Synopsis

Keywords: Alzheimer's Disease, Alzheimer's Disease, fMRI

Analysis of functional connectivity changes of olfactory neural circuits in subjective cognitive decline(SCD)under specific odor stimuli using generalized physiological and psychological interactions.

Objective

Olfactory involvement is an early feature of Alzheimer's disease. The purpose of this study was to investigate the functional connectivity(FC) changes of olfactory neural circuits in subjective cognition decline (SCD) in olfactory task fMRI under specific odor stimulation.

Methods

A total of 56 normal controls（NC）and 57 SCD were included. All subjects were tested with cognitive scale, olfactory behavior assessment, and olfactory task fMRI scanning. The FC difference of olfactory neural circuits between the two groups was analyzed by the method of generalized psychophysiological interaction (gPPI).

Results

There was no significant difference in olfactory behavior between the two groups. In the task fMRI under specific odor stimulation, the activation of bilateral POCs in SCD was lower. Taking bilateral POCs as the ROI, gPPI analysis showed that the FC of bilateral POCs to the right hippocampus, parahippocampal gyrus and fusiform gyrus in the SCD was reduced. Taking the right hippocampus as the ROI, gPPI analysis showed that the FC from the right hippocampus to the right middle frontal gyrus, the infrafrontal gyrus of the insular region and the infrafrontal gyrus of the triangle in the SCD was enhanced. Correlation analysis shows that the FC between bilateral POCs and right parahippocampal gyrus was positively correlated with the MMSE score (r=0.290, p=0.029); The FC between bilateral POCs and the right fusiform gyrus was positively correlated with the recognition memory score (r=0.272, p=0.041).

Conclusion

The olfactory behavior reflects the comprehensive performance of olfactory function, while the olfactory task fMRI reflects the functional connection between specific brain regions in the olfactory neural circuits. The results of this study indicate that although the olfactory behavior of SCD is at a normal level, the FC of olfactory neural circuits（POC-hippocampus-prefrontal lobe）has changed.

Acknowledgements

No acknowledgement found.

References

YAN C G, WANG X D, ZUO X N, et al. DPABI: Data Processing & Analysis for (Resting-State) Brain Imaging[J/OL]. Neuroinformatics, 2016, 14(3): 339-351. DOI:10.1007/s12021-016-9299-4.