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

This paper reports psychological observations on men during a simulated (pressure chamber) dive to 660 m of sea-water (msw) using a gas mixture known as Trimix (He-O2-N2). Recent studies by Bennett (1981) have suggested that this mixture allows for faster compression with less impairment in performance than the mixture traditionally used (He-O2). Data were obtained from two divers on tests of cognitive performance, namely arithmetic ability, grammatical reasoning, perceptual speed, visuo-spatial manipulation and semantic processing. At maximum depth there was a severe blanket impairment of ability to perform any of the tests. However, at shallower depths the impairments were not as marked, with performance at 300 msw close to that measured at surface pressure. Subjects were also required to fill in two questionnaires, one concerned with the quality of their previous night's sleep, the other with their mood at the time. Sleep quality was disrupted throughout the dive, with one subject affected rather more ...

A Trimix saturation dive to 660 m Studies of cognitive performance, mood and sleep quality

Five experiments tested the prediction, from a simple chaining model, that interleaving irrelevant material will substantially disrupt immediate serial recall. Experiment 1 interpolated long or short words between items in an auditory digit span test. These two "sandwich" conditions disrupted recall to an equal but moderate extent. Experiment 2 presented mixed lists of digits and words, cuing one or the other before or after presentation. Precuing led to substantially better recall. Experiment 3 used articulatory suppression to rule out the hypothesis that recall was protected from the sandwich effect by subvocal rehearsal. Experiment 4 combined the sandwich effect with a concurrent task, finding clear effects of both but no interaction. Experiment 5 showed that the predictability of interpolated material did not influence recall. These results can be explained by adding an attentional preprocessor to standard chaining models. Immediate memory span, like speech itself, requires that order information be preserved. This has presented a major problem both to models of immediate serial recall and to models of language behavior. Although the range of models of serial order is wide, they tend to fall into two broad categories, one assuming that order is imposed by means of an external structure and one assuming a form of chaining whereby associative links are formed between successive items (see Lewandowsky & Murdock, 1989, for a more detailed discussion of existing models).

The sandwich effect: The role of attentional factors in serial recall.

Sense and sensitivity in phonological memory and vocabulary development: a reply to Bowey (1996)

Seven- and eight-year-old skilled and less-skilled comprehenders were compared on a sentence recognition task in two conditions varying in memory load and retention interval. Integration of story information during comprehension was indexed by inflated recognition errors of foils that had been constructed by integrating information across original story sentences. Skilled comprehenders exhibited more accurate memory for sentences than less-skilled comprehenders. However, the groups did not differ in the degree to which they integrated information with minimal memory demand, or in their tendency to integrate information and retain the integrated representations with increased memory demand. These results were interpreted as evidence that integration deficits do not lie at the root of reading comprehension difficulties in mainstream children.

Does weak reading comprehension reflect an integration deficit

Recent research has indicated that visual working memory capacity for unidimensional items might be boosted by focusing on all presented items, as opposed to a subset of them. However, it is not clear whether the same outcomes would be observed if more complex items were used which require feature binding, a potentially more demanding task. The current experiments, therefore, examined the effects of encoding strategy using multidimensional items in tasks that required feature binding. Effects were explored across a range of different age groups (Experiment 1) and task conditions (Experiment 2). In both experiments, participants performed significantly better when focusing on a subset of items, regardless of age or methodological variations, suggesting this is the optimal strategy to use when several multidimensional items are presented and binding is required. Implications for task interpretation and visual working memory function are discussed.

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Alan D. Baddeley

Papers

A Trimix saturation dive to 660 m Studies of cognitive performance, mood and sleep quality

The sandwich effect: The role of attentional factors in serial recall.

Sense and sensitivity in phonological memory and vocabulary development: a reply to Bowey (1996)

Does weak reading comprehension reflect an integration deficit

Remember some or remember all? Ageing and strategy effects in visual working memory: