Effect of subanaesthetic dose of ketamine on mechanical stimulus on brain regions

Abstract

To investigate the effect of subanaesthetic dose of ketamine on mechanical stimulus on brain regions. Totally 13 healthy male volunteers were enrolled in this study, in whom 0 and 100 ng/ml ketamine were administrated by target controlled infusion system in pilot study. After von Frey filaments (vFFs) 300 g were used as mechanical stimuli, Visual Analogue Scale scores were evaluated. Functional magnetic resonance imaging (fMRI)was taken 1 week after pilot study at the following sequences: structure imaging + functional imaging (stimulus sequence with 300 g vFFs, ketamine sequence); stimulus sequence = 6×(20s on + 20s off), with target concentration of ketamine at 0,100 ng/ml.fMRI result was processed by SPM2 and Metlab 7.01 software package. Posterior cerebellum lobe and corpus callosum were inhibited at 100 ng/ml under vFFs stimulus, whereas cingulate gyrus, middle frontal gyrus, inferior parietal lobule, occipital lobe, and posterior cerebellum lobe were activated at 100 ng/ml under vFFs stimulus. Ketamine 100 ng/ml exerts its effect on pain related brain regions. It can both activate and inhibit these brain regions, with the activating effect being the primary effect.