The effect of spherical projection on spin tests for brain maps

Area of Science:

• Neuroimaging
• Computational Neuroscience
• Brain Mapping

Background:

• Statistical comparison of brain maps is crucial in neuroimaging research.
• Spatial autocorrelation is a key consideration in evaluating map similarity.
• The spin test is a common method for generating surrogate brain maps.

Purpose of the Study:

• To investigate the impact of spherical projection on spin test accuracy.
• To identify sources of error in generating surrogate brain maps.
• To propose methods for improving the reliability of map-to-map comparisons.

Main Methods:

• Analysis of geometric distortions introduced by projecting brain maps onto a spherical surface.
• Evaluation of spatial autocorrelation preservation in surrogate maps generated by the spin test.
• Assessment of false positive rates in map-to-map similarity testing.
• Method for identifying and removing distorted spins.

Main Results:

• Spherical projection distorts vertex distance relationships in brain maps.
• These distortions lead to imperfect spatial autocorrelation preservation in surrogate maps.
• The spin test, as commonly applied, yields inflated false positive rates.
• Targeted removal of highly distorted spins significantly reduces false positive rates.

Conclusions:

• Accurate representation of cortical geometry is essential for valid spin test applications.
• Geometric distortions in spherical projection compromise the integrity of surrogate maps.
• Improving spin test methodology by addressing geometric distortions enhances the reliability of neuroimaging statistical comparisons.