The puzzling planarian regrows its brain
An interesting look at brains and souls comes from research on a tiny worm called a planarian. If you cut them in half and wait a week or two, you get two planarians identical to the original. Planarians have a head with a couple eyes and a brain with about 8000 neurons. In fact, if you choose the right part you can grow a new worm from 1/279th of the original. (No fair asking me what magic happens when you go to 1/280th.)
A new study, described in the three papers at the bottom of this post, shows that if you cut off their heads, not only do they grow a new brain, but they also grow back their memories. Researchers built a computerized device to train the planarian worms to wiggle through brightly lit areas — which they usually fear — to reach a food source.
After their heads were chopped off and regrown, they were given one more lesson on finding food in the light. These worms remembered their training to ignore the bright lights, knowing there was food at the other end. The ones that had never been trained and/or never been decapitated didn’t catch on after only one lesson. Thanks to Mark Lawrence’s Market Blog for this summary. A longer article is also available here.
So there is the puzzle for scientists who believe learning is stored in the brain. What about those of us who believe that learning is stored in the mind part of the soul? These little guys are regenerating bodies that both have the same memories. Are they regenerating minds, too? Did we just see two small souls created out of one? If some new planarian soul walked into the newly created body, how did it get the memories from the other soul?
I’m really pleased when scientists come up with experiments that show problems with ordinary-reality assumptions. We need to accept the challenge when they pose problems for the soul/life force alternative. I welcome thoughts.
The research paper is available here: doi: 10.1242/jeb.087809 — “An automated training paradigm reveals long-term memory in planaria and its persistence through head regeneration”;. Related open-access papers: doi: 10.1242/bio.20123400 & doi:10.1371/journal.pcbi.1002481
