Lipid by-products linked to learning and memory formation


In a nutshell: The brain produces saturated free fatty acids during learning and memory formation, suggesting a previously unknown role for these lipid by-products.

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Lipid by-products linked to learning and memory formation

In response to learned fear, the concentration of saturated free fatty acids (FFAs) increases in certain parts of the brain. Brain Function CoE researchers made this discovery in the first brain-wide study of how FFA levels change in response to learning.

FFAs are derived from phospholipids in the brain. Unsaturated FFAs, such as arachidonic acid, have long been considered beneficial for learning and memory. But precisely how they and other FFAs contribute to these important processes was not known.

A research team led by Brain Function CoE researchers Frédéric Meunier and Pankaj Sah from the Queensland Brain Institute mapped the distribution of 18 saturated and unsaturated FFAs across the rat brain. The highest concentrations of FFAs were found in the amygdala, hippocampus and prefrontal cortex – which are involved in learning and memory. Saturated FFAs were more abundant than unsaturated FFAs across the brain.

To test how the concentration of FFAs changed during learning and memory formation, the researchers conducted an experiment involving auditory fear conditioning. This experiment teaches animals to associate a sound with an unpleasant sensation.

The researchers found that auditory fear conditioning led to an increase in saturated FFAs, mostly myristic and palmitic acids, in the same regions. It also led to a smaller increase in unsaturated FFAs like arachidonic acid. These changes were not seen when memory consolidation was chemically inhibited.

Studies of the brain often focus on the roles of proteins, genes and brain structures. The results of this study demonstrate the importance of studying the roles of phospholipids and FFAs as well.

Next steps:
The team will investigate the mechanisms that contribute to the observed increases in saturated FFAs. They will also study how the saturated FFAs contribute to the changes in brain cells that underpin learning and memory.

Wallis, T.P., Venkatesh, B.G., Narayana, V.K., Kvaskoff, D., Ho, A., Sullivan, R.K., Windels, F., Sah, P., & Meunier, F.A. (2021). Saturated free fatty acids and association with memory formation. Nature Communications, 12, 3443. doi: 10.1038/s41467-021-23840-3

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