Functional Brain Signal Processing: EEG & fMRI Lesson 9 Kaushik Majumdar Indian Statistical Institute Bangalore Center M.Tech. (CS), Semester III, Course B50

Action Potential, LFP, ECoG, EEG Buzsaki et al., Nat. Rev. Neurosci., 13: 407 – 420, 2012 Bentivogilo et al., Epileptic Disorders, 5: S27 – S34, 2003

Action Potential, LFP, ECoG, EEG (cont.) or ECoG Buzsaki et al., Nat. Rev. Neurosci., 13: 407 – 420, 2012

LFP Acquisition Buzsaki, Nat. Neurosci., 7(5): 446 – 451, 2004

Hemodynamic Response

MRI Machine

BOLD vs. LFP Logothetis & Wandell, Annu. Rev. Physiol., 66: 735 – 769, 2004

Blood Oxygen Level Dependent Signal HbO 2 is dimagnetic. Deoxy-Hb is paramagnetic.

Anatomical MRI

Elements of MRI Physics Kandel et al., Principles of Neural Science, 4e, 2000

Larmor Equation Pooley, 2005 Gyromagnetic ratio is nucleus dependent. For hydrogen it is 42.6 MHz/T.

Radio Frequency (RF) Pulse Pooley, 2005 T 1 relaxation time

Tissue Contrast Maximization by T 1 Relaxation Pooley, 2005

Relaxation Process and T 2 Relaxation Kandel et al., Principles of Neural Science, 4e, 2000

T 1 and T 2 Weighting Kandel et al., Principles of Neural Science, 4e, 2000

T 1, T 2 Time Constants in ms at 1 Tesla for Different Tissues Kandel et al., Principles of Neural Science, 4e, 2000

One Dimensional Frequency Encoding Noll, 2001 B(x) = B 0 + G.x ƒ(x) = γ(B 0 + G.x)

Slice Location Kandel et al., Principles of Neural Science, 4e, 2000

Slice Location (cont.) Kandel et al., Principles of Neural Science, 4e, 2000

T 1 and T 2 Relaxation Time Buxton, 2009

Functional Magnetic Resonance Imaging or T 2 * Relaxation Imaging Kandel et al., Principles of Neural Science, 4e, 2000

T 2 and T 2 * Dephasing Pooley, 2005

References G. Buzsaki, C. A. Anastassiou and C. Koch, The origin of extracellular fields and currents – EEG, ECoG, LFP and spikes, Nat. Rev. Neurosci., 13: 407 – 420, E. R. Kandel, J. H. Schwartz and T. M. Jessel, Principles of Neural Science, 4e, McGraw Hill, New York, 2000, p. 370 – 374. R. A. Pooley, Fundamental physics of MR imaging, RadioGraphics, 25(4): 1087 – 1099, 2005.

References (cont.) D. C. Noll, A primer on MRI and functional MRI, available online at MRI%20primer.pdf MRI%20primer.pdf R. B. Buxton, Introduction to Functional Magnetic Resonance Imaging, 2e, Cambridge University Press, Cambridge, UK, 2009.

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