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Frequency-specific alterations of large-scale functional brain networks in patients with Alzheimer's disease.

Qin YY, Li YP, Zhang S, Xiong Y, Guo LY, Yang SQ, Yao YH, Li W, Zhu WZ - Chin. Med. J. (2015)

Bottom Line: At lower-frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz), the global efficiency, the CC and the "small-world" properties of AD patients decreased compared to controls.The topological properties changed with different frequency bands, suggesting the existence of disrupted global and local functional organization associated with AD.This study demonstrates that the topological alterations of large-scale functional brain networks in AD patients are frequency dependent, thus providing fundamental support for optimal frequency selection in future related research.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.

ABSTRACT

Background: Previous studies have indicated that the cognitive deficits in patients with Alzheimer's disease (AD) may be due to topological deteriorations of the brain network. However, whether the selection of a specific frequency band could impact the topological properties is still not clear. Our hypothesis is that the topological properties of AD patients are also frequency-specific.

Methods: Resting state functional magnetic resonance imaging data from 10 right-handed moderate AD patients (mean age: 64.3 years; mean mini mental state examination [MMSE]: 18.0) and 10 age and gender-matched healthy controls (mean age: 63.6 years; mean MMSE: 28.2) were enrolled in this study. The global efficiency, the clustering coefficient (CC), the characteristic path length (CpL), and "small-world" property were calculated in a wide range of thresholds and averaged within each group, at three different frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz, and 0.11-0.25 Hz).

Results: At lower-frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz), the global efficiency, the CC and the "small-world" properties of AD patients decreased compared to controls. While at higher-frequency bands (0.11-0.25 Hz), the CpL was much longer, and the "small-world" property was disrupted in AD, particularly at a higher threshold. The topological properties changed with different frequency bands, suggesting the existence of disrupted global and local functional organization associated with AD.

Conclusions: This study demonstrates that the topological alterations of large-scale functional brain networks in AD patients are frequency dependent, thus providing fundamental support for optimal frequency selection in future related research.

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Related in: MedlinePlus

The structure-specific alterations of node degrees in AD patients. The red dots indicate increased node degrees in the AD group compared with healthy controls; the blue dots indicate reduced node degrees in the AD group. The size of the dot indicates the degree of alterations. AD: Alzheimer's disease; AMYG.R: Right amygdala; HIP.R: Right hippocampus; ITG.L: Inferior temporal gyrus; LING.L: Left lingual gyrus; MOG.R: Right middle occipital gyrus; MTG.L: Left middle temporal gyrus; MTG.R: Right middle temporal gyrus; ORBsupmed.R: Right orbital part of middle frontal gyrus; PoCG.L: Left postcentral gyrus; SFGmed.L: Medial part of left superior frontal gyrus; SFGmed.R: Medial part of right superior frontal gyrus.
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Figure 6: The structure-specific alterations of node degrees in AD patients. The red dots indicate increased node degrees in the AD group compared with healthy controls; the blue dots indicate reduced node degrees in the AD group. The size of the dot indicates the degree of alterations. AD: Alzheimer's disease; AMYG.R: Right amygdala; HIP.R: Right hippocampus; ITG.L: Inferior temporal gyrus; LING.L: Left lingual gyrus; MOG.R: Right middle occipital gyrus; MTG.L: Left middle temporal gyrus; MTG.R: Right middle temporal gyrus; ORBsupmed.R: Right orbital part of middle frontal gyrus; PoCG.L: Left postcentral gyrus; SFGmed.L: Medial part of left superior frontal gyrus; SFGmed.R: Medial part of right superior frontal gyrus.

Mentions: The differences of node degree between AD patients and healthy controls are further investigated [Figure 6]. The results demonstrate that a reduction of node degree was distributed in the left postcentral gyrus (PoCG.L), the right hippocampus (HIP.R), the left middle temporal gyrus (MTG.L), the right middle occipital gyrus (MOG.R), the right orbital part of middle frontal gyrus (ORBsupmed.R), the right amygdala (AMYG.R), the left lingual gyrus (LING.L), the medial part of right superior frontal gyrus (SFGmed.R), and the medial part of left superior frontal gyrus (SFGmed.L). Only a few regions show increased node degree in AD patients: The left inferior temporal gyrus (ITG.L), the left orbital part of superior frontal gyrus (ORBsup.L), and the right MTG (MTG.R).


Frequency-specific alterations of large-scale functional brain networks in patients with Alzheimer's disease.

Qin YY, Li YP, Zhang S, Xiong Y, Guo LY, Yang SQ, Yao YH, Li W, Zhu WZ - Chin. Med. J. (2015)

The structure-specific alterations of node degrees in AD patients. The red dots indicate increased node degrees in the AD group compared with healthy controls; the blue dots indicate reduced node degrees in the AD group. The size of the dot indicates the degree of alterations. AD: Alzheimer's disease; AMYG.R: Right amygdala; HIP.R: Right hippocampus; ITG.L: Inferior temporal gyrus; LING.L: Left lingual gyrus; MOG.R: Right middle occipital gyrus; MTG.L: Left middle temporal gyrus; MTG.R: Right middle temporal gyrus; ORBsupmed.R: Right orbital part of middle frontal gyrus; PoCG.L: Left postcentral gyrus; SFGmed.L: Medial part of left superior frontal gyrus; SFGmed.R: Medial part of right superior frontal gyrus.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834769&req=5

Figure 6: The structure-specific alterations of node degrees in AD patients. The red dots indicate increased node degrees in the AD group compared with healthy controls; the blue dots indicate reduced node degrees in the AD group. The size of the dot indicates the degree of alterations. AD: Alzheimer's disease; AMYG.R: Right amygdala; HIP.R: Right hippocampus; ITG.L: Inferior temporal gyrus; LING.L: Left lingual gyrus; MOG.R: Right middle occipital gyrus; MTG.L: Left middle temporal gyrus; MTG.R: Right middle temporal gyrus; ORBsupmed.R: Right orbital part of middle frontal gyrus; PoCG.L: Left postcentral gyrus; SFGmed.L: Medial part of left superior frontal gyrus; SFGmed.R: Medial part of right superior frontal gyrus.
Mentions: The differences of node degree between AD patients and healthy controls are further investigated [Figure 6]. The results demonstrate that a reduction of node degree was distributed in the left postcentral gyrus (PoCG.L), the right hippocampus (HIP.R), the left middle temporal gyrus (MTG.L), the right middle occipital gyrus (MOG.R), the right orbital part of middle frontal gyrus (ORBsupmed.R), the right amygdala (AMYG.R), the left lingual gyrus (LING.L), the medial part of right superior frontal gyrus (SFGmed.R), and the medial part of left superior frontal gyrus (SFGmed.L). Only a few regions show increased node degree in AD patients: The left inferior temporal gyrus (ITG.L), the left orbital part of superior frontal gyrus (ORBsup.L), and the right MTG (MTG.R).

Bottom Line: At lower-frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz), the global efficiency, the CC and the "small-world" properties of AD patients decreased compared to controls.The topological properties changed with different frequency bands, suggesting the existence of disrupted global and local functional organization associated with AD.This study demonstrates that the topological alterations of large-scale functional brain networks in AD patients are frequency dependent, thus providing fundamental support for optimal frequency selection in future related research.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.

ABSTRACT

Background: Previous studies have indicated that the cognitive deficits in patients with Alzheimer's disease (AD) may be due to topological deteriorations of the brain network. However, whether the selection of a specific frequency band could impact the topological properties is still not clear. Our hypothesis is that the topological properties of AD patients are also frequency-specific.

Methods: Resting state functional magnetic resonance imaging data from 10 right-handed moderate AD patients (mean age: 64.3 years; mean mini mental state examination [MMSE]: 18.0) and 10 age and gender-matched healthy controls (mean age: 63.6 years; mean MMSE: 28.2) were enrolled in this study. The global efficiency, the clustering coefficient (CC), the characteristic path length (CpL), and "small-world" property were calculated in a wide range of thresholds and averaged within each group, at three different frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz, and 0.11-0.25 Hz).

Results: At lower-frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz), the global efficiency, the CC and the "small-world" properties of AD patients decreased compared to controls. While at higher-frequency bands (0.11-0.25 Hz), the CpL was much longer, and the "small-world" property was disrupted in AD, particularly at a higher threshold. The topological properties changed with different frequency bands, suggesting the existence of disrupted global and local functional organization associated with AD.

Conclusions: This study demonstrates that the topological alterations of large-scale functional brain networks in AD patients are frequency dependent, thus providing fundamental support for optimal frequency selection in future related research.

Show MeSH
Related in: MedlinePlus