The brain and decision-making: What part of the brain makes the decisions? This question needs to be addressed with more interest. Long ignored or left unanswered, today’s new scientific discoveries allow us to know more about the part of the brain that makes decisions.
In our daily lives, we are able to make thousands of decisions, which can be more or less important.
If there is anything that characterizes human beings, it is that their whole life is based on continuous decision-making, not only covering basic needs or situations but having short-term effects – what to eat, what clothes to wear, etc. – but also other more complex – what political party to vote, where to invest, accept or not a job offer, to be operated, for example – whose consequences leave their traces for a long time, sometimes permanently and irreversibly.
Plato’s classical formula has ruled for nearly 20 centuries, according to which man has a soul in constant conflict, divided between reason and emotions held responsible for errors. However, modern science, especially since the twentieth century – with the development of psychology and neuroscience – has shown that, in fact, the process is much more complex.
According to the neuroscientist Lehrer, we should not underestimate, as classical philosophers do, emotions, because they play a major role in the process of thought. They are positive, even when mistakes are made because unless you feel the uncomfortable symptoms of the error, the brain will never examine its models.
How to make a quick and responsive decision in a complex and changing environment? This is a question that we all face, caught up in the sometimes contradictory flow of information peculiar to modern life.
More pragmatically, it is a survival issue for all living organisms that navigate between the need to seek resources and avoid predators. Therefore, it seems reasonable to postulate that the evolution has favored the development of brain architecture allowing fast and adapted decision making. Identifying functional principles is a major challenge for contemporary neuroscience.
*** How do the brain and neural circuits act to process information and choose accordingly?
We have to choose what to do, and while the decisions are logically very different, our neural circuits must work to process all the data and choose accordingly. Science has been asking for years exactly how the neural groups responsible for decision-making work. Before making a decision, we must analyze the surrounding conditions. The brain, before the election, must process this information and then be able to decide correctly.
Until now, scientists thought there were two groups of neurons: the first network of nerve cells would be responsible for filtering whether movement or color was more relevant to making the decision, while the second group of neurons should only take into account sensory information, previously filtered to choose what we were doing.
In other words, the researchers assumed that we could not process all the information globally and that, therefore, we needed two neural gateways, which would help us filter this data.
Let’s take a look at the evolution of some scientific studies concerning decision-making.
I – Researchers Discover an Area of the Brain and Decision-Making
A group of researchers from the University of Santiago de Compostela, whose study was published in the Proceedings of the Academy of the United States of America (PNAS) in October 2009, discovered an area of the brain, called the premotor cortex, responsible for monitoring and analyzing the consequences of decisions.
To adapt decisions to the needs of the environment, the human being must evaluate his actions and know if the answers given are correct, thanks to introspection, memory and decision making, functions that depend on the premotor cortex.
Researchers have shown that neurons in this part of the brain perform all the necessary procedures for decision-making, evaluate their results and, consequently, modify the behavioral adjustment criteria.
They said in a statement that this was a very important finding, as these functions are altered in many behavioral disorders and can, therefore, be therapeutic targets for these diseases.
II – Researchers Locate the Place of the Brain Where Decisions Are Made
According to a study by scientists at Stanford University and published in Nature magazine in November 2013, decisions are made in only one region of the brain. And it would be in the prefrontal cortex – the frontal lobe – an area in which a single group of neurons integrates the information to later make a decision about it. It is a discovery that, if confirmed, could change several concepts taken for granted in neuroscience, because until now, it was thought that two groups of neurons came into play, and not one as has been proven.
The line of inquiry, in which they used monkeys as animal models and complex computer programs, concluded that there is a specific point in the prefrontal cortex responsible for this type of data processing and decision-making.
In other words, there would not be two neural circuits – information filtering and final choice -. On the contrary, decisions would be made by a single group of neurons, located in the frontal lobe, which would integrate the information and then make a single choice.
Their work, which consisted of biological experiments and computer models, would change many of the concepts currently known in neuroscience. This study, like other projects related to neurobiological projects, once again demonstrates the unknown that the brain is today, in the 21st century.
III – The Area of the Brain for Decision Making and Planning Is “Exclusively Human”
Scientists from Oxford University, whose findings were published in Neuron magazine in January 2014, have discovered an area of the brain that seems to be exclusive to humans and most likely has something to do with cognitive.
An area the size of a walnut in the frontal cortex is called the lateral frontal pole. He is responsible for planning and decision-making and, according to new findings, has no equivalent in the monkey’s brain. The researchers, therefore, believe that this region of the brain could be responsible for the superiority of the human being in tasks that require strategic planning, decision-making and the execution of several tasks simultaneously.
The researchers compared magnetic resonance imaging of the ventrolateral frontal cortex in humans and in the macaque, a region of the brain that controls the language and complex processes of thought. Surprisingly, it was found that the area was largely connected in the same way between species. But the notable difference was the lateral frontal pole.
Parts of the large ventrolateral frontal cortex are involved in diseases such as ADHD (Attention Deficit Hyperactivity Disorder), substance abuse and compulsive disorders. The language is affected when parts of the area are damaged as a result of a stroke or neurological disease.
Therefore, a deeper understanding of this area will help scientists learn about brain changes due to disease and damage.
IV – Decision-Making Involves an Area of the Brain Hitherto Unknown
Scientists from the Institute of Cognitive and Integrative Neuroscience of Aquitaine (INCIA, CNRS / University of Bordeaux), whose work was published in The Journal of Neuroscience in September 2015, discovered that an area of the brain located in the thalamus also plays a key role in the implementation of a brain architecture allowing rapid and adapted decision-making.
Classically, it has been argued that the most advanced cognitive functions, such as the ability to reason, plan, or develop strategies to solve a problem, must necessarily be embodied in the most advanced brain regions. From this reasoning arises a wide interest of neuroscientists for the cortex, and more particularly for its so-called prefrontal part. This craze, if it is understandable, has the disadvantage of obscuring the functional contribution of other brain regions.
In both humans and rodents, the prefrontal cortex is the most anterior part of the brain. In these two species, the thalamus corresponds to a deep region, called subcortical.
A particular subcortical region is of particular interest: the thalamus, the main source of innervation of the entire cortex, and particularly of its prefrontal subdivision.
The thalamus must be conceived of as a strongly differentiated structure consisting of a multitude of “nuclei” – groups of neurons – each having cortical connectivity of its own.
Initially, the role of the thalamus was conceived as that of a passive transfer of information to the upper cortical stage, where complex mental operations are supposed to operate. By the early 1980s, however, the role of the thalamus in memory was recognized. A few years later, some theoretical conceptions from neurophysiology have argued that the cortex also sends back projections to the thalamus and therefore that the latter region cannot be limited to a relay role.
However, it is necessary to wait until the last years and the provision of new techniques in neurobiology to really tackle the functional principles at work in the “loops” formed by the reciprocal projections uniting cortex and thalamus.
Scientists can now specifically study the constitutive elements of these famous loops: the thalamocortical pathways (from the thalamus to the cortex) and the cortico-thalamic pathways (from the cortex to the thalamus).
To do this, they carried out two complementary rat experiments aimed at transiently and specifically inhibiting, by the pharmacogenetic method, the thalamic neurons innervating the prefrontal cortex or, on the contrary, the cortical neurons innervating the thalamus.
Each time, they examined the choice of animals when assessing the current value of the reward or the causal link between the action and its effect.
The results obtained make it possible to establish that these pathways have a complementary but different role: inhibiting the cortico-thalamic pathway prevents animals from basing their choice on the current value of the reward, but not on the expected effect of the action. Inhibiting the thalamocortical pathway, on the contrary, is essentially deleterious in order to base the choice on the causal link between the action and its effect.
A diagram of a rat brain showing that the two main attributes of decision-making, the value of action and contingency, are implemented in differential ways by the thalamocortical and corticothalamic pathways.
These results are clearly contrary to the classic vision of the thalamus as a relay since they instead show the prefrontal cortex and the thalamus as two partners each with a score to hold for a decision making adapted. The direction of propagation of the information, therefore, appears as an important functional characteristic of the thalamocortical circuits.
This characteristic opens up new perspectives to better understand the principles of neural circuit functioning. Many brain regions are reciprocally connected and experiencing the generality of the direction, the principle of information appears as an important goal.
This study makes it possible to identify the existence of a circuit between the thalamus and the cortex which is essential in decision-making adapted to the environment. The originality of this discovery comes from the fundamental role that researchers attribute to the submedian thalamus, a structure so far ignored in the field of adaptive behaviors. This result suggests that many functional circuits underlying this type of behavior would involve a contribution of the thalamus. The researchers plan to continue exploring these thalamocortical circuits, the understanding of which could improve our knowledge of many pathologies, such as schizophrenia or addiction.
V – Researchers Find an Area of the Brain That Generates “Almost Automatic” Decisions
Researchers from Pompeu Fabra University and Hospital Clinic in Barcelona (Spain), Bournemouth (United Kingdom) and Harvard University (USA), whose study was published in the journal Nature Communications in March 2017, discovered the region of the brain, the orbitofrontal cortex, where decisions are based on recent experiments, which would predict human behavior even before the stimulus.
The study showed that the orbitofrontal cortex could be much more involved in decision making than previously thought.
According to research, this region could be responsible for integrating sensory information with recent experience in order to make a decision that takes into account all available information and thus optimizes their chances of success.
For living beings, obtaining correct information from the outside world – through the senses – is an essential process for making the most appropriate decision in each particular situation.
The researchers worked with trained rats to solve a hearing discrimination task, in order to begin to understand the decision-making process at the neuronal level and the brain regions involved. Rats had the ability to combine the sensory information they had been given with data that was close to the past.
They discovered that the neurons of the orbitofrontal cortex encode all relevant variables for the correct execution of the task: the recent past, the current sensory information and, surprisingly, they revealed for the first time a predictive activity of the decision even before sensory information is presented.
According to the authors, this is one of the first studies to analyze, based on behavior and neurons, to which they should read their activity, in order to be able to predict their decision before the stimulus is presented.
Another progress has been made by performing electrophysiological recordings in the orbitofrontal cortex, which has allowed them to access the activity of a small group of neurons with a very high temporal resolution.
Another concern of science is to distinguish the female brain from the male brain. We now know that, beyond the sex of the person, the interaction of sex hormones feminises or masculinises the brain.
The “sex of the brain” is determined by the hormonal exposure of the baby before birth, which has no connection with the man having testes or ovaries, nor by the symmetry of the brain of the woman between the two hemispheres.
A combination of recent and current experiments are those that evaluate the orbitofrontal cortex of the brain to make a decision, a finding that scientists say would open the door to predicting human behavior.
VI – The Prefrontal and Orbitofrontal Cortex
The prefrontal cortex is the most sophisticated reflection of our development. From an evolutionary point of view, this is the last cortical region to develop. Its development is actually complete only at the age of 20 or 25 years.
It is easily identified because it is this rough and wrinkled area, located in the area closest to our faces, where the most complex mental and cognitive processes are contained.
It is the region of the brain associated with the planning of cognitively complex behaviors and the expression of personality. Scientists call “executive functions” all those sophisticated tasks performed by the prefrontal cortex.
As for the orbitofrontal cortex, it is one of the most interesting brain areas. It is related to our personality, our emotions and especially to social behavior.
The orbitofrontal cortex is located in the frontal part of the brain. It is just above our eye sockets, or ocular cavities, and also has direct connections to sensory areas and limbic system structures related to emotion and memory.
1 – The Parts of the Prefrontal Cortex
The prefrontal cortex is this sophisticated and at the same time extremely complex control center that has multiple connections to different regions of the brain. Thus, structures such as the hippocampus, the thalamus and the rest of the brain lobes share with him direct channels, channels where information comes and goes almost incessantly.
2 – The Functions of the Prefrontal Cortex
– It coordinates and adjusts our social behavior.
– It helps us control impulses and manages our emotions.
– It is in this area that we implement processes related to our personality (being more shy, more daring, more open to experience …).
– Motivation, the ability to have enough illusion and impulse to reach a goal, is also located in the prefrontal cortex.
– We focus attention, we organize complex information and plan.
– This is also where the working memory, these cognitive skills thanks to which we store information when we experiment or do things.
3 – Functions of the Orbitofrontal Cortex
*** The treatment of social emotions.
This zone is connected to the limbic system as well as to the amygdala. However, the particularity of this region is that it articulates the emotions related to our social behaviors: aggression, lack of respect, knowing how to live together by promoting appropriate interactions with others…
This structure also houses a “surveillance system”. In other words, we try through it to behave according to a context, adapting to a social balance where we control our most basic impulses.
*** The reward system.
The orbitofrontal cortex is also related to the behaviors that we humans perform according to the rewards or punishments we receive.
*** Decision making.
This area of our frontal cortex has a close relationship with this complex behavior that is the act of making a decision. In this structure lies our motivation when we take the initiative of a certain behavior or action. People with an orbitofrontal cortex lesion might show great apathy, inhibition or even dumbness when making decisions. If they take the step and initiate a type of action based on a problem, they will be unable to evaluate which option is the least risky, the most prudent and adapted to the expectations of the nearest social context.