Predicted selective increase of cortical magnification due to cortical folding

TL;DR

This paper introduces a cortical magnification matrix to analyze anisotropy in cortical folding, revealing that sulcal geometry may enhance visual processing capabilities along the horizon in the human brain.

Contribution

It presents a novel tensor-based cortical magnification matrix that links cortical folding geometry to functional specialization, advancing understanding of brain structure-function relationships.

Findings

Cortical folding correlates with increased cortical tissue for horizon visual representation.

The calcarine sulcus's geometry suggests adaptation for enhanced visual processing.

Folding may serve as an anatomical basis for functional specialization.

Abstract

The cortical magnification matrix M is introduced founded on a notion similar to that of the scalar cortical magnification factor M. Unlike M, this matrix is suitable to describe anisotropy in cortical magnification, which is of particular interest in the highly gyrified human cerebral cortex. The advantage of our tensor method over other surface-based 3D methods to explore cortical morphometry is that M expresses cortical quantities in the corresponding sensory space. It allows us to investigate the spatial relation between sensory function and anatomical structure. To this end, we consider the calcarine sulcus (CS) as an anatomical landmark for the primary visual cortex (V1). We found that a stereotypically formed 3D model of V1 compared to a flat model explains an excess of cortical tissue for the representation of visual information coming from the horizon of the visual field. This suggests that the intrinsic geometry of this sulcus is adapted to encephalize a particular function along the horizon. Since visual functions are assumed to be M-scaled, cortical folding can serve as an anatomical basis for increased functionality on the horizon similar to a retinal specialization known as visual streak, which is found in animals with lower encephalization. Thus, the gain of surface area by cortical folding links anatomical structure to cortical function in a previously unrecognized way, which may guide sulci development.