![]() ![]() Subject performance (accuracy and reaction time) was monitored during all scans. Blood was drawn at the beginning of each session and serum DEX levels were measured using gas chromatography.ĭuring each session, subjects completed a blocked fMRI paradigm consisting of two tasks. ![]() The order of drug administration was counterbalanced across subjects by the pharmacy. Approximately 120 min before each session, subjects received an oral dose of either placebo (PBO) or DEX (0.25 mg/kg body weight) in a double-blind manner. Each subject participated in two fMRI sessions, separated by three to ten days, with all conditions kept constant across sessions. Twelve healthy subjects (five males and seven females, mean age = 33 years) gave written informed consent according to the guidelines of the National Institute of Mental Health Institutional Review Board. We used dextroamphetamine (DEX), a potent monoaminergic agonist and anxiogenic, in a double-blind placebo controlled functional magnetic resonance imaging (fMRI) study to explore this possibility in human subjects. These convergent findings lead to the intriguing possibility that the emotion enhancing properties of amphetamine may be related to effects on the amygdala. Studies in animals suggest that such anxiogenic effects may reflect dopamine (DA) augmentation of amygdala activity ( Willick and Kokkinidis 1995 Harmer et al. Likewise, amphetamine and other dopaminergic psychostimulants have been shown to produce pronounced effects on emotional behavior, including the generation of fear and anxiety ( Angrist and Gershon 1970 Ellinwood et al. Recent work in both animal and human subjects has implicated limbic-based circuitry, centered on the amygdala, in the generation and regulation of normal fearful responses as well as pathological anxiety ( Damasio 1994 LeDoux 1997). ![]()
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