Flatworms lose their heads but not their memories: Study finds memories stored outside the brain

Aug 13, 2013
Flatworms lose their heads but not their memories
Automated testing apparatus made it possible to track how quickly and for how long each flatworm overcame its aversion to the blue light in order to get food.

(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 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 ?" 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 capabilities," said Tal Shomrat, Ph.D., first author on the paper. A former postdoctoral associate with Levin, Shomrat is now a 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.

Explore further: Hearing capabilities of bushcrickets and mammals

More information: "An automated training paradigm reveals long-term memory in planaria and its persistence through head regeneration" Journal of Experimental Biology jeb.087809  First posted online July 2, 2013, DOI: 10.1242/jeb.087809

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User comments : 15

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cantdrive85
1 / 5 (10) Aug 13, 2013
Exactly how this memory was retained and recalled remains unclear.

From the mechanistic view of modern science there can only be one answer;
"help unlock the secrets of how memories can be encoded in living tissues"
Rupert Sheldrake suggests the "mind" is not necessarily in the brain.
http://www.sheldr...morphic/
jsdarkdestruction
2.8 / 5 (4) Aug 13, 2013
Is it possible these worms are like cantdrive85 and have their brains in their asses?
kochevnik
1 / 5 (5) Aug 13, 2013
Exactly how this memory was retained and recalled remains unclear.

From the mechanistic view of modern science there can only be one answer;
"help unlock the secrets of how memories can be encoded in living tissues"
Rupert Sheldrake suggests the "mind" is not necessarily in the brain.
The mind like any quantum computer doesn't contain all of it's states in our classic world. That is basic quantum mechanics. What we are witnessing is elaborate mechanisms like the brain creating long-lasting structures in alternate worlds and accessing them by means we have yet to discover. Structure is the only thing that exists. Particles are simply transient states, the quantum vacuum being one example. Even nothing has structure
Gmr
2.3 / 5 (6) Aug 14, 2013
I'm wondering if, well, the way human nervous reflexes can short-circuit (as in reacting to a sharp pain or burn) has any bearing in this. The "brain" might have grown out of a need to process data close to the source (the eyes/forward senses) and "memory" instead stored in most of the rest of the system of tissue in the form of "remembered" action and response.

Kind of like using the wiring in a home to store details about what is turned on when rather than a central controller.
kochevnik
1.8 / 5 (5) Aug 14, 2013
I notice they employed a periodogram for analyzing mass correlations. I enjoy that tool and I think it's underused in biology and climate modeling
antialias_physorg
3.5 / 5 (2) Aug 15, 2013
The mind like any quantum computer doesn't contain all of it's states

The mind isn't a quantum computer. Neurons are way too large to be affected by changes in quantum states. At that size we're dealing with classical entities.

As for the article: That something can regenerate its brain is already pretty freaky.
The notion that previously trained muscle groups will continue to respond favorably to the environment they have been trained for seems less surprising (still: cool experiment)

If you have ever done any sports that require quick reactions you will know that there is such a thing as 'muscle memory' - which works faster than the cognitive loop via the brain. We DO have nerve cells in the muscles which aren't that dissimilar, functionally, from neurons. Some, like the patella reflex everybody should be familiar with from doctors' visits, bypass the brain and go via a vertebral loop. That the connectivity of such systems isn't static seems plausible.
Sean_W
1.6 / 5 (7) Aug 18, 2013
The mind like any quantum computer doesn't contain all of it's states

The mind isn't a quantum computer. Neurons are way too large to be affected by changes in quantum states. At that size we're dealing with classical entities.


While it is speculation at the moment, it has been suggested that unlike Schrödinger's cat--which has definite, macroscopic states which experience decoherance in response to the environment--cells may be able to exist in a superposition of two or more states which can not easily be differentiated. Cells which are about to make a "decision" like initiating cell death or reproduction (or, I would guess, neuron cells about to fire) might, if the speculation is right, exist in both a state of "just made the decision and about to initiate" as well as a state of "haven't quite committed yet".

They are discovering methods of creating macroscopic quantum systems as well as exploring quantum phenomena in biological systems like photosynthesis.
Gmr
1 / 5 (1) Aug 18, 2013
This example illustrates, it has no meaning to give the scientists money for research without applications, because they will forget it and they will repeat it again after few years.


That's not what I see at all. This, instead, appears to ask what the role of the brain is, if apparently learning can take place at the level of the body. What is the brain for? What was it for originally? That's an entirely different question from the previous experiments with planaria, and done with different tools and methods.
kochevnik
1 / 5 (2) Aug 18, 2013
The mind like any quantum computer doesn't contain all of it's states

The mind isn't a quantum computer. Neurons are way too large to be affected by changes in quantum states. At that size we're dealing with classical entities.
That's a classic dogma popularized in the 80s and before. You can read articles here documenting researchers building entangled systems a kilometer or longer. Macroscopic boson particles the size of a room have been made for over 20 years. The outer electron orbitals in a uranium atom extend out near Jupiter. Photons "experience" the world as 2D as they take no time to travel along their world lines: they don't experience depth. The brain drives and is driven by electromagnetic coupling and this is the engineering basis for new devices
antialias_physorg
not rated yet Aug 19, 2013
You can read articles here documenting researchers building entangled systems a kilometer or longer.

...made up of two photons (not even atoms) under VERY special/isolated circumstances.
And the systems are kilometers APART - not kilometers long.

A typical human cell has 100000000000000 (10E14) atoms. That is way, way, WAY beyond any size class where individual quantum effects matter. Singular quantum events (which do make a difference on the order of individual atoms) even out over such large numbers very quickly.
It's like tossing coins:
Is there unpredictability to the average outcome in an individual coin toss? Yes.
In 10? Some.
In 100? Not so much.
In 10E14? So little that you'd have to wait several lifetimes of the universe until you can expect to get one neuron (amongst the billions in a brain) to fire in an unexpected manner due to quantum effects (i.e. at odds with classical predictions).
antialias_physorg
5 / 5 (1) Aug 19, 2013
This example illustrates, it has no meaning to give the scientists money for research without applications, because they will forget it and they will repeat it again after few years.

Again your ignorance of anything scientific shows. Have you ever read any paper in your life? Seriously: The first section of EVERY paper is the state-of-the-art section where they recap what is already known.
Pick a paper at random. Any paper at all ever written in any scientific field.

This is the FIRST thing you do in research: See what has already been published. This involves reading hundreds of papers - and this is an ongoing process throughout your work (as others aren't stopping in theirs for the several years it takes you to get to results).

Without that effort you might as well not bother (and it's absolutely imperative to show you have done that effort if you want to apply for any grants. No overview of the field - no grant. It's that simple.)
VendicarE
1.8 / 5 (5) Aug 19, 2013
There is nothing surprising here. Flatworms - like Republicans - aren't complex enough to have much of a brain. so the computations can't be centralized.

What remains is a nervous system that is more distributed and where the distinction between muscle and nerve is less pronounced.
kochevnik
1 / 5 (2) Aug 20, 2013
You can read articles here documenting researchers building entangled systems a kilometer or longer.

...made up of two photons (not even atoms) under VERY special/isolated circumstances.
And the systems are kilometers APART - not kilometers long.

A typical human cell has 100000000000000 (10E14) atoms. That is way, way, WAY beyond any size class where individual quantum effects matter. Singular quantum events (which do make a difference on the order of individual atoms) even out over such large numbers very quickly.
And yet the combinatoric interactions increase to 100000000000000! (factorial). That divides time into such small sections that there are ALWAYS simultaneous, irreducible interactions coupled with electromagnetic energy. This same indistinguishably is what drives lasers. A point where photons and electrons couple and behave as unitary plasmons
antialias_physorg
not rated yet Aug 20, 2013
And yet the combinatoric interactions increase to 100000000000000! (factorial). That divides time into such small sections that there are ALWAYS simultaneous, irreducible interactions coupled with electromagnetic energy.

What does that even mean?
C'mon. That's just pseud techno-blurb.
The depolarization curves of neurons are very classical. We're dealing with electro-CHEMICAL reactions here which are slooooow (compared to quantum effects).

A point where photons and electrons couple and behave as unitary plasmons

A neuron isn't a laser. And the laser photons aren't indistinguishable. It is just resonant excitation of atoms. Notice that stuff like laser light does not occur in nature - because (as with the entanglement experiments we perform) you need precise conditions and setups that aren't available in nature.

Gmr
1 / 5 (1) Aug 20, 2013
The depolarization curves of neurons are very classical. We're dealing with electro-CHEMICAL reactions here which are slooooow (compared to quantum effects).


900 feet per second, from what I recall along motor/sensory neurons - far below the 186,000 miles per second of light, or the speed of an electrical signal in a wire... much less the instant "spooky action at a distance" speed of entanglement.

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