Interoceptive Insular Cortex Mediates Both Innate Fear and Contextual Threat Conditioning to Predator Odor

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Fear and Anxiety Research

Background:

• The insular cortex (IC) is implicated in human fear and anxiety, but its role in rat threat responses is less understood.
• Previous research indicated the primary interoceptive cortex (pIC) is crucial for auditory fear conditioning consolidation.
• The current study investigates the pIC's function in innate and learned defensive behaviors toward predator odors.

Purpose of the Study:

• To determine the role of the primary insular cortex (pIC) in innate and learned defensive responses to predator odor.
• To examine the effect of pIC inactivation on freezing behavior elicited by cat odor exposure.
• To assess the impact of pIC inactivation on contextual fear conditioning associated with predator odor.

Main Methods:

• Rats were exposed to a cat-worn collar to elicit freezing behavior.
• The primary insular cortex (pIC) was inactivated using muscimol or neosaxitoxin.
• Freezing behavior was video-recorded and scored; contextual fear conditioning was assessed.
• Neural activity in the IC was correlated with freezing behavior.

Main Results:

• Muscimol inactivation of the pIC significantly reduced freezing in response to single and repeated cat odor exposure.
• pIC inactivation impaired contextual fear conditioning to the environment where cat odor was present.
• Neosaxitoxin inactivation of the pIC led to a sustained reduction in freezing during subsequent odor re-exposures.
• Freezing behavior demonstrated a significant correlation with IC neural activity.

Conclusions:

• The primary insular cortex (pIC) is vital for the expression of both innate and learned fear responses to predator odors.
• The findings highlight the IC's significant role in processing threat-related information and mediating defensive behaviors.
• This research provides further evidence for the IC as a critical hub in fear circuitry.