Assessment of brain interactivity in the motor cortex from the concept of functional connectivity and spectral analysis of fMRI data

Biological Cybernetics

Volumn 98, Issue 2, 2008, Pages 101-114

  Fall, S ^a   De Marco, G ^a  

^a AMIENS UNIVERSITY HOSPITAL   (France)

Author keywords

[No Author keywords available]

Indexed keywords

BRAIN; DATA REDUCTION; MAGNETIC RESONANCE IMAGING; SPECTRUM ANALYSIS; TIME SERIES ANALYSIS;

BRAIN INTERACTIVITY; CEREBRAL MOTOR NETWORK; FUNCTIONAL CONNECTIVITY; FUNCTIONAL MAGNETIC RESONANCE IMAGING;

NATURAL SCIENCES COMPUTING;

OXYGEN;

ARTICLE; BLOOD; HUMAN; IMAGE PROCESSING; MOTOR CORTEX; MOVEMENT (PHYSIOLOGY); NERVE CELL NETWORK; NERVE TRACT; NUCLEAR MAGNETIC RESONANCE IMAGING; PHYSIOLOGY; PROBLEM SOLVING; SPECTROSCOPY; VASCULARIZATION; VISION;

HUMANS; IMAGE PROCESSING, COMPUTER-ASSISTED; MAGNETIC RESONANCE IMAGING; MOTOR CORTEX; MOVEMENT; NERVE NET; NEURAL PATHWAYS; OXYGEN; PROBLEM SOLVING; SPECTRUM ANALYSIS; VISUAL PERCEPTION;

EID: 38949120273     PISSN: 03401200     EISSN: 14320770     Source Type: Journal    
DOI: 10.1007/s00422-007-0198-5     Document Type: Article

References (126)

1. Aguirre GK, Zarahn E and D'Esposito M (1998). The variability of human, BOLD hemodynamic responses. NeuroImage 8: 360-369
2. Alexander GE and Crutcher MD (1990a). Neural representations of the target (goal) of visually guided arm movements in three motor areas of the monkey. J Neurophysiol 64: 164-178
3. Alexander GE and Crutcher MD (1990b). Preparation for movement: neural representations of intended direction in three motor areas of the monkey. J Neurophysiol 64: 133-150
4. Amjad AM, Halliday DM, Rosenberg JR and Conway BA (1997). An extended difference of coherence test for comparing and combining several independent coherence estimates: theory and application to the study of motor units and physiological tremor. J Neurosci Meth 73: 69-79
5. Andres FG, Mima T, Schulman AE, Dichgans J, Hallett M and Gerloff C (1999). Functional coupling of human cortical sensorimotor areas during bimanual skill acquisition. Brain 122: 855-870
6. Andrew C and Pfurtscheller G (1996). Event-related coherence as a tool for studying dynamic interaction of brain regions. Electroencephalogr Clin Neurophysiol 98: 144-148
7. Bartels A and Zeki S (2005). Brain dynamics during natural viewing conditions-a new guide for mapping connectivity in vivo. NeuroImage 24: 339-349
8. Besthorn C, Forstl H, Geiger-Kabisch C, Sattel H, Gasser T and Schreiter-Gasser U (1994). EEG coherence in Alzheimer disease. Electroencephalogr Clin Neurophysiol 90: 242-245
9. Birn RM, Diamond JB, Smith MA and Bandettini PA (2006). Separating respiratory-variation-related fluctuations from neuronal-activity-related fluctuations in fMRI. NeuroImage 31: 1536-1548
10. Biswal B, DeYoe AE and Hyde JS (1996). Reduction of physiological fluctuations in fMRI using digital filters. Magn Reson Med 35: 107-113
11. Brillinger DR (1981). Time series-data analysis and theory, 2nd edn. Holden Day, San Francisco
12. Brockwell PJ and Davis RA (1991). Time series: theory and methods, 2nd edn. Springer, Berlin
13. Buchel C and Friston KJ (1998). Dynamic changes in effective connectivity characterized by variable parameter regression and Kalman filtering. Hum Brain Mapp 6: 403-408
14. Bullmore ET, Rabe-Hesketh S, Morris RG, Williams SC, Gregory L, Gray JA and Brammer MJ (1996). Functional magnetic resonance image analysis of a large-scale neurocognitive network. NeuroImage 4: 16-33
15. Buxton RB, Wong EC and Frank LR (1998). Dynamics of blood flow and oxygenation changes during brain activation: the balloon model. Magn Reson Med 39: 855-864
16. Cannestra AF, Pouratian N, Shomer MH and Toga AW (1998). Refractory periods observed by intrinsic signal and fluorescent dye imaging. J Neurophysiol 80: 1522-1532
17. Carey JR, Greer KR, Grunewald TK, Steele JL, Wiemiller JW, Bhatt E, Nagpal A, Lungu O and Auerbach EJ (2006). Primary motor area activation during precision-demanding versus simple finger movement. Neurorehabil Neural Repair 20: 361-370
18. Carpenter AF, Georgopoulos AP and Pellizzer G (1999). Motor cortical encoding of serial order in a context-recall task. Science 283: 1752-1757
19. Classen J, Gerloff C, Honda M and Hallett M (1998). Integrative visuomotor behavior is associated with interregionally coherent oscillations in the human brain. J Neurophysiol 79: 1567-1573
20. Clower WT and lexander GE (1998). Movement sequence-related activity reflecting numerical order of components in supplementary and presupplementary motor areas. J Neurophysiol 80: 1562-1566
21. Cordes D, Haughton VM, Arfanakis K, Wendt GJ, Turski PA, Moritz CH, Quigley MA and Meyerand ME (2000). Mapping functionally related regions of brain with functional connectivity MR imaging. Am J Neuroradiol 21: 1636-1644
22. Cordes D, Haughton VM, Arfanakis K, Carew JD, Turski PA, Moritz CH, Quigley MA and Meyerand ME (2001). Frequencies contributing to functional connectivity in the cerebral cortex in resting-state data. Am J Neuroradiol 22: 1326-1333
23. Cui SZ, Li EZ, Zang YF, Weng XC, Ivry R and Wang JJ (2000). Both sides of human cerebellum involved in preparation and execution of sequential movements. Neuroreport 11: 3849-3853
24. Cunnington R, Windischberger C, Deecke L and Moser E (2002). The preparation and execution of self-initiated and externally-triggered movement: a study of event-related fMRI. NeuroImage 15: 373-385
25. Dechent P, Merboldt KD and Frahm J (2004). Is the human primary motor cortex involved in motor imagery. Cogn Brain Res 19: 138-144
26. deMarco G, de Bonis M, Vrignaud P, Henry-Feugeas MC and Peretti I (2006). Changes in effective connectivity during incidental and intentional perception of fearful faces. NeuroImage 30: 1030-1037
27. D'Esposito M, Deouell LY and Gazzaley A (2003). Alterations in the BOLD fMRI signal with ageing and disease: a challenge for neuroimaging. Nat Rev Neurosci 4: 863-872
28. Dum RP and Strick PL (1991). The origin of corticospinal projections from the premotor areas in the frontal lobe. J Neurosci 11: 667-689
29. Duyn JH, Moonen CT, de Boer RW, Luyten PR and van Ypren GH (1994). Inflow versus deoxyhemoglobin effects in BOLD functional MRI using gradient echoes at 1.5 T. NMR Biomed 7: 83-88
30. Frackowiak RSJ, Friston KJ, Frith CD, Dolan RJ and Mazziotta JC (1997). Human brain function. Academic, London
31. Frahm J, Merboldt KD, Hanicke W, Kleinschmidt A and Boecker H (1994). Brain or vein-oxygenation or flow? on signal physiology in functional MRI of human brain activation. NMR Biomed 7: 45-53
32. Fried I, Katz A, McCarthy G, Sass KJ, Williamson P, Spencer SS and Spencer DD (1991). Functional organization of human supplementary motor cortex studied by electrical stimulation. J Neurosci 11: 3656-3666
33. Friston KJ, Frith CD and Frackowiak RS (1993a). Time-dependent changes in effective connectivity measured with PET. Hum Brain Mapp 1: 69-79
34. Friston KJ, Frith CD, Liddle PF and Frackowiak RS (1993b). Functional connectivity: the principal-component analysis of large (PET) data sets. J Cereb Blood Flow Metab 13: 5-14
35. Friston KJ, Harrison L and Penny W (2003). Dynamic causal modelling. NeuroImage 19: 1273-1302
36. Georgopoulos AP (2000). Neural aspects of cognitive motor control. J Neurosci 10: 238-241
37. Georgopoulos AP, Lurito JT, Petrides M, Schwartz AB and Massey JT (1989). Mental rotation of the neuronal population vector. Science 243: 234-236
38. Gerardin E, Pochon JB, Poline JB, Tremblay L, de Moortele PFV, Levy R, Dubois B, Bihan DL and Lehericy S (2004). Distinct striatal regions support movement selection, preparation and execution. Neuroreport 15: 2327-2331
39. Gerstein GL and Perkel DH (1969). Simultaneously recorded trains of action potentials: analysis and functional interpretation. Science 164: 828-830
40. Golay X, Kollias S, Stoll G, Meier D, Valavanis A and Boesiger P (1998). A new correlation-based fuzzy logic clustering algorithm for fMRI. Magn Reson Med 40: 249-260
41. Goldman RI, Stern JM, Engel JJ and Cohen MS (2002). Simultaneous EEG and fMRI of the alpha rhythm. Neuroreport 13: 2487-2492
42. Gross J, Pollok B, Dirks M, Timmermann L, Butz M and Schnitzler A (2005). Task-dependent oscillations during unimanual and bimanual movements in the human primary motor cortex and SMA studied with magnetoencephalography. NeuroImage 26: 91-98
43. Halliday DM, Rosenberg JR, Amjad AM, Breeze P, Conway BA and Farmer SF (1995). A framework for the analysis of mixed time series/point process data-theory and application to the study of physiological tremor, single motor unit discharges and electromyograms. Prog Biophys Mol Biol 64: 237-278
44. Handwerker DA, Ollinger JM, Curtis CE, D'Esposito M (2002) Effects of regional and subject variability of the hemodynamic response function on modeling fMRI signals. Society for Neuroscience, New Orleans
45. Handwerker DA, Ollinger JM and D'Esposito M (2004). Variation of BOLD hemodynamic responses across subjects and brain regions and their effects on statistical analyses. NeuroImage 24: 1639-1651
46. Harrison L, Friston KJ (2003) Effective connectivity. In: Frackowiak RSJ, Friston KJ, Frith C, Dolan R, Price CJ, Zeki S, Ashburner J, Penny WDHuman brain function. 2nd edn. Academic
47. Harrison RV, Harel N, Panesar J and Mount RJ (2002). Blood capillary distribution correlates with hemodynamic-based functional imaging in cerebral cortex. Cereb Cortex 12: 225-233
48. Haughton V and Biswal B (1998). Clinical application of basal regional cerebral blood flow fluctuation measurements by fMRI. Adv Exp Med Biol 454: 583-590
49. Hebb D (1949). The organization of behavior: a neurophysiological theory. Wiley, New York
50. Henson RN, Price CJ, Rugg MD, Turner R and Friston KJ (2002). Detecting latency differences in event-related BOLD responses: application to words versus nonwords and initial versus repeated face presentations. NeuroImage 15: 83-97
51. Hikosaka O, Nakahara H, Rand MK, Sakai K, Lu X, Nakamura K, Miyachi S and Doya K (1999). Parallel neural networks for learning sequential procedures. Trends Neurosci 22: 464-471
52. Himberg J, Hyvarinen A and Esposito F (2004). Validating the independent components of neuroimaging time series via clustering and visualization. NeuroImage 22: 1214-1222
53. Horwitz B (2003). The elusive concept of brain connectivity. NeuroImage 19: 466-470
54. Huettel SA and McCarthy G (2000). Evidence for a refractory period in the hemodynamic response to visual stimuli as measured by MRI. NeuroImage 11: 547-553
55. Huettel SA and McCarthy G (2001). Regional differences in the refractory period of the hemodynamic response: an event-related fMRI study. NeuroImage 14: 967-976
56. Indovina I and Sanes JN (2001). On somatotopic representation centers for finger movements in human primary motor cortex and supplementary motor area. NeuroImage 13: 1027-1034
57. Kansaku K, Kitazawa S and Kawano K (1998). Sequential hemodynamic activation of motor areas and the draining veins during finger movements revealed by cross-correlation between signals from fMRI. Neuroreport 9: 1969-1974
58. Kansaku K, Muraki S, Umeyama S, Nishimori Y, Kochiyama T, Yamane S and Kitazawa S (2005). Cortical activity in multiple motor areas during sequential finger movements: an application of independent component analysis. NeuroImage 28: 669-681
59. Kawashima R, Okuda J, Umetsu A, Sugiura M, Inoue K, Suzuki K, Tabuchi M, Tsukiura T, Narayan SL, Nagasaka T, Yanagawa I, Fujii T, Takahashi S, Fukuda H and Yamadori A (2000). Human cerebellum plays an important role in memory-timed finger movement: an fMRI study. J Neurophysiol 83: 1079-1087
60. Kennerley SW, Sakai K and Rushworth MF (2004). Organization of action sequences and the role of the pre-SMA. J Neurophysiol 91: 978-993
61. Kim SG, Richter W and Ugurbil K (1997). Limitations of temporal resolution in functional MRI. Magn Reson Med 37: 631-636
62. Koopmans LH (1974). The spectral analysis of time series. Academic, New York
63. Krainik A, Lehericy S, Duffau H, Vlaicu M, Poupon F, Capelle L, Cornu P, Clemenceau S, Sahel M, Valery C, Boch A, Mangin J, Bihan D and Marsault C (2001). Role of the supplementary motor area in motor deficit following medial frontal lobe surgery. Neurology 57: 871-878
64. Krainik A, Lehericy S, Duffau H, Capelle L, Chainay H, Cornu P, Cohen L, Boch AL, Mangin JF, Bihan DL and Marsault C (2003). Postoperative speech disorder after medial frontal surgery: role of the supplementary motor area. Neurology 60: 587-594
65. Kyoung-Min L, Kee-Hyun C and Jae-Kyu R (1999). Subregions within the supplementary motor area activated at different stages of movement preparation and execution. NeuroImage 9: 117-123
66. Lai S, Hopkins A, Haacke EM, Li D, Wasserman BA, Buckley P, Friedman L, Meltzer H, Hedera P and Friedland R (1993). Identification of vascular structures as a major source of signal contrast in high resolution 2D and 3D functional activation imaging of the motor cortex at 1.5 T: preliminary results. Magn Reson Med 30: 387-392
67. Laplane D, Talairach J, Meininger V, Bancaud J and Orgogozo JM (1977). Clinical consequences of corticectomies involving the supplementary motor area in man. J Neurol Sci 34: 301-314
68. Lee AT, Glover GH and Meyer CH (1995). Discrimination of large venous vessels in time-course spiral blood-oxygen-level-dependent magnetic-resonance functional neuroimaging. Magn Reson Med 33: 745-754
69. Lee KM, Chang KH and Roh JK (1999). Subregions within the supplementary motor area activated at different stages of movement preparation and execution. NeuroImage 9: 117-123
70. Lee L, Harrison LM and Mechelli A (2003). A report of the functional connectivity workshop, Dusseldorf 2002. NeuroImage 19: 457-465
71. Leopold DA, Murayama Y and Logothetis NK (2003). Very slow activity fluctuations in monkey visual cortex: implications for functional brain imaging. Cereb Cortex 13: 422-433
72. LeRoc'h K (1994). EEG coherence in Alzheimer disease, by Besthorn et al. Electroencephalogr Clin Neurophysiol 91: 232-223
73. Locatelli T, Cursi M, Liberati D, Franceschi M and Comi G (1998). EEG coherence in Alzheimer's disease. Electroencephalogr Clin Neurophysiol 106: 229-237
74. Logothetis N, Pauls J, Augath M, Trinath T and Oeltermann A (2001). Neurophysiological investigation of the basis of the fMRI signal. Nature 412: 150-157
75. Lopez L and Sanjuan MA (2002). Relation between structure and size in social networks. Phys Rev E Stat Nonlin Soft Matt Phys 65: 036,107
76. Lu MT, Preston JB and Strick PL (1994). Interconnections between the prefrontal cortex and the premotor areas in the frontal lobe. J Comp Neurol 341: 375-392
77. Lu X and Ashe J (2005). Anticipatory activity in primary motor cortex codes memorized movement sequences. Neuron 45: 967-973
78. Luppino G, Matelli M, Camarda R and Rizzolatti G (1993). Corticocortical connections of area F3 (SMA-proper) and area F6 (pre-SMA) in the macaque monkey. J Comp Neurol 338: 114-140
79. Maier MA, Armand J, Kirkwood PA, Yang HW, Davis JN and Lemon RN (2002). Differences in the corticospinal projection from primary motor cortex and supplementary motor area to macaque upper limb motoneurons: an anatomical and electrophysiological study. Cereb Cortex 12: 281-296
80. Marchini LJ and Ripley BD (2000). A new statistical approach to detecting significant activation in funtional MRI. NeuroImage 12: 366-380
81. Marrelec G, Krainik A, Duffau H, Pelegrini-Issac M, Lehericy S, Doyon J and Benali H (2006). Partial correlation for functional brain interactivity investigation in functional MRI. NeuroImage 32: 228-237
82. Matelli M, Luppino G and Rizzolatti G (1991). Architecture of superior and mesial area 6 and the adjacent cingulate cortex in the macaque monkey. J Comp Neurol 311: 445-462
83. Matelli M, Rizzolatti G, Bettinardi V, Gilardi MC, Perani D, Rizzo G and Fazio F (1993). Activation of precentral and mesial motor areas during the execution of elementary proximal and distal arm movements: a PET study. Neuroreport 4: 1295-1298
84. Mathiesen C, Caesar K, Akgoren N and Lauritzen M (1998). Modification of activity-dependent increases of cerebral blood flow by excitatory synaptic activity and spikes in rat cerebellar cortex. J Physiol 512(Pt 2): 555-566
85. Matsuzaka Y, Aizawa H and Tanji J (1992). A motor area rostral to the supplementary motor area (presupplementary motor area) in the monkey: neuronal activity during a learned motor task. J Neurophysiol 68: 653-662
86. McIntosh AR and Gonzalez-Lima F (1994). Structural equation modeling and its application to network analysis in functiona brain imaging. Hum Brain Mapp 2: 2-22
87. McKeown MJ and Sejnowski TJ (1998). Independent component analysis of fMRI data: examining the assumptions. Hum Brain Mapp 6: 368-372
88. McKeown MJ, Makeig S, Brown GG, Jung TP, Kindermann SS, Bell AJ and Sejnowski TJ (1998). Analysis of fMRI data by blind separation into independent spatial components. Hum Brain Mapp 6: 160-188
89. Miezin FM, Maccotta L, Ollinger JM, Petersen SE and Buckner RL (2000). Characterizing the hemodynamic response: effects of presentation rate, sampling procedure, and the possibility of ordering brain activity based on relative timing. NeuroImage 11: 735-759
90. Muller K, Lohmann G, Bosch V and von Cramon DY (2001). On multivariate spectral analysis of fMRI time series. NeuroImage 14: 347-356
91. Nevado A, Young M and Panzeri S (2004). Functional imaging and neural information coding. NeuroImage 21: 1083-1095
92. Newton J, Sunderland A, Butterworth SE, Peters AM, Peck KK and Gowland PA (2002). A pilot study of event-related functional magnetic resonance imaging of monitored wrist movements in patients with partial recovery. Stroke 33: 2881-2887
93. Ngai AC, Jolley MA, D'Ambrosio R, Meno J and Winn H (1999). Frequency-dependent changes in cerebral blood flow and evoked potentials during somatosensory stimulation in the rat. Brain Res 837: 221-228
94. Obata T, Liu TT, Miller KL, Luh WM, Wong EC, Frank LR and Buxton RB (2004). Discrepancies between BOLD and flow dynamics in primary and supplementary motor areas: application of the balloon model to the interpretation of BOLD transients. NeuroImage 21: 144-153
95. Ogawa S, Menon RS, Tank DW, Kim SG, Merkle H, Ellerman JM and Ugurbil K (1993). Functional brain mapping by blood oxygenation level-dependent contrast magnetic resonance imaging. A comparison of signal characteristics with a biophysical model. Biophys J 64: 803-812
96. Parkes LM, Bastiaansen MC and Norris DG (2006). Combining EEG and fMRI to investigate the post-movement beta rebound. NeuroImage 29: 685-696
97. Penny WD, Stephan KE, Mechelli A and Friston KJ (2004). Modelling functional integration: a comparison of structural equation and dynamic causal models. NeuroImage 23(suppl 1): S264-S274
98. Picard N and Strick P (1996). Motor area of the medial wall: a review of their location and functional activation. Cereb Cortex 6: 342-353
99. Porro CA, Francescato MP, Cettolo V, Diamond ME, Baraldi P, Zuiani C, Bazzocchi M and di Prampero PE (1996). Primary motor and sensory cortex activation during motor performance and motor imagery: a functional magnetic resonance imaging study. J Neurosci 16: 7688-7698
100. Priestley MB (1981). Spectral analysis and time series, vol 2. Academic, London
101. Priestley MB (1981). Spectral analysis and time series, vol 1. Academic, London
102. Rappelsberger P and Petsche H (1988). Probability mapping: power and coherence analyses of cognitive processes. Brain Topogr 1: 46-54
103. Richter W, Andersan PM, Georgopoulos A and Kim S (1997). Sequential activity in human motor areas during a delay cued finger movement task studied by time-resolved fMRI. Neuroreport 8: 1257-1261
104. Rizzolatti G, Luppino G and Matelli M (1996). The classic supplementary motor area is formed by two independent areas. Adv Neurol 70: 45-56
105. Rosenberg JR, Amjad AM, Breeze P, Brillinger DR and M HD (1989). The Fourier approach to the identification of functional coupling between neuronal spike trains. Prog Biophys Mol Biol 53: 1-31
106. Rykhlevskaia E, Fabiani M and Gratton G (2006). Lagged covariance structure models for studying functional connectivity in the brain. NeuroImage 30: 1203-1218
107. Saad ZS, Ropella KM, Cox R and DeYoe E (2001). Analysis and use of fMRI response delays. Hum Brain Mapp 13: 74-93
108. Schack B, Grieszbach G, Nowak H and Krause W (1999). The sensitivity of instantaneous coherence for considering elementary comparison processing. Part II: similarities and differences between EEG and MEG coherences. Int J Psychophysiol 31: 241-259
109. Sheth SA, Nemoto M, Guiou M, Walker M, Pouratian N and Toga AW (2004). Linear and nonlinear relationships between neuronal activity, oxygen metabolism, and hemodynamic responses. Neuron 42: 347-355
110. Shibasaki H and Ikeda A (1996). Generation of movement-related potentials in the supplementary sensorimotor area. Adv Neurol 70: 117-125
111. Shibasaki H, Sadato N, Lyshkow H, Yonekura Y, Honda M, Nagamine T, Suwazono S, Magata Y, Ikeda A and Miyazaki M (1993). Both primary motor cortex and supplementary motor area play an important role in complex finger movement. Brain 116(Pt 6): 1387-1398
112. Shima K and Tanji J (1998). Both supplementary and presupplementary motor areas are crucial for the temporal organization of multiple movements. J Neurophysiol 80: 3247-3260
113. Sporns O, Chialvo DR, Kaiser M and Hilgetag CC (2004). Organization, development and function of complex brain networks. Trends Cogn Sci 8: 418-425
114. Stam CJ, Jones BF, Manshanden I, van Cappellen AM, van Walsum, Montez T, Verbunt JP, de Munck JC, van Dijk BW, Berendse HW and Scheltens P (2006). Magnetoencephalographic evaluation of resting-state functional connectivity in Alzheimer's disease. NeuroImage 32: 1335-1344
115. Sun FT, Miller LM and D'Esposito M (2005). Measuring temporal dynamics of functional networks using phase spectrum of fMRI data. NeuroImage 28: 227-237
116. Tanji J (1996). New concepts of the supplementary motor area. Curr Opin Neurobiol 6: 782-787
117. Tanji J and Shima K (1994). Role for supplementary motor area cells in planning several movements ahead. Nature 371: 413-416
118. Toma K, Honda M, Hanakawa T, Okada T, Fukuyama H, Ikeda A, Nishizawa S, Konishi J and Shibasaki H (1999). Activities of the primary and supplementary motor areas increase in preparation and execution of voluntary muscle relaxation: an event-related fMRI study. J Neurosci 19: 3527-3534
119. Toni I, Schluter ND, Josephs O, Friston K and Passingham RE (1999). Signal-, set- and movement-related activity in the human brain: an event-related fMRI study. Cereb Cortex 9: 35-49
120. Tononi G, Edelman GM and Sporns O (1998). Complexity and coherence:integrating information in the brain. Trends Cogn Sci 2: 474-484
121. Varela F, Lachaux JP, Rodriguez E and Martinerie J (2001). The brainweb: phase synchronization and large-scale integration. Nat Rev Neurosci 2: 229-239
122. Wang SY, Liu X, Yianni J, Miall RC, Aziz TZ and Stein JF (2004). Optimising coherence estimation to assess the functional correlation of tremor-related activity between the subthalamic nucleus and the forearm muscles. J Neurosci Meth 136: 197-205
123. Welch P (1967). The Use of Fast Fourier Transform for the Estimation of Power Spectra: A Method Based on Time Averaging Over Short, Modified Periodograms. IEEE Trans Audio Electroacous AU-15: 70-73
124. Wiener N (1930). Generalized harmonic analysis. Act Math 55: 117-258
125. Zang Y, Jia F, Weng X, Li E, Cui S, Wang Y, Hazeltine E and Ivry R (2003). Functional organization of the primary motor cortex characterized by event-related fMRI during movement preparation and execution. Neurosci Lett 337: 69-72
126. Zarahn E (2000). Testing for neural responses during temporal components of trials with BOLD fMRI. NeuroImage 11: 783-796