Original Research Article
Multiple effects of prefrontal lesions on task-switching
Tim Shallice 1, 2, Donald T. Stuss 3, 4*, Terence W. Picton 3, 4, Michael P. Alexander 5, 6 and Susan Gillingham 4
1 Institute of Cognitive Neuroscience, University College London, UK
2 Cognitive Neuroscience Sector, SISSA, Italy
3 Departments of Psychology and Medicine, University of Toronto, Canada
4 Rotman Research Institute at Baycrest, Canada
5 Harvard Medical School, USA
6 Behavioral Neurology Unit, Beth Israel Deaconess Medical Center, USA
2 Cognitive Neuroscience Sector, SISSA, Italy
3 Departments of Psychology and Medicine, University of Toronto, Canada
4 Rotman Research Institute at Baycrest, Canada
5 Harvard Medical School, USA
6 Behavioral Neurology Unit, Beth Israel Deaconess Medical Center, USA
This study examined the performance of 41 patients with focal prefrontal cortical lesions and 38 healthy controls on a task-switching procedure. Three different conditions were evaluated: single tasks without switches and two switching tasks with the currently relevant task signalled either 1500 ms (Long Cue) or 200 ms (Short Cue) before the stimulus. Patients with Superior Medial lesions showed both a general slowing of reaction time (RT) and a signifi cantly increased switch cost as measured by RT. No other prefrontal group showed this increased reaction time switch cost. Increased error rates in the switching conditions, on the other hand, were observed in patients with Inferior Medial lesions and, to a lesser extent, ones with Superior Medial lesions. Patients with left dorsolateral lesions (9/46v) showed slower learning of the task as indicated by a high error rate early on. Several different processes are involved in task-switching and these are selectively disrupted by lesions to specifi c areas of the frontal lobes.
Keywords: task-switching, switch-cost, anterior attentional system, frontal lobes, focal lesions, reaction time, errors
Copyright: © 2008 Shallice, Stuss, Picton, Alexander and Gillingham. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
*Correspondence: Donald T. Stuss, Rotman Research Institute, Baycrest 3560 Bathurst Street, Toronto, ON, M6A 2E1, Canada; Departments of Psychology and Medicine, University of Toronto, Toronto, ON, M5S 1A6, Canada. e-mail: dstuss@rotman-baycrest.on.ca
Citation: Shallice T, Stuss DT, Picton TW, Alexander MP and Gillingham S (2008) Multiple effects of prefrontal lesions on task-switching. Front. Hum. Neurosci. (2007) 1:2. doi:10.3389/neuro.09.002.2007
Received: 31 August 2007; paper pending published: 29 November 2007; accepted: 02 February 2008; published online: 28 March 2008.
Edited by:
Robert T. Knight, University of California Berkeley, USA
Reviewed by:
Marcel Brass, Ghent University, Belgium
Leon Deouell, Interdisciplinary Center for Neural Computation, Hebrew University, Israel; The Hebrew University of Jerusalem, Israel
Leon Deouell, Interdisciplinary Center for Neural Computation, Hebrew University, Israel; The Hebrew University of Jerusalem, Israel
*Correspondence: Donald T. Stuss, Rotman Research Institute, Baycrest 3560 Bathurst Street, Toronto, ON, M6A 2E1, Canada; Departments of Psychology and Medicine, University of Toronto, Toronto, ON, M5S 1A6, Canada. e-mail: dstuss@rotman-baycrest.on.ca
