Can we learn without a brain?

Some animals do not need a brain to be able to learn. This is what Professor Simon Sprecher of the University of Freiburg has revealed in a study that has just been published. With his team, the biologist taught a sea anemone to adapt its behavior according to past experiences.

We spontaneously associate the faculties of learning and memorization with the existence of a brain. Indeed, science already knows a lot about the functions of the different brain areas in humans, mice or insects. But not all animals have a brain. Cnidarians, such as anemones, jellyfish and corals, have a rudimentary nervous system. So we often naively assume that these creatures can only produce reflex-like behavior," says Professor Simon Sprecher of the Department of Biology at the University of Freiburg. In a study published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), he and his team explain that this is not the case. They have succeeded in proving that the sea anemone Nematostella vectensis has a simple form of memory and that it is capable of learning by association.

Classical conditioning
The research group tested the animals by subjecting them to light and electrical stimuli: either simultaneously so as to create an association, or offset so that no link was perceptible. The sea anemones responded well to this training. Over time, those that received both stimuli at the same time retracted their bodies as soon as the light pulse was emitted. They had learned that the light was accompanied by an electric discharge; a classic Pavlovian conditioning. The cnidarians were thus able to record in their memory a link between two elements and to adapt their behavior accordingly. This is exactly what we call learning by association. This proves that even animals without a brain are capable of complex behavior thanks to their nervous system," says Simon Sprecher.
This gives us the necessary framework for further research," he adds. Now that we know that brainless animals are capable of learning, the question arises: how do they do it? We know very little about how the learning process works in animals with apparently simple nervous systems. Our hypothesis is that certain synapses are strengthened in them as well.’ So is there some kind of nerve center? Are there areas that are primarily dedicated to organizing the learning process? Or is everything distributed evenly over the whole body? How do neurotransmitters communicate with each other? These are some of the questions that arise from the results of the study and that Simon Sprecher and his team will now investigate.

Since when have there been animals capable of learning?
These observations raise another question: when and how did the ability to learn emerge during evolution? The first ancestors of all animals with a brain lived about 560 million years ago. Those with a nervous system appeared 100 to 150 million years ago," says Simon Sprecher. So have animals capable of learning existed for longer than previously thought? This is a very interesting question that needs to be investigated.

Link to the publication