Learn More
OBJECTIVE Antidepressants that inhibit the reuptake of serotonin (SSRIs) or norepinephrine (SNRIs) are effective in the treatment of disorders such as depression and anxiety. Cognitive psychological theories emphasize the importance of correcting negative biases of information processing in the nonpharmacological treatment of these disorders, but it is not(More)
The amino-acid L-tryptophan is essential in the synthesis of brain serotonin, and its depletion can lead to a widespread reduction in central serotonergic activity. A placebo-controlled cross-over within-subjects design (n = 12) examined the effects of tryptophan depletion on human cognitive performance. A low-tryptophan (low-TRP) drink successfully reduced(More)
Enhancement of serotonin neurotransmission plays an important role in the antidepressant response to agents presently available to treat depression. This response forms the major evidence for the role of serotonin in affective and social behaviour in humans. The present study investigated the effects of acute administration of the selective serotonin(More)
BACKGROUND Pharmacological and postmortem investigations suggest that patients with major depressive disorder have alterations in function or density of brain serotonin1A (5-HT1A) receptors. The aim of the present study was to use positron emission tomography with the selective 5-HT1A receptor antagonist [11C]WAY-100635 to measure 5-HT1A receptor binding in(More)
Rationale. Serotonergic processes have been implicated in the modulation of fear conditioning in humans, postulated to occur at the level of the amygdala. The processing of other fear-relevant cues, such as facial expressions, has also been associated with amygdala function, but an effect of serotonin depletion on these processes has not been assessed.(More)
We report the effects of a tyrosine (and phenylalanine)-free amino acid mixture on tyrosine levels, ex vivo catecholamine synthesis and in vivo catecholamine release in brain regions of the rat. Administration of a tyrosine-free amino acid load reduced tissue levels of tyrosine (−50% after 2 h) in all brain regions examined (frontal cortex, hippocampus,(More)
BACKGROUND The amygdala is believed to play a key role in processing emotionally salient, threat-relevant, events that require further online processing by cortical regions. Emotional disorders such as depression and anxiety have been associated with hyperactivity of the amygdala, but it is unknown whether antidepressant treatment directly affects amygdala(More)
Peripheral administration of an amino acid load lacking tyrosine and its precursor, phenylalanine, causes a lowering of central tyrosine levels. The aim of the present study was to examine the effects of tyrosine depletion on extracellular noradrenaline using microdialysis. Extracellular noradrenaline was measured in hippocampus of the anaesthetized rat(More)
OBJECTIVE Antidepressants that increase serotonin or norepinephrine in the brain are effective in treating depression, but there is no neuropsychological account of how these changes relieve depressive states. Cognitive theories suggest that biases in information processing lead depressed patients to make unrealistically negative judgments about themselves(More)
Rationale: Tyrosine depletion has been shown to reduce dopamine over activity in animal and human investigations. However, the effects on basal dopamine function have not been explored. Such information could establish tyrosine depletion as an effective probe of dopamine function in healthy volunteers and would also have relevance for future therapeutic(More)