Can't Remember? Eat Some Chocolate

What do cocoa, green tea, blueberries, and red wine have in common? You’ve probably heard in the past few years that all of these things contain flavonoids, which are linked to health benefits such as antiviral, anti-inflammatory, and antioxidant effects. As it turns out, they also may be related to improvements in cognitive function…at least in rodents, and now snails.

A recent study conducted at the University of Calgary in Canada by a team of scientists at the Hotchkiss Brain Institute examined the effects of Epicatechin (epl)—a type of flavonoid—on long-term memory formation in the great pond snail. Since a snail’s experience can be easily manipulated, the effects of the epl to be isolated without having to take many other external factors into account. Furthermore, snail neurons are fairly large, so single unit recording can be used to pinpoint exactly where in the brain the memory is formed while the animal is still alive.

To actually conduct the study, the researchers were able to train these snails to memorize a behavior related to breathing. First, here's some useful information about snails. Great pond snails are bimodal breathers, meaning that they can breathe by absorbing oxygen in the water directly through their skin. However, if the oxygen level is lowered, the snails open their pneumostome—a respiratory orifice—above the surface of the water and take in oxygen through the air.

During the study, the researchers reduced the oxygen in the water, which prompted the snail to open their pneumostome to breathe. Each time they did this, the researchers gave them a gentle poke with a wooden stick, causing the snail to close the pneumostome. After a 30 minute training period, the snail’s memory only lasted up to 3 hours; they called this “intermediate memory.” However, after the snails received a dose of epl, the researchers found that after that same 30 minute training period, snails remembered to keep their pneumostomes closed up to 3 days later! This shows a significant improvement in memory. The researchers also wanted to see how long the long-term memories lasted, and did so by not poking the snails when they came up to breathe. Because the snails kept their pneumostomes shut even in the absence of pokes, the researchers concluded that the memory was persistent and not easily forgotten (as one might expect in extinction after classical conditioning). 

Though the researchers are not sure how exactly epl enhances memory, they theorize it could be that the antioxidant properties protects neurons from injury caused by oxidative stress. Alternatively, increased blood flow to the central nervous system is an effect of flavonoids, and this effect has also been linked to neurogenesis and memory enhancement.

If I had to guess, looking at the Atkinson and Shiffrin model of memory, epl’s effect occurs at the process of encoding from short term memory to long term memory. The training period acts as maintenance and rehearsal: with the epl, 30 minutes was sufficient to encode the memory; without epl, however, the training period was not enough, and thus the memory did not last as long since it was not fully encoded. Clearly, more research regarding this topic has yet to be conducted. 

To make this long story shorter, next time you want to remember something for a longer period of time, grab a piece of chocolate and a glass of red wine!

To read the whole article, go to http://blogs.scientificamerican.com/running-ponies/2012/09/30/how-to-improve-snail-memories-with-chocolate/