* Less wiring, more firing: low-performing older adults compensate for impaired white matter with greater neural activity.
- The reliable neuroimaging finding that older adults often show greater activity (over-recruitment) than younger adults is typically attributed to compensation. Yet, the neural mechanisms of over-recruitment in older adults (OAs) are largely unknown. Rodent electrophysiology studies have shown that as number of afferent fibers within a circuit decreases with age, the fibers that remain show higher synaptic field potentials (less wiring, more firing). Extrapolating to system-level measures in humans, we proposed and tested the hypothesis that greater activity in OAs compensates for impaired white-matter connectivity. Using a neuropsychological test battery, we measured individual differences in executive functions associated with the prefrontal cortex (PFC) and memory functions associated with the medial temporal lobes (MTLs). Using event-related functional magnetic resonance imaging, we compared activity for successful versus unsuccessful trials during a source memory task. Finally, we measured white-matter integrity using diffusion tensor imaging. The study yielded 3 main findings. First, low-executive OAs showed greater success-related activity in the PFC, whereas low-memory OAs showed greater success-related activity in the MTLs. Second, low-executive OAs displayed white-matter deficits in the PFC, whereas low-memory OAs displayed white-matter deficits in the MTLs. Finally, in both prefrontal and MTL regions, white-matter decline and success-related activations occurred in close proximity and were negatively correlated. This finding supports the less-wiring-more-firing hypothesis, which provides a testable account of compensatory over-recruitment in OAs.
=>安い, 低いところ, 卑劣に, 粗食で, 低い(もの), 弱い, 粗末な, 乏しい, 衿ぐりが深い, 建物の低い,
下劣な, 低級な
Overview of noun low
The noun low has 4 senses (no senses from tagged texts)
1. low, depression -- (an air mass of lower pressure; often brings precipitation; "a low moved in
over night bringing sleet and snow")
2. Low, David Low, Sir David Low, Sir David Alexander Cecil Low -- (British political cartoonist
(born in New Zealand) who created the character Colonel Blimp (1891-1963))
3. low -- (a low level or position or degree; "the stock market fell to a new low")
4. first gear, first, low gear, low -- (the lowest forward gear ratio in the gear box of a motor
vehicle; used to start a car moving)
Overview of verb low
The verb low has 1 sense (no senses from tagged texts)
1. moo, low -- (make a low noise, characteristic of bovines)
Overview of adj low
The adj low has 10 senses (first 6 from tagged texts)
1. (55) low -- (less than normal in degree or intensity or amount; "low prices"; "the reservoir is
low")
2. (23) low -- (literal meanings; being at or having a relatively small elevation or upward
extension; "low ceilings"; "low clouds"; "low hills"; "the sun is low"; "low furniture"; "a low
bow")
3. (11) low, low-toned -- (very low in volume; "a low murmur"; "the low-toned murmur of the surf")
4. (6) low -- (unrefined in character; "low comedy")
5. (4) low, low-pitched -- (used of sounds and voices; low in pitch or frequency)
6. (3) abject, low, low-down, miserable, scummy, scurvy -- (of the most contemptible kind; "abject
cowardice"; "a low stunt to pull"; "a low-down sneak"; "his miserable treatment of his family"; "You
miserable skunk!"; "a scummy rabble"; "a scurvy trick")
7. humble, low, lowly, modest, small -- (low or inferior in station or quality; "a humble cottage";
"a lowly parish priest"; "a modest man of the people"; "small beginnings")
8. depleted, low -- (no longer sufficient; "supplies are low"; "our funds are depleted")
9. broken, crushed, humbled, humiliated, low -- (subdued or brought low in condition or status;
"brought low"; "a broken man"; "his broken spirit")
10. gloomy, grim, blue, depressed, dispirited, down, downcast, downhearted, down in the mouth, low,
low-spirited -- (filled with melancholy and despondency ; "gloomy at the thought of what he had to
face"; "gloomy predictions"; "a gloomy silence"; "took a grim view of the economy"; "the darkening
mood"; "lonely and blue in a strange city"; "depressed by the loss of his job"; "a dispirited and
resigned expression on her face"; "downcast after his defeat"; "feeling discouraged and
downhearted")
Overview of adv low
The adv low has 1 sense (first 1 from tagged texts)
1. (3) low -- (in a low position; near the ground; "the branches hung low")
--- WordNet end ---