Adolescent C. elegans were studied with a chemical they like to eat and compared in their response with adults. The adults show more evidence of plasticity with more neurons responding to the smell in a more positive reaction:

http://www.salk.edu/news-release/worms-teenage-ambivalence/

Now, Salk Institute scientists studying roundworms suggest that, in both worms and humans, adolescent brains mature to stable adult brains by changing which brain cells they use to generate behavior. Teen worm brains drive wishy-washy behavior that allows them to stay flexible in an uncertain world, while adult worm brains drive efficient behavior. The discovery provides insight into the underlying drivers of neurological development that could help better understand the human brain and disease.

Our research shows that, despite having exactly the same genes and neurons as adults, adolescent roundworms have completely different food-seeking preferences and abilities,” says Sreekanth Chalasani, associate professor in Salk’s Molecular Neurobiology Laboratory. “It is in adulthood that we finally see the worms become more efficient and competent at finding food.”

The microscopic Caenorhabditis elegans worm may seem like an odd source of insight into human brain development. With only 302 neurons to humans’ almost 100 billion, C. elegans is a vastly simpler organism but its basic neurological circuitry has many similarities to ours. And, since scientists have already mapped the adult roundworms’ neurons anatomically and functionally, they can easily perform experiments and trace neural circuits in C. elegans tasks that are not possible in humans, yielding valuable information about both species.

For instance, both worms and people respond to the smell of the chemical diacetyl, known to humans as “buttered popcorn smell,” which is present in a number of foods, including ones in the C. elegans diet. In fact, the worms have a pair of neurons called AWA dedicated to sensing it. To observe behavioral variation between adult and adolescent worms, the Salk team placed the animals in the center of a dish with a drop of diacetyl on one side, and a neutral odor on the other. Then, in a series of trials over several days, they characterized the paths the worms took.

What the scientists saw surprised them: Adolescent worms meandered and took their time getting to the diacetyl, if they got there at all; adult worms made a beeline for it.

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When the scientists tested other smells known to be appealing to adults, adolescent preferences varied widely. But they responded with similar alacrity as adults in getting away from a repellent odor, which shows that adolescents’ senses aren’t impaired, they’re just different than adults’.

To understand what might be going on neurologically, the team used molecular techniques to make neurons fluoresce when they are activated by specific odors. As adult and adolescent worms were gently held in custom-built traps under microscopes, odors were wafted over their noses to see which smell neurons were activated. For adolescents, the AWA neuron pair fired solely in response to high concentrations of diacetyl. But in adults, AWA fired in the presence of subtler concentrations of diacetyl. More surprisingly, three other paired neurons called AWB, ASK and AWC fired in adults as well, indicating a more complex response to the stimulus. When the team blocked the three secondary neuron pairs and ran the experiment again, adults began to behave like adolescents toward diacetyl, suggesting that adult behavior results from combinations of neuronal inputs.

The Salk team thinks adolescents’ broad preferences afford them an evolutionary flexibility in an uncertain world. If they already have a strong preference for diacetyl, but sources of that food are lacking in their environment, they will starve, whereas if they are interested in lots of different foodstuffs they can adjust their tastes to what is available. Adults, having learned what foods are available, can afford to be choosier and are more efficient at seeking particular foods.

“These results support the idea that evolution works by making a juvenile plastic to learn a lot of things; then making an adult tuned to take advantage of that learning,” says Chalasani. “Instead of merely being rebellious, teens—both humans and worms—may just be staying flexible to adapt to an unpredictable world.”

Comment: Every cell in C. elegans is completely understood, including the 302 neurons. Plasticity in learning can be easily studied as this paper shows. Here it is easy to see a neural mechanism for intelligence and learning. My point is the single-celled organism, learns by a different mechanism and it is alterations in DNA as Shapiro has shown. It necessarily much simpler, and probably automatic once a new response is established

dhw: I am leaning quite heavily towards intelligence, but I do not reject the possibility of “automaticity”. You, however, insist – despite your 50/50 – that organisms CANNOT be intelligent because they do not have a brain, and that I regard as pure prejudice.

The intelligence we see in single-celled organisms is in their reactions to stimuli which chemically appear to be automatic. Where does the decision making take place if it not automatic?

I do wholly reject the idea of "automaticity" except maybe in the case of machines built by humans.

Nothing that is made (except by humans - that we know of) is automatic. Every thing that IS made from and within the universe, is ruled by the quantum world, which is where all decisions take place. Every thing has a degree of freedom within it's own purpose, but all is ruled by the ONE purpose of the quantum world. The quantum world/level is consciousness itself. This is how I see it.

dhw: Nobody is saying that organisms do not have instincts. We have instincts too. That has nothing to do with intelligence.
DAVID: Isn't intelligence stored somewhere? We know single-celled animals almost molecule by molecule. Where is the storage point?
dhw: I am leaning quite heavily towards intelligence, but I do not reject the possibility of “automaticity”. You, however, insist – despite your 50/50 – that organisms CANNOT be intelligent because they do not have a brain, and that I regard as pure prejudice.
DAVID: The intelligence we see in single-celled organisms is in their reactions to stimuli which chemically appear to be automatic. Where does the decision making take place if it not automatic?

I’m not sure why you use the word “stored”. Memory and information are stored, but nobody knows the source of intelligence in the sense of cognizance, information-processing, decision-making etc. Albrecht-Bühler thinks the control centre of the cell is the centrosome.
Guenter Albrecht-Buehler: Cell Intelligence
www.basic.northwestern.edu/g-buehler/FRAME.HTM
Unless you believe your God personally instructs every single bacterium on how to solve every single problem, where is his 3.8-billion-year computer programme for every solution “stored”? If we know every molecule, why hasn’t it been found?

DAVID: My version of God, based on the complexity in the living beings He created, is that He certainly knew what He was doing.
dhw: If he was experimenting to create a being like himself, he would have known he was experimenting to create a being like himself. So once again, what is your objection?
DAVID: But you stated above: "What is your objection to the theoretical proposal that his goal was to produce a creature resembling himself, but he didn’t know how to do it and spent a few billion years experimenting?" I'm confused by your thinking.

Perhaps I didn’t make the distinction clear. In this hypothesis, your God knows WHAT he is doing (trying to create a being resembling himself), but has to experiment because he doesn’t yet know HOW to do it. The result: lots of complex creatures that still can’t think in the way he wants. So on he goes. Of course this runs contrary to your personal view of a God who knows and is in control of absolutely everything, but this constantly brings you to the great impasse: if he knew how to do it from the start, why did he have to design the different stages of the pre-whale, the monarch’s lifestyle and the weaverbird’s nest? And please don’t tell me they were necessary in order to keep life going till humans could arrive. An experimenting God would at least explain the disappearance of 99% of what you insist he personally created. As of course would the autonomous, intelligent, inventive mechanism which in your last post you kindly accepted as a possibility.

dhw: That suits me fine. How does the organism FREELY try a change if it does not have an autonomous, intelligent, inventive mechanism?

David: But it may well have a mechanism with God dabbling as necessary.

BBella: But if God consciously (or better said, God conscious) dwells within all that IS, God can just as easily (if not more easily) dabble from within all that IS. So that would mean God that dwells outside all that IS (if there is such), would not have to watch over all that IS (every thing) and say to himself..."oh, not doing as I choose, so I must dabble here or there". That really makes no sense. At the quantum level, nothing is automatic and nothing is an automaton. So it makes no sense to say that God dabbles. All that IS, is what it IS, because at a quantum level, all is connected and moving towards a dual purpose: it's own purpose as well as the purpose of the whole.

It all depends on whether God is in or out of everything. I believe He is both within and without the universe, and He causes speciation. The issue from the dhw standpoint is whether organisms have enough intelligence to make their own changes, and I don't think so.

How is God then in "every thing" if the "thing" cannot make it's own changes?

Can they adapt, yes, in minor ways. What I call dabbling is God stepping in

Why does God have to "step in" when God is already in every thing?

to create species. As for quantum mechanics, I think that is God's way of creating the universe. The entire universe s totally connected and follows His purpose. And the universe is conscious, which I think is an expression of God's consciousness. For me human consciousness is an extension of universal God consciousness.

So, what you are saying above is that God generated/created every thing thru quantum mechanics (or God conscious) and is connected to the entire universe and ALL follows His will and/or purpose. That being so, why would God ever have to dabble when ALL is already following God's conscious will/purpose? Is God "dabbling" just your way of saying something suddenly changed for no earthly known reason so it had to be God's will/purpose that it changed?

dhw: That suits me fine. How does the organism FREELY try a change if it does not have an autonomous, intelligent, inventive mechanism?

DAVID: But it may well have a mechanism with God dabbling as necessary.

BBELLA: But if God consciously (or better said, God conscious) dwells within all that IS, God can just as easily (if not more easily) dabble from within all that IS. So that would mean God that dwells outside all that IS (if there is such), would not have to watch over all that IS (every thing) and say to himself..."oh, not doing as I choose, so I must dabble here or there". That really makes no sense. At the quantum level, nothing is automatic and nothing is an automaton. So it makes no sense to say that God dabbles. All that IS, is what it IS, because at a quantum level, all is connected and moving towards a dual purpose: it's own purpose as well as the purpose of the whole.

dhw: I’m not convinced that the whole has a purpose, but this is a fascinating approach to our subject. If God is inside ALL THAT IS, he should be able to direct organisms any way he pleases. If things go wrong and require a dabble, it CAN only be because organisms can act independently, and how do they manage that if he's inside them? Curiouser and curiouser!

If God guides evolution as His process to produce humans, He has to dabble. Evidence of His works is in the new design of new species, which is obvious in all of evolution that jumps huge gaps in form and function. Only a planning mind can do it.