The Association between the Binding Processes of Working Memory and Vascular Risk Profile in Adults

Episodic buffer (EB), a key component of working memory, seems to have a rather complicated function as part of binding processes. Recent papers on the field claim that binding processes of working memory (WM) are assisted by attention and executive functions. On the same page, vascular pathology is gaining more ground as the main underlying cause for many brain pathologies. Hypercholesterolemia, hypertension, obesity, diabetes, lack of exercise and smoking are the most common risk factors that people of all ages suffer from and constitute the main vascular risk factors responsible for a possible decline in executive functions and attention. Thus, this research is an attempt to examine the relation between the binding functions of WM and the existence of vascular risk factors via a computerized test focusing on feature binding. The study comprised adults (n = 229) with and without vascular risk factors. The main tools used were a biomarker questionnaire and a feature binding test (FBT). The results showed that participants who report suffering from one or more vascular risk factors had significantly lower performance on specific subtasks of the FBT in comparison to the participants who were healthy. This allows us to assume that there might be a positive association between feature binding and a vascular risk profile in adults, and such a test could be a useful diagnostic tool for early cognitive impairment due to incipient vascular pathology.

Is the Episodic Buffer of Baddeley independent of the Central Executive? A new measure of the Episodic Buffer

El Retén Episódico (RE) está tomando un creciente papel central en las explicaciones sobre el funcionamiento de la memoria operativa. De hecho, los últimos estudios de Baddeley y sus colaboradores sitúan al RE en el corazón del sistema de memoria. Recientemente la discusión también atañe a si este componente de la memoria operativa presenta una naturaleza independiente respecto a los recursos del ejecutivo central. Algunos estudios muestran como en tareas automatizadas, la construcción y mantenimiento de elementos almacenados en el RE no requieren de recursos desde el ejecutivo central. El presente trabajo pretende analizar esta cuestión para lo que se toman diferentes variables y se ha diseñado un nuevo test para medir el EB. En este test de doble tarea, la tarea secundaria consiste en la lectura de textos sencillos que contienen palabras ocultas. Los resultados muestran como a pesar del aumento del procesamiento debido al incremento de la longitud de los textos, no se produce un aumento en la carga demandada por el ejecutivo central, ni en la creación de los agrupamientos de información ni en su mantenimiento. Es por ello, que pensamos que el RE bajo ciertas circunstancias es independiente del ejecutivo central. The Episodic Buffer (EB) is taking on an increasingly central role in explanations regarding the functioning of working memory. In fact, in the most recent studies by Baddeley and his collaborators, the EB has situated itself at the core of this memory system. Recently under discussion is that this component of working memory seems to demonstrate an independent nature with respect to central executive resourcing. Some studies show that in automatic tasks the creation and maintenance of elements stored in the episodic buffer do not require resources from the central executive. The current work attempts to evaluate this assumption for what different variables are taken and a new test has been developed to measure the EB. In this double task test, the secondary task consists of reading short simple texts that contain missing words. The results show that further processing due to increasing the length of the texts does not correspond to higher load demands made on the central executive, nor in the creation (organization) of chucks or their maintenance. Thus, we believe the EB is under certain circumstances independent of the central executive.

Multicomponent Working Memory System with Distributed Executive Control

The working memory model with distributed executive control accounts for the interactions between working memory and multi-tasking performance. The working memory system supports planned actions by relying on two capacity-limited domain-general and two time-limited domain-specific modules. Domain-general modules are the episodic buffer and the executive module. The episodic buffer stores multimodal representations and uses attentional refreshment to counteract information loss and to consolidate information in episodic long-term memory. The executive module maintains domain-general information relevant for the current task. The phonological buffer and the visuospatial module are domain specific; the former uses inner speech to maintain and to rehearse phonological information, whereas the latter holds visual and spatial representations active by means of image revival. For its operation, working memory interacts with declarative and procedural long-term memory, gets input from sensory registers, and uses the motor system for output.

The Time-Based Resource-Sharing Model of Working Memory

The time-based resource-sharing model considers working memory as the workspace in which mental representations are built, maintained, and transformed for completing goal-oriented tasks. Its main component is made of an episodic buffer and a procedural system that form an executive loop in which processing and storage share domain-general attentional resources on a temporal basis. Because working memory representations decay with time when attention is diverted, the cognitive load of a given activity is the proportion of time during which it occupies attention and prevents it from counteracting this decay through attentional refreshing. Consequently, recall in working memory tasks is an inverse function of the cognitive load of concurrent processing. Besides this system, an independent domain-specific maintenance system exists for verbal, but not visuospatial, information. Within this framework, working memory development mainly results from increasing processing speed that affects both the duration of the distraction of attention by concurrent tasks and refreshing efficiency.

A Multicomponent Model of Working Memory

The multicomponent model aims to provide a broad theoretical framework enabling both more detailed fractionation and analysis of its components, and a capacity for it be used fruitfully beyond the laboratory. In its current form it comprises four interacting components. Two of these are modality-specific memory storage systems, one verbal-acoustic, the phonological loop, and one visuospatial, the sketchpad. Information in both these stores can be temporarily maintained via focused attention termed ‘refreshing’, while the phonological loop can also maintain familiar verbalizable material by subvocal or overt rehearsal. Both subsystems are controlled by a third component, the central executive, a supervisory system with limited resources. The central executive is principally concerned with internally directed attentional control processes but also has a role in the attentional selection of perceptual information. Information from these three components is coordinated with information from perception and long-term memory through the fourth component, a multidimensional, multimodal episodic buffer. This component is capable of holding up to around four episodic chunks, and is a valuable but essentially passive storage system, controlled by the central executive and accessible to conscious awareness. The multicomponent model has been systematically developed using a number of experimental tools. These include, principally, similarity effects to identify the type of coding involved, concurrent task methods to assess the contributions of the various subsystems to complex tasks, and neuropsychological evidence, in particular from the study of single cases with very specific deficits. The model continues to evolve and has proved successful both in accounting for a broad range of data on memory and related cognitive areas and in its application to the understanding of a wide range of cognitive activities and populations.

Parietal low beta rhythm provides a dynamical substrate for a working memory buffer

Working memory (WM) is a component of the brain’s memory systems vital for interpretation of sequential sensory inputs and consequent decision making. Anatomically, WM is highly distributed over the prefrontal cortex (PFC) and the parietal cortex (PC). Here we present a biophysically detailed dynamical systems model for a WM buffer situated in the PC, making use of dynamical properties believed to be unique to this area. We show that the natural beta1 rhythm (12 to 20 Hz) of the PC provides a substrate for an episodic buffer that can synergistically combine executive commands (e.g., from PFC) and multimodal information into a flexible and updatable representation of recent sensory inputs. This representation is sensitive to distractors, it allows for a readout mechanism, and it can be readily terminated by executive input. The model provides a demonstration of how information can be usefully stored in the temporal patterns of activity in a neuronal network rather than just synaptic weights between the neurons in that network.