Surface Vision Transformers: Attention-Based Modelling applied to Cortical Analysis

TL;DR

This paper introduces Surface Vision Transformers (SiT), a novel attention-based model for analyzing cortical surface data, outperforming traditional surface CNNs and enabling detailed study of brain development patterns.

Contribution

The paper presents a domain-agnostic transformer architecture for surface data, using spherical patches and self-attention, advancing surface analysis beyond convolutional methods.

Findings

SiT outperforms surface CNNs in phenotype regression tasks.

SiT performs comparably on registered and unregistered data.

Attention maps reveal subtle cognitive developmental patterns.

Abstract

The extension of convolutional neural networks (CNNs) to non-Euclidean geometries has led to multiple frameworks for studying manifolds. Many of those methods have shown design limitations resulting in poor modelling of long-range associations, as the generalisation of convolutions to irregular surfaces is non-trivial. Motivated by the success of attention-modelling in computer vision, we translate convolution-free vision transformer approaches to surface data, to introduce a domain-agnostic architecture to study any surface data projected onto a spherical manifold. Here, surface patching is achieved by representing spherical data as a sequence of triangular patches, extracted from a subdivided icosphere. A transformer model encodes the sequence of patches via successive multi-head self-attention layers while preserving the sequence resolution. We validate the performance of the proposed Surface Vision Transformer (SiT) on the task of phenotype regression from cortical surface metrics derived from the Developing Human Connectome Project (dHCP). Experiments show that the SiT generally outperforms surface CNNs, while performing comparably on registered and unregistered data. Analysis of transformer attention maps offers strong potential to characterise subtle cognitive developmental patterns.