The Neuroscience Of A Decision, The Existing Scientific Knowledge
Introduction
“What dress shall I wear?”
Every day we make several series of decisions that, one way or the other, shape our lives and our future. From simpler questions like ‟What dress shall I wear?” to more complex matters that may induce the most disparate consequences on our society. The beloved scientists are working to decipher the actions undertaken by our nervous system during this process. So far, though, this problem is not completely understood.
A philosophical or a science question?
One of the main issues is that decision-making often appears as a rather philosophical question that involves free will. Thus, one may cut out the problem from the field of science, believing that determinism cannot agree with such a concept. However, there are neural mechanisms that can at least explain which areas of our brain come into play during perceptual decision-making. That is when we choose one option from a list of possibilities.1
In fact, the first significant research papers started to appear in the fifties yet this topic has become a central issue in neuroscience only in the last two decades. Thanks to more advanced technologies, it is now possible to observe the brain at work and study the receptors which activate during the decision-making process.2,3
To comprehend the current state of the art, we shall proceed step by step. Due to evolution, there are animals whose nervous system is less complex than ours. Consequently in such cases, it is easier to predict and study how the brain behaves.
These models represent an approximation of the decision-making process in humans. Yet they give us a very clear idea of the situation: if we represent our possible choices with little walls scattered around, we can imagine our line of thoughts as a floating ball which, never touching the ground, continuously bounces on such walls and hits each of them several times until we choose what to do – then, the ball stops near the corresponding wall.
Neuroscience of Decision
The monkey experiment
Indeed, extraordinary progress has been recently made by some Stanford University researchers. When we are taking a decision, the choices our brain is in front of fluctuating, leading us to hesitation and doubts.3
More precisely, they used a very well-known method called ‘random dot motion discrimination task’. Every monkey was shown one or more dots on a screen. At first, the dots are still, so that the animal can focus on them and scan their position. After a while, the dots start moving, and the monkeys are asked to determine the direction.3
Meanwhile, researchers have developed a system which allowed them to visualize what was going on in the monkey’s brain cells as they decided whether the dots were shifting right or left. This led them to a striking achievement: they were capable of predicting what the animals were going to choose a few seconds before they took their final choice.3
Sound – Smell – Touch
Although this is already exciting, studies have not stopped with monkeys. These animals indeed provide interesting insights. However, it is useful to search for other suitable models to investigate the decision-making process.4
One of these is provided by rodents, which allowed researchers to extend the sensory modalities of their experiments, hence giving them the chance to take into account three other senses: sound, touch, and smell.4
This yielded a great result: neurons encode choice signals which are heavily influenced by the region of the brain and the sense we are dealing with. For instance, if the anterior lateral motor cortex is not activated in a mouse, then only decisions involving the touch are affected.4
Does the past determine our decisions?
At this point, one may wonder whether a similar argument can be carried on in more general cases, and the answer is yes. The decision-making process is influenced by lots of factors, and among them, we can find, apart from our senses, past decisions and the promise of some reward, which by the way are also bridged.5
To prove this, scientists have exploited game theory. In this context, the mathematical framework of game theory can be employed to estimate the behavior of animals and humans when they play a zero-sum game (which means that one player’s gain is equivalent to a loss for the opponent).5
It turned out, after analyzing monkeys playing free-trial and competitive games against a computer, that the essential information is encoded by neurons in the dorsolateral prefrontal cortex.5
Following this direction, scientists have found out that decision-making is a process that also involves memory and learning.6
The ventral striatum, the amygdala, the insula, and the orbitofrontal cortex – areas of the brain which are activated during the learning process – also have a crucial impact on social decisions.7
It appears that an individual often tries to figure out how other people are going to behave and subsequently adjusts personal decisions in a way that recalls the result of the theory of mind, expanding the areas of the brain involved in the process as the group of people enlarges.
The present and the future
This discussion on its own gives us an overview of how the decision-making process works, or at least of how it is understood to date. Researchers are currently approaching the problem from several perspectives, and the next few years may bring to light new important discoveries within this field.
In the meantime, we can additionally consider some applications of these studies. The most promising ones include the chance of having a more accurate overview of some mental issues like depression and schizophrenia; in a few cases, moreover, it has been possible to help people with paralysis, foreseeing their movements and, literally, readingtheir intentions thanks to a new real-time decoding technique.3
This opens the doors to a wide range of medical consequences that will probably shape the future treatment of these diseases.
Takeaway
To conclude our discussion about Decision-Making, we could point out that the investigation hasn’t to be only philosophical but scientific as well.
We constantly obsess our minds with everyday questions like “What shall I wear?”, “What shall I have for lunch?” or “What career fits better for me?”. And then we decide; I will wear my jeans with my favorite yellow TH T-shirt and I will eat salmon with rice. (Of course, I didn’t decide yet about the career thing, who did?)
However, behind this process, much more happened. Different regions of our brains are activating; memories and expectations are contributing; and surely, scientists will need more evidence to make more concrete conclusions.
Until then, stay informed and remember “Take care of your mind”.
References
- Shadlen MN, Roskies AL. The neurobiology of decision-making and responsibility: Reconciling mechanism and mindedness.
- Shubik M. Studies and Theories of Decision Making.
- Peixoto D, Verhein JR, Kiani R, et al. Decoding and perturbing decision states in real time.
- Hanks TD, Summerfield C. Perceptual Decision Making in Rodents, Monkeys, and Humans.
- Barraclough DJ, Conroy ML, Lee D. Prefrontal cortex and decision making in a mixed-strategy game.
- Fellows LK. The Neuroscience of Human Decision-Making Through the Lens of Learning and Memory.
- Seo H, Lee D. Neural basis of learning and preference during social decision-making.
