Psychopharmacology

, Volume 179, Issue 4, pp 791–803

Tryptophan depletion reduces right inferior prefrontal activation during response inhibition in fast, event-related fMRI

  • Katya Rubia
  • Francis Lee
  • Anthony J. Cleare
  • Nigel Tunstall
  • Cynthia H. Y. Fu
  • Michael Brammer
  • Phillip McGuire
Original Investigation

DOI: 10.1007/s00213-004-2116-z

Cite this article as:
Rubia, K., Lee, F., Cleare, A.J. et al. Psychopharmacology (2005) 179: 791. doi:10.1007/s00213-004-2116-z

Abstract

Rationale and objective

In animal and human studies, the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT) has been implicated in mediating impulsiveness and aggression. To test the hypothesis that 5-HT modulates neuro-cognitive brain activation during inhibitory control, we examined the effect of acute tryptophan depletion (ATD), a dietary challenge, which has been shown to decrease 5-HT synthesis in the brain, on functional brain activation during a go/no-go task.

Methods

Nine healthy, right-handed volunteers performed a rapid, event-related go/no-go task in two functional magnetic resonance imaging (fMRI) scanning sessions, 5 h after either a tryptophan-free or a balanced amino acid drink in a double-blind, sham depletion-controlled, counterbalanced, crossover design. The task required subjects to selectively execute or inhibit a motor response. Tryptophan depletion significantly lowered total plasma tryptophan concentration by 80%, but did not significantly alter inhibitory performance or mood ratings.

Results

ATD significantly reduced right orbito-inferior prefrontal activation during the no-go condition, and increased activation in superior and medial temporal cortices.

Conclusions

These findings provide neuro-functional evidence of a serotonergic modulation of right inferior prefrontal during inhibitory motor control. The increased engagement of temporal brain regions may reflect compensatory mechanisms.

Keywords

Event-related fMRIFunctional imagingTryptophan depletionATDSE5-HTSerotoninMotor response inhibitionGo/no-go taskImpulsivity

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Katya Rubia
    • 1
    • 2
  • Francis Lee
    • 1
  • Anthony J. Cleare
    • 1
  • Nigel Tunstall
    • 1
  • Cynthia H. Y. Fu
    • 1
  • Michael Brammer
    • 1
  • Phillip McGuire
    • 1
  1. 1.Institute of PsychiatryKing’s College LondonLondonUK
  2. 2.Department of PsychiatryInstitute of PsychiatryLondonUK