February 28, 2024

Rodents Found to Reconstruct Incidentally Encoded Episodic Memories

A team of neuroscientists at Indiana University has made a groundbreaking discovery that sheds light on the ability of rodents to access their episodic memory. This research expands on a previous study conducted in 2018, which first demonstrated that animals can replay past events. The findings have significant implications for the development of therapies to target episodic memory loss in individuals with Alzheimer’s disease.

Led by IU graduate student Cassandra Sheridan, the study aimed to investigate whether rats can utilize their episodic memory to answer unexpected questions. While primates are typically used in cognition research, the researchers believe that cognitive precursors may be more widespread in the animal kingdom. Rats, in particular, demonstrate remarkable olfactory specialization, making them ideal subjects for this study.

Using rats as research subjects could further advance the field of memory studies by enabling the identification and measurement of intricate behavioral patterns and changes. Moreover, employing rat models can help simulate diseases such as Alzheimer’s, allowing researchers to test potential treatments before reaching the clinical stage.

To test the rats’ ability to combine episodic memory with problem-solving, the researchers designed an experiment that required the rats to solve a series of tests. Nine rats were given a list of odors, including common household spices like cinnamon and paprika. In a memory assessment, the rats were then presented with two scents from the previous list and had to determine which scent was the third-to-last scent they encountered.

To assess their capacity to answer unexpected questions using episodic memory, the rats were placed in a radial maze with scented lids covering food. After navigating the maze, the rats were given the opportunity to recall the third-to-last scent from memory, drawing upon the episodic memories of previously presented scents.

Remarkably, the rats successfully remembered multiple pieces of seemingly unimportant information and were able to replay a stream of episodic memories when such information was needed to solve an unexpected problem. The experiment yielded a 100 percent success rate.

This study is the first to provide scientific evidence that non-human animals possess the ability to reconstruct streams of incidentally encoded episodic memories. According to Jonathon Crystal, Provost Professor of Psychological and Brain Sciences at IU Bloomington, the research aims to examine a fundamental cognitive property that had previously only been observed in humans.

The implications of this breakthrough extend to the field of Alzheimer’s research. Crystal highlights that the development of drugs and therapies for Alzheimer’s has had limited success due to the poor translatability from animal models to human treatments. Most research and clinical trials for Alzheimer’s focus on cognition broadly, rather than specifically targeting episodic memory. Crystal emphasizes the importance of addressing episodic memory loss in Alzheimer’s patients, as it is the ability to recall specific events and information that can have a significant impact on their daily lives.

Overall, this research opens new possibilities for understanding episodic memory in animals and may contribute to the development of more effective treatments for conditions such as Alzheimer’s disease.

1. Source: Coherent Market Insights, Public sources, Desk research
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