This paper aims to explore some of the published evidence concerning the skill of multitasking, including the neuroanatomy associated with this skill, and the assessments and interventions used within the rehabilitation setting. Multitasking is an essential skill for any person to be able to live independently. It involves a number of functions associated with the frontal lobe and is one of the components of dysexecutive syndrome. Although much has been written about other aspects of executive function, multitasking has only been researched in more detail over the last decade. It is an area of particular concern for occupational therapists aiming to rehabilitate people who have sustained a brain injury.
Key words: Multitasking, executive function, dysexecutive syndrome, assessment, rehabilitation.
Introduction
Executive function is a collective name for a number of actions, which are located primarily within the frontal lobes of the human brain. Rather than performing cognitive operations, such as learning, the frontal lobes are concerned with the organisation of capabilities that will be carried out elsewhere in the brain (Baddeley et al 1997). The frontal lobe, therefore, is seen as supervisory or managerial in function.
Executive functions are individual to each person. They are shaped by fluid intelligence and the ability to attend (Konig et al 2005) and possibly by life experiences, cultural background and social situations. Burgess and Simons (2005) described the executive system as 'the high level interface between the person and the environment' (p230).
The range of symptoms that can arise following damage to the frontal lobes is referred to as the dysexecutive syndrome. These symptoms can have particularly devastating consequences for the individual and are often seen as a major challenge within rehabilitation settings (Manly et al 2002). Dysexecutive symptoms have also been associated with a poor response to treatment (Burgess and Simons 2005). The symptoms tend to fall into three main categories: disinhibited behaviours arising primarily from damage to the orbitofrontal region; motivational or drive difficulties arising from changes to the anterior cingulate region; and disorganised behaviours resulting from injury to the dorsolateral region (Mega and Cummings 2001). Clinically, patients tend to be seen with diffuse injuries, which spread across these areas giving rise to a mixture of symptoms observed within the same patient at different times (Baddeley et al 1997). Non-frontal areas such as the basal ganglia are also involved in executive function.
For the purpose of this paper, the focus is on the disorganised behaviours of the dorsolateral region of the frontal lobe and, in particular, the skill of multitasking. The reasons for this are threefold. First, executive function is extremely complex and would demand an expanded analysis. Second, there appears to have been much research published on the behavioural aspects of disinhibition, apathy and insight, whereas multitasking would appear to have been an area discussed clinically for years but with little research until the past decade. Finally, multitasking is an area of particular interest to rehabilitation professionals aiming to maximise functioning in everyday skills.
Burgess and Simons (2005) described multitasking as:
the creation, maintenance and execution of delayed intentions; the ability to recognise the need for self initiative and carry out complex meta-strategies; dovetailing of tasks to be time effective; prioritisation of tasks and deciding for oneself in the absence of feedback whether a result is satisfactory (p228).
The essential elements of multitasking are thought to be retrospective memory, prospective memory and planning (Burgess et al 2000). Error monitoring also plays an important role in multitasking (Burgess et al 2000, McDonald et al 2002). Multitasking is relevant to many areas of occupational performance because, as human beings, we are constantly switching between tasks and responding to internal or environmental stimuli. Depending on the area of brain injury, people with a multitasking skill deficit may be physically and cognitively very able and yet experience difficulties with day-to-day occupations. For example, the demands of preparing a meal involve considerable planning and preparatory actions: deciding what to cook; purchasing the ingredients; consideration of the amounts required; and consideration of the cook's ability. Once cooking, the different elements of the meal need to be prioritised and the cooking dovetailed so that everything is ready at the same time. A person with a multitasking difficulty may be observed to cook one item at a time so that, by the time he or she has finished, the items cooked first are cold. People with a multitasking deficit may be observed to start tasks but not to complete them; they may appear unreliable and disorganised.
This paper aims to consider some of the literature on multitasking and to explore the neural control aspects, the assessments and the interventions relevant in clinical practice.
Neural control
There are a number of neural structures and circuits associated with executive function, all having many connections to other parts of the brain. The frontal lobe of the human brain is divided into several areas, including the premotor and primary motor areas, the frontal eye fields and Broca's area and the prefrontal cortex. Executive functioning is mostly associated with the prefrontal cortex, which consists of the dorsolateral prefrontal cortex (DLPFC), the medial prefrontal cortex, the orbital prefrontal cortex and the anterior cingulate cortex (Fig. 1). The prefrontal cortex has numerous connections to multiple cortical and subcortical sites. The DLPFC has afferent and efferent projections to the tertiary association areas and the visual, somatosensory and auditory areas. Consequently, the DLPFC has an important role in organising and interpreting incoming information and is known to be the primary area …
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