Frontal and Insular Input to the Dorsolateral Temporal Pole in Primates: Implications for Auditory Memory

Area of Science:

• Neuroscience
• Primate Brain Connectivity

Background:

• The temporal pole (TP) is implicated in diverse functions, including emotion, memory, and language.
• The specific roles of TP subdivisions remain unclear due to limited quantitative connectivity data.

Purpose of the Study:

• To quantitatively map the topographical, laminar, and weighted afferent connections of the dorsolateral subdivision of the TP (area 38DL) from frontal and insular cortices.
• To elucidate the anatomical basis for area 38DL's function within broader neural networks.

Main Methods:

• 11 retrograde tracer injections (Fast Blue, Diamidino Yellow) were administered into the lateral TP of rhesus monkeys.
• Analysis focused on identifying and quantifying inputs from frontal and insular cortical areas.

Main Results:

• Approximately 50% of area 38DL's cortical input originates from medial frontal (areas 14, 25, 32, 24; 25%), orbitofrontal (areas Pro, PAll; 15%), and insular cortices (10%).
• Auditory information processed in the superior temporal gyrus is conveyed to area 38DL and subsequently to memory-related regions like the entorhinal cortex.

Conclusions:

• Area 38DL receives substantial input from frontal and insular cortices, highlighting its integration into wider neural circuits.
• These findings suggest area 38DL contributes an auditory component to the limbic circuit involved in multimodal memory processing.