Oh My Science: Memories Without a Brain: How Worms Can Remember Stuff Without a Head

Over the summer, two biologists had fun training flatworms and cutting off their heads then letting them regrow to see if they would still remember their environment prior to the beheading. Guess what? The worms COULD remember.

Sounds weird, right? This can’t possibly be actual science. They’re literally messing with worms and then decapitating them and then observing what happens. The best part of science (to me) is that scientists get to be little kids forever and poke and prod at the world until something interesting emerges. In the case of the worms, the results shine a spotlight on just how fascinating life can be and the possibilities for how such a biological system can apply to humans.

The flatworm is somewhat famous in biological communities concerned with neurological functioning, as it can regenerate any part of its body. It is primarily made of pluripotent stem cells, which are cells that can differentiate into basically any other kind of cell the organism needs. This also means that the flatworm can completely regenerate its head. Now, although the planarian doesn’t have a brain like you or me, it does have a cluster of nerves in its head that involve memory and overall functioning and coordination of the animal.

In Shomrat and Levin’s work on the planarian flatworm, the two researchers trained flatworms using a regulated, computer-controlled training program to get the worms to not fear a light when searching for food (normally, planarian flatworms hate light). One group of worms had a familiar environment with rough-floored petri dishes, while the other group had a smooth-bottomed petri dish. They trained them for 10 days, then decapitated them and let the heads regrow for 14 days. They then reintroduced the worms with their newly grown heads into the training apparatus. After a single training session, a significant number of regrown worms could remember and had minimal issue with going directly into the light to get their food. When the familiarized worms were compared to the unfamiliarized worms now encountering the rough-bottomed petri dishes for the first time, the ones who had been trained in the rough-bottomed petri dishes found the food significantly more quickly than the unfamiliar worms. This means that a memory is retained for at least 14 days without a head!

Seriously. After 14 days of regrowing a head, these worms could remember that light wasn’t actually that bad and could navigate their environment better.

So, what does this mean for people who don’t care about flatworms? It means that there are really great prospects for learning more about how we, as humans, could potentially regenerate brain matter. This should also be another supporting point for why stem cell research is a good thing, but that is for a different article.

Just think of it: if we could regenerate brain tissue and possibly recover memories, we could have a much better chance at staving off diseases like Alzheimer’s or the cognition-killing effects of Huntington’s disease. It may seem like a far stretch, but that’s how science rolls: little discoveries here and there can provide BIG implications and a great base for further progress.

The original article is here.
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Shomrat, T., Levin, M. An automated training paradigm reveals long-term memory in planarians and its persistence through head regeneration. J Exp Biol. 2013;216(Pt 20):3799-810.