Functional Brain Signal Processing: EEG & fMRI

Lesson 9

Kaushik Majumdar

Indian Statistical Institute Bangalore Center

kmajumdar@isibang.ac.in

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