Dear Eric
>> vascalature. If there are differential effects of the drug (relative to
>> placebo) on your two (or more) different cognitive states it's difficult to
>> continue arguing for a non-specific vascular effect.
>
>
>I think it is important to keep in mind the possibility of a
>pharmacologic effect on the gain of the vascular response to neural activity
>changes. Such a mechanism would be manifest as an interaction of
>task and pharmacologic treatment.
Perhaps I didn't explain what I meant clearly enough, and anyway please
correct me if I'm wrong, but isn't your argument true only if the drug
affects the *entire* network that is normally activated by the task?
For example, if a Task-Control comparison activated regions A, B & C under
placebo conditions, and then the drug affects area A only, does your
argument still apply?
As far as I can see, a REGIONALLY-specific task x drug interaction cannot
be explained by a non-specific (ie. not regionally specific) effect of drug
on the neurovascular pattern. In other words, to demonstrate a drug x task
interaction (from which one can make cognitive inferences) the areas
activated/deactivated by the interaction term should not be identical to
those produced by the main effect of the task.
Best wishes
Jenny
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Dr. Jennifer T Coull
Senior Research Fellow
Wellcome Department of Cognitive Neurology
Institute of Neurology
12 Queen Square
London WC1N 3BG
UK
phone: +44 171 833 7484
fax: +44 171 813 1420
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