The effect of acute tryptophan depletion on the BOLD response during performance monitoring and response inhibition in healthy male volunteers.
BACKGROUND
Serotonin (5-HT) was implicated in both clinical and experimental studies in flexible, goal-directed behavior. However, the way in which 5-HT manipulations affect brain activation patterns underlying different subprocesses of cognitive flexibility remains largely unknown.


OBJECTIVE
The aim of this study was to investigate the effect of a transient lowering of 5-HT on brain activation during performance monitoring and response inhibition.


METHODS
We used acute tryptophan depletion (ATD), a well-known method to reduce central 5-HT, to investigate the effect of a transient lowering of 5-HT on the blood-oxygen-level dependent (BOLD) response in an event-related functional MRI study. Thirteen healthy male volunteers performed a modified Go/NoGo task in a counterbalanced, placebo-controlled, within-subject design.


RESULTS
ATD significantly lowered plasma tryptophan but did not affect mood and cognitive performance. ATD decreased the BOLD response in the dorsomedial prefrontal cortex (BA 8) during performance monitoring. ATD did not affect the BOLD response during response inhibition.


CONCLUSIONS
This study provides more evidence for the suggested role of 5-HT in performance monitoring. Because ATD studies have revealed inconsistent effects of ATD on performance and on brain activation, it was suggested that gender and personality traits are important variables to take into account for future research.
Evers
Elisabeth A T
EA
Department of Psychiatry and Neuropsychology (DRT 10), Brain and Behavior Institute, Maastricht University, P.O. Box 616, 6200 MD Maastricht, Netherlands. l.evers@np.unimaas.nl
van der Veen
Frederik M
FM
van Deursen
Jeroen A
JA
Schmitt
Jeroen A J
JA
Deutz
Nicolaas E P
NE
Jolles
Jelle
J
D000328:Adult; D000339:Affect / Q000502:physiology; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D018592:Cross-Over Studies; D004193:Discrimination Learning / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D004311:Double-Blind Method; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011340:Problem Solving / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012701:Serotonin / Q000502:physiology*; D014364:Tryptophan / Q000172:deficiency*
D012701:Serotonin; D014364:Tryptophan; D010100:Oxygen