Measuring Olfactory Learning and Memory in Rodents

Abstract

Age-related cognitive dysfunction is a symptom of many neurodegenerative diseases, and these diseases often involve olfactory deficits. As rodents are the most popular animal models for age-related cognitive dysfunction, it is important to understand their olfactory system and their capacity for olfactory learning and memory in both the main and accessory olfactory systems. After a brief review of learning and memory in the accessory olfactory (primer pheromone) system, we focus on behavioural tasks used to measure odour detection, odour discrimination, working memory, reversal learning, episodic and semantic olfactory based tasks in rodents. We then review our studies using an operant olfactometer to evaluate genotype, sex, and age differences in odour detection ability, olfactory discrimination learning and memory, learning strategies and cognitive flexibility in working memory and reversal learning. The final section reviews our experiments using the Pavlovian conditioned odour preference paradigm to study odour discrimination learning and describes our new one-day conditioning procedure. We discuss the parameters of this one-day test and how it is used to measure genotype, sex and age effects on short-, long- and very long-term memory. The paper thus reviews the methods for studying olfactory learning and memory in rodents and argues that their high level of ability to perform olfactory tasks should be considered as a reliable method for studying cognitive function in rodent models of human neurological disorders.