19 EVERYONE’S TOMORROW
IN EACH
PERSON’S BRAIN

• Suzana Herculano-Houzel is a neuroscientist and associate professor at the Federal University of Rio de Janeiro (UFRJ), where she directs the Comparative Neuroanatomy Laboratory. She has an undergraduate degree in biology from UFRJ, an MS from Case Western Reserve University in the United States, a PhD from Pierre and Marie Curie University in France, and trained as a postdoc at the Max Planck Institute for Brain Research in Germany. She is the author of a number of books for the general public and many scientific articles. She also writes regularly for the newspaper “Folha de São Paulo”.

“Living in the past is for museums.” This Brazilian expression condemns attachment to the past, the overvaluation of things gone by and the difficulties in moving ahead. But users of this phrase beware: we all live in the past. And this is a good thing. More than just good, our capacity to use our memories to constantly revisit the past is fundamental for our ability to experience the present and forecast the future. It is according to our forecasts for tomorrow, based on yesterday, that we make better decisions today.

This capacity to represent the past, present and future is the work of the human cerebral cortex, with its remarkable number of neurons, unparalleled in nature and organized in a complex architecture that endows us with amazing cognitive abilities which allow us to do much more than react to stimuli. Thanks to the cerebral cortex, not only do we have a past and a future, but we are also able to represent others, their feelings, emotions and intentions, which enables us to live in society and envision a tomorrow shared by all.

However, what is the basis for these abilities? How do they work? In what way do we use them? For what purposes, and with what results? What future can be built from them?

Over time, the most palpable thing to our brain is the present: our empirical experience of the here and now. The present exists thanks to the senses, which keep the brain updated about what is going on in our body and around us, thereby allowing it to constantly build and rebuild a representation of the current reality.

This process occurs simultaneously on various levels. The sense organs, sensitive to energy variations in the body and its environment, process and transmit information about them to the brain. The sensory regions of the brain represent these variations, building veritable maps of the environment and body, which are combined in other regions of the brain to create a single map that guides our movements and behaviors. In this way, our actions are well adjusted to each moment, to the current circumstances, to the present. Other regions of the brain then use these representations of reality to create “representations of representations”, which is how we create concepts about something: the chair to which we have turned our back, the face of someone who has just left the room. Because these concepts can be activated in the absence of the external object, we then have the basis for abstract thinking and also for evoking past and future.

The representations of the outside world that we build in the brain are, however, not perfect, given that they are necessarily limited by our own senses and influenced by our expectations and previous experiences. Bees see ultraviolet light, which our eyes ignore. Snakes detect infrared radiation, for which we need night vision goggles. Electromagnetic fields interact with our body, but we do not sense them, as electric fish and birds do. In other words, we only capture part of the sensory information from the outside world. Furthermore, the way we interpret this sensory information depends on our previous experiences and mental state. The same sentence can be interpreted in different ways by different people, depending on their mood and expectations; the same object may be recognized more or less quickly, and with more or fewer details, by different people, depending on their level of familiarity toward them.

In addition, our past experiences, present emotional state and future objectives distort the real world, to which we never have true access. Our “reality” is in fact a private, personalized version of the real world, built by our brain as it represents the sensory environment. Accordingly, even living in the same world, different people share different realities and presents.

At first sight, the fact that our sensory system is limited and prone to external influence may seem a disadvantage, but it isn’t. Detecting stimuli in the environment and responding to them objectively is such a simple thing that even bacteria and amoebas can do it, and with the single cell that they are. But this is not the life that we lead. Our actions are internally directed and not only responsive. Individuals who merely detected stimuli and responded to them, even if in a coordinated and controlled way, would live eternally in the present, incapable of looking back or forward in time. They would not have the least capacity to relive past experiences and much less use these experiences in order to make plans for the future. Even worse, they would spend life running after events, given that the representations that the brain creates from sensations necessarily lag behind reality by at least one-tenth of a second. [1]

Our “reality” is in fact a private, personalized version of the real world, built by our brain as it represents the sensory environment.

Life is punctuated by a series of experiences and events, some more striking and others less so. It so happens that the very activation of neurons that represent these experiences in the brain modifies the activated neurons and their connections, especially when the represented occurrences are emotionally significant. As a consequence, the brain has a memory of such events, stored in its new, slightly altered pattern of connections and activation. Each event thus has the potential to change the brain. This process of modification according to experience is called learning; its consequence, the evidence that learning has happened, is called memory.

There are various types of memories, however, and with different storage times. Many of them, generated by unimportant events and considered of little use, fade away almost instantly, making room for new memories. Others, however, especially those associated with other important factors in our repertoire and accessed more often, may last a lifetime. Furthermore, memories are reinforced by the very act of remembering, making us increasingly personalized versions of ourselves. [2]

It is thanks to the brain’s capacity to learn and form memories that we have a past. However, memory is much more than a database. The accumulation of past records makes us unique individuals, endowed with personality, autobiography and our own values. When we lose these important records of our past, we lose the essence of our individuality. In Alzheimer’s disease, for example, the erasure of autobiographic memories undoes one’s personal history and thereby dissolves one’s individuality. Patients end up without a past of which to live, and without a future to forecast. They are left merely with a meaningless present, in which even relatives, untethered from a cerebral anchor in the past, are no longer familiar.

The capacity to anticipate a tomorrow, or even better, to anticipate different possibilities for tomorrow, gives meaning to the present and is crucial in shaping our decisions. We evoke the past when we react to stimuli in the present; past and present shape our anticipation of future events.

Anticipation is fundamental, because if we were to wait for events to occur before we respond to them, we would often act too late. Soccer goalkeepers know this well. With around half a second to react to a penalty, they need to anticipate the player’s kick if they want to catch the ball. Tennis players also anticipate their opponent’s serves, positioning themselves in the place where they estimate that ball will go instants before each serve. This “power” of anticipation is not unique to athletes: we anticipate events all the time in our everyday lives, and just like a trained tennis player or goalkeeper, we do this so automatically that we don’t realize it. Some call this anticipation intuition; neuroscience calls it forecasting the future based on the past.

The accumulation of past records makes us unique individuals, endowed with personality, autobiography and our own values. When we lose these important records of our past, we lose the essence of our individuality.

When making more complex decisions, the brain goes beyond automatic anticipation. Events have emotional value, which is taken into account when weighing up alternatives. The hippocampus, which has access to various parts of the cerebral cortex, generates a “memory of the future” based on projections of past memories. Other parts of the brain access these projections and represent them as objectives and goals; others then plot action strategies. In the brain, the future begins in the past.

The chances of an event going badly – such as failing an exam, for example, or ever more serious and constant floods –worry us thanks to the brain’s capacity to learn and update probabilities and to forecast the chance of errors, problems and conflicts in advance. This early apprehension is called anxiety: the ability to worry starting today about things that might become a problem tomorrow. The downside of anxiety is the chance we may lose emotional control and become overwhelmed and paralyzed by negative expectations. The good aspect, however, is that by anticipating bad events, we can act now to prevent them from materializing, or at least start preparing in advance and thus be able to deal with them more efficiently when they actually happen.

Positive expectations, however, are highly motivating – including the expectation of solving a problem that has been anticipated. Positive forecasts activate the brain’s reward system, responsible for the sensation of pleasure that, associated with an idea, transforms it into a wish. In turn, wishes are the basis for formulating goals. In other words, envisaging good things motivates us to act upon our wishes.[3]

We have a brain that is fully equipped to wish for a better tomorrow and to act to achieve it. This is not enough, however. A goal without a plan is but a wish.

We thus have a brain that is fully equipped to wish for a better tomorrow and act to achieve it. This is, however, not enough. A goal without a plan is but a wish. Without these three well-aligned elements, we are no more capable or free than amoebas reacting to events. We need wishes in order to have goals; we need goals to guide our behavior; and we need appropriate strategies to act today to work toward our desired goals. To this end, it is also fundamental to find motivations in the near future – in other words, to envision something positive that makes our efforts worthwhile.

There is an extra detail, however: individual goals, plans and actions do not guarantee a better tomorrow for all. Society needs to be in harmony with respect to people’s desires and motivations to plan for a future in common.

It is thanks to having a brain that also processes not only our emotional state, but also that of others, that we are able to live in harmony, concerned about one another’s future. Our decisions take into account not only the anticipated impacts of our choices on our own immediate and distant futures, but also their anticipated impacts upon other people and their emotions.

We are able to place ourselves in other people’s shoes thanks to empathy: the brain’s ability to automatically represent and feel other people’s emotions, thus taking them into consideration. Observing the expression of emotions on someone else’s face is enough for our brain to internally imitate their emotion and thereby identify it.

Projecting how others will emotionally react to our own actions also works, activating the same areas of the cortex that represent our and other people’s emotions. With one major difference: while empathy is automatic, putting ourselves systematically in other people’s shoes before making a decision is something we can consciously work to make a habit. Thinking of others is something that our brain can always do, but actually doing so is something we can choose – and it enormously facilitates good social relationships.

We are able to place ourselves in other people’s shoes thanks to empathy: the brain’s ability to automatically represent and feel other people’s emotions, thus taking them into consideration.

And, with a little more effort, we can go even further. Structures located in the temporal lobe of the cerebral cortex allow us to form a representation of someone else’s point of view and, based upon this, infer their intentions. Forming a “theory of other people’s minds” is extremely important for social judgment (the evaluation of other people’s actions as right or wrong) and for life in society in general. It is through our ability to take other people’s intentions into consideration that we achieve tolerance, understanding why someone acted or thought in a certain way, and that we can act based on a common goal, believing that we share it with other people.

Living in society is complex – and thankfully so. Different people have different temperaments, preferences, life stories, and moral, political and religious beliefs. Diversity is enriching and creates a multiplicity of possible futures. Acting to promote a harmonious and positive tomorrow for as many people as possible necessarily involves striving now to cultivate good habits of thinking about others, adopting their point of view and understanding their intentions. We neither live alone nor build our tomorrow by ourselves. But we do all have something in common: the ability to use our past to work toward a better future.

• [1] Daniel Wegner, “The Illusion of Conscious Will”, Cambridge: MIT Press, 2002.
  [2] Daniel L. Schacter, “Os sete pecados da memória: como a gente esquece e lembra”, Rio de Janeiro: Rocco, 2001.
  [3] Suzana Herculano-Houzel, “Fique de bem com seu cérebro”, Rio de Janeiro: Sextante, 2007.