The unity and diversity of executive functions and their contributions to complex "Frontal Lobe" tasks: a latent variable analysis.

▪ Abstract The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed

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An integrative theory of prefrontal cortex function

Publisher Summary This chapter focuses on the modern notion of short-term memory, called working memory. Working memory refers to the temporary maintenance of information that was just experienced or just retrieved from long-term memory but no longer exists in the external environment. These internal representations are short-lived, but can be maintained for longer periods of time through active rehearsal strategies, and can be subjected to various operations that manipulate the information in such a way that makes it useful for goal-directed behavior. Working memory is a system that is critically important in cognition and seems necessary in the course of performing many other cognitive functions, such as reasoning, language comprehension, planning, and spatial processing. This chapter demonstrates the functional importance of dopamine to working memory function in several ways. Elucidation of the cognitive and neural mechanisms underlying human working memory is an important focus of cognitive neuroscience and neurology for much of the past decade. One conclusion that arises from research is that working memory, a faculty that enables temporary storage and manipulation of information in the service of behavioral goals, can be viewed as neither a unitary, nor a dedicated system. Data from numerous neuropsychological and neurophysiological studies in animals and humans demonstrates that a network of brain regions, including the prefrontal cortex, is critical for the active maintenance of internal representations.

Chapter 11 Working memory

Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Attention and Effort

Amnesia, autobiographical memory, and confabulation

From vocabulary learning to imitating sequences of motor actions, the ability to plan, represent, and recall a novel sequence of items in the correct order is fundamental for many verbal and nonverbal higher level cognitive activities. Here we review phenomena of serial order documented across the verbal, visual, and spatial short-term memory domains and interpret them with reference to the principles of serial order and ancillary assumptions instantiated in contemporary computational theories of memory for serial order. We propose that functional similarities across domains buttress the notion that verbal, visual, and spatial sequences are planned and controlled by a competitive queuing (CQ) mechanism in which items are simultaneously active in parallel and the strongest item is chosen for output. Within the verbal short-term memory CQ system, evidence suggests that serial order is represented via a primacy gradient, position marking, response suppression, and cumulative matching. Evidence further indicates that output interference operates during recall and that item similarity effects manifest during both serial order encoding and retrieval. By contrast, the principles underlying the representation of serial order in the visual and spatial CQ systems are unclear, largely because the relevant studies have yet to be performed. In the spatial domain, there is some evidence for a primacy gradient and position marking, whereas in the visual domain there is no direct evidence for either of the principles of serial order. We conclude by proposing some directions for future research designed to bridge this and other theoretical gaps in the literature.

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Memory for serial order across domains:An overview of the literature and directions for future research.

A study of 4-and 5-year-old children investigated whether measures of phonological memory and rhyme awareness reflect a common phonological processing skill or differentiable phonological abilities. Tests of phonological memory, rhyme oddity detection, reading, vocabulary and non-verbal intelligence were given to the children in each age group. Factor analyses performed on the measures showed that phonological memory and rhyme awareness measures did indeed share a common phonological processing component, but other analyses established that the two types of phonological processing task were nonetheless differentially linked with reading and vocabulary development. The two phonological memory measures taken in the study–non-word repetition and digit span–were significantly related to vocabulary knowledge in both the ages 4 and 5 groups, and to reading achievement at age 5, but not age 4. These findings replicate and extend our earlier findings. In contrast, rhyme awareness scores were not significantly associated with vocabulary knowledge at either age, but were strongly related to scores on one of the reading tests, a multiple-choice measure, at both ages 4 and 5. The pattern of findings indicates that, although there appears to be a common phonological processing component underpinning phonological memory and phonological awareness tasks, the tasks also reflect separate cognitive skills which make differential contributions to reading and vocabulary development.

Differentiating phonological memory and awareness of rhyme: Reading and vocabulary development in children

Two studies investigated recognition of pictures of faces, focusing on the effects of changes in appearance of the face from presentation to test and type of processing or encoding. Experiment 1 demonstrated that (a) previously seen faces changed in pose and facial expression were discriminated from "new" faces essentially as well as pictures identical at presentation and test; (b) major changes in the appearance of a face ("disguises") reduced recognition almost to the level of chance; and (c) subjects encoding faces in terms of personality characteristics showed better recognition performance than subjects whose processing was based on physical, facial features. Experiment 2 expanded on result (b), utilizing photographs with systematic variations in pose and in the presence/absence of glasses, wig, and beard. The design required subjects to learn names for target faces and then to identify those targets in a series of test photographs. The manipulation of pose and disguising features produced effects on probability of identification that were orderly and dramatic in magnitude. Simple changes in appearance can effectively interfere with recognition of faces.

Alan D. Baddeley

Papers

Amnesia, autobiographical memory, and confabulation

Memory for serial order across domains:An overview of the literature and directions for future research.

Differentiating phonological memory and awareness of rhyme: Reading and vocabulary development in children

When face recognition fails.

Analysis of the episodic memory deficit in early Alzheimer's disease: Evidence from the doors and people test