The pattern and magnitude of brain activation during a WM task depends on the nature and the amount (or load) of information maintained in WM. These studies have been performed with adults, and here we examined the development of the brain basis of WM in children. In delayed match-to-sample tasks in humans, such as the Sternberg WM task ( Sternberg, 1966), reliable activations have been observed in dorsolateral prefrontal, ventrolateral prefrontal, premotor, and parietal cortices during the maintenance of information in WM after stimulus encoding and before stimulus response ( Cabeza & Nyberg, 2000 D’Esposito, Ballard, Zarahn, & Aguirre, 2000 Haxby, Petit, Ungerleider, & Courtney, 2000 Jonides et al., 1998). Electrophysiological, lesion, and cooling studies with primates ( Barone & Joseph, 1989 Quintana, Fuster, & Yajeya, 1989 Fuster, Bauer, & Jervey, 1985 Bauer & Fuster, 1976 Fuster & Alexander, 1971 Kubota & Niki, 1971) and functional neuroimaging studies with humans ( Nystrom et al., 2000 Smith & Jonides, 1999 Courtney, Petit, Haxby, & Ungerleider, 1998 Jonides et al., 1993, 1998 Cohen et al., 1997 Manoach et al., 1997 Awh, 1996 Sweeney et al., 1996 Paulesu, Frith, & Frackowiak, 1993) (reviewed by Wager & Smith, 2003) provide convergent evidence that prefrontal and parietal cortices support the maintenance of information in WM in the absence of perceptual information.
WM is fundamental to higher cognitive functions, including reasoning and reading comprehension ( Engle, Tuholski, Laughlin, & Conway, 1999 Just & Carpenter, 1992 Kyllonen & Christal, 1990 Daneman & Carpenter, 1980), and is linked to scholastic development ( Hitch, Towse,& Hutton, 2001). Working memory (WM) refers to the ability to maintain goal-relevant information in mind.
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