Reproducible sampling regimen for specific cortical regions: application to speech-associated areas

Area of Science:

• Neuroscience
• Neuroanatomy

Background:

• Human brain's external gyri pattern variability complicates identification of specific cortical areas.
• Previous studies correlating cortical structure and function have not consistently controlled for this anatomical variability.

Purpose of the Study:

• To develop a reliable and reproducible method for sampling five speech-associated and one non-speech associated cortical region in the human brain.
• To establish internal brain landmarks for consistent cortical region sampling.

Main Methods:

• Utilized non-aqueous dye to label gyri of interest before coronal brain slicing at 3 mm intervals.
• Established internal brain landmarks based on percentage of total brain length and breadth for sampling.
• Employed analysis of variance to assess landmark position consistency and cytoarchitectural variability via cortical layer depth measurement.

Main Results:

• Internal landmarks demonstrated consistent positioning in three dimensions across cases.
• Achieved 100% point-to-point agreement in correlating sampled cortical regions to internal landmarks, contrasting with external gyri variability.
• Cytoarchitectural analysis confirmed consistent sampling of distinguishable regions with significant differences in cortical layer depths.

Conclusions:

• The developed regimen provides a reliable and reproducible method for sampling specific human cortical regions.
• This technique overcomes the challenge of external gyri variability, enabling more accurate studies of brain structure and function.
• High interrater agreement (90-100%) validates the accuracy of identifying external gyri and internal landmarks.