Intrinsic functional clustering of the macaque insular cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Primate Brain Research

Background:

• The primate insula's functional organization is complex, studied via architecture, connectivity, and function.
• Connectivity-based parcellation methods are popular for human insula research but their functional validity is debated.

Purpose of the Study:

• To investigate the functional organization of the macaque insula using hierarchical clustering.
• To determine if data-driven clustering methods yield meaningful functional subdivisions of the insula.

Main Methods:

• Employed hierarchical clustering on macaque insula data, exploring 2-10 cluster solutions.
• Utilized fingerprinting, silhouette, and elbow methods for cluster validation.
• Analyzed functional response properties and brain-wide connectivity of identified clusters.

Main Results:

• A four-cluster solution was identified as optimal via multiple validation methods.
• These four clusters showed functional specialization for gustatory, somato-motor, vestibular, and social visual processing.
• More detailed functional differentiation emerged at higher cluster numbers, highlighting limitations of purely data-driven approaches.

Conclusions:

• Resting-state-based hierarchical clustering provides a meaningful, albeit partially detailed, description of insula functional organization.
• Combining connectivity-based parcellation with other neuroimaging modalities is crucial for a comprehensive understanding of insula subfield functions.