A new study led by Cornell University has shed light on the different functions of memory housed in the hippocampus, potentially opening doors for more targeted interventions in treating memory and navigational deficits seen in conditions like dementia and Alzheimer’s disease.
The research, published in Science, used optogenetic techniques to isolate and manipulate specific memory functions in rats. By disabling one type of memory while leaving the other intact, the study revealed two distinct neural codes responsible for associative memory and predictive memory based on past experiences.
Associate Professor of Neurobiology and Behavior at Cornell University, Antonio Fernandez-Ruiz, explained, “We uncovered that two different neural codes support these very important aspects of memory and cognition, and can be dissociated, as we did experimentally.”
One type of neural code is responsible for making associations, such as remembering that apples are sold at the neighborhood grocery store. The other code is predictive and involves using memory to plan new behaviors based on past experiences.
The researchers conducted experiments using rats with perturbed hippocampi. In one experiment, the rats had to explore a maze and find a new path every day to collect a reward. Those with impaired predictive capabilities were unable to remember how to get the reward. In a second experiment, rats had to learn to associate a particular location in the environment with a reward. This associative memory remained intact even when the predictive capabilities were impaired.
The implications of this research extend to the treatment of Alzheimer’s disease and dementia, where patients experience neural degeneration in the hippocampus along with memory and navigation difficulties. Fernandez-Ruiz stated, “By looking at which type of memory deficits occur in a patient, we can try to infer what type of underlying neuronal mechanism has been compromised, which will help us develop more targeted interventions.”
This breakthrough in understanding the distinct memory functions in the hippocampus brings us one step closer to effectively treating memory-related conditions and improving the lives of those affected.