Short association fibres form topographic sheets in the human V1-V2 processing stream.

Area of Science:

• Neuroscience
• Neuroimaging
• Human Brain Anatomy

Background:

• Short association fibres (SAF) are crucial for human brain function but remain understudied.
• Understanding SAF organization and individual consistency is vital for neuroscience research.

Purpose of the Study:

• To precisely map the structures of SAF within the primary (V1) and secondary (V2) visual cortex.
• To assess the consistency of SAF geometries and their topography across individuals.
• To investigate the relationship between SAF structure and local cortical folding.

Main Methods:

• Utilized sub-millimetre-resolution diffusion-weighted MRI and functional MRI retinotopic mapping in vivo.
• Employed probabilistic tractography to analyze SAF geometries and locations.
• Corroborated in vivo findings with a post mortem specimen for validation.

Main Results:

• Identified dense SAF connecting V1 and V2, forming sheet-like structures.
• Demonstrated retinotopic topography of SAF, consistent with local V1-V2 cortical folding.
• Confirmed high consistency in SAF geometries and locations across participants.

Conclusions:

• The study provides novel insights into the organization and consistency of short association fibres in the human visual cortex.
• The developed in vivo methodology offers a powerful tool for studying cortical and SAF reorganisation.
• Findings support potential applications in neuronavigation and comparative neuroanatomy across species.