CYCLES IN BRAIN

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CYCLES IN BRAIN

• Kaushik Majumdar
• Systems Science and Informatics Unit
• ISI, Bangalore Centre

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Talking and Understanding Brocas Area
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Talking and Understanding Wernickes Area
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Cortical Interconnections
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Functional Areas
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Sensory Processing Vision
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Bottom-Up and Top-Down Processing

Engel et al., Nat. Rev.
Neurosci., Oct 2001
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Feed Forward and Feed Back Connections

Jantzen et al., Journal of Cognitive
Neuroscience, 2009
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Thalamo-Cortical Loops and Cortico-Cortical Loops
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Schematic Thalamo-Cortical Connections

Mumford, Biological Cybernetics, 65 135
145, 1991.
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Thalamus as Active Black Board

Mumford, Biological Cybernetics, 65 135
145, 1991.
Process 1
Process 2
Process 4
Process 3
Shared Memory
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Cortico-Cortical Pathways by Layer

Mumford, Biological Cybernetics, 66 241
251, 1992.
A
B
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How to find the loops?

• Magnetic Resonance Imaging (MRI)
• a) Granger causality
• b) Diffusion tensor imaging
• Mathematical modeling

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Magnetic Resonance Imaging
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T1 and T2 Time
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MRI (cont)
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MRI (summarized)
Grey matter
White matter
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Diffusion Tensor Imaging (DTI) and functional MRI
(fMRI)

Wandell Dougherty, SPIE Vol. 6057, 605701,
2006.
www.csulb.edu/cwalli
s/482/fmri/fmri.html
y
x ? y or y ? x
x
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Granger Causality

http//www.scholarpedia.org/article/Granger_c
ausality
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3D Fiber Tracts of Human Brain
C.
Lenglet, PhD Thesis, INRIA Sophia Antipolis,
France, 2006.
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Probabilistic Estimation of Loops

Majumdar, Cognitive Neurodynamics,
2(1), 2008.
Probability in each direction is 1/6.
Z6
-Y
X
-X
5 4 3 2 1 0
Probability of a cortical path to loop around is
0.2782.
Y
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THANK YOU