Daniele Piomelli and fellow colleagues from the University of California at Irving trained a group of rats in two different tasks.
In one, they were trained to avoid an area that would produce a shock if they entered (inhibitory avoidance task). In the other task, the rats were trained to locate a dry platform surrounded by water (Morris water maze task).
The Piomelli team published their results in the journal Proceedings of the National Academy of Sciences (doi: 10.1073/pnas.0903038106). Its title is “Fat-induced satiety factor oleoylethanolamide enhances memory consolidation.”
Dr. Piomellit’s colleagues, from the University of Rome (Italy), University of California, (Irvine), and Inalian Institute of Technology (Genoa), are Patrizia Campolongo, Benno Roozendaal, Viviana Trezza, Vincenzo Cuomo, Giuseppe Astarita, Jin Fu, and James L. McGaugh.
In the history of animals, including humans, the ability to forage and find meals is especially apparent when they find fatty foods. Thus, the Piomelli team state in the abstract to their paper, “The ability to remember contexts associated with aversive and rewarding experiences provides a clear adaptive advantage to animals foraging in the wild.”
Consequently, the researchers wanted to find out if hormones released during eating might help the memory of animals with regards to functions of eating and foraging.
In the abstract, they state, “The present experiments investigated whether hormonal signals released during feeding might enhance memory of recently experienced contextual information.”
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The tests on the rats were designed to see if oleoylethanolamide (OEA), a chemical produced in the small intestines that tells the body that the stomach is full after eating fatty foods, has a role in intelligence and memory.
It's actually an "endogenous peroxisome proliferator-activated receptor alpha (PPAR-α) agonist" that is a naturally-occurrring lipid derivator that regulates feeding and body weight in vertebrate animals.
The rats were first tested without OEA injected into their bodies. They were later tested, one or two days later, with some rats receiving injections of OEA, while others were not injected with the hormone.
The researchers found the rats injected with OEA performed better in the tests than the rats not given the chemical OEA.
Thus, “Here we show that post-training administration of OEA in rats improves retention in the inhibitory avoidance and Morris water maze tasks. These effects are blocked by infusions of lidocaine into the nucleus tractus solitarii (NTS) and by propranolol infused into the basolateral complex of the amygdala (BLA).” [Abstract]
They suggest that the OEA improved their memories by affecting parts of the brain that involve “emotionally charged” memory. [New Scientist]
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Since rats improved their memory when OEA is injected into their body, the researchers suggest that OEA may also boost memory in humans, since they also produce OEA in their system.
"The results indicate that OEA, acting as a PPAR-α agonist, facilitates memory consolidation through noradrenergic activation of the BLA, a mechanism that is also critically involved in memory enhancement induced by emotional arousal.”
What it comes down to, the scientists found that unsaturated fats (good, healthy fats) helped to boost the memory in rats.
It does so by activating certain memory-facilitating areas in the brain that involved emotional arousal.
The New Scientist article “Remember the facts by cramming with fat” (May 2-8, 2009, page 15) states “OEA is only produced after eating a healthy unsaturated fat called oleic acid, so a cheeseburger after a night of cramming may not work—try food with olive oil or soybean oil. Says Piomelli.”
For additional information, read the BBC News article "Fatty foods 'offer memory boost'."