Acute tryptophan depletion does not change somatosensory evoked magnetic fields.
BACKGROUND
Serotonin is shown to regulate the activity of primary auditory cortex, but little is known about serotonin modulation of other sensory cortices.


METHODS
We investigated somatosensory evoked magnetic fields (SEF) to left median nerve stimulation in eight healthy subjects in a double-blind, controlled, cross-over design study after acute tryptophan depletion (ATD) and control mixture. SEFs were recorded with the whole-head magnetoencephalography 6 h after ingestion of mixtures. The SEF sources and strength were estimated by a least-squares fit of a single equivalent current dipole.


RESULTS
ATD decreased the total and free TPR levels by 75 and 48% and control mixture increased them by 98% and 44%. ATD had no effect on the amplitudes or latencies of SEF components. The source locations of the responses were not significantly affected by ATD.


CONCLUSIONS
Serotonin does not affect stimuli processing in the primary somatosensory cortex.
Kähkönen
Seppo
S
Cognitive Brain Research Unit, University of Helsinki, Helsinki, Finland. seppo.kahkonen@helsinki.fi.|BioMag Laboratory, Helsinki University Central Hospital, PO Box 340, 00290, Helsinki, Finland. seppo.kahkonen@helsinki.fi.
Ahveninen
Jyrki
J
Massachusetts General Hospital-NMR Center, Harvard Medical School, Charlestown, Mass., USA.|Laboratory of Computational Engineering, Helsinki University of Technology, Espoo, Helsinki, Finland.
Jääskeläinen
Iiro P
IP
BioMag Laboratory, Helsinki University Central Hospital, PO Box 340, 00290, Helsinki, Finland.|Massachusetts General Hospital-NMR Center, Harvard Medical School, Charlestown, Mass., USA.|Laboratory of Computational Engineering, Helsinki University of Technology, Espoo, Helsinki, Finland.|Apperception & Cortical Dynamics, Department of Psychology, University of Helsinki, Finland.
Pennanen
Sirpa
S
Occupational Hygiene and Toxicology Section, Kuopio Regional Institute of Occupational Health, Kuopio, Finland.
Liesivuori
Jyrki
J
Department of Pharmacology and Toxicology, University of Kuopio, Kuopio, Finland.
Nikulin
Vadim V
VV
BioMag Laboratory, Helsinki University Central Hospital, PO Box 340, 00290, Helsinki, Finland.|Department of Clinical Neurophysiology, Karolinska Hospital, Stockholm, Sweden.
D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004594:Electrophysiology; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000187:drug effects; D008297:Male; D012701:Serotonin / Q000502:physiology*; D014364:Tryptophan / Q000172:deficiency*
D012701:Serotonin; D014364:Tryptophan