The Brain in Trouble. Emotions and Decisions in the Risk Crossroads

THE DAILY DILEMMA
The smell of freshly made tacos comes floating from the corner. Your stomach growls. In front of you, a street full of cars crossing at high speed, and a broken traffic light senselessly changing. You are in a hurry and right in front of you there’s your favorite taquería. The decision seems easy: you can riskily cross the street right away and eat what you wish in the moment you want, or you can wait, keep yourself safe, but lose the opportunity to satisfy your hunger and craving.

Without you noticing it, in half a second your brain evaluates what is preferrable: immediate pleasure or your safety. Behind everyday life situations like this one, an internal conflict takes place in which emotions, wishes, and caution fight to guide your behavior. And although it occurs in just a moment, this process shows how our most basics decisions are deeply determined by our emotions.

BRAIN PROCESSES IN ACTION
Every single day we face choices like this. Not all of them involve tacos and traffic, but all of them imply a balance between what we desire and what we fear. It is our brain that evaluates these forces. On one side, the amygdala—a small almond-shaped structure located in the deepest part of the brain—activates when it perceives a threat. On the other side, the ventral striatum, part of the reward system, pushes us towards what we like. And in the very frontal part of the brain, the prefrontal cortex acts as mediator, evaluating and regulating these signals to make a fast and proper decision.

ANIMAL MODELS ON CONFLICT
In the lab we have designed experiments with rats to understand how decisions are made while being in emotional trouble. We trained rats to cross a safe zone so they could obtain food and, later, we presented to them an obstacle representing danger: a grid discharging mild electric shocks. When there’s no danger, rats cross without doubting, but when risk appears, they doubt, they get close, they stop, they get back, and finally they decide. This hesitation is very similar to what we experiment to decide if we cross or not a dangerous street to reach a reward.

By observing what occurs in the rats’ brains, we reveal how defense and reward systems are activated. While the amygdala emits alarm signals, the ventral striatum boosts the search for pleasure, and the prefrontal cortex modulates these answers to find balance. Under some conditions, this system modulates the balance so well that the animal takes the risk and obtains the reward. Under other conditions, fear prevails over hunger. This dynamic is not exclusive to rats but is also present in us when we face personal decisions, from choosing to talk or not, to deciding between running or staying.

COMPETING MEMORIES
Previous experiences also have a significant influence. When a rat associates a signal (e.g. a sound) with a negative experience, it develops a danger-memory. If this signal is repeated without negative consequences, the rat acquires a safety-memory. Both memories contest to influence our next answer. A vital element in this process is the hippocampus, a fundamental structure to form and update memories. When we promote the production of new neurons in this zone, animals are more likely to be able to “change their mind”: they leave fear behind and act in a more adaptive way. This flexibility is essential because, without it, decisions would get trapped in past experiences.

We also have studied scenarios in which the animal has to choose between a well-known reward and safety. For example, a rat that has learnt to push a lever to obtain food has to decide when noticing a danger signal, if it refuses its reward and rather climbs to a safe platform. This choice reflects conflict between desire and caution. In these cases, the habenula—latin for “little reins”—intervenes to evaluate if taking the risk is worth the pain or if it is better to stop.

These findings, obtained along almost a decade at UNAM, in collaboration with national and international teams, allow us to fully understand how emotionally significant experiences are transformed into memories that guide decisions. In other words, our decisions are based on the interaction of what we have learnt as dangerous and what we have experienced as safe or as a reward.
 
EMOTIONALLY SIGNIFICANT EXPERIENCES ARE TRANSFORMED INTO MEMORIES THAT GUIDE DECISIONS

APPLICATIONS FOR HEALTH AND SOCIETY
This knowledge has important applications in mental health. For example, understanding how the brain balances reward and safety behaviors allow us to design specific intervention strategies to prevent risky actions. If we identify that some impulsive behaviors emerge, for example, from a hyperactive amygdala and a weak prefrontal regulation, therapies or educational programs can be developed to “re-train” these brain circuits, helping people to make safer decisions. Thus, with therapies based on evidence (like interventions combining cognitive techniques with full attention), it would be possible to improve emotional regulation and to prevent risky behaviors, which represents concrete benefits for society.

These discoveries have an impact beyond the doctor’s cabinet. In a society like Mexico today, marked by inequalities, violence, and stress, understanding how the brain decides in difficult situations allows us to design interventions that act directly in the circuits of fear and reward, favoring safer decisions. This means safer environments, more sensitive public politics, and educational programs that help reducing impulsiveness in critical situations.

FINAL REFLECTIONS
A question rises inviting us to think: Are we machines processing information in a rational and cold way, or emotional beings that feel before making decisions? Beyond the Cartesian motto, “I think, therefore I am”, it may be more accurate to say “I feel, therefore I decide”. For our decisions don’t come just from rational calculations, but from a complex dance of emotions, memories, contexts, and wishes. Better understanding how our brain reaches balance to face danger and to look for pleasure gets us closer to developing therapies able to improve decision-making and emotional well-being. With every new discovery, we get closer to a more complete vision of what being human means, because understanding how we decide is, basically, understanding who we are.

OUR DECISIONS DON’T COME JUST FROM RATIONAL CALCULATIONS, BUT FROM A COMPLEX DANCE OF EMOTIONS, MEMORIES, CONTEXTS, AND WISHES

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