Academic journal article Cognitive, Affective and Behavioral Neuroscience

On How High Performers Keep Cool Brains in Situations of Cognitive Overload

Academic journal article Cognitive, Affective and Behavioral Neuroscience

On How High Performers Keep Cool Brains in Situations of Cognitive Overload

Article excerpt

What happens in the brain when we reach or exceed our capacity limits? Are there individual differences for performance at capacity limits? We used functional magnetic resonance imaging (fMRI) to investigate the impact of increases in processing demand on selected cortical areas when participants performed a parametrically varied and challenging dual task. Low-performing participants respond with large and load-dependent activation increases in many cortical areas when exposed to excessive task requirements, accompanied by decreasing performance. It seems that these participants recruit additional attentional and strategy-related resources with increasing difficulty, which are either not relevant or even detrimental to performance. In contrast, the brains of the high-performing participants "keep cool" in terms of activation changes, despite continuous correct performance, reflecting different and more efficient processing. These findings shed light on the differential implications of performance on activation patterns and underline the importance of the interindividual-differences approach in neuroimaging research.

Increasing demands in cognitive tasks are often correlated with increasing stress for the performer. The risk of a breakdown in performance at the edge of mental overload creates an emergency state in which calmness, combined with fully functional thinking and focused attention, is the key determinant for making the most of the situation. There are many settings in everyday life in which good performers can turn potential harm into accomplishment. in many professional domains, society is concerned to select and train such individuals for demanding activities. Therefore, learning about what happens in the brain when we reach and exceed our capacity limits while performing complex tasks and learning more about individual differences in performing these tasks not only is of relevance for basic research, but also has practical implications-for example, when staff designated for work in highly manding situations is selected.

In this study, we used a brain-imaging approach to examine individual differences in cognitive performance at the limits of working memory (WM) capacity and beyond, WM, in this context, is seen as "the set of mental processes holding limited information in a temporarily accessible state in service of cognition" (Cowan et al., 2005, p. 42) and seems to predict a wide variety of higher order cognitive tasks (Daneman & Carpenter, 1980; Kyllonen & Christal, 1990). Capacity limits in WM are expressed as decreasing performance in response to increasing demands. The nature of capacity limits has been discussed extensively in the literature (e.g., Cowan, 2001 , 2005), but there still is no consensus about the exact definition of the limits and how best to characterize them. Also, little is known about the underlying neural processes as the capacity limits of WM are reached and, especially, exceeded. Numerous functional neuroimaging studies have consistently reported load-dependent activation changes in prefrontal areas (e.g., Braver et al., 1997; Carlson et al., 1998; Linden et al., 2003; Nystrom et al., 2000; Owen, McMillan, Laird, & Bullmore, 2005; Schumacher et al., 1996) and also in parietal cortices (e.g., Linden et al., 2003; Todd & Marois, 2004; Xu & Chun, 2006). Although WM load has been parametrically manipulated in these studies, it has been restricted to relatively easy levels and usually has not explicitly challenged or exceeded the capacity limits of the participants, which was the focus of our interest in the present study. In a review, Kane and Engle (2002) have argued that the prefrontal cortices (PFCs) are critical for effective WM capacity and have suggested that individual differences in WM capacity might also be mirrored by individual differences in prefrontal areas, especially in the dorsolateral PFC (DLPFC). In the neuroimaging literature, some authors have indeed observed prefrontal activation changes in response to task load - that is, a decrease in prefrontal activation at high levels of load, which has been interpreted as a breakdown in neural networks (Goldberg et al. …

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