The Study On Structural Basis Correlated With Spatial Navigation Skill In Patients With Mild Cognitive Impairment

Part 1 The change of white matter neuronal integrity associated with spatial navigation impairment in MCIPurpose:To analyze the correlation between the disruption of white matter integrity and spatial navigation impairment with Tract-based spatial statistics(TBSS)in patients with mild cognitive impairment(MCI),further to reveal the white matter structural basis correlated with spatial navigation skill in MCI.Materials and Methods:A total of 27 MCI patients with memory complaints were enrolled from the Neurology Clinic of the Affiliated Drum Tower hospital of Nanjing university medical school from May 2015 to February 2016,and then 24 normal healthy controls were enrolled from the community with no significant difference in age,gender and education between groups.All of them underwent DTI(Diffusion Tensor Imaging)by a 3.0T MRI scan and 2D-computer version spatial navigation test.PANDA was used to preprocess the original DTI data and then TBSS was performed to compare the FA(Fractional Anisotropy)map between groups with non-parameter statistics and partial correlation was performed to investigate the correlation of white matter impairments and spatial navigation skill.Results:Relative to controls,MCI patients showed worse spatial navigation skill,and the egocentric navigation(t=-2.202,p<0.05)had statistical differences.Decreased FA in superior longitudinal fasciculus(Left t=2.95,Right t=2.95,p<0.05),inferior longitudinal fasciculus(Left t=2.66,Right t=2.96,p<0.05),corpus callosum(t=2.09,p<0.05),cingulum(Left t=2.76,Right t=2.41,p<0.05),fornix(t=4.83,p<0.05),and corticospinal tract(Left t=2.33,Right t=2.26,p<0.05)were found in the MCI subjects.The decreased FA value of superior longitudinal fasciculus(Left r=-0.354,Right r=-0.347,p<0.05),inferior longitudinal fasciculus(Left r=-0.338,Right r=-0.336,p<0.05),cingulum(Left r=-0.395,Right r=-0.370,p<0.05),right corticospinal tract(r=-0.362,p<0.05)and fornix(r=-0.369,p<0.05)were correlated with increased ego average total error.Allo average total error were negatively correlated with the FA value of superior longitudinal fasciculus(Left r=-0.329,Right r=-0.350,p<0.05),inferior longitudinal fasciculus(Left r=-0.349,Right r=-0.378,p<0.05),splenium of corpus callosum(r=-0.364,p<0.05)and cingulum(Left r=-0.340,Right r=-0.406,p<0.05).Conclusion:This study implicated the neuronal basis of white matter structural disruption related with spatial navigation impairment and will have an impact on the further study of the neurobiological mechanisms of human spatial navigation ability.Part 2 The study on the correlation of subcortical nuclei volume and spatial navigation performance in patients with MCIPurpose:To evaluate the volume change in the subcortical nuclei in mild cognitive impairment(MCI)and then analyze the correlation between the volume of subcortical nuclei and spatial navigation performance.Further to reveal the structural basis correlated with spatial navigation skill in MCI.Materials and Methods:Thirty MCI patients and 28 normal healthy controls were enrolled in this study from Jan 2016 to Oct 2016,and all of them underwent 3.0T 3DTiW MRI scan and 2D-computer version spatial navigation test.The volume of each subcortical nuclei was automatically analyzed by FreeSurfer 5.3.0 software.Partial correlation analysis was performed to investigate the correlation of the volume of subcortical nuclei and spatial navigation skills with each participant's age,gender,total intracranial volume(TIV)as covariates.Results:Relative to controls,MCI patients showed smaller subcortical nuclei volume,but none of them had statistical differences.The volume of left pallidum(r=-0.284,p<0.05)and left hippocampus(r=-0.265,p<0.05)was related to allocentric and egocentric navigation in MCI,indicating that patients with smaller volume of left pallidum and left hippocampus had worse mixed(allocentric +egocentric)spatial navigation skill.And the volume of left putamen(r=-0.305,p<0.05)was associated with allocentric navigation,indicating that patients with smaller volume of left putamen had worse allocentric spatial navigation skill.Conclusion:This study implicated the association between the atrophy of subcortical nuclei and spatial navigation impairment,which will have an impact on the further study related to the mechanisms of human spatial navigation ability.