The Effect of Acute Tryptophan Depletion on the Neural Correlates of Emotional Processing in Healthy Volunteers

Abstract

The processing of affective material is known to be modulated by serotonin (5-HT), but few studies have used neurophysiological measures to characterize the effect of changes in 5-HT on neural responses to emotional stimuli. We used functional magnetic resonance imaging to investigate the effect of acute tryptophan depletion, which reduces central 5-HT synthesis, on neural responses to emotionally valenced verbal stimuli. Though no participants experienced significant mood change, emotional information processing was substantially modified following 5-HT depletion. A behavioral bias toward positive stimuli was attenuated following depletion, which was accompanied by increased hemodynamic responses during the processing of emotional words in several subcortical structures. Inter-individual differences in tryptophan depletion-elicited anxiety correlated positively with the caudate bias toward negative stimuli. These data suggest that 5-HT may play an important role in mediating automatic negative attentional biases in major depression, as well as resilience against negative distracting stimuli in never-depressed individuals.

Understanding vulnerability for depression from a cognitive neuroscience perspective: A reappraisal of attentional factors and a new conceptual framework

“…These results fully concur with the above-mentioned SPECT study of Baeken et al (2010), which showed that increased 5-HT 2A receptor binding is related to the antidepressant effect of rTMS in depressed people. Importantly, in a recent study, tryptophan depletion also reduced the normal attentional bias toward positive stimuli in healthy people, which was accompanied by increased hemodynamic responses (f MRI) during the processing of emotional words in several subcortical structures (Roiser et al, 2008). In a review including 25 studies (Merens, Van der Does, & Spinhoven, 2007), serotonin manipulations were found to affect facial emotion recognition, attentional bias, emotional memory, dysfunctional attitudes, and decision making.…”

Genetic Deletion of Fatty Acid Amide Hydrolase Alters Emotional Behavior and Serotonergic Transmission in the Dorsal Raphe, Prefrontal Cortex, and Hippocampus

“…Chronic antidepressant treatment facilitates exocytosis of 5-HT and/or increases its synaptic availability in corticolimbic regions extensively innervated by the DR, such as the prefrontal cortex, hippocampus, amygdala, and other forebrain structures implicated in mood regulation and stress adaptation (Steinbusch, 1981;Holmes, 2008). In contrast, 5-HT-depleting manipulations, such as through the 5-HT synthesis inhibitor, parachlorophenylalanine, or a diet deprived of the 5-HT precursor, tryptophan, precipitate anxiety and depression-like symptoms in animals (Blokland et al, 2002;Zhou et al, 2008;Roiser et al, 2008), exacerbate anxiogenic responses in human participants (Miller et al, 2000), and inflict a relapse in depressive patients (Smith et al, 1997). The delay in therapeutic onset of antidepressants has been attributed to gradual neuroplastic adaptations at the presynaptic and postsynaptic levels that result from the progressive augmentation in 5-HT activity.…”

Hubungan antara Kadar Total Triptofan Plasma dan Indeks Massa Tubuh dengan Gejala Depresi dan Skor Children Depression Inventory pada Siswa SMP

“…Terdapat beberapa penelitian yang melaporkan hubungan linier efek kadar total triptofan plasma yang rendah dengan respon depresi, yaitu Wang dkk, 25 Roiser dkk, 26 Booij dkk, 27 dan Williams dkk. 28 Hasil berbeda dari penelitian Plasse 29 yang melaporkan efek kadar total triptofan plasma yang rendah (menurun 30%), belum memengaruhi kadar serotonin dan fungsi prefrontal cortex.…”