The Neural Mechanism Of Transcranial Direct Current Stimulation On Smoking Craving: A BOLD-fMRI Study

Objective: By using functional magnetic resonance imaging, the aim of this study is to explore the clinical application value and neural mechanism of transcranial direct current stimulation on regulation smoking craving, which can provide the basic theory and research support for the clinical practice of brain stimulation methods in treating nicotine addiction. Methods: 19 Chinese nicotine addicts(19male, 26.8 ± 5.9 years old) were recruited in this experiment. They should take a short smoking abstinence of 2 hours before the research, and then receive two different direct current stimulation under the scaning of magnetic resonance imaging. One kind of the trial condition lasted for 30 minutes with 1mA direct current was called anodal stimulus, and the other sham stimulus was the control. Several tasks consisted of cognitive control task, monetary incentive delay task, attentional bias task, emotional task and a series of statistical counting(four times smoking craving visual analogue scale, three times heartbeat monitoring and two times positive and negative affect scale) were arranged in the whole experiment. The data of functional magnetic resonance imaging was processed by AFNI and Matlab software, and according to our hypothesis, the statistical means of variance analysis and t test were chosen to analyse whole data from the behavioral tasks and functional magnetic resonance imaging. Results: 1) Compared with sham control, the smoking craving of subjects after anodal stimulation was less elevated when they saw smoking cues again(t=2.18, p=0.04). 2) Through the analysis of whole brain functional magnetic resonance imaging data about cognitive control task and attentional bias task, we found that the activation of some brain regions associated with cognitive control were significantly reduced by transcranial direct current stimulation on dorsolateral prefrontal cortex, such as bilateral dorsolateral prefrontal cortex, left inferior occipital gyrus, right superior temporal gyrus, right inferior parietal lobule and right caudate. 3) With the purpose of attentional bias task was to objectively evaluate the change of smoking craving, we then managed a contrast analysis on brain activation between viewing smoking cues and control pictures, left superior frontal gyrus and bilateral parahippocampal with increased activation were found. 4) Furthermore, we analysed the functional connectivity from the data of attentional bias task and resting state, both the functional connectivity between left dorsolateral prefrontal cortex and bilateral parahippocampal were regulated by the anodal stimulus(task state: with left parahippocampal- t=2.56, p=0.02, with right parahippocampal- t=2.22, p=0.04; resting state: with left parahippocampal- t=2.30, p=0.03, with the right parahippocampal-t=3.20, p<0.01). 5) The other data which did not mentioned here all has no significant statistical results. Conclusion: Transcranial direct current stimulation on dorsolateral prefrontal cortex can reduce cue-elicited smoking craving on nicotine addicts, and the neural mechanism of this phenomenon may be related to enhancing cognitive control processing combined with altering smoking cue’s memory. Our study based on the previous behavioral research about short-term effect of transcranial direct current stimulation explores the neural biological basis, verifies several hypothesis with theoretical basis, and provides the basic research support for the further research about clinical practice of transcranial direct current stimulation in treating nicotine cessation.