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Table 2 Key findings related to functional connectivity of default mode network or deactivation during cognitive tasks

From: Role of emerging neuroimaging modalities in patients with cognitive impairment: a review from the Canadian Consensus Conference on the Diagnosis and Treatment of Dementia 2012

Condition Findings in Alzheimer's disease Findings in MCI
Functional connectivity of DMN during resting state ↓ FC between HC and mPFC, PCC, precuneus and ventral ACC ↓ FC between PCC and ACC, PCC and frontal cortex, mPFC and PCC, mPFC and ACC, mPFC and frontal cortex
  ↓ FC between PCC with mPFC, precuneus, and parietal
Cortex
↓ whole-brain FC to PCC and precuneus
   ↓ regional homogeneity in PCC and precuneus
  ↑ FC between left HC and right lPFC  
   ↓ amplitude of low-frequency fluctuations in mPFC, PCC, precuneus and HC
  ↑ FC between parietal and occipital cortex  
  ↓ Connectivity and activity in HC and PCC  
  ↓ in coherence in the PCC and precuneus  
  ↑ local homogeneity in cuneus and left fusiform gyrus  
Deactivation during cognitive task ↓ deactivation in medial and lateral parietal regions during associative memory paradigm ↓ deactivation in PCC, precuneus and anterior frontal lobe
   Depends on severity with increased deactivation in mild MCI
  ↓ deactivation in medial parietal and PCC during semantic classification  
   Cognitive reserve affects deactivation indicating decompensation
  ↓ in mPFC, PCC, precuneus, parietal cortex and HC during
nonspatial working memory and episodic visual memory encoding
 
  1. Summary of the key findings related to functional connectivity of the DMN during the rest state or as evident by deactivation during cognitive tasks in patients with Alzheimer's disease and those with MCI compared with healthy controls [29]. DMN, default mode network; FC, functional connectivity; HC, hippocampus; MCI, mild cognitive impairment; mPFC, medial prefrontal cortex; PCC, posterior cingulate cortex; ACC, anterior cingulate cortex; lPFC, left prefrontal cortex.