CYCLES IN BRAIN
Kaushik Majumdar
Systems Science and
Informatics Unit
ISI, Bangalore Centre
Talking and Understanding:
Broca’s Area
Talking and Understanding:
Wernicke’s Area
Cortical Interconnections
Functional Areas
Sensory Processing: Vision
Engel et al., Nat. Rev. Neurosci., Oct 2001
Bottom-Up and Top-Down
Processing
Jantzen et al., Journal of Cognitive Neuroscience, 2009
Feed Forward and Feed Back
Connections
Thalamo-Cortical Loops and
Cortico-Cortical Loops
Mumford, Biological Cybernetics, 65: 135 – 145, 1991.
Schematic Thalamo-Cortical
Connections
Mumford, Biological Cybernetics, 65: 135 – 145, 1991.
Thalamus as Active Black Board
Process 1
Process 2
Process
4
Process
3
Shared Memory
Mumford, Biological Cybernetics, 66: 241 – 251, 1992.
Cortico-Cortical Pathways by
Layer
A
B
How to find the loops?

Magnetic Resonance Imaging (MRI)
a) Granger causality
b) Diffusion tensor imaging

Mathematical modeling
Magnetic Resonance Imaging
T1 and T2 Time
MRI (cont)
MRI (summarized)
Grey
matter
White matter
Wandell & Dougherty, SPIE Vol. 6057, 605701, 2006.
www.csulb.edu/~cwallis/482/fmri/fmri.html
Diffusion Tensor Imaging (DTI) and
functional MRI (fMRI)
x → y or y → x
x
y
http://www.scholarpedia.org/article/Granger_causality
Granger Causality
C. Lenglet, PhD Thesis, INRIA Sophia Antipolis, France, 2006.
3D Fiber Tracts of Human Brain
Majumdar, Cognitive Neurodynamics, 2(1), 2008.
Probabilistic Estimation of Loops
Probability in
-Y each direction is
1/6.
Z6
-X
5
4
+Y
3
2
1
0
+X
Probability of a
cortical path to
loop around is
0.2782.
THANK YOU