Working memory retention systems: A state of activated long-term memory

Abstract

High temporal resolution event-related brain potential and electroencephalographic coherence studies of the neural substrate of short-term storage in working memory indicate that the sustained coactivation of both prefrontal cortex and the posterior cortical systems that participate in the initial perception and comprehension of the retained information are involved in its storage. These studies further show that short-term storage mechanisms involve an increase in neural synchrony between prefrontal cortex and posterior cortex and the enhanced activation of long-term memory representations of material held in short-term memory. This activation begins during the encoding/comprehension phase and evidently is prolonged into the retention phase by attentional drive from prefrontal cortex control systems. A parsimonious interpretation of these findings is that the long-term memory systems associated with the posterior cortical processors provide the necessary representational basis for working memory, with the property of short-term memory decay being primarily due to the posterior system. In this view, there is no reason to posit specialized neural systems whose functions are limited to those of short-term storage buffers. Prefrontal cortex provides the attentional pointer system for maintaining activation in the appropriate posterior processing systems. Short-term memory capacity and phenomena such as displacement of information in short-term memory are determined by limitations on the number of pointers that can be sustained by the prefrontal control systems.

On the capacity of attention: Its estimation and its role in working memory and cognitive aptitudes

“…Although this distinction is not clean and absolute, frontal lobe damage often results in dysfunctions of the central executive control of attention, whereas parietal lobe damage more often results in dysfunctions of consciousness, such as unilateral neglect and anosognosia (in which an individual shows no sign of awareness of an ostensibly obvious disability, such as paralysis of a limb). Ruchkin, Grafman, Cameron, and Berndt (2003) summarized physiological evidence leading to the idea that the frontal region does not contain the information in WM directly but contains pointers to that information in more posterior regions of the cortex, potentially reinforcing the notion of a difference between a frontal control mechanism and a posterior seat of attention.…”

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

“…However, discrepancies about the definition of WM exist in the current literature: it has been defined a) as a STM system applied to cognitive tasks (Engle, Tuholski, Laughlin, 1999;Conway, Kane, Bunting, Hambrick, Wilhelm, Engle, 2005); a) as a multi-component system that stores and manipulates information in STM (Baddeley & Hitch, 1974); (c) as the use of attention to manage STM (Engle, 2002); d) as immediate perceptions together with related activated long-term memories, semi-activated contextual information not in consciousness plus information that has just been in consciousness (Snyder, 2000). In this line (d) other authors' views (Engel & Singer, 2001;Ruchkin, Grafman, Cameron, & Berndt, 2003;Ward, 2003;Cowan, 1999;Ericsson & Kintsch, 1995) regard WM not as a separate system, but as an activated subset of LTM.…”

Intuition, Insight, Imagination and Creativity

“…active part of the long-term memory (LTM) network due to priming and spreading of neural activation (see the review of the evidence for this point of view in [58]). The same brain regions are involved in perception, storage and reactivation of LTM representations.…”