As scientists continue to learn more about the brain, knowing how much brain matter is needed to perform certain functions can be helpful. It turns out that a few hundred neurons are enough to make complex decisions.
Two distinct strategies
Published in the journal Current Biologythe new study looked at the predatory worm Pristionchus pacificus. Rather than examining neurons and cellular connections for signs of decision-making, researchers at the Salk Institute looked at the behavior of the nematode, specifically how it chose to use its biting abilities when faced with different types of threats.
In experiments involving the worm Caenorhabditis elegansconstituting both a prey and a competitor for P. pacificusthe neurobiologist Sreekanth Chalasani and his colleagues observed the latter adopt two distinct strategies: bite to devour and bite to deter.
And P. pacificus chose to bite to kill when confronted with larvae of C. eleganseasier to control, the nematode tended to perform this same action in order to deter adults from approaching its food source or eggs, which is evidence of a change in strategy and choice deliberate, not just failed predation attempts.
Although we are used to this type of decision-making in vertebrates, until now there has been no firm evidence that worms have enough gray matter to weigh the pros, cons, and consequences of particular actions in this way.
D’importantes implications
It appears that P. pacificus has only 302 neurons, compared to some 86 billion for humans, which suggests that the fundamental principles of decision-making are quite simple to code, from a biological point of view.
Such a discovery could notably have implications in the field of artificial intelligence, where it will be a question of teaching software to make complex decisions with as little programming and neural networks as possible.
For the team, the next step will be to determine to what extent this decision-making is anchored in the brain of P. pacificus and how flexible it is, which could potentially improve our understanding of the decision-making process in more complex organisms, including our species.