Macaque monkey retrosplenial cortex: I. three-dimensional and cytoarchitectonic organization

Area of Science:

• Neuroscience
• Primate Neuroanatomy
• Comparative Neuroanatomy

Background:

• The retrosplenial cortex (RSC) plays a crucial role in spatial navigation and memory.
• Understanding the RSC's organization is key to deciphering its function.
• Previous studies have provided limited detailed topographic information on the macaque RSC.

Purpose of the Study:

• To provide a detailed three-dimensional (3D) neuroanatomic map of the macaque monkey retrosplenial cortex (areas 29 and 30).
• To elucidate the topographic organization and cytoarchitectonic subdivisions of the RSC and adjacent cortical regions.
• To establish a foundational understanding for future studies on RSC connectivity and function.

Main Methods:

• Three-dimensional computer reconstructions of the posterior cingulate region, including the RSC.
• Cytoarchitectonic analysis of macaque monkey cerebral hemispheres.
• Histological staining techniques, including immunohistochemistry for nonphosphorylated neurofilament protein.

Main Results:

• Detailed mapping of RSC subdivisions (areas 29l, 29m, 30) on the dorsal bank of the callosal sulcus and isthmus.
• Identification of posterior cingulate areas (23i, 23e, 23v) on the medial surface of the cingulate gyrus.
• Definition of a transitional zone (area 30v) between the RSC and prestriate visual cortex on the calcarine sulcus.

Conclusions:

• The study provides a comprehensive neuroanatomic framework for the macaque RSC and surrounding areas.
• Distinct cytoarchitectonic areas within the RSC and posterior cingulate cortex are identified and localized.
• This detailed map serves as a crucial reference for future research on RSC function and connectivity.