Is It Possible to Learn without a Brain?

Certain animals have no need of a brain for learning things. This is the surprising discovery that Prof. Simon Sprecher of the University of Fribourg has laid out in a recently published study. With his team, the biologist was able to teach sea anemones to adapt their behavior based on past experiences.

We spontaneously associate the faculties of learning and memorization with the existence of a brain. Indeed, science already knows quite a lot about the various functions located in different zones of the brains of humans, mice, and insects. However, not all animals possess a brain. Cnidarians like anemones, jellyfish and corals have a rudimentary nervous system. “We often suppose then, a bit naively, that these creatures can only behave at the level of reflex,” Prof. Simon Sprecher of the Department of Biology at the University of Fribourg explained. In a recently published study in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), Dr. Sprecher and his team made clear that the supposition is simply not true. They successfully proved that the starlet sea anemone (Nematostella vectensis) is endowed with a kind of simple memory and that it is able to learn through association.

Classic conditioning
The research group carried out tests on animals, subjecting individuals to light and electric stimuli, either simultaneously (light flashed and electric “shock” administered together) to create an association, or with an interval between the two so that no link would be perceptible. This constituted training which the anemones did indeed react to. Over time, those that had received the two stimuli simultaneously retracted their bodies as soon as the light pulse was emitted. They had learned that a flash of light was accompanied by an electric shock, classic Pavlovian conditioning. The cnidarians were therefore able to register in some kind of memory a link between two elements and adapt their behavior accordingly. “This is exactly what is called associative learning, proof that even animals without brains are able to display complex behavior thanks to their nervous system,” Dr. Sprecher said.
“So we have the necessary framework,“ he added, “to push our research further.” Now that we know creatures without brains are capable of learning, a question arises. How do they do it? “We know very little about the workings of the learning process in animals that have an apparently simple nervous system. Our hypothesis is that certain synapses are reinforced in them as well.” Does there exist then a kind of nervous center? Are there zones that are mainly devoted to organizing the process of learning? Or is the entire process spread uniformly throughout the whole body? How do neurotransmitters communicate among themselves? These are some of the questions that stem from the study and which Dr. Sprecher and his team are now going to look at.

Since when have animals capable of learning existed?
These observations raise another question. When and how did the ability to learn emerge in evolution? “The first ancestors of all the animals that possess a brain lived around 560 million years ago. Those endowed with a nervous system appeared 100 to 150 million years before that,” Dr. Sprecher pointed out. Have animals that are capable of learning existed for even longer than we have thought until now? “That is a very interesting question that certainly deserves study.”

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