Source: UCLouvain

Motor system neurons not only control movement, but stimulate it. This is the surprising discovery made by the UCLouvain Cognition and Action Laboratory.

Have you ever made a decision too quickly, resulting in a poor choice? The answer is certainly yes: the propensity to make good choices systematically decreases as the speed at which decisions are made increases. What explains this? The “speed-accuracy trade-off,” which is universal in the animal kingdom.

There’s no escaping this trade-off, but it’s possible to voluntarily regulate it according to the context, by favoring either decision-making speed (to the detriment of the propensity to make good choices) or caution (to the detriment of decision-making speed).

Uninvolved muscles

In a recent study published in PLOS Biology, researchers from the Cognition and Actions Lab (UCLouvain Institute of Neuroscience, IoNS) made a surprising discovery. Dr. Gérard Derosière and Prof. Julie Duqué, in collaboration with Dr. David Thura (INSERM, Lyon) and Prof. Paul Cisek (University of Montreal), demonstrated that the activity of neurons projecting to the muscles involved in the execution of a chosen action was strongly amplified when subjects favored quick decisions.

More important, they discovered that this amplification is present in other groups of neurons that project to muscles that are not at all involved in the execution of the chosen action.

Another discovery was that the activity of a third type of neuron is rapidly reduced during the decision, which not only allows us to decide quickly but also to contract specific muscles quickly and thus move more quickly.

The motor system is involved in our choices

“We’ve succeeded in demonstrating that motor system neurons not only control movement but also incite action,” explains FNRS scientific collaborator Dr. Derosière.

“While decision-making is commonly associated with the brain’s prefrontal structures, located just above the eyes, our work shows the importance of the motor system in the speed of our choices and in impulsivity.”

Recent research on decision-making seemed to suggest that rapidly made choices were based on global changes in the activity of these neurons.

However, this hypothesis remained speculative and it remained unclear how decision speed was regulated, because the tools used by scientists did not, until now, allow the activity of these neurons to be recorded accurately.

That’s the myth we frequently tell ourselves about Einstein. That he, an outcast and a dropout, taught himself everything he needed to know on his own and revolutionized the field of physics in a number of ways. In the early days, his work thinking about light gave us the photoelectric effect, special relativity, and E = mc², among other advances. Later on, his work alone gave us General Relativity, arguably his greatest achievement. All by his lonesome, Einstein single-handedly dragged the field out of Newtonian stagnation and into the 20th, and now the 21st, centuries. Here’s why that couldn’t be farther from the truth.