Conditioned taste aversion and motion sickness in cats and squirrel monkeys

Area of Science:

• Neuroscience
• Behavioral Pharmacology
• Gastroenterology

Background:

• The area postrema is a key chemosensory organ in the brainstem involved in emesis.
• Conditioned taste aversion (CTA) is a learned response to avoid substances that cause illness.
• The role of the area postrema in CTA, particularly for motion sickness, requires further investigation.

Purpose of the Study:

• To investigate the necessity of the area postrema for drug- and motion-induced conditioned taste aversion (CTA).
• To determine if CTA can serve as a valid measure for subemetic motion sickness.

Main Methods:

• Area postrema ablation was performed in cats and squirrel monkeys using thermal cautery.
• Conditioned taste aversion was induced using xylazine (cats) or lithium chloride (monkeys) in both ablated and intact animals.
• Motion-induced CTA was assessed in ablated and intact animals exposed to a vomiting-inducing motion.

Main Results:

• Ablation of the area postrema prevented xylazine- and lithium chloride-induced vomiting and CTA in cats and monkeys.
• Intact animals exhibited vomiting and CTA following drug administration.
• Motion-induced CTA and vomiting were observed in ablated animals, indicating the area postrema is not essential for this form of aversion.

Conclusions:

• The area postrema is critical for drug-induced conditioned taste aversion but not for motion-induced CTA.
• Motion can induce CTA even after area postrema destruction, suggesting alternative neural pathways.
• Caution is advised when interpreting CTA as a measure of nausea, necessitating identification of physiological nausea correlates.