Gustatory cortex of primates: anatomy and physiology

Area of Science:

• Neuroscience
• Gustatory System Research
• Primate Brain Studies

Background:

• The precise location of the primary gustatory area (area G) in the brain is debated, with conflicting evidence from human and primate studies.
• Human clinical and physiological data suggest area G is in the anterior insula or near the central sulcus.
• Primate studies, however, localize area G to the buried frontal operculum (Fop) and dorsal insula.

Purpose of the Study:

• To reconcile discrepancies in the localization of the primary gustatory area (area G) between human and primate studies.
• To investigate the functional and anatomical distinctions between primary and secondary gustatory areas.
• To clarify the role of different brain regions in taste processing.

Main Methods:

• Review of clinical and physiological studies in humans.
• Analysis of physiological and anatomical studies in subhuman primates (squirrel monkeys, macaque monkeys).
• Comparison of taste neuron properties in different brain regions, including the anterior insula, frontal operculum (Fop), precentral opercular area (PrCO), and orbitofrontal cortex (OFC).

Main Results:

• Human studies implicate the anterior insula/base of the central sulcus as area G.
• Primate studies identify area G in the buried frontal operculum (Fop) and dorsal insula.
• Secondary gustatory areas (PrCO, OFC) contain taste neurons with specific sensitivities (e.g., single basic tastes, sensory-specific hunger).
• The anterior insula may interface area G with the amygdala.

Conclusions:

• Primate anatomical and physiological data provide a more consistent localization of the primary gustatory area (area G) to the frontal operculum (Fop) and dorsal insula.
• Distinct physiological properties differentiate primary and secondary gustatory areas, with secondary areas showing specialized neuronal responses.
• Further research is needed to precisely define histological boundaries and integrate findings across species for a comprehensive understanding of the gustatory cortex.