Prefrontal Cortex Dysfunction In Internet Addiction: A Study Of Mismatch Negativity And Resting State FMRI

Objective To explore the ability of discriminating the deviant auditory information in automatic pre-attentive state by investigating characteristics and variation of MMN in patients with Internet addiction, in order to evaluate the function of prefrontal cortex in Internet addiction;To explore the changes of prefrontal functional connectivity of resting-state fMRI in Internet addicts so as to understanding role of the prefrontal cortex in Internet Addiction.Methods MMN examinations were performed in internet addiction group and normal controls group appling Oddball mode in non-attention state, then the characteristics of waveform and the variations of MMN latency and amplitude were analyzed. Resting fMRI examination were performed on 15 internet addicts and normal volunteers. After pre-processing of resting-state fMRI data, the prefrontal cortex was selected as the seed region,with which a whole-brain voxel temporal correlation in low frequency fMRI fluctuations was calculated to investigate the changes of the prefrontal functional connectivity. The group differences of prefrontal functional connectivity were calculated with SPM5( P<0.01, t=2.048, pixel extent>54).Results (1) Typical MMN waveforms were record both in Internet addiction group and control group, of which the largest amplitude was at Fz lead. (2) The amplitude of MMN at Fz lead in Internet addiction group was significantly higher than control group (Internet addiction group: 9.38±3.27μV, control group 7.52±3.36μV, p <0.05), while latency was no significant difference between the two groups ( Internet Addiction Group: 212.00±22.53ms, control group 217.55±25.81ms, p>0.05). (3) Compare with the control group, the functional connectivity between left prefrontal cortex and left hippocampus, right prefrontal cortex, right cingulated gyrus, right medial prefrontal cortex, right supramarginal gyrus,right precuneus was significantly decreased, while the functional connectivity between left prefrontal cortex and right temporal cortex, parietal cortex was increased. (4) The functional connectivity between right prefrontal cortex and left middlel frontal gyrus, left superior temporal gyrus, right cerebrum was also significantly decreased, but the functional connectivity between right prefrontal cortex and right temporal cortex, left occipital cortex was increased.Conclusion (1) Abnormal MMN appeared in Internet Addiction Group, indicating that auto-detection function of information changes declined, which may related to prefrontal dysfunction. (2) Functional connectivity between prefrontal cortex and the certain structures of reward system, such as cingulated gyrus, medial prefrontal cortex, hippocampus, etc, was decreased in internet addicts, which may be involved in the maintenance of internet addiction.