Neuroimaging of brain changes associated with cognitive impairment in Parkinson's disease

Journal of Neuropsychology

Volumn 7, Issue 2, 2013, Pages 225-240

  Christopher, Leigh ^a   Strafella, Antonio P ^a,b  

^a UNIVERSITY OF TORONTO   (Canada)

^b TORONTO WESTERN HOSPITAL   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

BRAIN; COGNITIVE DEFECT; CONFERENCE PAPER; HUMAN; MYELINATED NERVE; NERVE TRACT; NEUROIMAGING; NONMYELINATED NERVE; PARKINSON DISEASE; PATHOLOGY; PATHOPHYSIOLOGY; SCINTISCANNING;

BRAIN; COGNITION DISORDERS; HUMANS; NERVE FIBERS, MYELINATED; NERVE FIBERS, UNMYELINATED; NEURAL PATHWAYS; NEUROIMAGING; PARKINSON DISEASE;

EID: 84883685662     PISSN: 17486645     EISSN: 17486653     Source Type: Journal    
DOI: 10.1111/jnp.12015     Document Type: Conference Paper

References (77)

1. Aalto, S., Brück, A., Laine, M., Någren, K., &, Rinne, J. O., (2005). Frontal and temporal dopamine release during working memory and attention tasks in healthy humans: A positron emission tomography study using the high-affinity dopamine D2 receptor ligand [(11)C]FLB 457. Journal of Neuroscience, 25, 2471-2477. doi: 10.1523/JNEUROSCI.2097-04.2005
2. Aarsland, D., Larsen, J. P., Karlsen, K., Lim, N. G., &, Tandberg, E., (1999). Mental symptoms in Parkinson's disease are important contributors to caregiver distress. International Journal of Geriatric Psychiatry, 14, 866-874 doi: 10.1002/(SICI)1099-1166(199910)14:10<866::AID-GPS38>3.0.CO;2-Z
3. Aarsland, D., Larsen, J., Lolk, A., &, Andersen, K., (2003). Prevalence and characteristics of dementia in Parkinson disease: An 8-year prospective study. Archives of Neurology, 60, 387-392. doi: 10.1001/archneur.60. 3.387
4. Aarsland, D., Larsen, J. P., Tandberg, E., &, Laake, K., (2000). Predictors of nursing home placement in Parkinson's disease: A population-based, prospective study. Journal of the American Geriatrics Society, 48, 938-942.
5. Apostolova, L. G., Beyer, M., Green, A. E., Hwang, K. S., Morra, J. H., Chou, Y. Y.,., Thompson, P. M., (2010). Hippocampal, caudate, and ventricular changes in Parkinson's disease with and without dementia. Movement Disorders, 25, 687-688. doi: 10.1002/mds.22799
6. Beyer, M. K., Janvin, C. C., Larsen, J. P., &, Aarsland, D., (2007). A magnetic resonance imaging study of patients with Parkinson's disease with mild cognitive impairment and dementia using voxel-based morphometry. Journal of Neurology, 78, 254-259. doi: 10.1136/jnnp.2006.093849
7. Bohnen, N. I., Kaufer, D. I., Hendrickson, R., Ivanco, L. S., Lopresti, B. J., Constantine, G. M.,., Dekosky, S. T., (2006). Cognitive correlates of cortical cholinergic denervation in Parkinson's disease and parkinsonian dementia. Journal of Neurology, 253, 242-247. doi: 10.1007/s00415-005-0971-0
8. Bohnen, N. I., Kaufer, D. I., Ivanco, L. S., Lopresti, B., Koeppe, R. A., Davis, J. G.,., Dekosky, S. T., (2003). Cortical cholinergic function is more severely affected in parkinsonian dementia than in Alzheimer disease: An in vivo positron emission tomographic study. Archives of Neurology, 60, 1745-1748. doi: 10.1001/archneur.60.12.1745
9. Bohnen, N. I., Koeppe, R. A., Minoshima, S., Giordani, B., Albin, R. L., Frey, K. A., &, Kuhl, D. E., (2011). Cerebral glucose metabolic features of Parkinson disease and incident dementia: Longitudinal study. Journal of Nuclear Medicine, 52, 848-855. doi: 10.2967/jnumed.111.089946
10. Bohnen, N. I., Muller, M. L. T. M., Kotagal, V., Koeppe, R. A., Kilbourn, M. R., Gilman, S.,., Frey, K. A., (2012). Heterogeneity of cholinergic denervation in Parkinson's disease without dementia. Journal of Cerebral Blood Flow & Metabolism, 32, 1609-1617. doi: 10.1038/jcbfm.2012.60
11. Boileau, I., Warsh, J. J., Guttman, M., Saint-Cyr, J. A., McCluskey, T., Rusjan, P.,., Kish, S. J., (2008). Elevated serotonin transporter binding in depressed patients with Parkinson's disease: A preliminary PET study with [11C]DASB. Movement Disorders, 23, 1776-1780. doi: 10.1002/mds.22212
12. Brück, A., Aalto, S., Nurmi, E., Bergman, J., &, Rinne, J. O., (2005). Cortical 6-[(18)F]fluoro-L-dopa uptake and frontal cognitive functions in early Parkinson's disease. Neurobiology of Aging, 26, 891-898. doi: 10.1016/j.neurobiolaging.2004.07.014
13. Brück, A., Kurki, T., Kaasinen, V., Vahlberg, T., &, Rinne, J. O., (2004). Hippocampal and prefrontal atrophy in patients with early non-demented Parkinson's disease is related to cognitive impairment. Journal of Neurology, Neurosurgery & Psychiatry, 75, 1467-1469. doi: 10.1136/jnnp.2003.031237
14. Brück, A., Portin, R., Lindell, A., Laihinen, A., Bergman, J., Haaparanta, M.,., Rinne, J. O., (2001). Positron emission tomography shows that impaired frontal lobe functioning in Parkinson's disease is related to dopaminergic hypofunction in the caudate nucleus. Neuroscience Letters, 311, 81-84. doi: 10.1016/S0304-3940(01)02124-3
15. Burton, E. J., Mckeith, I. G., Burn, D. J., Williams, E. D., &, Brien, J. T. O., (2004). Cerebral atrophy in Parkinson's disease with and without dementia: A comparison with Alzheimer's disease, dementia with Lewy bodies and controls. Brain, 127, 791-800. doi: 10.1093/brain/awh088
16. Camicioli, R., Gee, M., Bouchard, T. P., Fisher, N. J., Hanstock, C. C., Emery, D. J., &, Martin, W. R. W., (2009). Voxel-based morphometry reveals extra-nigral atrophy patterns associated with dopamine refractory cognitive and motor impairment in Parkinsonism. Parkinsonism & Related Disorders, 15, 187-195. doi: 10.1016/j.parkreldis.2008.05.002
17. Candy, J. M., Perry, R. H., Perry, E. K., Irving, D., Blessed, G., Fairbairn, A. F., &, Tomlinson, B. E., (1983). Pathological changes in the nucleus of meynert in Alzheimer's and Parkinson's diseases. Journal of the Neurological Sciences, 59, 277-289. doi: 10.1016/0022-510X(83)90045-X
18. Caviness, J. N., Driver-Dunckley, E., Connor, D. J., Sabbagh, M. N., Hentz, J. G., Noble, B.,., Adler, C. H., (2007). Defining mild cognitive impairment in Parkinson's disease. Movement Disorders, 22, 1272-1277. doi: 10.1002/mds.21453
19. Chaudhuri, K. R., Healy, D. G., &, Schapira, A. H. V., (2006). Non-motor symptoms of Parkinson's disease: Diagnosis and management. Lancet Neurology, 5, 235-245. doi: 10.1016/S1474-4422(06)70373-8
20. Cheesman, A. L., Barker, R. A., Lewis, S. J. G., Robbins, T. W., Owen, A. M., &, Brooks, D. J., (2005). Lateralisation of striatal function: Evidence from [(18)F]-dopa PET in Parkinson's disease. Journal of Neurology, Neurosurgery & Psychiatry, 76, 1204-1210. doi: 10.1136/jnnp.2004.055079
21. Clatworthy, P. L., Lewis, S. J. G., Brichard, L., Hong, Y. T., Izquierdo, D., Clark, L.,., Robbins, T. W., (2009). Dopamine release in dissociable striatal subregions predicts the different effects of oral methylphenidate on reversal learning and spatial working memory. Journal of Neuroscience, 29, 4690-4696. doi: 10.1523/JNEUROSCI.3266-08.2009
22. Cools, R., (2001). Enhanced or impaired cognitive function in Parkinson's disease as a function of dopaminergic medication and task demands. Cerebral Cortex, 11, 1136-1143. doi: 10.1093/cercor/11.12.1136
23. Cools, R., (2006). Dopaminergic modulation of cognitive function-implications for L-DOPA treatment in Parkinson's disease. Neuroscience and Biobehavioural Reviews, 30, 1-23. doi: 10.1093/brain/awf052
24. Cools, R., Altamirano, L., &, D'Esposito, M., (2006). Reversal learning in Parkinson's disease depends on medication status and outcome valence. Neuropsychologia, 44, 1663-1673. doi: 10.1016/j.neuropsychologia.2006. 03.030
25. Cools, R., Stefanova, E., Barker, R. A., Robbins, T. W., &, Owen, A. M., (2002). Dopaminergic modulation of high-level cognition in Parkinson's disease: The role of the pre-frontal cortex revealed by PET. Brain, 125, 584-594. doi: 10.1093/brain/awf052
26. Cropley, V. L., Fujita, M., Bara-Jimenez, W., Brown, A. K., Zhang, X.-Y., Sangare, J.,., Innis, R. B., (2008). Pre- and post-synaptic dopamine imaging and its relation with frontostriatal cognitive function in Parkinson disease: PET studies with [(11)C]NNC 112 and [(18)F]FDOPA. Psychiatry Research, 163, 171-182. doi: 10.1016/j.pscychresns.2007.11.003
27. Dagher, A., Owen, A. M., Boecker, H., &, Brooks, D. J., (2001). The role of the striatum and hippocampus in planning: A PET activation study in Parkinson's disease. Brain, 124, 1020-1032. doi: 10.1093/brain/124.5.1020
28. Dalrymple-Alford, J. C., Kalders, A. S., Jones, R. D., &, Watson, R. W., (1994). A central executive deficit in patients with Parkinson's disease. Journal of Neurology, Neurosurgery & Psychiatry, 57, 360-367. doi: 10.1136/jnnp.57.3.360
29. Downes, J. J., Roberts, A. C., Sahakian, B. J., Evenden, J. L., Morris, R. G., &, Robbins, T. W., (1989). Impaired extra-dimensional shift performance in medicated and unmedicated Parkinson's disease: Evidence for a specific attentional dysfunction. Neuropsychologia, 27, 1329-1343. doi: 10.1016/0028-3932(89)90128-0
30. Edison, P., Rowe, C. C., Rinne, J. O., Ng, S., Ahmed, I., Kemppainen, N.,., Brooks, D. J., (2008). Amyloid load in Parkinson's disease dementia and Lewy body dementia measured with [(11)C]PIB positron emission tomography. Journal of Neurology, Neurosurgery & Psychiatry, 79, 1331-1338. doi: 10.1136/jnnp.2007.127878
31. Emre, M., Aarsland, D., Brown, R., Burn, D. J., Duyckaerts, C., Mizuno, Y.,., Dubois, B., (2007). Clinical diagnostic criteria for dementia associated with Parkinson's disease. Movement Disorders, 22, 1689-1707. doi: 10.1002/mds.21507
32. Foltynie, T., Brayne, C. E. G., Robbins, T. W., &, Barker, R. A., (2004). The cognitive ability of an incident cohort of Parkinson's patients in the UK. The CamPaIGN study. Brain, 127 (Pt 3), 550-560. doi: 10.1093/brain/awh067
33. Gelb, D., Oliver, E., &, Gilman, S., (1999). Diagnostic criteria for Parkinson disease. Archives of Neurology, 56, 33-39. doi: 10.1001/archneur.56.1. 33
34. Halliday, G. M., Blumbergs, P. C., Cotton, R. G., Blessings, W. W., &, Geffen, L. B., (1990). Loss of brainstem serotonin- and substance P-containing neurons in Parkinson's disease. Brain Research, 510, 104-107. doi: 10.1016/0006-8993(90)90733-R
35. Hattori, T., Orimo, S., Aoki, S., Ito, K., Abe, O., Amano, A.,., Mizusawa, H., (2012). Cognitive status correlates with white matter alteration in Parkinson's disease. Human Brain Mapping, 33, 727-739. doi: 10.1002/hbm.21245
36. Hely, M. A., Reid, W. G. J., Adena, M. A., Halliday, G. M., &, Morris, J. G. L., (2008). The Sydney multicenter study of Parkinson's disease: The inevitability of dementia at 20 years. Movement Disorders, 23, 837-844. doi: 10.1002/mds.21956
37. Huang, C., Mattis, P., Perrine, K., Brown, N., Dhawan, V., &, Eidelberg, D., (2008). Metabolic abnormalities associated with mild cognitive impairment in Parkinson disease. Neurology, 70, 1470-1477. doi: 10.1212/01.wnl.0000304050.05332.9c
38. Huang, C., Mattis, P., Tang, C., Perrine, K., Carbon, M., &, Eidelberg, D., (2007). Metabolic brain networks associated with cognitive function in Parkinson's disease. NeuroImage, 34, 714-723. doi: 10.1016/j.neuroimage.2006.09.003
39. Ito, K., Nagano-Saito, A., Kato, T., Arahata, Y., Nakamura, A., Kawasumi, Y.,., Brooks, D. J., (2002). Striatal and extrastriatal dysfunction in Parkinson's disease with dementia: A 6-[(18)F]fluoro-l-dopa PET study. Brain, 125, 1358-1365. doi: 10.1093/brain/awf134
40. Janvin, C. C., Aarsland, D., &, Larsen, J. P., (2005). Cognitive predictors of dementia in Parkinson's disease: A community-based, 4-year longitudinal study. Journal of Geriatric Psychiatry and Neurology, 18, 149-154. doi: 10.1177/0891988705277540
41. Janvin, C. C., Aarsland, D., Larsen, J. P., &, Hugdahl, K., (2003). Neuropsychological profile of patients with Parkinson's disease without dementia. Dementia and Geriatric Cognitive Disorders, 15, 126-131. doi: 10.1159/000068483
42. Janvin, C. C., Larsen, J. P., Aarsland, D., &, Hugdahl, K., (2006). Subtypes of mild cognitive impairment in Parkinson's disease: Progression to dementia. Movement Disorders, 21, 1343-1349. doi: 10.1002/mds.20974
43. Jokinen, P., Scheinin, N., Aalto, S., Någren, K., Savisto, N., Parkkola, R.,., Rinne, J. O., (2010). [(11)C]PIB-, [(18)F]FDG-PET and MRI imaging in patients with Parkinson's disease with and without dementia. Parkinsonism & Related Disorders, 16, 666-670. doi: 10.1016/j.parkreldis. 2010.08.021
44. Kish, S. J., Shannak, K., &, Hornykiewicz, O., (1988). Uneven pattern of dopamine loss in the striatum of patients with idiopathic Parkinson's disease. New England Journal of Medicine, 318, 876-880. doi: 10.1056/NEJM198804073181402
45. Ko, J. H., Antonelli, F., Monchi, O., Ray, N., Rusjan, P., Houle, S.,., Strafella, A. P., (2012). Prefrontal dopaminergic receptor abnormalities and executive functions in Parkinson's disease. Human Brain Mapping. Advance online publication. doi: 10.1002/hbm.22006
46. Ko, J. H., Ptito, A., Monchi, O., Cho, S. S., Van Eimeren, T., Pellecchia, G.,., Strafella, A. P., (2009). Increased dopamine release in the right anterior cingulate cortex during the performance of a sorting task: A [(11)C]FLB 457 PET study. NeuroImage, 46, 516-521. doi: 10.1016/j.neuroimage. 2009.02.031
47. Lewis, S. J. G., Cools, R., Robbins, T. W., Dove, A., Barker, R. A., &, Owen, A. M., (2003). Using executive heterogeneity to explore the nature of working memory deficits in Parkinson's disease. Neuropsychologia, 41, 645-654. doi: 10.1016/S0028-3932(02)00257-9
48. Lewis, S. J., Dove, A., Robbins, T. W., Barker, R. A., &, Owen, A. M., (2003). Cognitive impairments in early Parkinson's disease are accompanied by reductions in activity in frontostriatal neural circuitry. Journal of Neuroscience, 23, 6351-6356. Retrieved from http://ukpmc.ac.uk/abstract/MED/ 12867520
49. Litvan, I., Aarsland, D., Adler, C. H., Goldman, J. G., Kulisevsky, J., Mollenhauer, B.,., Weintraub, D., (2011). MDS task force on mild cognitive impairment in Parkinson's disease: Critical review of PD-MCI. Movement Disorders, 26, 1814-1824. doi: 10.1002/mds.23823
50. Litvan, I., Goldman, J. G., Tröster, A. I., Schmand, B. A., Weintraub, D., Petersen, R. C.,., Emre, M., (2012). Diagnostic criteria for mild cognitive impairment in Parkinson's disease: Movement disorder society task force guidelines. Movement Disorders, 27, 349-356. doi: 10.1002/mds.24893
51. Lyoo, C. H., Jeong, Y., Ryu, Y. H., Rinne, J. O., &, Lee, M. S., (2010). Cerebral glucose metabolism of Parkinson's disease patients with mild cognitive impairment. European Neurology, 64, 65-73. doi: 10.1159/000315036
52. Marsh, L., Biglan, K., Gerstenhaber, M., &, Williams, J. R., (2009). Atomoxetine for the treatment of executive dysfunction in Parkinson's disease: A pilot open-label study. Movement Disorders, 24, 277-282. doi: 10.1002/mds.22307
53. Matsui, H., Nishinaka, K., Oda, M., Niikawa, H., Komatsu, K., Kubori, T., &, Udaka, F., (2007). Wisconsin card sorting test in Parkinson's disease: Diffusion tensor imaging. Acta Neurologica Scandinavica, 116, 108-112. doi: 10.1111/j.1600-0404.2006.00795.x
54. Mattay, V. S., Tessitore, A., Callicott, J. H., Bertolino, A., Goldberg, T. E., Chase, T. N.,., Weinberger, D. R., (2002). Dopaminergic modulation of cortical function in patients with Parkinson's disease. Annals of Neurology, 156-164, doi: 10.1002/ana.10078
55. Monchi, O., Ko, J. H., &, Strafella, A. P., (2006). Striatal dopamine release during performance of executive functions: A [(11)C] raclopride PET study. NeuroImage, 33, 907-912. doi: 10.1016/j.neuroimage.2006.06.058
56. Monchi, O., Petrides, M., Doyon, J., Postuma, R. B., Worsley, K., &, Dagher, A., (2004). Neural bases of set-shifting deficits in Parkinson's disease. Journal of Neuroscience, 24, 702-710. doi: 10.1523/JNEUROSCI.4860-03. 2004
57. Monchi, O., Petrides, M., Mejia-Constain, B., &, Strafella, A. P., (2007). Cortical activity in Parkinson's disease during executive processing depends on striatal involvement. Brain, 130 (Pt 1), 233-244. doi: 10.1093/brain/awl326
58. Müller, T., Kuhn, W., &, Przuntek, H., (1997). Non-motor symptoms of Parkinson disease. Significant impact on quality of life-using possible treatments. Fortschritte der Medizin, 115, 45-48. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/19901251
59. Nagano-Saito, A., Washimi, Y., Arahata, Y., Kachi, T., Lerch, J. P., Evans, A. C.,., Ito, K., (2005). Cerebral atrophy and its relation to cognitive impairment in Parkinson disease. Neurology, 64, 224-229. doi: 10.1212/01.WNL.0000149510.41793.50
60. Owen, A. M., Doyon, J., Dagher, A., Sadikot, A., &, Evans, A. C., (1998). Abnormal basal ganglia outflow in Parkinson's disease identified with PET: Implications for higher cortical functions. Brain, 121, 949-965. doi: 10.1093/brain/121.5.949
61. Park, A., &, Stacy, M., (2009). Non-motor symptoms in Parkinson's disease. Journal of Neurology, 256 (Suppl 3), 293-298. doi: 10.1007/s00415-009- 5240-1
62. Petersen, R., Waring, S., Ivnik, R., Tangalos, E., Kokmen, E., &, Smith, G., (1999). Mild cognitive impairment: Clinical characterization and outcome. Archives of Neurology, 56, 303-308. doi: 10.1001/archneur.56.3.303
63. Remy, P., Doder, M., Lees, A., Turjanski, N., &, Brooks, D., (2005). Depression in Parkinson's disease: Loss of dopamine and noradrenaline innervation in the limbic system. Brain, 128, 1314-1322. doi: 10.1093/brain/awh445
64. Rogers, R. D., Sahakian, B. J., Hodges, J. R., Polkey, C. E., Kennard, C., &, Robbins, T. W., (1998). Dissociating executive mechanisms of task control following frontal lobe damage and Parkinson's disease. Brain, 121, 815-842. doi: 10.1093/brain/121.5.815
65. Rowe, J. B., Hughes, L., Williams-Gray, C. H., Bishop, S., Fallon, S., Barker, R. A., &, Owen, A. M., (2010). The val158met COMT polymorphism's effect on atrophy in healthy aging and Parkinson's disease. Neurobiology of Aging, 31, 1064-1068. doi: 10.1016/j.neurobiolaging.2008.07.009
66. Sawamoto, N., Piccini, P., Hotton, G., Pavese, N., Thielemans, K., &, Brooks, D. J., (2008). Cognitive deficits and striato-frontal dopamine release in Parkinson's disease. Brain, 131 (Pt 5), 1294-1302. doi: 10.1093/brain/awn054
67. Scatton, B., Javoy-Agid, F., Rouquier, L., Dubois, B., &, Agid, Y., (1983). Reduction of cortical dopamine, noradrenaline, serotonin and their metabolites in Parkinson's disease. Brain Research, 275, 321-328. doi: 10.1016/0006-8993(83)90993-9
68. Schrag, A., (2004). Psychiatric aspects of Parkinson's disease-an update. Journal of Neurology, 251, 795-804. doi: 10.1007/s00415-004-0483-3
69. Swainson, R., (2000). Probabilistic learning and reversal deficits in patients with Parkinson's disease or frontal or temporal lobe lesions: Possible adverse effects of dopaminergic medication. Neuropsychologia, 38, 596-612. doi: 10.1016/S0028-3932(99)00103-7
70. Taylor, A. E., Saint-Cyr, J. A., &, Lang, A. E., (1986). Frontal lobe dysfunction in Parkinson's disease. The cortical focus of neostriatal outflow. Brain, 109 (Pt 5), 845-883. doi: 10.1093/brain/109.5.845
71. Weintraub, D., Dietz, N., Duda, J. E., Wolk, D. A., Doshi, J., Xie, S. X.,., Siderowf, A., (2012). Alzheimer's disease pattern of brain atrophy predicts cognitive decline in Parkinson's disease. Brain, 135, 170-180. doi: 10.1093/brain/awr277
72. Weintraub, D., Doshi, J., Koka, D., Davatzikos, C., Siderowf, A. D., Duda, J. E.,., Clark, C. M., (2011). Neurodegeneration across stages of cognitive decline in Parkinson disease. Archives of Neurology, 68, 1562-1568. doi: 10.1001/archneurol.2011.725
73. Weintraub, D., Moberg, Ã. P. J., Duda, Ã. J. E., Katz, Ã. I. R., &, Stern, M. B., (2004). Effect of psychatric and other nonmotor symptoms on disability in Parkinson's disease. Journal of the American Geriatrics Society, 784-788, doi: 10.1111/j.1532-5415.2004.52219.x
74. Williams-Gray, C.H., Evans, J.R., Goris, A., Foltynie, T., Ban, M., Robbins, T.W.,., Barker, R.A., (2009). The distinct cognitive syndromes of Parkinson's disease: 5 year follow-up of the CamPaIGN cohort. Brain, 132 (Pt 11), 2958-2969. doi: 10.1093/brain/awp245
75. Williams-Gray, C. H., Foltynie, T., Brayne, C. E. G., Robbins, T. W., &, Barker, R. A., (2007). Evolution of cognitive dysfunction in an incident Parkinson's disease cohort. Brain, 130 (Pt 7), 1787-1798. doi: 10.1093/brain/awm111
76. Williams-Gray, C. H., Hampshire, A., Barker, R. A, &, Owen, A. M., (2008). Attentional control in Parkinson's disease is dependent on COMT val 158 met genotype. Brain, 131 (Pt 2), 397-408. doi: 10.1093/brain/awm313
77. Williams-Gray, C. H., Hampshire, A., Robbins, T. W., Owen, A. M., &, Barker, R. A., (2007). Catechol O-methyltransferase Val158Met genotype influences frontoparietal activity during planning in patients with Parkinson's disease. Journal of Neuroscience, 27, 4832-4838. doi: 10.1523/JNEUROSCI.0774-07. 2007