EEG-fMRI methods for the study of brain networks during sleep

Frontiers in Neurology

Volumn JUL, Issue , 2012, Pages

  Duyn, Jeff H ^a  

^a NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE   (United States)

Author keywords

Dynamic causal modeling; EEG; fMRI; Graph analysis; Independent component analysis; Methodology; Neuroimaging; Sleep networks

Indexed keywords

EID: 84865842682     PISSN: None     EISSN: 16642295     Source Type: Journal    
DOI: 10.3389/fneur.2012.00100     Document Type: Article

References (121)

1. Andrade, K. C., Spoormaker, V. I., Dresler, M., Wehrle, R., Holsboer, E, Samann, P. G., and Czisch, M. (2011). Sleep spindles and hip-pocampal functional connectivity in human NREM sleep. J. Neurosci. 31, 10331-10339.
2. Aserinsky, E., and Kleitman, N. (1953). Regularly occurring periods of eye motility, and concomitant phenomena, during sleep. Science 118, 273-274.
3. Aston-Jones, G., and Bloom, E E. (1981). Activity of norepinephrine-containing locus coeruleus neurons in behaving rats anticipates fluctuations in the sleep-wake cycle. J. Neurosci. 1, 876-886.
4. Attwell, D., and Iadecola, C. (2002). The neural basis of functional brain imaging signals. Trends Neurosci. 25, 621-625.
5. Attwell, D., and Laughlin, S. B. (2001). An energy budget for signaling in the grey matter of the brain. J. Cereb. Blood Flow Metab. 21, 1133-1145.
6. Auer, D. P. (2008). Spontaneous low-frequency blood oxygenation level-dependent fluctuations and functional connectivity analysis of the "resting" brain. Magn. Reson. Imaging 26, 1055-1064.
7. Benar, C., Aghakhani, Y., Wang, Y., Izenberg, A., Al-Asmi, A., Dubeau, E, and Gotman, J. (2003). Quality of EEG in simultaneous EEG-fMRI for epilepsy. Clin. Neurophysiol. 114, 569-580.
8. Bergmann, T. O., Molle, M., Diedrichs, J., Born, J., and Siebner, H. R. (2012). Sleep spindle-related reactivation of category-specific cortical regions after learning face-scene associations. Neuroimage 59, 2733-2742.
9. Bianciardi, M., Fukunaga, M., van Gelderen, P., de Zwart, J. A., and Duyn,J.H. (2011). Negative BOLD-fMRI signals in large cerebral veins. J. Cereb. Blood Flow Metab. 31, 401-412.
10. Bianciardi, M., Fukunaga, M., van Gelderen, P., Horovitz, S. G., de Zwart, J. A., Shmueli, K., and Duyn, J. H. (2009a). Sources of functional magnetic resonance imaging signal fluctuations in the human brain at rest: a 7 T study. Magn. Reson. Imaging 27, 1019-1029.
11. Bianciardi, M., van Gelderen, P., Duyn, J. H., Fukunaga, M., and de Zwart, J. A. (2009b). Making the most of fMRI at 7 T by suppressing spontaneous signal fluctuations. Neuroimage 44, 448-454.
12. Biswal, B., Yetkin, F.Z., Haughton, V. M., and Hyde, J. S. (1995). Functional connectivity in the motor cortex of resting human brain using echo-planar MRI. Magn. Reson. Med. 34, 537-541.
13. Blake, H., and Gerard, R. W (1937). Brain potentials during sleep. Am. J. Physiol. 119,692-703.
14. Boly, M., Tshibanda, L., Vanhau-denhuyse, A., Noirhomme, Q., Schnakers, C., Ledoux, D., Boveroux, P., Garweg, C., Lambermont, B., Phillips, C., Luxen, A., Moo-nen, G., Bassetti, C., Maquet, P., and Laureys, S. (2009). Functional connectivity in the default network during resting state is preserved in a vegetative but not in a brain dead patient. Hum. Brain Mapp. 30, 2393-2400.
15. Born, A. P., Law, I., Lund, T. E., Ros-trup, E., Hanson, L. G., Wilds-chiodtz, G., Lou, H. C., and Paulson, O. B. (2002). Cortical deactiva-tion induced by visual stimulation in human slow-wave sleep. Neuroimage 17,1325-1335.
16. Boveroux, P., Bonhomme, V., Boly, M., Vanhaudenhuyse, A., Maquet, P., and Laureys, S. (2008). Brain function in physiologically, pharmacologically, and pathologically altered states of consciousness. Int. Anesthe-siol. Clin.46, 131-146.
17. Braun, A. R., Balkin, T. J., Wesenten, N. J., Carson, R. E., Varga, M., Baldwin, P., Selbie, S., Belenky, G., and Her-scovitch, P. (1997). Regional cerebral blood flow throughout the sleep-wake cycle. An H2[15]O PET study. Brain 120,1173-1197.
18. Britz, J., Van De Ville, D., and Michel, C. M. (2010). BOLD correlates of EEG topography reveal rapid resting-state network dynamics. Neuroimage 52,1162-1170.
19. Bullmore, E., and Sporns, O. (2009). Complex brain networks: graph theoretical analysis of structural and functional systems. Nat. Rev. Neurosci. 10, 186-198.
20. Buzsaki, G. (1998). Memory consolidation during sleep: a neurophysiolog-ical perspective.J. Sleep Res. 7(Suppl. 1), 17-23.
21. Calhoun, V. D., Liu, J., and Adali, T. (2009). A review of group ICA for fMRI data and ICA for joint inference of imaging, genetic, and ERP data. Neuroimage 45, S163-S172.
22. Chambers, J., Bullock, D., Kahana, Y., Kots, A., and Palmer, A. (2007). Developments in active noise control sound systems for magnetic resonance imaging. Appl. Acoust. 68, 281-295.
23. Czisch, M., Wehrle, R., Stiegler, A., Peters, H., Andrade, K., Holsboer, E, and Samann, P. G. (2009). Acoustic oddball during NREM sleep: a combined EEG/fMRI study. PLoS ONE 4, e6749. doi:10.1371/journal.pone.0006749
24. Czisch, M., Wetter, T. C., Kaufmann, C., Pollmacher, T., Holsboer, F., and Auer, D. P. (2002). Altered processing of acoustic stimuli during sleep: reduced auditory activation and visual deactivation detected by a combined fMRI/EEG study. Neuroimage 16,251-258.
25. Dang-Vu, T. T., Bonjean, M., Sch-abus, M., Boly, M., Darsaud, A., Desseilles, M., Degueldre, C., Bal-teau, E., Phillips, C., Luxen, A., Sejnowski, T. J., and Maquet, P. (2011). Interplay between spontaneous and induced brain activity during human non-rapid eye movement sleep. Proc. Natl. Acad. Sci. U.S.A. 108,15438-15443.
26. Dang-Vu, T. T., Schabus, M., Desseilles, M., Albouy, G., Boly, M., Darsaud, A., Gais, S., Rauchs, G., Sterpenich, V., Vandewalle, G., Carrier, J., Moo-nen, G., Balteau, E., Degueldre, C., Luxen, A., Phillips, C., and Maquet, P. (2008). Spontaneous neural activity during human slow wave sleep. Proc. Natl. Acad. Sci. U.S.A. 105, 15160-15165.
27. de Zwart, J. A., Silva, A. C., van Gelderen, P., Kellman, P., Fukunaga, M., Chu, R., Koretsky, A. P., Frank, J. A., and Duyn, J. H. (2005). Temporal dynamics of the BOLD fMRI impulse response. Neuroimage 24, 667-677.
28. Demertzi, A., Soddu, A., Faymonville, M. E., Bahri, M. A., Gosseries, O., Vanhaudenhuyse, A., Phillips, C., Maquet, P., Noirhomme, Q., Luxen, A., and Laureys, S. (2011). Hypnotic modulation of resting state fMRI default mode and extrinsic network connectivity. Prog. Brain Res. 193, 309-322.
29. Dresler, M., Koch, S. P., Wehrle, R., Spoormaker, V. I., Holsboer, F., Steiger, A., Samann, P. G., Obrig, H., and Czisch, M. (2011). Dreamed movement elicits activation in the sensorimotor cortex. Curr. Biol. 21, 1833-1837.
30. Drummond, S. P., Smith, M. T., Orff, H. J., Chengazi, V., and Perlis, M. L. (2004). Functional imaging of the sleeping brain: review of findings and implications for the study of insomnia. Sleep Med. Rev. 8, 227-242.
31. Duong, T. Q., Kim, D. S., Ugurbil, K., and Kim, S. G. (2001). Localized cerebral blood flow response at submillimeter columnar resolution. Proc. Natl. Acad. Sci. U.S.A. 98, 10904-10909.
32. Duyn, J. (2011). Spontaneous fMRI activity during resting wakefulness and sleep. Prog. Brain Res. 193, 295-305.
33. Eichele, T., Calhoun, V. D., and Debener, S. (2009). Mining EEG-fMRI using independent component analysis. Int. J. Psychophysiol. 73, 53-61.
34. Esposito, F., and Goebel, R. (2011). Extracting functional networks with spatial independent component analysis: the role of dimensionality, reliability and agregation scheme. Curr. Opin. Neurol. 24, 378-385.
35. Fox, M. D., Zhang, D., Snyder, A. Z., and Raichle, M. E. (2009). The global signal and observed anticorrelated resting state brain networks. J. Neu-rophysiol. 101,3270-3283.
36. Frankland, P. W., and Bontempi, B. (2005). The organization of recent and remote memories. Nat. Rev. Neurosci.6, 119-130.
37. Fransson, P., Skiold, B., Engstrom, M., Hallberg, B., Mosskin, M., Aden, U., Lagercrantz, H., and Blennow, M. (2009). Spontaneous brain activity in the newborn brain during natural sleep - an fMRI study in infants born at full term. Pediatr. Res. 66, 301-305.
38. Friston, K. J. (1994). Functional and effective connectivity in neuroimag-ing: a synthesis. Hum. Brain Mapp. 2, 56-78.
39. Friston, K. J., Penny, W., and David, O. (2005). Modeling brain responses. Int. Rev. Neurobiol. 66, 89-124.
40. Fucke, T., Suchanek, D., Nawrot, M. P., Seamari, Y., Heck, D. H., Aertsen, A., and Boucsein, C. (2011). Stereotypical spatiotemporal activity patterns during slow-wave activity in the neocortex. J. Neurophysiol. 106, 3035-3044.
41. Fukunaga, M., Horovitz, S., Carr, W., Picchioni, D., de Zwart, J., van Gelderen, P., Balkin, T., Braun, A., and Duyn, J. (2007). "Spatially structured BOLD fMRI activity during deep sleep," in Poster presented at the meeting of the Organization for Human Brain Mapping, Chicago, IL.
42. Goebel, R., Roebroeck, A., Kim, D. S., and Formisano, E. (2003). Investigating directed cortical interactions in time-resolved fMRI data using vector autoregressive modeling and Granger causality mapping. Magn. Reson. Imaging 21, 1251-1261.
43. Goldman, R. I., Stern, J. M., Engel, J. Jr., and Cohen, M.S. (2000). Acquiring simultaneous EEG and functional MRI. Clin. Neurophysiol. 111, 1974-1980.
44. Goldman, R. I., Stern, J. M., Engel, J. Jr., and Cohen, M. S. (2002). Simultaneous EEG and fMRI of the alpha rhythm. Neuroreport 13,2487-2492.
45. Grouiller, F., Vercueil, L., Krainik, A., Segebarth, C., Kahane, P., and David, O. (2007). A comparative study of different artefact removal algorithms for EEG signals acquired during functional MRI. Neuroimage 38, 124-137.
46. Hamalainen, M., Hari, R., Ilmoniemi, R., Knuutila, J., and Lounasmaa, O.V. (1993).Magnetoencephalogra-phy - theory, instrumentation, and applications to noninvasive studies of the working human brain. Rev. Mod. Phys. 65,413-497.
47. Hasselmo, M. E. (1999). Neuromod-ulation: acetylcholine and memory consolidation. Trends Cogn. Sci. (Regul. Ed.) 3, 351-359.
48. He, B. J. (2011). Scale-free properties of the functional magnetic resonance imaging signal during rest and task. J.Neurosci. 31, 13786-13795.
49. He, B. J., Zempel, J. M., Snyder, A. Z., and Raichle, M. E. (2010). The temporal structures and functional significance of scale-free brain activity. Neuron 66, 353-369.
50. Hobson, J. A. (2005). Sleep is of the brain, by the brain and for the brain. Nature 437, 1254-1256.
51. Honey, C. J., Sporns, O., Cammoun, L., Gigandet, X., Thiran, J. P., Meuli, R., and Hagmann, P. (2009). Predicting human resting-state functional connectivity from structural connectivity. Proc. Natl. Acad. Sci. U.S.A. 106, 2035-2040.
52. Hong, C. C., Harris, J. C., Pearlson, G. D., Kim, J. S., Calhoun, V. D., Fallon, J. H., Golay, X., Gillen, J. S., Sim-monds, D. J., van Zijl, P. C., Zee, D. S., and Pekar, J. J. (2009). fMRI evidence for multisensory recruitment associated with rapid eye movements during sleep. Hum. Brain Mapp. 30, 1705-1722.
53. Horovitz, S. G., Braun, A. R., Carr, W. S., Picchioni, D., Balkin, T. J., Fukunaga, M., and Duyn, J. H. (2009). Decoupling of the brain's default mode network during deep sleep. Proc. Natl. Acad. Sci. U.S.A. 106, 11376-11381.
54. Horovitz, S. G., Fukunaga, M., de Zwart, J. A., van Gelderen, P., Fulton, S. C., Balkin, T. J., and Duyn, J. H. (2008). Low frequency BOLD fluctuations during resting wakefulness and light sleep: a simultaneous EEG-fMRI study. Hum. Brain Mapp. 29, 671-682.
55. Huber, R., Ghilardi, M. F., Massimini, M., and Tononi, G. (2004). Local sleep and learning. Nature 430, 78-81.
56. Iadecola, C., and Nedergaard, M. (2007). Glial regulation of the cerebral microvasculature. Nat. Neu-rosci. 10, 1369-1376.
57. Jueptner, M., and Weiller, C. (1995). Review: does measurement of regional cerebral blood flow reflect synaptic activity? Implications for PET and fMRI. Neuroimage 2, 148-156.
58. Kaufmann, C., Wehrle, R., Wetter, T. C., Holsboer, F., Auer, D. P., Poll-macher, T., and Czisch, M. (2006). Brain activation and hypothala-mic functional connectivity during human non-rapid eye movement sleep: an EEG/fMRI study. Brain 129, 655-667.
59. Koike, T., Kan, S., Misaki, M., and Miyauchi, S. (2011). Connectivity pattern changes in default-mode network with deep non-REM and REM sleep. Neurosci. Res. 69, 322-330.
60. Krueger, J. M., Rector, D. M., Roy, S., Van Dongen, H. P., Belenky, G., and Panksepp,J. (2008). Sleep as afunda-mental property of neuronal assemblies. Nat. Rev. Neurosci. 9, 910-919.
61. Kuhl, D. E., Edwards, R. Q., Ricci, A. R., Yacob, R. J., Mich, T. J., and Alavi,A. (1976).TheMarkIVsystem for radionuclide computed tomography of the brain. Radiology 121, 405-413.
62. Kwong, K. K., Belliveau, J. W., Chesler, D. A., Goldberg, I. E., Weisskoff, R. M., Poncelet, B. P., Kennedy, D. N., Hoppel, B. E., Cohen, M. S., Turner, R., Cheng, H., Brady, T. J., and Rosen, B. R. (1992). Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation. Proc. Natl. Acad. Sci. U.S.A. 89, 5675-5679.
63. Larson-Prior, L. J., Zempel, J. M., Nolan, T. S., Prior, F. W., Snyder, A. Z., and Raichle, M. E. (2009). Cortical network functional connectivity in the descent to sleep. Proc. Natl. Acad. Sci. U.S.A. 106,4489-4494.
64. Laufs, H., Daunizeau, J., Carmichael, D. W., and Kleinschmidt, A. (2008). Recent advances in recording elec-trophysiological data simultaneously with magnetic resonance imaging. Neuroimage 40, 515-528.
65. Laufs, H., Kleinschmidt, A., Bey-erle, A., Eger, E., Salek-Haddadi, A., Preibisch, C., and Krakow, K. (2003). EEG-correlated fMRI of human alpha activity. Neuroimage 19, 1463-1476.
66. Lauritzen, M. (2001). Relationship of spikes, synaptic activity, and local changes of cerebral blood flow. J. Cereb. Blood Flow Metab. 21, 1367-1383.
67. Lemieux, L., Allen, P. J., Franconi, F., Symms, M. R., and Fish, D. R. (1997). Recording of EEG during fMRI experiments: patient safety. Magn. Reson. Med. 38, 943-952.
68. Leopold, D. A., Murayama, Y., and Logo-thetis, N. K. (2003). Very slow activity fluctuations in monkey visual cortex: implications for functional brain imaging. Cereb. Cortex 13, 422-433.
69. Liu, W. C., Flax, J. F., Guise, K. G., Sukul,V.,and Benasich, A.A. (2008). Functional connectivity of the sensorimotor area in naturally sleeping infants. Brain Res. 1223, 42-49.
70. Liu, Z., de Zwart, J. A., van Gelderen, P., Kuo, L. W., and Duyn, J. H. (2002). Statistical feature extraction for artifact removal from concurrent fMRI-EEG recordings. Neuroimage 59,2073-2087.
71. Loehlin, J. C. (2004). Latent Variable Models: An Introduction to Factor, Path, andStructural Equation Analysis, 4th Edn. Mahwah, NJ: Lawrence Erlbaum Associates.
72. Logothetis, N. K. (2008). What we can do and what we cannot do with fMRI. Nature 453, 869-878.
73. Logothetis, N. K., Pauls, J., Augath, M., Trinath, T., and Oeltermann, A. (2001). Neurophysiological investigation of the basis of the fMRI signal. Nature 412, 150-157.
74. Lohmann, G., Margulies, D. S., Horstmann, A., Pleger, B., Lep-sien, J., Goldhahn, D., Schloegl, H., Stumvoll, M., Villringer, A., and Turner, R. (2010). Eigenvector centrality mapping for analyzing connectivity patterns in fMRI data of the human brain. PLoS ONE 5, e10232. doi:10.1371/journal.pone.0010232
75. Maier, A., Wilke, M., Aura, C., Zhu, C., Ye, F. Q., and Leopold, D. A. (2008). Divergence of fMRI and neural signals in V1 during perceptual suppression in the awake monkey. Nat. Neurosci. 11,1193-1200.
76. Mandelkow, H., Halder, P., Boe-siger, P., and Brandeis, D. (2006). Synchronization facilitates removal of MRI artefacts from concurrent EEG recordings and increases usable bandwidth. Neuroimage 32, 1120-1126.
77. Mantini, D., Perrucci, M. G., Del Gratta, C., Romani, G. L., and Corbetta, M. (2007). Electrophysiological signatures of resting state networks in the human brain. Proc. Natl. Acad. Sci. U.S.A. 104, 13170-13175.
78. Maquet, P., Peters, J., Aerts, J., Delfiore, G., Degueldre, C., Luxen, A., and Franck, G. (1996). Functional neu-roanatomy of human rapid-eye-movement sleep and dreaming. Nature 383,163-166.
79. Marrosu, F., Portas, C., Mascia, M. S., Casu, M. A., Fa, M., Giagheddu, M., Imperato, A., and Gessa, G. L. (1995). Microdialysis measurement of cortical and hippocampal acetyl-choline release during sleep-wake cycle in freely moving cats. Brain Res. 671, 329-332.
80. Massimini, M., Ferrarelli, F., Huber, R., Esser, S. K., Singh, H., and Tononi, G. (2005). Breakdown of cortical effective connectivity during sleep. Science 309, 2228-2232.
81. McGinty, D., and Szymusiak, R. (2000). The sleep-wake switch: a neuronal alarm clock. Nat Med. 6, 510-511.
82. Miyauchi, S., Misaki, M., Kan, S., Fuku-naga, T., and Koike, T. (2009). Human brain activity time-locked to rapid eye movements during REM sleep. Exp. Brain Res. 192, 657-667.
83. Moosmann, M., Schonfelder, V. H., Specht, K., Scheeringa, R., Nordby, H.,andHugdahl,K. (2009). Realignment parameter-informed artefact correction for simultaneous EEG-fMRI recordings. Neuroimage 45, 1144-1150.
84. Musso, F., Brinkmeyer, J., Mobascher, A., Warbrick, T., and Winterer, G. (2010). Spontaneous brain activity and EEG microstates. A novel EEG/fMRI analysis approach to explore resting-state networks. Neuroimage 52,1149-1161.
85. Nofzinger, E. A. (2005). Neuroimaging and sleep medicine. Sleep Med. Rev. 9,157-172.
86. Noirhomme, Q., Soddu, A., Lehem-bre, R., Vanhaudenhuyse, A., Bover-oux, P., Boly, M., and Laureys, S. (2010). Brain connectivity in pathological and pharmacological coma. Front. Syst. Neurosci. 4:160. doi:10.3389/fnsys.2010.00160
87. Ogawa, S., Tank, D. W., Menon, R., Eller-mann, J. M., Kim, S. G., Merkle, H., and Ugurbil, K. (1992). Intrinsic signal changes accompanying sensory stimulation: functional brain mapping with magnetic resonance imaging. Proc. Natl. Acad. Sci. U.S.A. 89, 5951-5955.
88. Peigneux, P., Laureys, S., Fuchs, S., Collette, F., Perrin, F., Reggers, J., Phillips, C., Degueldre, C., Del Fiore, G., Aerts, J., Luxen, A., and Maquet, P. (2004). Are spatial memories strengthened in the human hippocampus during slow wave sleep? Neuron 44, 535-545.
89. Phelps, M. E., Kuhl, D. E., and Mazziota, J. C. (1981). Metabolic mapping of the brain's response to visual stimulation: studies in humans. Science 211, 1445-1448.
90. Picchioni, D., Horovitz, S. G., Fuku-naga, M., Carr, W. S., Meltzer, J. A., Balkin, T. J., Duyn, J. H., and Braun, A. R. (2011). Infra-slow EEG oscillations organize large scale cortical-subcortical interactions during sleep: a combined EEG/fMRI study. Brain Res. 1374, 63-72.
91. Portas, C. M., Krakow, K., Allen, P., Josephs, O., Armony, J. L., and Frith, C. D. (2000). Auditory processing across the sleep-wake cycle: simultaneous EEG and fMRI monitoring in humans. Neuron 28, 991-999.
92. Power, J. D., Cohen, A. L., Nelson, S. M., Wig, G. S., Barnes, K. A., Church, J. A., Vogel, A. C., Laumann, T. O., Miezin, F. M., Schlaggar, B. L., and Petersen, S. E. (2011). Functional network organization of the human brain. Neuron 72, 665-678.
93. Qin, Y.L.,McNaughton, B.L.,Skaggs, W. E., and Barnes, C. A. (1997). Memory reprocessing in corticocortical and hippocampocortical neuronal ensembles. Philos. Trans. R. Soc. Lond. B Biol. Sci. 352,1525-1533.
94. Rasch, B., Buchel, C., Gais, S., and Born, J. (2007). Odor cues during slow-wave sleep prompt declarative memory consolidation. Science 315, 1426-1429.
95. Rechtschaffen, A., and Kales, A. (1968). A Manual of Standardized Terminology, Techniques, and Scoring System for Sleep Stages of Human Subjects. Los Angeles: Brain Research Institute.
96. Ritter, P., and Villringer, A. (2006). Simultaneous EEG-fMRI. Neurosci. Biobehav. Rev. 30, 823-838.
97. Sadaghiani, S., Scheeringa, R., Lehon-gre, K., Morillon, B., Giraud, A. L., and Kleinschmidt, A. (2010). Intrinsic connectivity networks, alpha oscillations, and tonic alertness: a simultaneous electroencephalogra-phy/functional magnetic resonance imaging study. J. Neurosci. 30, 10243-10250
98. Salvador, R., Suckling, J., Coleman, M. R., Pickard, J. D., Menon, D., and Bullmore, E. (2005). Neuro-physiological architecture of functional magnetic resonance images of human brain. Cereb. Cortex 15, 1332-1342.
99. Samann, P. G., Wehrle, R., Hoehn, D., Spoormaker, V. I., Peters, H., Tully, C., Holsboer, F., and Czisch, M. (2011). Development of the brain's default mode network from wakeful-ness to slow wave sleep. Cereb. Cortex 21, 2082-2093.
100. Saper, C. B., Chou, T. C., and Scam-mell, T. E. (2001). The sleep switch: hypothalamic control of sleep and wakefulness. Trends Neurosci. 24, 726-731.
101. Schabus, M., Dang-Vu, T. T., Albouy, G., Balteau, E., Boly, M., Carrier, J., Darsaud, A., Degueldre, C., Des-seilles, M., Gais, S., Phillips, C., Rauchs, G., Schnakers, C., Ster-penich, V., Vandewalle, G., Luxen, A., and Maquet, P. (2007). Hemo-dynamic cerebral correlates of sleep spindles during human non-rapid eye movement sleep. Proc. Natl. Acad. Sci. U.S.A. 104, 13164-13169.
102. Shmuel, A., Yacoub, E., Chaimow, D., Logothetis, N. K., and Ugurbil, K. (2007). Spatio-temporal point-spread function of fMRI signal in human gray matter at 7 Tesla. Neuroimage 35, 539-552.
103. Smith, S. M., Fox, P. T., Miller, K. L., Glahn, D. C., Fox, P. M., MacKay, C. E., Filippini, N., Watkins, K. E., Toro, R., Laird, A. R., and Beckmann, C. F. (2009). Correspondence of the brain's functional architecture dur ing activation and rest. Proc. Natl. Acad. Sci. U.S.A. 106, 13040-13045.
104. Smith, S. M., Miller, K. L., Moeller, S., Xu, J., Auerbach, E. J., Wool-rich, M. W., Beckmann, C. F., Jenk-inson, M., Andersson, J., Glasser, M. F., Van Essen, D. C., Feinberg, D. A., Yacoub, E. S., and Ugurbil, K. (2012). Temporally-independent functional modes of spontaneous brain activity. Proc. Natl. Acad. Sci. U.S.A. 109, 3131-3136.
105. Smith, S. M., Miller, K. L., Salimi-Khorshidi, G., Webster, M., Beckmann, C. F., Nichols, T. E., Ramsey, J. D.,and Woolrich, M.W. (2011).Network modelling methods for fMRI. Neuroimage 54, 875-891.
106. Spoormaker, V. I., Schroter, M. S., Gleiser, P. M., Andrade, K. C., Dresler, M., Wehrle, R., Samann, P. G., and Czisch, M. (2010). Development of a large-scale functional brain network during human non-rapid eye movement sleep. J. Neurosci. 30, 11379-11387.
107. Triantafyllou, C., Hoge, R. D., Krueger, G., Wiggins, C. J., Potthast, A., Wiggins, G. C., and Wald, L. L. (2005). Comparison of physiological noise at 1.5 T, 3 T and 7 T and optimization of fMRI acquisition parameters. Neuroimage 26, 243-250.
108. Trulson, M. E., and Jacobs, B. L. (1979). Raphe unit activity in freely moving cats: correlations with level of behavioral arousal. Brain Res. 163, 135-150.
109. Turner, R. (2002). How much cortex can a vein drain? Downstream dilution of activation-related cerebral blood oxygenation changes. Neuroimage 16, 1062-1067.
110. van der Werf, Y. D., Altena, E., Schoonheim, M. M., Sanz-Arigita, E. J., Vis, J. C., De Rijke, W., and van Someren, E. J. (2009). Sleep benefits subsequent hippocampal functioning. Nat. Neurosci. 12, 122-123.
111. van Dongen, E. V., Takashima, A., Barth, M., and Fernandez, G. (2011). Functional connectivity during light sleep is correlated with memory performance for face-location associations. Neuroimage 57, 262-270.
112. Vanderperren, K., De Vos, M., Ramau-tar, J. R., Novitskiy, N., Mennes, M., Assecondi, S., Vanrumste, B., Stiers, P., Van den Bergh, B. R., Wage-mans, J., Lagae, L., Sunaert, S., and Van Huffel, S. (2010). Removal of BCG artifacts from EEG recordings inside the MR scanner: a comparison of methodological and validation-related aspects. Neuroimage 50, 920-934.
113. Wackermann, J., Lehmann, D., Michel, C.M.,and Strik, W.K. (1993).Adaptive segmentation of spontaneous EEG map series into spatially defined microstates. Int. J. Psychophysiol. 14, 269-283.
114. Waldvogel, D., van Gelderen, P., Muell-bacher, W., Ziemann, U., Immisch, I., and Hallett, M. (2000). The relative metabolic demand of inhibition and excitation. Nature 406, 995-998.
115. Watts, D. J., and Strogatz, S. H. (1998). Collective dynamics of "small-world" networks. Nature 393, 440-442.
116. Wehrle, R., Czisch, M., Kaufmann, C., Wetter, T. C., Holsboer, F., Auer, D. P., and Pollmacher, T. (2005). Rapid eye movement-related brain activation in human sleep: a functional magnetic resonance imaging study. Neuroreport 16, 853-857.
117. Wehrle, R., Kaufmann, C., Wetter, T. C., Holsboer, F., Auer, D. P., Pollmacher, T., and Czisch, M. (2007). Functional microstates within human REM sleep: first evidence from fMRI of a thalamo-cortical network specific for phasic REM periods. Eur. J. Neurosci. 25, 863-871.
118. Wilson, D. A., and Yan, X. (2010). Sleep-like states modulate functional connectivity in the rat olfactory system. J. Neurophysiol. 104, 3231-3239.
119. Yoo, S. S., Hu, P. T., Gujar, N., Jolesz, F. A., and Walker, M. P. (2007). A deficit in the ability to form new human memories without sleep. Nat. Neurosci. 10, 385-392.
120. Yoshida, H., Peterfi, Z., García-Garcia, F., Kirkpatrick, R., Yasuda, T., and Krueger, J. M. (2004). State-specific asymmetries in EEG slow wave activity induced by local application of TNFalpha. Brain Res. 1009, 129-136.
121. Zang, Y., Jiang, T., Lu, Y., He, Y., and Tian, L. (2004). Regional homogeneity approach to fMRI data analysis. Neuroimage 22, 394-400.