TY - JOUR
T1 - Local gradient analysis of human brain function using the Vogt-Bailey Index
AU - Farrugia, Christine
AU - Galdi, Paola
AU - Irazu, Irati Arenzana
AU - Scerri, Kenneth
AU - Bajada, Claude J.
N1 - Funding Information:
The authors would like to thank Dr L. Q. Costa Campos for his valuable input to the software. Preliminary results were outlined in the poster entitled VB Cut: a measure of local correlations in brain function, which was presented at OHBM 2022. ABIDE I funding: Primary support for the work by Adriana Di Martino was provided by NIMH K23MH087770 and the Leon Levy Foundation. Primary support for the work by Michael P. Milham and the INDI team was provided by gifts from Joseph P. Healy and the Stavros Niarchos Foundation to the Child Mind Institute, as well as by an NIMH award to MPM (NIMH R03MH096321).
Funding Information:
Data were provided in part by the Human Connectome Project, WU-Minn Consortium (Principal Investigators: David Van Essen and Kamil Ugurbil; 1U54MH091657) funded by the 16 NIH Institutes and Centers that support the NIH Blueprint for Neuroscience Research; and by the McDonnell Center for Systems Neuroscience at Washington University.
Funding Information:
This article was produced as part of the BEyond BOundaries on the Brain (BE-BOB) project, financed by the University of Malta Internal Research Grants Programme (Research Excellence Fund—Grant Agreement No. 202201). It is based on work from COST Action CA18106-The neural architecture of consciousness (NeuralArchCon), supported by COST (European Cooperation in Science and Technology: www.cost.eu ).
Publisher Copyright:
© 2024, The Author(s).
PY - 2024/1/31
Y1 - 2024/1/31
N2 - In this work, we take a closer look at the Vogt-Bailey (VB) index, proposed in Bajada et al. (NeuroImage 221:117140, 2020) as a tool for studying local functional homogeneity in the human cortex. We interpret the VB index in terms of the minimum ratio cut, a scaled cut-set weight that indicates whether a network can easily be disconnected into two parts having a comparable number of nodes. In our case, the nodes of the network consist of a brain vertex/voxel and its neighbours, and a given edge is weighted according to the affinity of the nodes it connects (as reflected by the modified Pearson correlation between their fMRI time series). Consequently, the minimum ratio cut quantifies the degree of small-scale similarity in brain activity: the greater the similarity, the ‘heavier’ the edges and the more difficult it is to disconnect the network, hence the higher the value of the minimum ratio cut. We compare the performance of the VB index with that of the Regional Homogeneity (ReHo) algorithm, commonly used to assess whether voxels in close proximity have synchronised fMRI signals, and find that the VB index is uniquely placed to detect sharp changes in the (local) functional organization of the human cortex.
AB - In this work, we take a closer look at the Vogt-Bailey (VB) index, proposed in Bajada et al. (NeuroImage 221:117140, 2020) as a tool for studying local functional homogeneity in the human cortex. We interpret the VB index in terms of the minimum ratio cut, a scaled cut-set weight that indicates whether a network can easily be disconnected into two parts having a comparable number of nodes. In our case, the nodes of the network consist of a brain vertex/voxel and its neighbours, and a given edge is weighted according to the affinity of the nodes it connects (as reflected by the modified Pearson correlation between their fMRI time series). Consequently, the minimum ratio cut quantifies the degree of small-scale similarity in brain activity: the greater the similarity, the ‘heavier’ the edges and the more difficult it is to disconnect the network, hence the higher the value of the minimum ratio cut. We compare the performance of the VB index with that of the Regional Homogeneity (ReHo) algorithm, commonly used to assess whether voxels in close proximity have synchronised fMRI signals, and find that the VB index is uniquely placed to detect sharp changes in the (local) functional organization of the human cortex.
KW - Cortical organization
KW - Functional connectivity
KW - Regional homogeneity
KW - Vogt-Bailey index
UR - http://www.scopus.com/inward/record.url?scp=85183759517&partnerID=8YFLogxK
U2 - 10.1007/s00429-023-02751-7
DO - 10.1007/s00429-023-02751-7
M3 - Article
C2 - 38294531
AN - SCOPUS:85183759517
SN - 1863-2653
VL - 229
SP - 497
EP - 512
JO - Brain Structure and Function
JF - Brain Structure and Function
ER -