by Неизвестный
But the pains of love also have a chemistry. When separated for too long, lovers crash and experience withdrawal, crave their beloved, get anxious, doubt themselves, lose their energy, and feel run- down if not depressed. Like a little fix, a letter, an e-mail, or a telephone message from the beloved provides an instant shot of energy. Should they break up, they get depressed— the opposite of the manic high. These “addictive symptoms”— the highs, crashes, cravings, withdrawal, and fixes— are subjective signs of plastic changes occurring in the structure of our brains, as they adapt to the presence or absence of the beloved.
A tolerance, akin to tolerance for a drug, can develop in happy lovers as they get used to each other. Dopamine likes novelty. When monogamous mates develop a tolerance for each other37 and lose the romantic high they once had, the change may be a sign, not that either of them is inadequate or boring, but that their plastic brains have so well adapted to each other that it’s harder for them to get the same buzz they once got from each other.
Fortunately, lovers can stimulate their dopamine, keeping the high alive, by injecting novelty into their relationship. When a couple go on a romantic vacation or try new activities together, or wear new kinds of clothing, or surprise each other, they are using novelty to turn on the pleasure centers, so that everything they experience, including each other, excites and pleases them. Once the pleasure centers are turned on and globalization begins, the new image of the beloved again becomes associated with unexpected pleasures and is plastically wired into the brain, which has evolved to respond to novelty. We must be learning if we are to feel fully alive, and when life, or love, becomes too predictable and it seems like there is little left to learn, we become restless— a protest, perhaps, of the plastic brain when it can no longer perform its essential task.
Love creates a generous state of mind. Because love allows us to experience as pleasurable situations or physical features that we otherwise might not, it also allows us to unlearn negative associations, another plastic phenomenon.
The science of unlearning is a very new one. Because plasticity is competitive, when a person develops a neural network, it becomes efficient and self- sustaining and, like a habit, hard to unlearn. Recall that Merzenich was looking for “an eraser” to help him speed up change and unlearn bad habits.
Different chemistries are involved in learning than in unlearning. When we learn something new, neurons fire together and wire together, and a chemical process occurs at the neuronal level called “long-term potentiation,” or LTP, which strengthens the connections between the neurons. When the brain unlearns associations and disconnects neurons, another chemical process occurs, called “long-term depression,” or LTD (which has nothing to do with a depressed mood state). Unlearning and weakening connections between neurons is just as plastic a process, and just as important, as learning and strengthening them. If we only strengthened connections, our neuronal networks would get saturated. Evidence suggests that unlearning existing memories is necessary to make room for new memories in our networks.38
Unlearning is essential when we are moving from one developmental stage to the next. When at the end of adolescence a girl leaves home to go to college in another state, for example, both she and her parents undergo grief and massive plastic change, as they alter old emotional habits, routines, and self- images.
Falling in love for the first time also means entering a new developmental stage and demands a massive amount of unlearning. When people commit to each other, they must radically alter their existing and often selfish intentions and modify all other attachments, in order to integrate the new person in their lives. Life now involves ongoing cooperation that requires a plastic reorganization of the brain centers that deal with emotions, sexuality, and the self. Millions of neural networks have to be obliterated and replaced with new ones— one reason that falling in love feels, for so many people, like a loss of identity. Falling in love may also mean falling out of love with a past love; this too requires unlearning at a neural level.
A man’s heart is broken by his first love when his engagement breaks off. He looks at many women, but each pales in comparison to the fiancée he came to believe was his one true love and whose image haunts him. He cannot unlearn the pattern of attraction to his first love. Or a woman married for twenty years becomes a young widow and refuses to date. She cannot imagine she will ever fall in love again, and the idea of “replacing” her husband offends her. Years pass, and her friends tell her it is time to move on, to no avail.
Often such people cannot move on because they cannot yet grieve; the thought of living without the one they love is too painful to bear. In neuroplastic terms, if the romantic or the widow is to begin a new relationship without baggage, each must first rewire billions of connections in their brains. The work of mourning is piecemeal,39 Freud noted; though reality tells us our loved one is gone, “its orders cannot be obeyed at once.” We grieve by calling up one memory at a time, reliving it, and then letting it go. At a brain level we are turning on each of the neural networks that were wired together to form our perception of the person, experiencing the memory with exceptional vividness, then saying good- bye one network at a time. In grief, we learn to live without the one we love, but the reason this lesson is so hard is that we first must unlearn the idea that the person exists and can still be relied on.
Walter J. Freeman, a professor of neuroscience at Berkeley, was the first to make the connection between love and massive unlearning. He has assembled a number of compelling biological facts that point toward the conclusion that massive neuronal reorganization occurs at two life stages: when we fall in love and when we begin parenting. Freeman argues that massive plastic brain reorganization— far more massive than in normal learning or unlearning— becomes possible because of a brain neuromodulator.
Neuromodulators are different from neurotransmitters. While neurotransmitters are released in the synapses to excite or inhibit neurons, neuromodulators enhance or diminish the overall effectiveness of the synaptic connections and bring about enduring change. Freeman believes that when we commit in love, the brain neuromodulator oxytocin is released, allowing existing neuronal connections to melt away so that changes on a large scale can follow.
Oxytocin is sometimes called the commitment neuromodulator because it reinforces bonding in mammals. It is released when lovers connect and make love— in humans oxytocin is released in both sexes during orgasm40— and when couples parent and nurture their children. In women oxytocin is released during labor and breast- feeding. An fMRI study shows that when mothers look at photos of their children, brain regions41 rich in oxytocin are activated. In male mammals a closely related neuromodulator called vasopressin is released when they become fathers. Many young people who doubt they will be able to handle the responsibilities of parenting are not aware of the extent to which oxytocin may change their brains, allowing them to rise to the occasion.
Studies of a monogamous animal called the prairie vole have shown that oxytocin, which is normally released in their brains during mating, makes them pair off for life. If a female vole has oxytocin injected into her brain, she will pair- bond for life with a nearby male. If a male vole is injected with vasopressin, it will cuddle with a nearby female. Oxytocin appears also to attach children to parents, and the neurons that control its secretion may have a critical period of their own. Children reared in orphanages without close loving contact often have bonding problems when older. Their oxytocin levels remain low for several years after they have been adopted by loving families.42
Whereas dopamine induces excitement, puts us into high gear, and triggers sexual arousal, oxytocin induces a calm, warm mood that increases tender feelings and attachment and may lead us to lower our guard. A recent study shows that oxytocin also triggers trust. When people sniff oxytocin and then participate in a financial game, they are more prone to trust43 others with their money. Though there is still more work to be done on oxytocin in humans, evide
nce suggests that its effect is similar to that in prairie voles: It makes us commit to our partners and devotes us to our children.44
But oxytocin, Freeman argues, works in a unique way, related to unlearning. In sheep, oxytocin is released in the olfactory bulb, a part of the brain involved in odor perception, with each new litter. Sheep and many other animals bond with, or “imprint” on, their offspring by scent. They mother their own lambs and reject the unfamiliar. But if oxytocin is injected into a mother ewe when exposed to an unfamiliar lamb, she will mother the strange lamb45 too.
Oxytocin is not, however, released with the first litter— only with those litters that follow— suggesting to Freeman that the oxytocin plays the role of wiping out the neural circuits that bonded the mother with her first litter, so she can bond with her second. (Freeman suspects that the mother bonds with her first litter using other neurochemicals.46) Oxytocin’s ability to wipe out learned behavior has led some scientists to call it an amnestic hormone.47 Freeman proposes that oxytocin melts down existing neuronal connections48 that underlie existing attachments, so new attachments can be formed. Oxytocin, in this theory, does not teach parents to parent. Nor does it make lovers cooperative and kind; rather, it makes it possible for them to learn new patterns.
There is some dispute over the idea that oxytocin is solely responsible for this new burst of learning, for change in our existing attachments, or how it might facilitate these changes. Neuroscientist Jaak Pankseep argues that oxytocin, in combination with other brain chemicals, is so overwhelmingly good at reducing our feeling of separation-distress that the pain of losing previous attachments makes less of an impression than it would otherwise. This relative lack of distress may also free us to learn new things and form new bonds, while partially reconfiguring our existing relationships.
Freeman’s theory helps to explain how love and plasticity affect each other. Plasticity allows us to develop brains so unique— in response to our individual life experiences— that it is often hard to see the world as others do, to want what they want, or to cooperate. But the successful reproduction of our species requires cooperation. What nature provides, in a neuromodulator like oxytocin, is the ability for two brains in love to go through a period of heightened plasticity, allowing them to mold to each other and shape each other’s intentions and perceptions. The brain for Freeman is fundamentally an organ of socialization, and so there must be a mechanism that, from time to time, undoes our tendency to become overly individualized, overly self- involved, and too self- centered.
As Freeman says, “The deepest meaning of sexual experience lies not in pleasure, or even in reproduction, but in the opportunity it affords to surmount the solipsistic gulf, opening the door, so to speak, whether or not one undertakes the work to go through. It is the afterplay, not the foreplay, that counts in building trust.”49
Freeman’s concept reminds us of many variations on love: the insecure man who leaves a woman quickly after making love during the night, because he fears being overly influenced by her should he stay through the morning; the woman who tends to fall in love with whomever she has sex with. Or the sudden transformation of the man who barely noticed children into a devoted father; we say “he’s matured” and “the kids come first,” but he may have had some help from oxytocin, which allowed him to go beyond his deep- seated patterns of selfish concern. Contrast him with the inveterate bachelor50 who never falls in love and becomes more eccentric and rigid with each passing year, plastically reinforcing his routines through repetition.
Unlearning in love allows us to change our image of ourselves— for the better, if we have an adoring partner. But it also helps account for our vulnerability when we fall in love and explains why so many self- possessed young men and women, who fall in love with a manipulative, undermining, or devaluing person, often lose all sense of self and become plagued with self- doubt, from which it may take years to recover.
Understanding unlearning, and some of the fine points of brain plasticity, turned out to be crucial in the treatment of my patient A. By the time A. went to college, he found himself replaying his critical-period experience and being attracted to emotionally disturbed, already attached women very much like his mother, feeling it was his job to love and rescue them.
A. was caught in two plastic traps.
The first was that a relationship with a thoughtful, stable woman who might have helped him unlearn his love for problem women, and teach him a new way to love, simply didn’t turn him on, though he wished it would. So he was stuck with a destructive attraction, formed in his critical period.
His second, related trap can also be understood plastically. One of his most tormenting symptoms was the almost perfect fusion in his mind of sex with aggression. He felt that to love someone was to consume her, to eat her alive, and that to be loved was to be eaten alive. And his feeling that sexual intercourse was a violent act upset him greatly, yet excited him. Thoughts of sexual intercourse immediately led to thoughts of violence, and thoughts of violence, to sex. When he was effective sexually, he felt he was dangerous. It was as though he lacked separate brain maps for sexual and violent feelings.
Merzenich has described a number of “brain traps”51 that occur when two brain maps, meant to be separate, merge. As we have seen, he found that if a monkey’s fingers were sewn together and so forced to move at the same time, the maps for them would fuse, because their neurons fired together and hence wired together. But he also discovered that maps fuse in everyday life. When a musician uses two fingers together frequently enough while playing an instrument, the maps for the two fingers sometimes fuse, and when the musician tries to move only one finger, the other moves too. The maps for the two different fingers are now “dedifferentiated.” The more intensely the musician tries to produce a single movement, the more he will move both fingers, strengthening the merged map. The harder the person tries to get out of the brain trap, the deeper he gets into it, developing a condition called “focal dystonia.” A similar brain trap occurs in Japanese people who, when speaking English, can’t hear the difference between r and l because the two sounds are not differentiated in their brain maps. Each time they try to say the sounds properly, they say them incorrectly, reinforcing the problem.
This is what I believe A. experienced. Each time he thought of sex, he thought of violence. Each time he thought of violence, he thought of sex, reinforcing the connection in the merged map.
Merzenich’s colleague Nancy Byl, who works in physical medicine, teaches people who can’t control their fingers to redifferentiate their finger maps.52 The trick is not to try to move the fingers separately, but to relearn how to use their hands the way they did as babies. When treating guitarists with focal dystonias who have lost control of their fingers, for example, she first instructs them to stop playing guitar for a while, to weaken the merged map. Then they just hold an unstrung guitar for a few days. Then a single string with a different feel from a normal guitar string is put on the guitar, and they feel it carefully, but with only one finger. Finally they use a second finger, on a separate string. Eventually the fused brain maps for their fingers separate into two distinct maps, and they can play again.
A. came into psychoanalysis. Early on we sorted out why love and aggression had fused, tracing the roots of his brain trap to his experience with his drunken mother who often gave free rein to sexual and violent feelings simultaneously. But when he still couldn’t change what attracted him, I did something similar to what Merzenich and Byl do to redifferentiate maps. For a long period in the therapy, whenever A. expressed any kind of physical tenderness outside the sexual arena untainted by aggression, I pointed it out and asked him to observe it closely, reminding him that he was capable of a positive feeling and capable of intimacy.
When violent thoughts came up, I got him to search his experience to find even a single instance in which aggression or violence was untainted with sex or was even praiseworthy, as in justified self- defense. Whenever th
ese areas came up— a pure physical tenderness, or aggression that wasn’t destructive—I drew his attention to them. As time passed, he was able to form two different brain maps, one for physical tenderness, which had nothing to do with the seductiveness he experienced with his mother, and another for aggression— including healthy assertiveness— which was quite different from the senseless violence he’d experienced when his mother was drunk.
Separating sex and violence in his brain maps allowed him to feel better about relationships and sex, and improvement followed in stages. While he wasn’t immediately able to fall in love with or become excited by a healthy woman, he did fall in love with a woman who was a bit healthier than his previous girlfriend, and he benefited from the learning and unlearning that that love provided. This experience allowed him to enter progressively healthier relationships, unlearning more each time. By the end of therapy he was in a healthy, satisfying, happy marriage; his character, and his sexual type, had been radically transformed.
The rewiring of our pleasure systems, and the extent to which our sexual tastes can be acquired, is seen most dramatically in such perversions as sexual masochism, which turns physical pain into sexual pleasure. To do this the brain must make pleasant that which is inherently unpleasant, and the impulses that normally trigger our pain system are plastically rewired into our pleasure system.
People with perversions53 often organize their lives around activities that mix aggression and sexuality, and they often celebrate and idealize humiliation, hostility, defiance, the forbidden, the furtive, the lusciously sinful, and the breaking of taboos; they feel special for not being merely “normal.” These “transgressive” or defiant attitudes are essential to the enjoyment of perversion. The idealization of the perverse, and the devaluation of “normalcy,” is brilliantly captured in Vladimir Nabokov’s novel Lolita, in which a middle- aged man idolizes and has sex with a prepubescent, twelve- year- old girl, while showing contempt for all older females.