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Is auditory evoked potential augmenting/reducing affected by acute tryptophan depletion?
Stefan Debener1, Alexander Strobel, Katharina Kürschner
1Department of Psychology II, Dresden University of Technology, Dresden, Germany. s.debener@fz-juelich.de
Biological Psychology
|March 26, 2002
Summary
The auditory evoked potential (AEP) amplitude stimulus intensity function slope (ASF-slope) may indicate brain serotonin activity. This study found no evidence that depleting tryptophan alters the ASF-slope, suggesting it does not reflect central serotonergic function.
Area of Science:
- Neuroscience
- Psychiatry
- Auditory Neuroscience
Background:
- The auditory evoked potential (AEP) augmenting/reducing slope is proposed as a biological marker for central serotonergic activity.
- Reduced serotonergic activity is hypothesized to correlate with an increased AEP amplitude stimulus intensity function slope (ASF-slope).
Purpose of the Study:
- To investigate the hypothesis that the ASF-slope reflects central serotonergic function.
- To examine the effect of acute tryptophan depletion on the ASF-slope in healthy females.
Main Methods:
- Employed a within-subject, placebo-controlled, double-blind crossover design.
- Administered a 50g amino acid drink with or without tryptophan to 18 healthy females.
- Measured the N1/P2-slope of the AEP amplitude stimulus intensity function (ASF-slope) at baseline and 5-6 hours post-ingestion.
Main Results:
- Test-retest reliability for the N1/P2-slope was adequate (r=0.56-0.58) over a 1-week interval.
- Tryptophan depletion did not significantly alter affect or the ASF-slope.
- No significant changes in ASF-slope were observed between placebo and tryptophan depletion conditions.
Conclusions:
- The study's findings do not support the hypothesis that the ASF-slope serves as a reliable indicator of central serotonergic function.
- Acute tryptophan depletion in healthy females did not impact the ASF-slope, challenging its role as a biomarker for serotonin activity.