Interview with Michele Scaltritti. From the brain to the motor response: a sequence of processes as simple as it seems?

In his research at DiPSCo, Michele Scaltritti investigates the boundaries between cognition and action in the context of decision-making. In other words, he studies the relation between decisional processes and the overt motor behavior that translates the decisional content into an overt response.
Experimental results, so far, suggest that even simple motor acts, such as pressing a button, carry a decisional content inherited from complex decision-making processes.

What does this mean exactly? Why are the implications relevant? We asked these questions to dr. Scaltritti.

Let’s start from the basics: what type of experiments are you working on?

In these experiments participants are asked to decide, via a button-press response, if the letter string they are seeing on the PC corresponds to a word or to a pseudoword, that is a readable string with no actual meaning.

A first series of evidence suggests that decisional processes are still unfolding when we begin to move in order to perform the behavioral motor response. The clearest example of that would be that, sometimes, participants begin an incorrect response but they stop it to issue the correct one: they do begin responding with a hand, the incorrect one, but they manage to stop it and to provide the final response with the opposite hand, the correct one.

In a recently published paper, you have tackled the relation between brain and muscles. Can you clarify this idea?

What we’ve seen in past research is that even peripheral aspects such as the physiological features of a muscle’s contraction, or the duration of a simple button-press response, are modulated by decisional variables that have been traditionally linked with higher-level cognitive processes.

In this more recent paper, we tried to reconstruct the chain of electrophysiological processes underlying these simple muscular responses. Previously, we only addressed very peripheral aspects related to pure muscular activity. We thus decided to move backwards, and investigated the chain all the way from the muscles to the brain.

Why is it relevant to understand what happens throughout the pathway going from our brain to the motor response?

These simple decisions are very common in our daily lives. I just typed a somewhat delicate message. Should I click on “Send” or on “Delete”? I am driving and the traffic light suddenly turns to yellow. Should I accelerate or should I hit the brakes? These are just a few examples. These types of decisions are very common even in more specialized contexts. The performance of an athlete, for example, can be viewed as a continuous series of highly-detailed decisions unfolding on a par with the actual action. Shall I dribble to the left or to the right? Should I block the ball with the right or the left hand?

Knowing that part of these decisions can still be revised even when the corresponding action is still unfolding may leave some room to improve their accuracy, for example by monitoring peripheral muscular activation.

The results from this line of research may prompt a reconsideration of some traditional assumptions that, to be honest, so far have proven to be very fruitful.

What are you trying to find out?

We were trying to understand how decisions are forwarded from the cerebral cortex to the muscles. This was the idea: our brain first computes a general motor goal, for example, “I am going to press the right-hand button; then, it begins to translate this general goal into fine-grained motor-programs, with a detailed specification of the temporal and spatial parameters of the to-be-performed movement. This information is then forwarded to the periphery, that is to our muscles, for an overt action. The question was whether the decisional dynamics we have been observing at the muscular level were traceable all across this hierarchy of motor-processes.

Was your hypothesis correct?

Not at all. We found some rather unexpected results. We found similar effects at the two extremes of the motor hierarchy, that is at the highest level where general motor-goals are computed, and at the most peripheral levels of muscular activity. In the intermediate levels, however, these decisional effects were nowhere to be found.

How do you explain these results?

Possibly, what we thought to be a single decisional process that begins in the brain and is continuously propagated to the muscles, may actually be made of multiple components that are mapped onto different levels of the motor hierarchy.

We are still trying to understand what type of decisional components are reflected across different levels of motor-processing. Maybe at the muscular level we’re just performing some type of control on the accuracy of the response, a sort of action monitoring performed to double-check whether our response is correct. We’re now investigating this possibility.

Your research has recently received a grant in the context of the PNRR program. This specific project also deals with aging. How does the issue of aging fit with what you told me so far?

One goal of these studies is to understand the specificities of decision-making in older adults.

We should not take for granted any equivalence between young and older adults. For example, even within very simple decision making tasks, older adults typically display a slower performance. One may suspect this is due to slower information processing, or to an increased difficulty with the task, but this is not the case. The scientific literature has demonstrated that older adults are slower simply because they are more cautious in their decisions. All else being equal, older adults need more information and evidence before committing to a decision and, hence, to the corresponding response. They take more time because they want to be sure about the accuracy of their response.

Together with Simone Sulpizio (University of Milano-Bicocca) we would like to understand whether this type of specificity in the aging population may influence the interactions between cognition and action in the context of decision making.

Additional Information

The research project “Functional characterization of decisional components in motor responses for young and older adults” has been financed in the context of the funding scheme “Progetti di Ricerca di Interesse Nazionale (PRIN)” of the PNRR. The experimental plan consists of five studies. Three experiments are going to be conducted within the laboratories of the University of Trento, under the supervision of Michele Scaltritti and Saman Kamari Songhorabadi. The other two studies are supervised by Simone Sulpizio (PI of the project) at the University of Milano-Bicocca.

Contacts: michele.scaltritti [at]