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 Hendler School of Physics – Tel Aviv University

Tel-Aviv Human Brain Mapping May 2005 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

Tel-Aviv Human Brain Mapping May 2005 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) -

Tel-Aviv Human Brain Mapping May 2005 FH- Functional Holography Affinity Combining the two is done by calculating the Affinity matrix:

Tel-Aviv Human Brain Mapping May 2005 FH- Functional Holography PCA By reducing the number of dimensions, we get the FH manifold:

Tel-Aviv Human Brain Mapping May 2005 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

Tel-Aviv Human Brain Mapping May 2005 Applying FH to fMRI Selection of ROIs, and calculating correlations between channels RLRL

Tel-Aviv Human Brain Mapping May 2005 Applying FH to fMRI Clustering and Focusing on larger groups

Tel-Aviv Human Brain Mapping May 2005 Applying FH to fMRI Projecting the clusters on the brain RLRL

Tel-Aviv Human Brain Mapping May 2005 Applying FH to fMRI And computing the FH manifold RLRL L Hemis R Hemis L Handed I, R hand movement

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Aim: Exploring functional asymmetry in the motor cortex as a means of determining hemispheric dominance

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Structural functional differences between hemispheres RLRL R Hemis L Hemis L Handed 1, R hand movement

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Structural functional differences between hemispheres R Hemis L Hemis

Tel-Aviv Human Brain Mapping May Determining Dominance R Hemis L Hemis Calculating R G :

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Calculating R G : RLRL R Hemis L Hemis L Handed 1, R hand movement

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Calculating R G : R Hemis L Hemis Dominance Functional Structure ?

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Calculating R G : L Hemis R Hemis

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Right handed subject: Right hand movement RLRL R Hemis L Hemis R Handed 2, R hand movement

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Right handed subject: Left hand movement RLRL R Hemis L Hemis R Handed 2, L hand movement

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Left handed subject: Right hand movement RLRL R Hemis L Hemis L Handed 1, R hand movement

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Left handed subject: Left hand movement Matrix RLRL R Hemis L Hemis L Handed 2, L hand movement

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Average ratio nondominant/dominant of 4 subjects:

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Average ratio nondominant/dominant of 4 subjects : –Left handed 1: 0.62±0.34 –Left handed 2: 0.72±0.13 –Right handed 1: 0.63±0.11 –Right handed 2:0.58±0.20

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Discussion Degree of hemispheric dominance? Acquired dominancy? Functional rigidness and plasticity?

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance Future Tasks More Data Cross referencing Lots of other new routes to explore

Tel-Aviv Human Brain Mapping May 2005 Applying FH to fMRI – Other properties Functional Connectivity Maps Connectivity between M1s through SMA SMA L M1 R M1 RLRL

Tel-Aviv Human Brain Mapping May 2005 Applying FH to fMRI Thanks to: Itay Baruchi, Michal Kafri, Yaniv Assaf

Tel-Aviv Human Brain Mapping May 2005 Determining Dominance