Literature Review of Disrupted Neurobiological Mechanisms in Adolescents with Internet Addiction :fMRI Studies

Literature Review of Disrupted Neurobiological Mechanisms in Adolescents with Internet Addiction :fMRI Studies Introduction and Purpose:Internet addiction (IA) or problematic ınternet use (PIU) is characterized by excessive or poorly controlled urges or behaviors regarding internet use that leads to impairment or distress.Internet addiction is a serious condition that affects millions around the world, especially adolescence and affect their overall aspect of lifestyle.The aim of this study is to understand the neurobiological mechanisms underlying IA, imaging studies have been performed to investigate structural and functional abnormalities associated with IA. Method:We review current literature studies about neuroimaging studies of IA-related changes in specific brain regions and connections of adolescents. Results:Two studies ,which we reviewed, showed that IA subjects showed increased connectivity between the left dorsal caudal putamen and bilateral caudal cigulate motor area. IA adolescents demonstrated significantly reduced functional connectivity (FC) with the caudate head and subcallosal anterior cinguate cortex (ACC) bilaterally.Decreased FC was also found between the left inferior ventral striatum (VSi) and the posterior cingulated cortex (PCC) bilaterally. The left DC also showed reduced FC with the left ventral lateral thalamus, as well as the right DC displayed lower positive relationships with the left IFG in IAD. IA adolescents showed decreased voxel-mirrored homotopic connectivity (VMHC) of dorso-lateral prefrontal cortex (DLPFC) and reduced fractional anisotropy (FA) values in the genu of corpus callosum (CC). In addition,another study showed that IA subjects showed reduced inter-hemispheric FC of the right fronto-parietal network (FPN), whereas increased intra-hemispheric FC of the left FPN; reduced FC in the dorsal medial prefrontal cortex (mPFC) of the anterior default mode network (DMN); reduced FC between the salience network (SN) and anterior DMN.Another study shows that two inter-hemispheric connections, one between the left angular gyrus and right middle orbitofrontal cortex and another between the left fusiform gyrus and right angular gyrus, exhibit increased connectivity strength in IA adolescents. One intra-hemispheric connection, between the right caudate and right supra-marginal gyrus, shows decreased connectivity in IA adolescents. Conclusion and Discussion : Studies showed that IA-related alterations in functional interactions between the cerebral hemispheres and its anatomical basis, especially the relationship between functional and structural deficits during resting state and the VMHC deficits of DLPFC were also associated with craving mechanisms. IA adolescents brain had the imbalanced interactions within and between large-scale brain networks may serve as system-level neural underpinnings. The results demonstrate that IA is characterized by impairment of corticostriatal functional circuits involving affective and emotional processing, and cognitive control. Moreover, the studies suggests that IA may share similar neurobiological abnormalities,psychological and neural mechanisms with other types of impulse control disorders and addictive disorders. In addition, the associations between the connectivity strength of the corticostriatal circuits and behavioral measures indicate that corticostriatal circuits may serve as a potential new treatment target for IA. key words:ınternet addiction,neuroanatomy, fMRI