Analyzing the Self: When Mind Meets Matter
Linking the self – our passions, our hatreds, our temperaments and such – to the physical wiring and physiological functioning of the brain.
Published August 1, 2002
By Rosemarie Foster
Academy Contributor

Each living creature exists as a unit: a self. But what makes each of us the person we are? It’s a question that’s been pondered for hundreds of years.
Seventeenth century philosopher and mathematician René Descartes’ most famous quotation – “I think, therefore I am” – postulated that the self is a nonphysical entity, rather than a being identical to one’s body. Two centuries later, in his celebrated essay Self Reliance, transcendentalist Ralph Waldo Emerson wrote, “To believe your own thought, to believe that what is true for you in your private heart is true for all men – that is genius.” And modern-day screenwriter Woody Allen expressed self-doubt when he said, “My one regret in life is that I’m not someone else.”
Today the study of the self goes beyond the realm of philosophy, bridging this ancient science with contemporary neurobiology. At universities around the world, investigators are using modern analytical methods, laboratory tools and sophisticated imaging techniques in an attempt to link the self – our passions, our hatreds, our temperaments and such – to the physical wiring and physiological functioning of the brain. “If you really want to understand the nature of the mind, you have to understand the nature of the brain,” explains Patricia S. Churchland, professor of Philosophy at the University of California, San Diego.
Nature and Nurture
One thing is certain: Who we become and what personalities we develop is a combination of nature – the influence of genes – and nurture, the experiences we encounter throughout our lives. Both influence the development of the brain’s neural circuitry. “The relationship between genes and personality is not a simple one, but they do contribute,” says Joseph LeDoux, Henry and Lucy Moses Professor of Science at the Center for Neural Science at New York University. “But just because something is biological doesn’t mean it’s genetic. Experiences are also very important in shaping our neural wiring.”
Specifically, our experiences help us to learn, through an intricate system of memory processing employed by our brains. This learning results in the formation of actual neural networks.
Our peers may heavily influence such learning. According to social scientist Mahzarin Banaji, Richard Clarke Cabot Professor of Social Ethics in the Department of Psychology at Harvard University and Carol K. Pforzheimer Professor at Radcliffe, the self is the result of one’s collective social experiences.
“Our attitudes and beliefs come from the groups we associate with,” Banaji explains. “The thoughts and opinions we claim to be uniquely ours may in fact not be uniquely ours.” Indeed, a battery of “implicit association tests” Banaji has developed and implemented may reveal hidden biases in ourselves that we may not be aware of, and that many of us may not like.
From Soul to Brain
Churchland, LeDoux and Banaji will be among a cadre of distinguished scientists who will gather from around the world at the Mount Sinai School of Medicine from September 26-28 to speak at a unique conference called The Self: From Soul to Brain, sponsored by The New York Academy of Sciences (the Academy). “This will be the first time this group will assemble at one meeting to focus on this novel topic,” said LeDoux, who is organizing and chairing the event. “We want to address how the brain pieces itself together as we go through life.” The conference will foster a dialogue among researchers exploring the neuroscientific, philosophical, theological, and social aspects of the complex entity we call the self.
How do our brains make us who we are? LeDoux explains that it’s all in the brain’s wiring, and the exchange of neurotransmitters between billions of neurons across synapses. Such synaptic wiring regulates all brain functions, such as perception, emotion, motivation, thinking and memory. “But the trick is to understand how we as people can emerge out of all of this,” says LeDoux.
“That the self is synaptic can be a curse – it doesn’t take much to break it apart,” he writes in his book Synaptic Self: How Our Brains Become Who We Are, published this year. “But it is also a blessing, as there are always new connections waiting to be made. You are your synapses. They are who you are.”
Traumatic Memories and Physiological Responses
LeDoux’s group is focusing on the study of traumatic memories and the physiological responses they can incite. The brain does not process all of our memories the same way. For traumatic memories, two systems interact: one conscious, one unconscious. For example, if you were in a car accident and you returned to the accident scene, you might remember objective details of the event: “conscious memories.” But your blood pressure and heart rate might escalate, you may sweat, and your muscles might tense – all “unconscious memories” that surface as a result of the past experience.
Moreover, neuroanatomists have learned that these memory systems are mediated by two structures in the brain’s temporal lobe: the hippocampus, which regulates conscious memories, and the amygdala, an almond-shaped area of tissue controlling unconscious memories. LeDoux has focused two decades of inquiry on the latter structure, which he calls “the emotional processing system of fear.” His team has pioneered the study of emotions on the biological level, deep within the recesses of the brain: the amygdala of the rat brain, to be exact.
According to LeDoux, nature installed the amygdala as a survival mechanism. Early on, evolution wired the brain to produce responses to keep an organism alive in dangerous situations. This solution has not changed much over centuries, and works essentially the same way in rats as in people.
The LeDoux lab conducts “fear conditioning” in rats to study the function of the amygdala, its connections with other parts of the brain – such as the cortex, which is responsible for thought – and what happens in the brain when the amygdala is damaged. At the heart of their studies is a tone-shock system: They condition a rat by sounding a tone and delivering a minor shock, and they measure the rat’s physiological responses.
The Sensory Thalamus and the Amygdala
Thereafter, whenever the rat hears the tone it may either freeze in its tracks or respond with an increase in blood pressure and heart rate, even when no shock is delivered. Just the anticipation of a shock is enough to trigger a physical reaction in the animal. LeDoux’s group now studies how fear-arousing experiences alter synapses in the rats’ brains – particularly those in the lateral nucleus of the amygdala, the gateway into the system – and thereby create long-lasting memories.
The amygdala doesn’t work alone. One key interaction exists between the amygdala, the sensory thalamus and the sensory cortex. When we see or hear something frightening, we may freeze, jump or turn to see what caused it. That reaction can be traced to the connection between the sensory thalamus and the amygdala, between which signals travel quite quickly but not so precisely.
The same signal is processed several milliseconds more slowly between the thalamus and the sensory cortex, but in a way that allows us to assess the situation more accurately. LeDoux’s findings may be relevant to the management of anxiety disorders, which account for about half of the mental health problems reported in the U.S. and which can result from malfunctions in the way we deal with fear.
In Synaptic Self, LeDoux points out that neuroscientists have done an excellent job of studying how individual systems work, but as persons with selves, we are more than a mere collection of systems. To understand the self, he contends, neuroscientists will have to figure out how the various individual systems work together. One of his reasons for organizing the September conference was to engage scientists from a variety of research areas to begin to think about the self in ways that might be compatible with the tools and findings of brain research.
Not a Solitary Entity
“When we talk about ‘the self,’ it’s misleading to think of it as a single entity,” says Patricia Churchland. “Rather, it’s a number of different capacities engaged in monitoring the body and the various aspects of brain function.” When we perceive objects and events in our external environment – distinguishing them from our inner experiences such as emotions – and when we plan in our minds how, for example, to portage a canoe or to build a shelter, we are exercising what Churchland calls “self-representational capacities.” For 30 years, she has explored the complex connections between neural systems that have developed over time to enable humans to cope with and adapt to external signals, allowing us to improve our behavioral strategies.
In a paper published in the April 12, 2002 issue of the journal Science, Churchland emphasizes the brain-based nature of self-representational capacities. Our internal organs, for example, are represented by chemical and neural pathways aimed mainly at the brainstem and hypothalamus, while autobiographical memories appear to be governed by structures in the medial temporal lobe. The prefrontal lobe and limbic structures are important for deferring gratification and controlling impulses, so much so that damage to these areas may result in personality changes. “Hitherto quiet and self-controlled, a person with lesions in the ventromedial region of the frontal cortex is apt to be more reckless in decision-making, impaired in impulse control, and socially insensitive,” writes Churchland.
Self-Representational Capacities
Indeed, studies of patients who’ve experienced brain damage as a result of stroke, tumors or other disease or injury have shed light on specific areas of the brain associated with such self-representational capacities. Researchers have compared these patients’ abilities and personalities before and after the damage, and coupled that data with the results of contemporary diagnostic tools such as functional magnetic resonance imaging. Churchland aims for a panoramic view of a vast range of data, scrutinizing the findings of investigators in various laboratories to “try to make the story come together,” she explains.
One dramatic example Churchland describes is a patient known as R.B., who has been studied for two decades by Antonio Damasio’s neurology lab at the University of Iowa. R.B. is a middle-aged man who suffers from bilateral damage to his temporal lobes, resulting from herpes simplex viral infection. In particular, his hippocampus was destroyed. As a result, R.B. has catastrophic amnesia: he is unable to learn anything new, and is bereft of essentially all autobiographical memory. He lives within a 40-second time window and has no memory of events that occurred just moments ago, let alone those that happened before his illness.
R.B. does, however, have some social aspects of self-representation, thus demonstrating the dissociation of self-representing capacities. “Although he suffers diminished self-understanding, he nevertheless retains many elements of normal self-capacities,” Churchland notes, “including self-control in social situations and the fluent and correct use of ‘I.’”
The Amygdala and the Frontal Cortex
He also knows where his body stands in space at any given time, can identify feelings such as happiness, and is able to show sympathy with the distress of others. “This shows that the structures of the brain necessary for memory storage and retrieval are probably not those responsible for social skills,” explains Churchland.
At the September meeting, Churchland plans to speak on the topic of self-control, specifically linking self-control to parameters such as connectivity between the amygdala and the frontal cortex, as well as levels of hormones, neurotransmitters such as serotonin, and appetite-regulating proteins such as leptin. “Defining a neurobiological basis for self-control by identifying the relevant neurobiological parameters may be difficult, but I suspect it is possible,” she says.
“As we come to understand the nature of decision-making and choice, and how we acquire habits of self-control in childhood, it is bound to have an impact on how we understand ethics and the criminal justice system. The precise impact of new discoveries concerning the neurobiology of self-control remains to be seen, especially as technologies for intervention become increasingly available.”
Do You Have Hidden Biases?
Men are better suited for math and science than women. Many of us trust whites more than blacks. And we favor youth over age.
These statements may seem like extraordinary generalizations. But they represent hidden biases that many individuals learn they may have after taking Mahzarin Banaji’s implicit association tests (IATs), co-developed with the University of Washington’s Anthony Greenwald and Yale University’s Brian Nosek. If we think we’re open-minded and able to make free choices, then why might we unconsciously harbor such potentially disturbing beliefs? The answer, says Banaji, may lie in the people with whom we associate.
“The self is our most unique aspect. It is what distinguishes us from everyone else,” she explains. “And yet this most unique component of personality is itself socially constructed, a part of a larger collective gathered from everything we live and breathe.” That means we are most likely to hold opinions similar to those of our peers, and the social groups with which we identify most strongly. Moreover, these attitudes are often expressed without conscious awareness.
“Implicit Patriotism”
Banaji and her student Kristin Lane investigated “implicit patriotism” among 74 New England beachgoers who took IATs during the summer of 2000. The IATs compared how they identified with their nation (United States) and their region (New England) on both Independence Day and on a nonholiday in August. The results from tests taken on Independence Day showed a significantly stronger association between the concepts of “self ” and “American” on July 4th than on the August test date.
Moreover, regional identity was weaker on July 4th than in August. “Implicit identity is susceptible even to very subtle, naturally occurring events that can strengthen or weaken aspects of identity,” the researchers conclude. They are also being mindful of the impact of events like September 11th on shaping one’s implicit self and identity.
In another example, Banaji notes that more men than women tend to go into math and science, while women gravitate toward language and the arts. But in elementary school, there are no differences between males and females with regard to math test performance. Gender differences favoring men begin to surface in high school, and become progressively greater as the level of education increases. We’d like to think that anything’s possible for anyone, but in reality, the groups we identify with (in this case, males or females) may exert an unconscious influence on our choices and decisions.
Self-Imposed Segregation
In a paper to be published in the Journal of Personality and Social Psychology, Banaji, Nosek and Greenwald report that this is the case. Their conclusions were based on the findings of several IATs taken by groups of college students. They analyzed whether individuals link subjects such as math and the arts with good words (such as “love, rainbow, heaven”) or bad words (“death, torture, hatred”), and determined if they associated themselves more with math (“algebra=me”) or the arts (“poetry=me”).
While both sexes demonstrated negativity toward math, especially compared to the arts, that negativity was twice as strong among women than men. Moreover, the more strongly a woman identified with the female gender, the more negatively she felt toward math; conversely, the more strongly a man identified with being male, the greater his preference for math. “Knowledge of stereotypes, even implicit knowledge, may be sufficient to perpetuate stereotypes and even discourage women’s subsequent participation and performance in math domains,” concludes Banaji.
“The blunt reality is that not everything is equally possible for everyone,” she continues. “Societies that aspire to purer forms of democracy need be aware that wanting and choosing can be firmly shaped by membership in social groups. Until the internal, mental constraints that link group identity with preference are removed, the patterns of self-imposed segregation may not change.”
Also read:How the Brain Gives Rise to the Mind