Brain Transfer: Spectral Analysis of Cortical Surfaces and Functional Maps
Abstract
The study of brain functions using fMRI often requires an accurate
matching of cortical surface data for comparing brain activation across
a population. In this context, several tasks are critical, such as surface in-
flation for cortical visualizations and measurements, surface matching and
alignment of functional data for group-level analyses. Present methods typically
treat each task separately and can be computationally expensive. It takes
for example several hours to smooth and match a single pair of cortical surfaces.
Furthermore, conventional methods rely on anatomical features to drive
the alignment of functional data across individuals, whereas their relation to
function can vary across a population. To address these issues, we propose
Brain Transfer, a spectral framework that unifies cortical smoothing, point
matching with confidence regions, and transfer of functional maps, all within
minutes of computation. Spectral methods have the advantage of decomposing
shapes into intrinsic geometrical harmonics, but suffer from the inherent
instability of these harmonics. This limits their direct comparison in surface
matching, and prevents the spectral transfer of functions. Our contributions
consist of, first, the optimization of a spectral transformation matrix, which
combines both, point correspondence and change of eigenbasis, and second,
a localized spectral decomposition of functional data, via focused harmonics.
Brain Transfer enables the transfer of surface functions across interchangeable
cortical spaces, accounts for localized confidence, and gives a new way to
perform statistics on surfaces. We illustrate the benefits of spectral transfers
by exploring the shape and functional variability of retinotopy, which remains
challenging with conventional methods. We find a higher degree of accuracy
in the alignment of retinotopy, exceeding those of conventional methods.
Domains
Computer Science [cs]Origin | Files produced by the author(s) |
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