Combinatorial Inputs to the Ventral Striatum from the Temporal Cortex, Frontal Cortex, and Amygdala: Implications for...

Area of Science:

• Neuroscience
• Primate Neuroanatomy

Background:

• The striatum is traditionally mapped based on frontal inputs, dividing it into limbic, association, and motor territories.
• Recent evidence suggests a more complex striatal topography due to converging frontal and nonfrontal cortical inputs.
• The ventral striatum (VS) is often considered purely limbic but receives multimodal information.

Purpose of the Study:

• To systematically map inputs from the frontal cortex, amygdala, temporal pole, and medial temporal cortex onto the striatum.
• To refine the understanding of the ventral striatum's complex subregional organization.
• To provide a detailed map of VS connectivity for interpreting functional interactions and guiding therapeutic targets.

Main Methods:

• Anatomical tract-tracing techniques were employed in 17 adult male monkeys (Macaca nemestrina, Macaca fascicularis, Macaca mulatta).
• Inputs from frontal cortex, amygdala, temporal pole, and medial temporal cortex were systematically mapped.
• The ventral striatum was parcellated based on the identity and strength of converging inputs.

Main Results:

• The ventral striatum exhibits heterogeneous subregions, not fitting a simple limbic-only model.
• A ventromedial sector receives motivation/emotion signals (e.g., from amygdala, vmPFC).
• A dorsolateral sector receives these signals alongside cognitive/sensorimotor information (e.g., from dlPFC, premotor cortex).
• Further parcellation revealed smaller regions with distinct input proportions within these sectors.

Conclusions:

• The striatum, particularly the VS, possesses complex, selective input combinations supporting diverse associations.
• This detailed VS parcellation offers a refined map for understanding brain function in health and disease.
• The findings may aid in developing targeted treatments for psychiatric conditions.