| 제목 |
Near-Infrared Spectroscopy during Complex Cognitive Function Tasks in Mild Cognitive Impairment |
| 소속 |
Pusan National University Hospital, Department of Rehabilitation Medicine1, OBELAB, Inc.2, Pusan National University Hospital, Department of Neurology3, Pusan National University Yangsan Hospital, Department of Rehabilitation Medicine4, Chonbuk National University Hospital, Department of Physical Medicine and Rehabilitation5 |
| 저자 |
Da Hwi Jung1*, Ra Yu Yun1, In Joo Kong2, JongKwan Choi2, Ji Yeong Baek3, Eun Joo Kim4, Yong-Il Shin5, Myoug-Hwan Ko1, Yong Beom Shin1, Myung Jun Shin1, Jin A Yoon1† |
Objective
The present pilot study aimed to conduct a comparative analysis of the level of activation in the prefrontal cortex among a normal elderly group and amnestic and non-amnestic mild cognitive impairment (MCI) groups, and investigate the presence of neural compensatory mechanisms according to types of MCI and different cognitive tasks.
Method
We performed functional near-infrared spectroscopy (fNIRS) along with cognitive tasks, including two-back test, Korean color word Stroop test and semantic verbal fluency task (SVFT), to investigate hemodynamic response and the presence of neural compensation and neuroplasticity in the prefrontal cortex of patients with amnestic and non-amnestic MCI compared with a healthy elderly group. (Fig. 1, 2)
Result
During two back test, there was showed no significant difference in bilateral region-of interest analysis (ROI) in three groups. (Fig. 3) During Stroop test, right sided hyperactivation compared to the left side during task was shown in non-amnestic MCI and normal group with statistical significance. (Fig. 4) Mean acc∆〖HbO〗_2 on the right side was highest in non-amnestic MCI group (0.30 uM) followed by normal group (0.07 uM) and amnestic MCI group (-0.10 uM). Otherwise, inter group ROI analysis of acc∆〖HbO〗_2 in these activated right sides showed no significant difference. During VFT test, there was showed no significant difference in bilateral region-of interest analysis in three groups. The highest mean acc∆〖HbO〗_2 was showed in normal group (0.79 uM) followed by non-amnestic MCI group (0.52 uM) and amnestic MCI group (0.21 uM). Otherwise, there was no significant difference between groups. (Fig. 5)
Discussion
Although the neuroplasticity of the right prefrontal cortex in MCI has been described earlier, this is the first study to compare its effect between amnestic and non-amnestic MCI groups preforming various cognitive tasks. According to the results of our study, the neuroplasticity of the right prefrontal cortex during Stroop test was preserved only in the non-amnestic MCI group. First, Stroop test might be a sensitive tool to evaluate cognition flexibility impairment, which has shown strong relationship with episodic memory in a previous study. Our finding of hypoactivation in the amnestic MCI group and compensatory hyperactivation in the non-amnestic MCI group on the right prefrontal cortex can be explained with this approach. The cognitive flexibility impairment could sufficiently be compensated for in the non-amnestic MCI group but not in the amnestic MCI group. Stroop test could be used for evaluating cognitive control and preservation of neural compensatory mechanisms in MCI.
Conclusion
The hemodynamic response during fNIRS showed different findings according to MCI types and cognitive tasks. Among the three tasks, Stroop test showed results that were suggestive of neural compensatory mechanisms in the prefrontal cortex in non-amnestic MCI. |
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Figure 1. Cognitive task protocol used for the NIRSIT system. K-CWST, Korean color word Stroop test; SVFT, semantic verbal fluency task
Figure 2. Arrangement of sources and detectors, and location of region of interest channels
Figure 3. Activation map during two-back test in three groups showing no significant difference between groups. MCI, mild cognitive impairment
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