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From the Department of Neurology (Dr. Alexander), Beth Israel Deaconess Medical Center, Boston, MA; The Rotman Research Institute (Drs. Alexander, Stuss, and Picton and S. Gillingham), Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada; Memory Disorders Research Center (Dr. Alexander), Boston University; Institute of Cognitive Neuroscience (Dr. Shallice), University College, London, UK and SISSA, Trieste, Italy.
Address correspondence and reprint requests to Dr. Michael P. Alexander, Behavioral Neurology Unit, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215; malexand{at}bidmc.harvard.edu
Background: Investigations of cognitive deficits after frontal lobe damage have commonly relied on multidimensional tests and relatively coarse specification of lesion anatomy. Some form of impairment in attention is often asserted to cause the revealed deficits.
Objective: To describe a disorder of attention in patients with frontal damage using a theoretical model of the fundamental cognitive processes that underlie attention.
Methods: The ability to perform a task of concentrated responding was studied in 43 patients with well-defined chronic frontal lesions and 38 control subjects using a continuous reaction time (RT) test. Performance measures were mean RT, RT across blocks of the test, and errors. Lesion measures were coarse localization and a hot-spot analysis to detect finer grained lesion effects.
Results: Only patients with lesions in the right superomedial (SM) frontal regions had significantly prolonged RT consistently across the entire test. The critical lesion was in Brodmann’s areas 24, 32, 9, and 46 days and in the adjacent corpus callosum. Patients with lesions in left lateral frontal (LL) regions made significantly more errors on the 20% of trials in the first block. The critical lesion was in areas 44, 45, and 47/12.
Conclusion: Concentrating attention to respond is affected by lesions in two different frontal regions for reasons that reflect impairments in different cognitive processes. Right superomedial lesions cause an insufficient energizing of attention to respond. Left lateral lesions cause defective setting of specific stimulus-response contingencies. Constrained tests of attention can demonstrate impairments in specific cognitive operations following lesions to different regions of the frontal lobes.
Supported in part by Canadian Institutes of Health Research MT12853 and GR14974, and NS 26985 (Memory Disorders Research Center) from the NIH; Reva James Leeds Chair in Neuroscience and Research Leadership (Dr. Stuss) and Anne and Max Tanenbaum Chair in Cognitive Neuroscience (Dr. Picton).
Disclosure: The authors report no conflicts of interest.
Received July 30, 2004. Accepted in final form April 27, 2005.
This article has been cited by other articles:
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  M. P. Alexander, D. T. Stuss, T. Picton, T. Shallice, and S. Gillingham Regional frontal injuries cause distinct impairments in cognitive control Neurology, May 1, 2007; 68(18): 1515 - 1523. [Abstract] [Full Text] [PDF]
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 T. W. Picton, D. T. Stuss, M. P. Alexander, T. Shallice, M. A. Binns, and S. Gillingham Effects of Focal Frontal Lesions on Response Inhibition Cereb Cortex, April 1, 2007; 17(4): 826 - 838. [Abstract] [Full Text] [PDF]
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 V. Hachinski, C. Iadecola, R. C. Petersen, M. M. Breteler, D. L. Nyenhuis, S. E. Black, W. J. Powers, C. DeCarli, J. G. Merino, R. N. Kalaria, et al. National Institute of Neurological Disorders and Stroke-Canadian Stroke Network Vascular Cognitive Impairment Harmonization Standards Stroke, September 1, 2006; 37(9): 2220 - 2241. [Abstract] [Full Text] [PDF]
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