Exploring Short-and Long-term Effects Of Shallow Reading On The Brain Of Undergraduates By Using Multimodal Neuroimaging

Experiment 1 Effects of short-term and long-term shallow reading on mental health and imaging featuresMedia shallow reading（MSR）refers to the shallow reading behavior of users while surfing social media,which is assumed to activate only the visual network（VN）and deteriorate the ability to think deeply.To date,no research has focused on the impact of MSR and its underlying mechanism on the human brain;therefore,we combined neuropsychological and longitudinal neuroimaging methods to investigate this issue.A total of 289 subjects were enrolled in this study.Neuropsychological assessments included smartphone addiction,academic achievement attribution,attentional control and self-control,emotion,and sleep.The longitudinal neuroimaging study included a short-term（2 h）MSR task and a long-term（4 weeks）MSR task as well as multimodal magnetic resonance imaging（MRI）scanning at baseline and after the short-and long-term tasks.The study findings were as follows.First,heavy daily MSR use was related to heavy smartphone addiction（productivity loss:β=0.240,P=0.01;anxiety and feeling loss:β=0.280,P=0.005;inability to control craving:β=0.277,P=0.004;withdraw and escape:β=0.209,P=0.027）,increased sleep medication use(β=0.453,P=6.37×10^–6),and worse attentional control（β=–0.255,P=0.009）and self-control(β=0.348,P=3.52×10^–4).Second,short-term MSR mainly led to increased cerebral blood flow（CBF）in the VN(P_FDR<0.05),along with changes in the adaptive brain network.Third,long-term MSR impaired white matter integrity and disrupted the adaptive ability,leading to enhanced information transmission efficiency within each network,while attenuating information transmission efficiency between the VN and other networks.In conclusion,MSR is related to addiction,sleep,and control disorders.MSR also makes the brain“shallower,”thereby preventing one from processing visual information deeply.This process is related to the development of structural network lesions after long-term MSR,which is associated with chronic repetition of disorganized CBF and functional network after short-term MSR.Experiment 2 Combining functional MRI and cerebral carryover effect to study the dynamic functional network characteristics of shallow reading and deep reading in natural statePrevious studies hypothesize that deep reading can lead to deductive reasoning,critical thinking,and meditation,while shallow reading can only stimulate the visual cortex without further in-depth thinking.Dynamic functional network connectivity based on f MRI can reveal the dynamic neural activity and coordination of brain in reading state.In addition,the effects of cognitive tasks on the brain usually last for a while after the task,an effect known as the“carryover effect”.Therefore,we can use this special physiological mechanism to study the characteristics of dynamic functional network of reading in natural state.We performed functional magnetic resonance imaging（f MRI）scans on all subjects and then assigned them to deep reading or shallow reading tasks.Immediately after the task,the subjects were scheduled for another f MRI scan.We obtained the d FNC features of the subjects based on the scanned data,and conducted intra-group comparison to study the changes of these features after deep reading or shallow reading.After deep reading,the variation between d FNC states（baseline=21.90±9.66,after reading=28.81±9.84,P=0.028,FDR correction）,the number of d FNC states（baseline=14.05±7.62,after reading=18.62±7.02,P=0.035,FDR correction）,and the total distance increased（baseline=25.33±12.74,after reading=33.19±12.61,P=0.024,FDR correction）.After deep reading,the global efficiency（baseline=0.035±0.055,after reading=0.080±0.057,P=0.054,FDR correction）,local efficiency（baseline=0.015±0.027,after reading=0.036±0.029,P=0.060,FDR correction）,and nodal efficiency of deep-thinking state were increased.After shallow reading,functional connectivity（FC）between the default mode network（DMN）and bilateral fronto-parietal network（FPN）decreased,while FC between the DMN and visual network（VN）increased.Based on the results so far,we conclude that deep reading is associated with increased brain activity and network efficiency,while shallow reading is associated with abnormal changes in FC between the DMN,FPN,and VN.Experiment 3 Inter-subject correlation analysis reveals the plasticity of cerebral functional connectivity in the long-term use of social mediaOwing to the limitations of cross-sectional studies,it is unclear whether social media induce brain changes,or if individuals with certain biological traits are more likely to use social media.Functional connectivity（FC）can reflect cerebral functional plasticity,and if social media can influence cerebral FC,the FC of light social media users should be more similar to that of heavy users after they“heavily”used social media for a long period.We combined longitudinal study design and inter-subject correlation（ISC）analysis to investigate this similarity.Thirty-five heavy and 21 light social media users underwent cognitive tests and functional MRIs.The 21 light social media users underwent another functional MRI scan after completing an additional four-week social media task.We conducted the ISC at the group,individual,and brain-region levels to investigate the similarity of FC and locate the brain regions most affected by social media.The FC of light social media users was more similar to that of heavy social media users after they completed the four-week social media task（P=0.002,Cohen’s d=0.243;P<0.001,accuracy=86.2%）.Then,social media had an impact on half of the brain,involving almost all brain networks.Finally,cerebral FC that mostly affected by social media was associated with selective attention.The FC between visual network（VN）and limbic system（LS）was positively correlated with the pronunciation relevant correct number（r=0.411,P=0.004）and reaction time（RT）of Stroop word color test（SWCT）（r=0.430,P=0.003）.The FC between somato-motor network（SMN）and LS was negatively correlated with the congruent correct number of SWCT（r=-0.317,P=0.030）.FC between default mode network（DMN）and the cerebellum was positively correlated with the false number of SWCT（r=0.297,P=0.043）,and negatively correlated with the irrelevant correct number of SWCT（r=-0.304,P=0.038）.We concluded that the impact of social media use on cerebral functional connectivity changes is revealed by ISC method and longitudinal design,which may provide guidance for clinical practice.The methods used in the current research could also be applied to similar domains.