An intricately patterned prefronto-caudate projection in the rhesus monkey

Area of Science:

• Neuroscience
• Neuroanatomy

Background:

• Previous studies suggested Brodmann area 9 projects only to the head of the caudate nucleus.
• The precise distribution of prefronto-caudate fibers remains incompletely understood.

Purpose of the Study:

• To investigate the distribution of prefronto-caudate fibers originating from Brodmann area 9 in the caudate nucleus.
• To characterize the topographical organization of cortico-caudate projections.

Main Methods:

• Autoradiographic study in monkeys of various ages.
• Injection of tritiated amino acids into the dorsal bank of the principal sulcus (area 9).

Main Results:

• Brodmann area 9 projects to the entire length of the caudate nucleus, challenging prior assumptions.
• Fibers in the caudate nucleus head exhibit a clustered, non-uniform distribution with grain-free cores.
• These clustered patterns are more distinct in newborn monkeys compared to older individuals.

Conclusions:

• The caudate nucleus is organized as an anatomical and functional mosaic.
• This mosaic organization challenges the view of the caudate nucleus as a homogeneously structured entity.