Discover magazine reports that "Slime Molds Show Surprising Degree of Intelligence"
Single-celled slime molds demonstrate the ability to memorize and anticipate repeated events, a team of Japanese researchers reported in January. The study [pdf] clearly shows “a primitive version of brain function” in an organism with no brain at all.
In their experiment, biophysicist Toshiyuki Nakagaki of Hokkaido University and colleagues manipulated the environment of Physarum slime-mold amoebas (near right). As the cells crawled across an agar plate, the researchers subjected them to cold, dry conditions for the first 10 minutes of every hour. During these cool spells, the cells slowed down their motion. After three cold snaps the scientists stopped changing the temperature and humidity and watched to see whether the amoebas had learned the pattern. Sure enough, many of the cells throttled back right on the hour in anticipation of another bout of cold weather. When conditions stayed stable for a while, the slime-mold amoebas gave up on their hourly braking, but when another single jolt of cold was applied, they resumed the behavior and correctly recalled the 60-minute interval. The amoebas were also able to respond to other intervals, ranging from 30 to 90 minutes.
The scientists point out that catching on to temporal patterns is no mean feat, even for humans. For a single cell to show such a learning ability is impressive, though Nakagaki admits he was not entirely surprised by the results. After working with the slime mold for years, he had a hunch that “Physarum could be cleverer than expected.” The findings of what lone cells are capable of “might be a chance to reconsider what intelligence is,” he says.
Over at Science Clarified, they have a few notes on training plants:
The instinctive behavior of a plant depends mainly on growth or movement in a given direction due to changes in its environment. The growth or movement of a plant toward or away from an external stimulus is known as tropism. Positive tropism is growth toward a stimulus, while negative tropism is growth away from a stimulus. Tropisms are labeled according to the stimulus involved, such as phototropism (light) and gravitropism (gravity). Plants growing toward the direction of light exhibit positive phototropism.
Charles Darwin wrote a book that details his exploits training earth worms. In The Formation of Vegetable Mould Through the Actions of Worms, with Observations on Their Habits, published in 1881, Darwin explains that he tested the brain power of earthworms by placing fat-soaked paper triangles on the ground and observed how the earthworms carefully pulled them into their burrows, always grasping them by the pointiest end, which was the most efficient way to pulling the fake "leaves" into a hole.
Planarian Flat Worms can also be trained.
In 1962, a fascinating and seminal paper was published by James V. McConnell of the University of Michigan. In it, he describes his pioneering studies with planaria in 1953, when he began wondering what would happen if he ‘‘conditioned a flatworm, that cut it in two and let both halves regenerate.
Which half would retain the memory? He found that “the tails not only showed as much retention as did the heads, but in many cases did much better than the heads and
showed absolutely no forgetting whatsoever. Obviously memory, in the flatworm, was being stored throughout the animal’s body ....”
In 1957, two groups of “worm runners” hypothesized that memory could be transferred from a trained animal to an untrained one.
They tried grafting the heads of trained flatworms onto the tails of untrained planaria. They tried grinding up the trained worms and injecting the pieces into the untrained worms. Finally, they decided to take advantage of the factthat under certain conditions, one flatworm will eat another. They conditioned a group of worms,
chopped them into small pieces, and hand-fed the pieces to untrained “cannibal” worms.
They found that the cannibals which had eaten trained worms gave 50% more conditioned responses than a control group of cannibals which had eaten untrained
worms. This demonstrated that a chemical substance being stored throughout the worms’
bodies -- probably RNA -- was responsible for memory transfer.
And then there is the training of snails, a task accomplished despite the fact that snails have a decision tree in their brain made up of all of just two cells.
First the team had to train their snails to remember a specific event. They used a technique called conditioned taste aversion, where snails are fed a yummy treat – sucrose or carrot juice – followed by a horrible taste, in this case bitter potassium chloride (KCl) solution. If the snails have learned, they will avoid the same sweet treat in the future, knowing that it is followed by a bitter aftertaste.The world has trained Fleas for a pretty long time:
To see how well the snails had learned, the team tested their trainees 9 min 30 s after training, counting how many bites they took of sucrose solution. The team found that 42% of the snails were good learners, not feeding on sucrose. The remainder fed on the sucrose solution, showing that some snails had remembered the bitter aftertaste, while others had not
The flea is taken up gently, and a noose of the finest 'glass-silk' is passed round his neck, and there tied with a peculiar knot. The flea, unfortunately for himself, has a groove or depression between his neck and body, which serves as a capital hold-fast for the bit of silk.
Crickets have been trained.
In China, cricket fighting is an ancient sport with gambling stakes at some matches exceeding a million yuan. Masters try to pick the strongest warriors and then train them using mouse whiskers or yard grass to be even more aggressive. To promote prowess and focus, a cricket needs to have sex before combat, and the fighting space must be free of pollutants like perfume, smoke and alcohol fumes.