paradoxical if we play a bit of word magic with 'stimulating'
>
> Sorry! But this is semantic bullshit.Paradoxal refers to an opposite
> effect compared to the common effect on the majority of people - eg
> excitatory, increased psychomotor tempo and activity and soforth.
>
> >
> > >together with the findings of reduced cerebral bloodflow
> > >(SPECT) on brainstem level , suggests not only a dysfunction in
> > >attention centre (RAS) but also that it is the dopaminergic systems
that
> > >are malfunctious. It is therefore possible in the true cases of ADDH to
> > >treat ex juvantibus with these drugs , and confirming the diagnose.
> > >
> > >orkeltatte
> >
> > --                                                            .---.
> >   It was once believed that a million monkeys at a million   { o o }
> >   keyboards would eventually type the works of Shakespeare,  _(---)_
> >   but the Internet has since disproved this theory.         /       \
>
> I am sorry - but you lost this monkey there - maybe my cognitional
> capacity is to slow?
>
> orkeltatte ,
> specialist in child and youth psychiatry amongst other things





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