A resource model of the neural basis of executive working memory

Abstract

Working memory (WM) refers to the temporary storage and processing of goal-relevant information. WM is thought to include domain-specific short-term memory stores and executive processes, such as coordination, that operate on the contents of WM. To examine the neural substrates of coordination, we acquired functional magnetic resonance imaging data while subjects performed a WM span test designed specifically to measure executive WM. Subjects performed two tasks (sentence reading and short-term memory for five words) either separately or concurrently. Dual-task performance activated frontal-lobe areas to a greater extent than performance of either task in isolation, but no new area was activated beyond those activated by either component task. These findings support a resource theory of WM executive processes in the frontal lobes.

Figure 1

Schematic representation of the four Trial types in (a) Experiment 1, and (b) Experiment 2.

Figure 2

Whole-brain renderings of group-averaged activations for the three Trial types relative to Control. A lenient threshold was chosen to display all trends toward activation (P < 0.05 corrected for multiple comparisons). Lighter colors indicate higher Z values.

Figure 3

VOI analyses. (a) Experiment 1. Changes in mean signal intensity in the prefrontal activations common to all three trial types relative to baseline. (b) Experiment 2. Changes in mean signal intensity in the regions identified by a conjunction analysis as being more active for the dual task than for component tasks. Changes in signal intensity were determined from parameter estimates of the fit between each contrast and the estimated hemodynamic response, as calculated by the general linear model implemented in SPM99. Statistical significance of t tests for each condition relative to baseline. *, P < 0.05; **, P < 0.025; ****, P < 0.01.