Academic journal article Cognitive, Affective and Behavioral Neuroscience

The Neural Bases of Distracter-Resistant Working Memory

Academic journal article Cognitive, Affective and Behavioral Neuroscience

The Neural Bases of Distracter-Resistant Working Memory

Article excerpt

Published online: 24 December 2013

© Psychonomic Society, Inc. 2013

Abstract A major difference between humans and other animals is our capacity to maintain information in working memory (WM) while performing secondary tasks, which enables sustained, complex cognition. A common assumption is that the lateral prefrontal cortex (PFC) is critical for WM performance in the presence of distracters, but direct evidence is scarce. We assessed the relationship between fMRI activity and WM performance within subjects, with performance matched across distracter and no-distracter conditions. Activity in the ventrolateral PFC during WM encoding and maintenance positively predicted performance in both conditions, whereas activity in the presupplementary motor area (pre-SMA) predicted performance only under distraction. Other parts of the dorsolateral and ventrolateral PFCs predicted performance only in the no-distracter condition. These findings challenge a lateral-PFC-centered view of distracter resistance, and suggest that the lateral PFC supports a type of WM representation that is efficient for dealing with taskirrelevant input but is, nonetheless, easily disrupted by dualtask demands.

Keywords Working memory . Prefrontal cortex

Working memory (WM) refers to a system that maintains currently relevant goals and information for use in guiding ongoing information processing. Information in WM is thought to guide the deployment of attention (de Fockert, Rees, Frith & Lavie, 2001) and the manipulation of information to achieve current task goals (Baddeley, 1986; Hitch & Baddeley, 1976). Probably no factor has more effect on WM performance than the presence of distracters (e.g., Keppel & Underwood, 1962). Consider the simple task of remembering a group of three letters-atrigram-over an interval of a few seconds. In a classic article (Peterson & Peterson, 1959), participants rehearsed a trigram for intervals of up to 18 s while counting backward by threes. With this distracting secondary counting task, what would otherwise have been trivial to remember became virtually impossible, with nearzero recall by 18 s, with proactive inhibition amassed from prior trials having been shown to underlie this type of memory impairment (Keppel & Underwood, 1962). The powerful effect of distraction is evident in everyday situations: Memory for the contents of a book or a phone number just memorized may be obliterated by a few moments of idle conversation.

Distracters in WM are of two basic types. They may not require any intentional processing, in which case they are simply perceptual experiences to be ignored while remembering other items, or they may constitute a secondary task that must be performed during maintenance of the memory set. Successful inhibition of merely perceptual distracters may rely on perceptual filtering mechanisms that can operate at an early processing stage (Bundesen, 1990; Treisman, 1985), whereas dual-task interference is likely to rely more heavily on task switching, coordination, and information selection processes. Performance on tasks involving these two distracter types is essentially uncorrelated (Miyake, Friedman, Emerson, Witzki, Howerter & Wager, 2000). Crucially, performance on WM tasks with dual-task distracters, rather than perceptual distracters, predicts performance on complex tests of fluid intelligence (Conway, Cowan, Bunting, Therriault & Minkoff, 2002; Conway, Kane & Engle, 2003; Engle, Kane & Tuholski, 1999;Fry&Hale,1996;Kane&Engle,2002, 2003), correlates with other indices of "executive function" (Bleckley, Durso, Crutchfield, Engle & Khanna, 2003; Kane & Engle, 2003), and predicts everyday cognitive failures (Friedman & Miyake, 2004).

Although there have been many studies investigating the brain mechanisms of selective attention and perceptual distracter suppression, very few studies have investigated those involved in creating WM representations resistant to dual-task distracters. …

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