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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
http://www.ece.unm.edu/~vcalhoun/courses/fMRI_Spring07/Lecture02_IntroTofMRI.pdf
MRI Machine
http://www.ece.unm.edu/~vcalhoun/courses/fMRI_Spring07/Lecture02_IntroTofMRI.pdf
BOLD vs. LFP
Logothetis & Wandell, Annu. Rev. Physiol., 66: 735 – 769, 2004
Blood Oxygen Level Dependent Signal
http://www.ece.unm.edu/~vcalhoun/courses/fMRI_Spring07/Lecture02_IntroTofMRI.pdf
HbO2 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
T1 relaxation time
Tissue Contrast Maximization by T1 Relaxation
Pooley, 2005
Relaxation Process and T2 Relaxation
Kandel et al., Principles of Neural Science, 4e, 2000
T1 and T2 Weighting
Kandel et al., Principles of Neural Science, 4e, 2000
T1, T2 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) = B0 + G.xƒ(x) = γ(B0 + 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
T1 and T2 Relaxation Time
Buxton, 2009
Functional Magnetic Resonance Imaging or T2
* Relaxation Imaging
Kandel et al., Principles of Neural Science, 4e, 2000
T2 and T2* 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, 2012.
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 http://www.cs.ucsb.edu/~mturk/imaging/Misc/MRI%20primer.pdf
R. B. Buxton, Introduction to Functional Magnetic Resonance Imaging, 2e, Cambridge University Press, Cambridge, UK, 2009.
THANK YOU
This lecture is available at http://www.isibang.ac.in/~kaushik