Layer- and Cell Type-Specific Response Properties of Gustatory Cortex Neurons in Awake Mice

Area of Science:

• Neuroscience
• Gustatory System
• Sensory Cortex Organization

Background:

• Sensory cortices possess a laminar structure with distinct cell types and layers exhibiting varied stimulus responses.
• The generalization of these layer and cell type-specific response differences to the gustatory cortex (GC) is not well understood.
• Investigating GC neuronal activity based on laminar position and cell type is crucial for understanding taste processing.

Purpose of the Study:

• To investigate layer and cell type-specific response profiles of neurons in the gustatory cortex (GC).
• To determine how baseline firing rates, prestimulus activity, and taste responses differ between neuronal populations in GC.
• To explore the influence of licking behavior on GC neuronal activity and taste coding.

Main Methods:

• Extracellular recordings were performed in adult female mice to monitor neuronal activity in superficial and deep layers of the GC.
• Awake, head-restrained mice were trained to lick various tastants (sucrose, salt, citric acid, quinine, water).
• Analysis focused on baseline firing rates, prestimulus modulations, licking-related activity, and taste-evoked responses across different cell types and layers.

Main Results:

• Deep layer neurons in GC exhibited higher baseline firing rates compared to superficial layers, with deep-layer inhibitory neurons showing the highest activity.
• GC activity was modulated before tastant presentation, particularly in deep-layer inhibitory neurons, and licking strongly influenced GC pyramidal neuron spiking.
• A greater percentage of taste-coding neurons were found in deep layers, with similar tuning breadth but different decoding performance across layers.

Conclusions:

• Neuronal processing in the gustatory cortex is significantly influenced by cortical layer and cell type.
• Distinct baseline and stimulus-evoked firing profiles exist for different neuronal populations within the GC.
• These findings highlight the importance of laminar and cellular organization in gustatory information processing.