Multivariate Concavity Amplitude Index (MCAI) for characterizing Heschl's gyrus shape.

Area of Science:

• Neuroscience
• Neuroimaging
• Computational anatomy

Background:

• Heschl's gyrus (HG), part of the primary auditory cortex, exhibits significant individual variability in shape and gyrification patterns.
• Previous research suggests HG shape differences correlate with phonetic learning, expertise, and professional musicianship.
• Common HG configurations include single HG and common stem duplications (CSD), characterized by the presence of a sulcus intermedius (SI).

Purpose of the Study:

• To introduce and validate a novel computational toolbox, the Multivariate Concavity Amplitude Index (MCAI), for automated assessment of HG shape.
• To quantify shape variations in HG using continuous indices of concavity.
• To explore the application of MCAI in analyzing HG morphology in relation to individual differences, expertise, and potential disorders.

Main Methods:

• Development of the Multivariate Concavity Amplitude Index (MCAI) toolbox, which processes output from the TASH toolbox for HG segmentation.
• MCAI computes directional, continuous indices of concavity along the perimeter of an inflated HG representation.
• Application of MCAI to structural MRI data from 181 participants, including musicians (professional and amateur) and non-musicians.

Main Results:

• MCAI provides a reproducible and sensitive multivariate measure of HG shape, capable of detecting subtle variations.
• High correlations were observed between MCAI's dominant lateral concavity values and visual assessments of lateral gyrification.
• MCAI successfully replicated previous findings, indicating a higher prevalence of bilateral CSDs in musicians compared to non-musicians.

Conclusions:

• The MCAI toolbox offers an automated, objective, and sensitive method for quantifying HG shape.
• MCAI facilitates the investigation of HG morphology in diverse contexts, including individual differences, skill acquisition, and neurological conditions.
• This tool has broad potential for research in auditory cortex development, plasticity, and clinical applications.