Flatworms Lose Their Heads But Not Their Memories

We often walk around with ideas we regard as facts, which in actuality are false.  Recently, an article was published showing that two thirds of Americans mistakenly believe we only use 10% of our brains, which is now known to be false.  A significant number of people still regard as fact that creative folks are right-brained and analytical folks are left-brained, which has also been shown to be false, starting with a study done at the University of Utah.  These ideas are both "myths" in the simplest sense of that term.  Their continuing presence is, however, quite natural and expected.  As science progresses, it either refines or negates existing theories, eventually replacing them with more accurate ones.  In the meantime, old ideas do linger for a while.

However, there is an even more subtle source of mistaken notions.  This source is our worldviews, which are images of reality we form as a culture that enable us to operate in the world.  This corresponds to the broader meaning of "myth" as it is used in comparative mythology and similar fields.  Rather than showing up as one simple incorrect fact, these manifest as paradigms under which the whole of society operates, including science.  The paradigms influence not only how we view a problem, but what we think the form of the potential solution must come in.  Worldviews are always self-limiting, but we do not let go of them easily.

The dominant worldview, or myth, within Western society is materialism, which typically holds to some basic assumptions, such as physicalism ('everything is physical'), reductionism ('sum of its parts') and objectivism ('reality exists independent of consciousness'), as far as science goes, but ultimately even leads to other ideals like consumerism and the accumulation of wealth.  This isn't too say materialism is inherently wrong, but rather self-limiting and incomplete like all worldviews have historically been.  Being under the influence of this materialistic worldview, many of us would immediately assume that the brain must be the source of consciousness.  As Richard Dawkins so bluntly stated, "We are all biological meat robots", or as AI pioneer Marvin Minsky said, "The brain is just a computer made of meat".  However, since we have no idea how consciousness actually works, these are assumptions, not facts.

Since memory is an aspect of consciousness, the automatic assumption would be that it too must be sourced somehow by the brain.  Indeed, most theories in neuroscience generally assume that memory is somehow encoded within the structures of the brain.  However, neuroscientists have had a hard time pinning down just how this happens, with some studies indicating that memories are stored across the entire brain, as if stored in a fashion similar to a hologram.  Further, Near Death Experience (NDEs) research and Psi (psychic ability) research seem to indicate that memories are stored external to the brain.  Reputable guys like Rupert Sheldrake have gone as far as coming up with theories like his Morphic Resonance, which is a kind of consciousness-as-a-field theory, where the brain acts more like a filter/transceiver of this field.  Even such noted folks like Roger Penrose are considering ideas where consciousness may be a fundamental and irreducible aspect of reality.

Indeed, the number of individuals starting to look at ideas beyond the typical mainstream, materialistic views is growing, at least in part because explaining consciousness under the materialistic paradigm has made very little progress.  The so-called "hard problem" of consciousness - that is, how does subjective, inner experience (i.e. qualia) arise from unconscious, inanimate matter - remains completely unsolved to this day.

However, more and more studies are coming out of the mainstream that also hint at a potential science beyond materialism.  The point of this blog post was to introduce one of these studies.  For example, one would assume that if memories are really stored in the brain, decapitation would eliminate those memories.  This is rather difficult to test for in humans, but not so difficult with flatworms (planaria), since they can regrow a head!  The results of a recent study (full text below) seem to strongly indicate that memories are not solely stored in the flatworms brain.   It's possible the memories here are stored in some kind of "cellular memory" within somatic tissue and I am sure they will exhaust what will be considered more pragmatic explanations before jumping to something like Morphic Resonance.  However, when these results are considered alongside the results coming out of Psi research, I think this make it more compelling for us to begin to consider the possibility that memory is not only stored external to the brain, but even the body, thereby allowing non-materialist theories like Morphic Resonance to be considered a valid, competing hypothesis for attempting to explain memory formation/recall.

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"(Phys.org) —Tufts University biologists using new, automated training and testing techniques have found that planarian flatworms store memory outside their brains and, if their heads are removed, can apparently imprint these memories on their new brains during regeneration.

The work, published online in the Journal of Experimental Biology, can help unlock the secrets of how memories can be encoded in living tissues, noted Michael Levin, Ph.D., Vannevar Bush professor of biology at Tufts and senior author on the paper.

"As bioengineering and biomedicine advance, there's a great need to better understand the dynamics of memory and the brain-body interface. For example, what will happen to stored memory if we replace big portions of aging brains with the progeny of fresh stem cells?" said Levin, who directs the Center for Regenerative and Developmental Biology in Tufts' School of Arts and Sciences.

Planaria have a remarkable capacity to quickly re-grow new body parts, and decades-old research on planarian learning had suggested that memory can survive brain regeneration. Difficulties inherent in complex and tedious manual worm training experiments contributed to planaria falling out of favor as a model for such research, but the new automated training system developed by the Tufts researchers may reverse that.

"We now have a reliable, state-of-the-art approach that moves beyond past controversies to identify quantitative, objective, high-throughput protocols for studying planarian long-term memory capabilities," said Tal Shomrat, Ph.D., first author on the paper. A former postdoctoral associate with Levin, Shomrat is now a postdoctoral researcher at the Hebrew University of Jerusalem. "I believe that investigating this unique animal that displays relatively complex behavior and can regenerate its entire brain in only a few days will provide answers to the enigma of acquisition, storage and retrieval of memories," he added.

Toward the light

Shomrat and Levin focused their attention on planaria of the species Dugesia japonica. One planarian group lived in containers with a textured floor while the other was housed in smooth-floored Petri dishes. The worms, which naturally avoid light, were then tested to see how readily they would eat liver in an illuminated quadrant on the bottom of a rough-textured dish.

Automated video tracking and subsequent computer analysis of the worms' movements (image above) showed that the group familiarized to the rough-floored dishes overcame aversion to the light significantly more quickly and spent more time feeding in the illuminated space than did the non-familiarized group.

Off with their heads

Both groups of worms were then decapitated and housed in a smooth-floored environment while their heads regenerated. Two weeks later, the fully regenerated segments were again tested. Worms regenerated from the familiarized group were slightly but not significantly quicker to feed in the lighted part of the container. However, when both groups of worms were given a brief refresher session of feeding in the textured environment, then removed and retested four days later, the planaria generated from familiarized segments were significantly quicker to feed than those regenerated from unfamiliarized worms—showing that they retained recognition of the link between this type of surface and a safe feeding environment.

Exactly how this memory was retained and recalled remains unclear. Shomrat and Levin suggest that traces of memory of the learned behavior were stored outside the brain, and imprinted on the newly-regenerated brain through mechanisms not yet identified. More investigation is needed to determine the basis for these interactions between the regenerating central nervous system and remote somatic tissues, as well as the mechanism by which specific memories are encoded in physical changes within the brain and body."

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PhysOrg Article: Flatworms Lose Their Heads But Not Their Memories: Study Finds Memories Stored Outside the Brain


The Journal of Experimental Biology:  An Automated Training Paradigm Reveals Long-Term Memory in Planarians and Its Persistence Through Head Regeneration