Are core component processes of executive function dissociable within the frontal lobes? Evidence from humans with focal prefrontal damage

Ami Tsuchida, Lesley K. Fellows
Cortex. 2013-07-01; 49(7): 1790-1800
DOI: 10.1016/j.cortex.2012.10.014

PubMed

Tsuchida A(1), Fellows LK.

Author information:
(1)Department of Neurology & Neurosurgery, Montreal Neurological Institute,
McGill University, Montreal, Quebec, Canada.

Executive function encompasses a range of control processes supporting flexible,
goal-directed behaviour. Attentional set-shifting, updating of information in
working memory, and inhibitory control have been proposed as key components of
executive function, but debate continues as to the validity of this conceptual
framework, and the neural substrates of these putative components. Here we
examined prefrontal structure-function relationships for each of these component
processes in a large cohort of patients with focal prefrontal damage. Forty-five
patients with focal damage to various sectors of prefrontal cortex (PFC), and 50
demographically matched healthy control subjects performed an attention shifting
task, the Stroop colour naming task, and a spatial search task. Voxel-based
lesion-symptom mapping revealed that damage to left ventrolateral PFC led to
impaired performance on both the Stroop and attention shifting tasks. In
contrast, performance of the spatial search task depended on several regions
within PFC, but notably not left ventrolateral PFC. These observations were
confirmed with direct comparison of performance between patients grouped
according to lesion location. This dissociation partly supports the component
process view of executive function, distinguishing the goal-directed regulation
of attention (perhaps specifically in the verbal domain) from the requirements
of the spatial search task, including the updating of information in spatial
working memory. These findings are easier to reconcile with modular,
material-specific accounts than with more unitary models of executive function.