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Fluid intelligence and naturalistic task impairments after focal brain lesions.

Published version
Peer-reviewed

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Authors

Smith, Verity 
Pinasco, Clara 
Achterberg, Jascha 
Mitchell, Daniel J 
Das, Tilak 

Abstract

Classical executive tasks, such as Wisconsin card-sorting and verbal fluency, are widely used as tests of frontal lobe control functions. Since the pioneering work of Shallice and Burgess (1991), it has been known that complex, naturalistic tasks can capture deficits that are missed in these classical tests. Matching this finding, deficits in several classical tasks are predicted by loss of fluid intelligence, linked to damage in a specific cortical "multiple-demand" (MD) network, while deficits in a more naturalistic task are not. To expand on these previous results, we examined the effect of focal brain lesions on three new tests-a modification of the previously-used Hotel task, a new test of task switching after extended delays, and a test of decision-making in imagined real-life scenarios. As potential predictors of impairment we measured volume of damage to a priori MD and default mode (DMN) networks, as well as cortical damage outside these networks. Deficits in the three new tasks were substantial, but were not explained by loss of fluid intelligence, or by volume of damage to either MD or DMN networks. Instead, deficits were associated with diverse lesions, and not strongly correlated with one another. The results confirm that naturalistic tasks capture cognitive deficits beyond those measured by fluid intelligence. We suggest, however, that these deficits may not arise from specific control operations required by complex behaviour. Instead, like everyday activities, complex tasks combine a rich variety of interacting cognitive components, bringing many opportunities for processing to be disturbed.

Description

Keywords

Default mode network, Executive function, Fluid intelligence, Naturalistic tasks, Brain, Cognition Disorders, Cognitive Dysfunction, Executive Function, Frontal Lobe, Humans, Intelligence, Magnetic Resonance Imaging, Neuropsychological Tests

Journal Title

Cortex

Conference Name

Journal ISSN

0010-9452
1973-8102

Volume Title

146

Publisher

Elsevier BV
Sponsorship
Medical Research Council (MC_UU_00005/6)