Prefrontal cortical contributions to working memory: evidence from event-related fMRI studies

Abstract

Working memory refers to the short-term retention of information that is no longer accessible in the environment, and the manipulation of this information, for subsequent use in guiding behavior. In this review, we will present data from a series of event-related functional magnetic-resonance-imaging (fMRI) studies of delayed-response tasks that were designed to investigate the role of different regions of the prefrontal cortex (PFC) during different working-memory component processes. From these data, we conclude that: (1) lateral PFC is anatomically organized according to the types of cognitive operations that one performs when attempting to temporarily maintain and manipulate information; and (2) consistent with the picture that has emerged from the monkey electrophysiological literature, human lateral PFC is involved in several encoding- and response-related processes as well as mnemonic and nonmnemonic processes that are engaged during the temporary maintenance of information. Thus, lateral PFC activity cannot be ascribed to the function of a single, unitary cognitive operation.

Cortical dysfunction in patients with Huntington's disease during working memory performance

“…In healthy controls, these regions are part of a neural network, which is thought to subserve manipulation during WM as well as covert subvocal rehearsal [Baddeley, 2003;D'Esposito et al, 2000]. The load-dependent patterns which were found in these cortical and subcortical areas suggest a linear relationship between WM demand and activation in patients, similar to the activation pattern found in controls subjects.…”

Working memory for complex figures: An fMRI comparison of letter and fractal n-back tasks.

“…These authors concluded that dorsolateral PFC is involved in both maintenance and manipulation. Similarly, D'Esposito, Postle, and Rympa (2000) found sustained activation in both aspects of the PFC for tasks requiring maintenance only and for tasks involving maintenance plus manipulation. Thus, it appears that the dorsolateral PFC is not only involved in executive processes, such as the manipulation and monitoring of information, but also may work in concert with the ventrolateral PFC during active maintenance.…”

Dynamics of brain activity underlying working memory for music in a naturalistic condition

“…Executive control is thought to be embodied by the PFC; however, consensus regarding the loci of maintenance functions has not been reached so far. Some locate maintenance functions in posterior (parietal) regions of the brain, assigning the PFC a mediator role in controlling the information stored in those posterior areas (Knight & D'Esposito, 2003;Postle & Rypma, 2000;Curtis & D'Esposito, 2003;Postle, 2006). Others, in contrast, hypothesize dorsolateral regions to also reflect maintenance of online sensory representations per se (Cohen, Perlstein, Braver, Nystrom, Noll, Jonides, & Smith, 1997;Goldman-Rakic, 1987).…”

“…However, in the light of an theory of WM as an non-modular, emergent property arising from the interaction of a highly distributed neural network advanced by some researchers (Postle, 2006;Hazy, Frank, & O'Reilly, 2006;D'Esposito, Postle, & Rypma, 2000;Collete et al, 2006, Miyake & Shah, 1999, we can make some observations, namely, that filtering out the acoustic features from the music in order to find the underlying WM main executive function might be the wrong approach to studying music-driven WM networks, and the only purpose of this subtraction operation, whereby the acoustic correlates are removed, is to observe the significant implication of the subcortical sensory subsystems co-responsible for WM retrieval, filtered out with the exclusion of the acoustic correlates that are necessary for the encoding of the memoranda they represent.…”