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Non-invasive assessment of human neurotransmitter function is a highly valuable tool in clinical research. Despite the current interest in task-based pharmacological MRI (phMRI) for the assessment of neural correlates of serotonin (5-HT) function, test-retest reliability of this technique has not yet been established. Using a placebo-controlled crossover design, we aimed to examine the repeatability of task-related phMRI with a single dose of oral citalopram in twelve healthy female subjects. Since we were interested in the drug's effect on neural correlates of 5-HT related cognitive processes, a sensorimotor and an emotional face processing paradigm were used. For both paradigms, we found no significant effects of the oral citalopram challenge on task-positive brain activity with whole-brain analysis. With ROI-based analysis, there was a small effect of the challenge related to emotional processing in the amygdala, but this effect could not be reproduced between sessions. We did however find reproducible effects of the challenge on task-negative BOLD-responses, particularly in the medial frontal cortex and paracingulate gyrus. In conclusion, our data shows that a single oral dose of citalopram does not reliably affect emotional processing and sensorimotor activity, but does influence task-negative processes in the frontal cortex. This latter finding validates previous studies indicating a role for 5-HT in suppression of the task-negative network during goal-directed behavior., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: Dopamine (DA) is involved in systems governing motor actions, motivational processes and cognitive functions. Preclinical studies have shown that even relatively low doses of d-amphetamine (dAMPH) (equivalent to doses used in clinical Practice) can lead to DA neurotoxicity in rodents and non-human primates (Ricaurte et al., 2005)., Methods: Therefore, we investigated the DAergic function in eight male recreational users of dAMPH and eight male healthy controls using functional magnetic resonance imaging (fMRI). We compared brain activation between both groups during a monetary incentive delay task (Knutson et al., 2001) with and without an oral methylphenidate (MPH) challenge. All subjects were abstinent for at least 2 weeks during the baseline scan. The second scan was performed on the same day 1.5 h after receiving an oral dose of 35 mg MPH (approximately 0.5 mg/kg) when peak MPH binding was assumed., Results: When anticipating reward, dAMPH users showed lower striatal activation in comparison to control subjects. In addition, MPH induced a reduction in the striatal activation during reward anticipation in healthy controls, whereas no such effect was observed in dAMPH users., Conclusion: The combination of these findings provides further evidence for frontostriatal DAergic dysfunction in recreational dAMPH users and is consistent with preclinical data suggesting neurotoxic effects of chronic dAMPH use. The findings of this explorative study could have important implications for humans in need for treatment with dAMPH, such as patients suffering from ADHD and therefore this study needs replication in a larger sample., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

D-amphetamine (dAMPH) and methylphenidate (MPH) are stimulants used in the treatment of Attention Deficit Hyperactivity Disorder (ADHD). Preclinical studies have shown that in healthy animals, dAMPH induces dopamine (DA) dysfunction, as evidenced for instance by loss of DA levels and its transporters. It has also been suggested that DA plays an important role in emotional processing, and that altered DA-ergic intervention may modulate amygdala function. To explore the role of the DA system in emotional processing we examined emotional processing using functional magnetic resonance imaging (fMRI) in eight male recreational users of dAMPH and eight male healthy controls. We compared brain activation between both groups during an emotional face-processing task with and without an oral MPH challenge. All subjects were abstinent for at least 2 weeks during the baseline scan. The second scan was performed on the same day 1½ hours after receiving an oral dose of 35 mg MPH. A significant Valence*Group interaction (p = .037) indicated amygdala hyperreactivity to fearful facial expressions in dAMPH users that was robust against adjustment for age (p = .015). Furthermore, duration of amphetamine use in years was positively correlated with amygdala reactivity in dAMPH users (r = .76; p = .029). These exploratory findings are in line with previous findings suggesting that DA plays a role in emotional processing. [ABSTRACT FROM AUTHOR]

Background. Functional neuroimaging studies have shown increased Stroop interference coupled with altered anterior cingulate cortex (ACC) and insula activation in post-traumatic stress disorder (PTSD). These brain areas are associated with error detection and emotional arousal. There is some evidence that treatment can normalize these activation patterns. Method. At baseline, we compared classic and emotional Stroop performance and blood oxygenation level- dependent responses (functional magnetic resonance imaging) of 29 child abuse-related complex PTSD patients with 22 non-trauma-exposed healthy controls. In 16 of these patients, we studied treatment effects of psycho-educational and cognitive behavioural stabilizing group treatment (experimental treatment; EXP) added to treatment as usual (TAU) versus TAU only, and correlations with clinical improvement. Results. At baseline, complex PTSD patients showed a trend for increased left anterior insula and dorsal ACC activation in the classic Stroop task. Only EXP patients showed decreased dorsal ACC and left anterior insula activation after treatment. In the emotional Stroop contrasts, clinical improvement was associated with decreased dorsal ACC activation and decreased left anterior insula activation. Conclusions. We found further evidence that successful treatment in child abuse-related complex PTSD is associated with functional changes in the ACC and insula, which may be due to improved selective attention and lower emotional arousal, indicating greater cognitive control over PTSD symptoms. [ABSTRACT FROM AUTHOR]