Using fMRI to compare the effects of benzylpiperazine with dexamphetamine - Their differences during the Stroop paradigm.

RATIONALE: Benzylpiperazine (BZP) has been found to increase neural activation in the dorsal striatum when compared to placebo in response to a Stroop paradigm, in addition, subjective effects have been compared to dexamphetamine (DEX). Despite their similarities, the two have not been directly compared in respect to their effects on selective attention and inhibition.

OBJECTIVES: To use a double-blind placebo-controlled crossover study to compare the acute effects of BZP and DEX on executive function using functional magnetic resonance imaging (fMRI) and an event-related Stroop task.

METHODS: Eleven healthy participants aged 18-40 years undertook the Stroop task 90[Formula: see text]min after taking an oral dose of either BZP (200[Formula: see text]mg), DEX (20[Formula: see text]mg) or placebo.

RESULTS: BZP induced a greater increase in activation than DEX in the inferior frontal gyrus (IFG) during the Stroop task. DEX increased BOLD signal in the thalamus and decreased it in the IFG in comparison to placebo.

CONCLUSION: Despite BZP and DEX reportedly inducing similar subjective effects, there are different patterns of neural activation. We believe this differential activity is due to pharmacological differences in their receptor binding profiles and that subsequent inhibitory effects might be due to their direct effect on dopaminergic activity.