加齢に伴う「デフォルト・ネットワーク」の休息状態の脳活動の低下
Reduced resting-state brain activity in the "default network" in normal aging.
Damoiseaux JS, Beckmann CF, Arigita EJ, Barkhof F, Scheltens P, Stam CJ, Smith SM, Rombouts SA
Cereb Cortex. 2007 Dec 5;
Normal aging is associated with cognitive decline even in the absence of disease. Functions such as attention, information processing, and working memory are compromised. Based on the observation of age-related white matter degeneration, O'Sullivan et al. (2001) proposed the "disconnection" hypothesis, stating that decline in normal aging emerges from changes in connections between brain areas, in addition to dysfunction of specific areas. Here, we examined the functional properties of brain networks based on spontaneous fluctuations within brain systems using functional magnetic resonance imaging. We hypothesized that functional connectivity of intrinsic brain activity in the "default-mode" network (DMN) is affected by normal aging and that this relates to cognitive function. Ten younger and 22 older subjects were scanned at "rest," that is, lying awake with eyes closed. Our results show decreased activity in older versus younger subjects in 2 resting-state networks (RSNs) resembling the previously described DMN, containing the superior and middle frontal gyrus, posterior cingulate, middle temporal gyrus, and the superior parietal region. These results remain significant after correction for RSN-specific gray matter volume. The relevance of these findings is illustrated by the correlation between reduced activity of one of these RSNs and less effective executive functioning/processing speed in the older group.
O'Sullivan らの仮説 (2001)
「断絶」仮説 discconection hypothesis
- 加齢による認知機能の低下は、特定の領域の機能尾低下に加え、脳領域間の接続の変化による
⇒default-mode network (DMN) の自発的な変動が加齢によって影響を受け、認知機能に影響を与えるのでは？
結果
これから読むところ
default-mode network と resting-state network を使い分けているのだが、違いは？
