Gustatory cortex in the rat. I. Physiological properties and cytoarchitecture

Area of Science:

• Neuroscience
• Sensory Physiology
• Cortical Mapping

Background:

• The precise location of the taste cortex in the rat brain has been a subject of debate.
• Traditional views assigned gustatory functions to the granular insular cortex.

Purpose of the Study:

• To precisely determine the cytoarchitectural localization of taste-elicited cortical responses in the rat.
• To differentiate the cortical representation of gustatory, tactile, and thermal tongue stimuli.

Main Methods:

• Combined anatomical and physiological techniques were employed.
• Multi-unit responses to various tongue stimuli were recorded across 97 electrode penetrations.
• Marking lesions identified transitions in functional properties and cytoarchitectural subdivisions.

Main Results:

• Taste-elicited cortical responses were localized to the agranular insular cytoarchitectural region.
• This finding contrasts with the traditional assignment of taste cortex to the granular insular cortex.
• Tongue temperature responses were identified in the ventral granular cortex, a region previously termed gustatory.

Conclusions:

• The rat taste cortex is located in the agranular insular cortex.
• The ventral granular cortex represents tongue temperature, not taste.
• This study refines our understanding of sensory cortical organization in rodents.