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Applying Functional Holography to fMRI

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Title: Applying Functional Holography to fMRI


1
Applying Functional Holography to fMRI
Exploring functional asymmetry in the motor
cortex as a means of determining hemispheric
dominance
Amir Rapson, Eshel Ben-Jacob, Talma
HendlerSchool of Physics Tel Aviv University
2
FH- Functional Holography
  • A new approach for analyzing complex activity in
    biological networks in the space of functional
    correlations.
  • Holography as in holograms, where a part of a
    hologram will still reveal an entire picture, we
    hope to gain the whole functional picture by
    sampling only part of the data
  • Itay Baruchi, Vernon L. Towle and Eshel
    Ben-Jacob, Functional Holography of Complex
    Networks Activity From Cultures to the Human
    Brain, Complexity 2005

3
FH- Functional Holography
  • This is done by combining two parameters to find
    structural resemblance (affinity)
  • Time propagation by computing correlations
    between time sequences -
  • Functional properties by computing distances
    between correlations (correlation of
    correlations) -

4
FH- Functional Holography

Combining the two is done by calculating the
Affinity matrix
Affinity
5
FH- Functional Holography

By reducing the number of dimensions, we get the
FH manifold
PCA
6
Applying FH to fMRI
  • Motor Cortex Unilateral hand movements
  • 5 hand movements for each hand
  • 15 seconds for each movement
  • Instructions to start and to end movements
  • Rest period of 10 seconds between movements
  • Every block of rest, instruction, movement, rest
    is analyzed as a single event

7
Applying FH to fMRI
  • Selection of ROIs, and calculating correlations
    between channels

R L
8
Applying FH to fMRI
  • Clustering and Focusing on larger groups

9
Applying FH to fMRI
  • Projecting the clusters on the brain

R L
10
Applying FH to fMRI
  • And computing the FH manifold

L Hemis
R L
R Hemis
L Handed I, R hand movement
11
Determining Dominance
  • Aim
  • Exploring functional asymmetry in the motor
    cortex as a means of determining hemispheric
    dominance

12
Determining Dominance
  • Structural functional differences between
    hemispheres

L Hemis
R L
R Hemis
L Handed 1, R hand movement
13
Determining Dominance
  • Structural functional differences between
    hemispheres

L Hemis
R Hemis
14
Determining Dominance
  • Calculating RG

L Hemis
R Hemis
15
Determining Dominance
  • Calculating RG

L Hemis
R L
R Hemis
L Handed 1, R hand movement
16
Determining Dominance
  • Calculating RG

L Hemis
R Hemis
323.29
261.47
17
Determining Dominance
  • Calculating RG

L Hemis
R Hemis
323.29
261.47
18
Determining Dominance
  • Right handed subject Right hand movement

R Hemis
R Handed 2, R hand movement
L Hemis
R L
169.93
215.17
19
Determining Dominance
  • Right handed subject Left hand movement

R Handed 2, L hand movement
R L
L Hemis
291.4
R Hemis
151.06
20
Determining Dominance
  • Left handed subject Right hand movement

L Handed 1, R hand movement
L Hemis
R L
R Hemis
21
Determining Dominance
  • Left handed subject Left hand movement

L Handed 2, L hand movement
R L
L Hemis
R Hemis
254.79
120.5
Matrix
22
Determining Dominance
  • Average ratio nondominant/dominant of 4
    subjects

23
Determining Dominance
  • Average ratio nondominant/dominant of 4
    subjects
  • Left handed 1 0.620.34
  • Left handed 2 0.720.13
  • Right handed 1 0.630.11
  • Right handed 2 0.580.20

24
Determining Dominance
  • Discussion
  • Degree of hemispheric dominance?
  • Acquired dominancy?
  • Functional rigidness and plasticity?

25
Determining Dominance
  • Future Tasks
  • More Data
  • Cross referencing
  • Lots of other new routes to explore

26
Applying FH to fMRI Other properties
  • Functional Connectivity MapsConnectivity between
    M1s through SMA

SMA
R L
R M1
L M1
27
Applying FH to fMRI
  • Thanks to
  • Itay Baruchi,
  • Michal Kafri, Yaniv Assaf

28
Determining Dominance
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