5-HT modulation of pain in SI and SII revealed by fMRI

To observe the different cerebral activations between pre-administration and post-administration of tryptophan-depleted amino acid mixture (TRP-)/balanced amino acid mixture (BAL) in healthy volunteers through functional magnetic resonance imaging (fMRI) when they received electrical stimulation at the same time. Furthermore, the effects of 5-hydroxytryptamine (5-HT) were explored in pain modulation network. Two-phase crossover design was adopted. Six right-handed healthy volunteers participated in the experiment. TRP- and BAL were administered to each participant according to the Young's method. Volunteers were scanned under fMRI with or without administration of TRP- or BAL when receiving electrical stimulation simultaneously. Analysis of functional neuroimages (AFNI) software was used to show the different activations in the human brain between pre- and post-administration of TRP-/BAL. Then all the results were analyzed by SPSS 14.0. (1) Bilateral primary somatosensory cortex (SI) and secondary somatosensory cortex (SII) were activated during pre-administration and post-administration of TRP-, but the activated volumes of bilateral SI and SII during post-administration of TRP- were found significantly larger than that during pre-administration of TRP (P