Can Two Brains Act as One? New Research Illuminates the Biggest Mystery of Human Relations

Are we fated to be solitary for all time, or can we become one with another? New developments in brain research are shedding light on one of our most elusive questions: the nature of human relations

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Illustration: An woman looks into a baby's eyes.
Illustration by Yael Bogen.
Gid'on Lev
Gid'on Lev

Like a snowflake, every intimate relationship is unique. Nevertheless, is there something that is present in each – something through which love can be defined? The philosopher Robert Nozick maintained that there is in fact a common factor: In all loving relationships, the well-being and the mood of the two people involved are always intertwined.

If someone we love feels sad, we shall unavoidably grow sad; if something good happens to the other person, something good happens to us, too. This happens of its own volition; we don’t need to reflect on our beloved’s sorrow in order to feel sorrow ourselves. Love means that there are no longer two completely separate individuals, each experiencing and feeling separate things; rather, a new entity is created – “we,” the product of that network of connections, with which each loved one identifies and merges as an extension of his or her own being.

Heartwarming as it may be, the idea of the loving union has come in for trenchant criticism. Two streams can merge, and so can two chemical materials, argued philosopher Irving Singer – like Nozick, another Brooklyn Jew – but not two human beings! At most, someone who is naive and sentimental can imagine that they are becoming one with their partner, and thereby distort the reality of their bond.

“A merging of two people is an impossibility,” poet Rainer Maria Rilke wrote, “even between the closest human beings, infinite distances continue.”

Are we therefore fated to be solitary for all time, or is it possible for us to actually merge with another? To answer that question – perhaps the most important of all when we’re talking about interpersonal relations – the primary essence of humanity should be identified. The oak is already inherent in the acorn; what is the human being’s core?

Sigmund Freud saw man as a narcissistic being at base, concerned with himself and his survival above all else. The infant is thrust into an alien, cruel world of competition and frustration, and will cope with those things throughout life, selfish, envious and lonely.

Such was the accepted psychoanalytic perception, until analyst Donald Winnicott burst into a discussion held at the British Psychoanalytical Society in the mid-20th century and exclaimed, “There is no such thing as a baby!” A baby alone is an impossible, imaginary entity, he maintained, as all of the infant’s thoughts, emotions and feelings exist within a bond: the bond with the person caring for him or her. Just as there is no fish without water, so there is no infant without a mother. Thus, the basic human unit, its very core, Winnicott said, is “mother-infant.”

‘Sixth sense’

These notions can be seen as no more than poetic images. After all, it seems obvious that infants are separate from their mothers – here, this one is lying in her cradle, while the other is cradling her smartphone. However, a new study, published in the journal Neurolmage, provides empirical validity for the approach that suggests the possibility of two people actually merging.

A team of scientists from Cambridge University used dual EEG testing to measure brain signals in mothers and infants during mutual interaction. They discovered that in certain emotional situations, the mother’s brain and the baby’s brain operate in tandem, forging between them what is called interpersonal neural connectivity. There is connectivity between their neurons, even though they are in two separate brains!

Participants in a Cambridge University study. Neural-synchronous communication in a child's first years is vital. Credit: University of Cambridge Baby-LINC Lab

“The degree of connectivity inside a single brain reflects how freely and efficiently information flows from one area in the brain to another,” Dr. Victoria Leong, head of the research team, explained in a Skype conversation. “In the experiment, we found that information flowed not only within each brain, but also between mother and infant, which supports infants’ social learning from their mothers.” According to Leong, the interpersonal neural signals are explicitly different from the intrapersonal signals that brain researchers measure as a matter of course.

“Our data so far indicate that there is a fundamental human propensity for social connection. In some ways, our intuitive knowledge of others can be thought of as a sixth ‘social sense,’” she said. “When we synchronize and connect neurally with others, we are also opening ourselves to receiving information and influence from them.”

Leong admits that there is as yet no sufficient scientific explanation for the phenomenon of synchrony between brains, though it is clear that it involves a connection at some level with the other’s inner mental state.

“This is a new frontier that is ripe for exploration. We are only just starting to understand what sort of information is transmitted and encoded in interpersonal signals, and we are only just coming to grips with how to measure interpersonal neural signals at all,” she said.

The Cambridge study made use of advanced technology to measure brain activity in infants. “Infants are the most honest experimental subjects I have ever encountered,” Leong related enthusiastically.

'Positive maternal emotions produced stronger brain connectivity between mother and baby. The mother and baby were working together as a single unit, or one mega-network.'

“If they are ready and interested in the proffered task, they will obligingly sit and engage with naked, wide-eyed attention. If you are lucky enough to be recording their brain activity during these periods, the data is, for us developmental neuroscientists, like pure nectar. You feel like you’ve been granted exclusive backstage access to one of the most exciting reality shows on the planet: ‘This is your learning brain, on live now…’

“On the other hand, if they are having a tummy ache, or they’re teething, or they would just rather be left alone, thank-you-very-much – then this sentiment is expressed loudly, firmly and with rising urgency until the nice lady who is trying to put a funny hat with wires on me retreats permanently into her corner.”

Leong and her associates subjected the data they gleaned from the mother-infant interactions to mathematical processing. One index examined was divisibility, which shows the degree of connectivity between the two brains.

“If two brains are completely disconnected – that is, there are two fully separated systems – the divisibility index will be high. Conversely, if the brains are fully connected, the divisibility index will be low,” she said. “Our data indicated that positive maternal emotions produced stronger brain connectivity between mother and baby. Their brains showed low divisibility, indicating that mother and baby were working together as a single unit, or one mega-network.”

To a contemporary Western individual, that discovery is almost incomprehensible, I tell her, agitated. How do two separate individuals become one system, a network?

A couple kiss in Milano Centrale railway station in Milan on March 8, 2020, after millions of people were placed under quarantine in northern Italy amid the coronavirus outbreak.Credit: AFP

“You still have two people, they do not become one, but they are also not exactly separate,” she replied. “When two things are separate, one can change without influencing the other; when they are connected, however, if one of them changes, the other necessarily changes too, even if not in the same manner.”

Leong suggested an analogy, one of two dancers. “When you watch a pair of people dancing together, we can tell that they are in synchrony because they are both moving in time to the same rhythm. This doesn’t mean that they are doing exactly the same thing at the same time; it means that there is a predictable temporal pattern to their movement. For example, one partner may step forward at the same time that the other partner steps backward. Also, if they are good dance partners, they will be continuously adjusting to each other. So if one partner decides to slow down, the other will also slow down to maintain their synchrony.

“Neural synchrony is similar. We can tell that two people are in neural synchrony, because when we measure their patterns of brain activity using a method like electroencephalography, their brainwaves fluctuate predictably with respect to each other.”

Simulators and mirrors

In his autobiographical novel “Look Homeward, Angel,” Thomas Wolfe adopted the perspective of a babe in the cradle: “He knew he would always be the sad one: caged in that little round of skull, imprisoned in that bearing and most secret heart, his life must always walk down lonely passages. Lost. He understood that men were forever strangers to one another, that no one ever comes to really know any one.”

According to research, every day of loneliness causes physiological damage equivalent to the smoking of 15 cigarettes.

The latest brain research puts forward a completely different position. Empirical evidence points to the possibility inherent in us to “open” the cage of our little round skull, to transcend the bounds of the self, to connect with the Other and really know him or her.

Another Cambridge University study, published several months ago in the journal Cell, was the first to identify nerve cells of a new type, termed “simulation neurons.” These neurons simulate the activity of the other person’s brain, and create within us the state of mind that exists in the person opposite us.

In an experiment, two macaque monkeys were placed opposite one another with a touchscreen between them, on which were screened pictures that led to them receiving a reward with different degrees of probability. One monkey was given the option of pressing on the screen; the other was only able to look at it.

The researchers, led by Fabian Grabenhorst, measured the activity of individual neurons and were surprised to discover neural cells in the amygdala of the observing monkey that signaled the choice its partner was expected to make. Simulation neurons are distinctly different in their activity from “regular” neurons that are responsible for making calculations and decisions, Dr. Grabenhorst told Haaretz in an email exchange: “These neurons did not simply predict the choices of the partner monkey, they actually seemed to simulate the partner’s decision computation.”

The simulation neurons join another exceptional type of nerve cell: mirror neurons. Identified 30 years ago, these cells respond identically when the organism performs an action and when it observes the same action performed by another organism. In other words, as a result of the neuron’s action, the other’s behavior is manifested and experienced in the observer’s brain as though it were the behavior of the person observing.

Uruguayan cellist Karina Nunez playing on the balcony of her apartment in Panama City, during the mandatory quarantine amid the COVID-19 novel coronavirus pandemic, March 23, 2020.Credit: AFP

Brain researchers have discovered mirror neurons that are activated not only when another is viewed doing something, but also when we see another person who feels something. For example, when I see someone else being caressed, mirror neurons in my brain will signal as if I am being caressed. We don’t actually feel it because sensory neurons on our skin send a different message; when these are anesthetized, the caress is actually felt.

Epidemic of loneliness

Two brains can become a single unit, with information flowing between its different parts, and each can also echo what is happening in the brain of the other while it initiates an action, feels something or even is thinking. “We” is an entity possessing ontological – not only metaphorical – status. The natural environment in which the members of our species exist – our “water,” if you will – is not spatial but relational. We do not each occupy a distinct coordinate in space-time; we belong to a network. A single human brain, as psychologist Louis Cosolino suggested, is a theoretical entity that does not exist in nature, like unicorns.

Still, a glance at the reality of many people turns up a radically different picture. Loneliness is one of the most common ailments of our time. About one-third of the people living in the industrialized countries suffer from it, irrespective of race, sex, income or education.

The stronger social networking services become, the weaker human networks become. In the United States, the number people an individual is close with – that is, people with whom one can speak frankly about personal matters – shrank by almost a third within two decades: from nearly three on average, to slightly more than two; the percentage of those who don’t have a single friend to talk to tripled and constitutes a quarter of the population.

One must not make light of loneliness. It’s a serious, dangerous disease that increases by about 30 percent the likelihood of premature death (and it’s also been found harmful to people who prefer to be alone). According to research, every day of loneliness causes physiological damage equivalent to the smoking of 15 cigarettes.

The recent Cambridge studies perhaps explain the scale of loneliness’ gravity: In the same way that our lungs developed to inhale oxygen, so too our brains developed to be involved in joint neural activity.

Loneliness is not a 21st-century invention, even if it sometimes seems that today’s society is very much occupied with cultivating it. The character and depth of our relationships depends more on our early experiences than on cultural or social frames of mind. Leong’s study found that inter-brain connectivity is not automatic but very influenced by the emotional state of the mother-infant relations. Existing as “we” is only a potential with which we come into the world, like the ability to acquire a language; if in our first years we did not experience enough moments of merging-synchronic communication, we will tend as adults to escape, to one degree or another, into a solitary existence, into silence.

• • •

We enter the world equipped with an extraordinarily sophisticated technology, wired and fine-tuned to what Martin Buber called “I-Thou” relations – and then we sustain battering after battering. The mouth that kisses us also gives us a name, unique, that differentiates us; the hands that embrace soon also push away, ordering us to look after ourselves. We follow a path that’s the opposite of the chick’s: It emerges from the egg, but we encase ourselves with shell upon shell.

Human civilization labors to expel us from the paradise of unity onto the battlefields of individuality. But like the salmon, we always retain a longing to return to the sweet waters of merging from which we arrived. The thing is that this simply cannot be done alone, as an individual. “Love,” Buber wrote, “does not cling to the I in such a way as to have the Thou only for its ‘content,’ its object; but love is between I and Thou. The man who does not know this, with his very being know this, does not know love.”

Love’s space is never mine or for me, but always ours, for-us.