Functional Magnetic Resonance Imaging Research Of Smoker's Responses To Smoking Olfactory Cue

Objective:Make a paired test of the smoker's response to the smoking olafctory cue under different physiological status (satiated vs. abstinent) by using the functional magnetic resonance imaging (fMRI),and make a comparison between groups of the smoker and nonsomker's response to the smoking olafctory cue, we try to seek how the smoking olafctory cue impact the smoker's physiological and psychological factors, localizing the smoking olafctory cue related brain region and analyse the related response,and complete the established theoretical system of the related brain region's response to the smoking visual cue.Material and methods: Seventeen han smokers and five han nonsmokers underwent this study,they were right-handed, healthy and non-psychiatric disorder.All of them used cigarette as stimulus,paper for control,and the author put them on the subjects'nose.We adopted block design in this experiment. MRI examination was performed on GE signa 1.5T echospeed MRI using echo planner imaging(EPI)sequence, adopting dorsal position. A 8-channel head coil was used for transmission and detection of signal.Scaning parameters: TR/TE=3000/45ms , flip angle 90°, slice thickness 3mm,gap 0.5mm,NEX 1,FOV[field of view] 240×240mm,matrix 64×64,the whole scaning time is 9 minutes and 42 seconds,.The functional images were acquired in the same FOV and orientation as T1-weighted anatomic images.Collect and record fMRI datas to CD-ROM,and then input them into special data-processing computers.The raw fMRI datas were dealed with Matlab 6.5.1, SPM2 and Xjview4 tool software,P value was 0.001. Results: When smokers were exposed to the smoking olfactory cue in the abstinent state, we could find the activation on the left superior frontal gyrus(BA8,9,10,11),left middle frontal gyrus(BA8,10,11,46),left inferior frontal gyrus(BA9),left medial frontal gyrus(BA6,8,10,11),right superior frontal gyrus(BA10),right middle frontal gyrus(BA8,9),right inferior frontal gyru(sBA45,47),right medial frontal gyru(sBA9,11),left callosal gyrus( BA21,31),right callosal gyrus(BA24,37),right middle temporal gyrus( BA21) ,both sides of the thalamus and cerebellum.When smokers were exposed to the smoking olfactory cue in the satiated state,we could find the activation on both sides of the prefrontal lobe and cerebellar hemisphere,while there were no activation on the other brain regions. There was no activation on the whole brain of the nonsmokers,only a little small volume active points appeared in individual subjects,which we thought caused by the picture noise.After the paired test of the smoker's response to the smoking olafctory cue under different physiological status (satiated vs. abstinent),we could find the the more notable activation on the prefrontal lobe,left callosal gyrus,right middle temporal gyrus,right thalamus in the smoking forbidden state(P<0.05 or activition rate>4/12,for details see the following text table 2).There were no statistical differences between the satiated and abstinent status (P>0.1,for details see the following text table 2) in both sides of the cerebellum.After the comparison between groups of the smoker and nonsomker's response to the smoking olafctory cue,we could find the activation on the the prefrontal lobe,left callosal gyrus,right middle temporal gyrus,right thalamus and both sides of the cerebellum(P<0.05 or activition rate>4/12,for details see the following text table 4),it appeared only in the smokers,while there was no notable activation on the whole brain of the nonsmokers.Besides, in the abstinent state, there were no statistical differences of the craving value before and after the experiment(P=0.695).Conclusions:1.The Limbic system(cingulate cortex,thalamus)and the prefrontal loab and the paly an important role in the cue-induced smoking craving,and thiis experiment approved this theory from the new perspective of the olfactory.2.Compared with the previous experiments about the smoking visual cue,we found the brain region related to the memory and familiarity—right middle temporal gyrus active.3.Both sides of the cerebellar of the smokers were active in satiated and abstinent status ,while neither of the cerebellar of the nonsmokers were active, experiments showed that the activity of the cerebellar was not associated with activities including coordinating movement and maintaining posture and equilibrium,but associated with the cognitive fuction.4.It was a availible experiment method to research smoking addicts'brain activation and the role of neural mechanisms using olfactory stimulation in the clinical 1.5T MRI equipment.