title: Acute tryptophan depletion does not change somatosensory evoked magnetic fields.
abstract: 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.
authors.affiliation: 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.
authors.forename: Seppo
authors.initials: S
authors.lastname: Kähkönen
authors.affiliation: Massachusetts General Hospital-NMR Center, Harvard Medical School, Charlestown, Mass., USA.|Laboratory of Computational Engineering, Helsinki University of Technology, Espoo, Helsinki, Finland.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ahveninen
authors.affiliation: 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.
authors.forename: Iiro P
authors.initials: IP
authors.lastname: Jääskeläinen
authors.affiliation: Occupational Hygiene and Toxicology Section, Kuopio Regional Institute of Occupational Health, Kuopio, Finland.
authors.forename: Sirpa
authors.initials: S
authors.lastname: Pennanen
authors.affiliation: Department of Pharmacology and Toxicology, University of Kuopio, Kuopio, Finland.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Liesivuori
authors.affiliation: BioMag Laboratory, Helsinki University Central Hospital, PO Box 340, 00290, Helsinki, Finland.|Department of Clinical Neurophysiology, Karolinska Hospital, Stockholm, Sweden.
authors.forename: Vadim V
authors.initials: VV
authors.lastname: Nikulin
mesh_terms: 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*
chemical_list: D012701:Serotonin; D014364:Tryptophan