The Neurobiology Of Love Harvey Joanning, Ph.D. University .

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Brain in LoveThe Neurobiology of LoveHarvey Joanning, Ph.D.University of South AlabamaIowa State University1

Brain in LoveFalling in love and attempting to stay in love is a time honored human tradition. Why weare driven to be in love, and how we behave during the process has been the subject of endlesspoems, songs and stories. The advent of modern brain imaging technology and continuingresearch regarding the functioning of the human body has laid the ground work for this paper; atheoretical model of how we fall in love, stay in love, parent children, and lose a close partnerthough divorce or death. The Neurobiological Model of Love (NBML) focuses on biologicalprocesses that drive our intimate behavior.The Neurobiological Model of Love draws from the author’s own research focused oncouples in committed relationships and the work of other researchers, particularly Helen Fisherand Jaak Panksepp. Helen Fisher (Fisher, 1996; Fisher, 2016; Fisher, Aron, & Brown, 2005) hasdescribed three stages couples go through as they begin and establish a relationship: Lust,Attraction, and Attachment. Jaak Panksepp (2011) has identified seven basic emotional circuitscommon to mammalian brains. The author’s ongoing research has attempted to link thesecircuits to Fisher’s stages of falling in love. The NBML goes beyond Fisher’s work to includeadditional stages of love focused on parenting and partner loss. In sum, the model attempts todescribe the neurobiology of love throughout the life span.What motivates humans to spend so much time and energy pursuing relationships withother people? To answer this question we must examine how our brains work. Panksepp (2012)and other affective neuroscientists have identified primary emotional systems that underlie andmotivate all human behavior. These systems are outlined in Table 1.2

Brain in LoveTable 1: Primal Emotions and Associated FeelingsPrimary Emotional SystemsAssociated Feeling SEEKING/EXPECTANCYEnthusiastic RAGE/ANGERPissed Off FEAR/ANXIETYAnxious LUST/SEXUALITYHorny CARE/NUTURANCETender & Loving PANIC/GRIEFLonely & Sad PLAY/JOYJoyousThe names of primary emotional systems are all capital letters to distinguish theseneurological systems from the everyday language used by humans to describe how they arefeeling. These primary emotional systems have very specific biological characteristics andpromote specific behaviors. Our everyday use of these terms is much more variable.These primary emotional systems are buried deep in the brain, are ancient from anevolutionary perspective and are highly connected to the limbic system and the neocortex, morerecently evolved regions of the brain. Affective neuropsychologists argue that our emotionalexperiences in everyday life stem from these primary emotional systems and are modified bylearning and our ability to think about our experiences. For many years neuroscientists believed3

Brain in Lovethat our “thinking brain”, the neocortext, generated emotions; but that view is being challengedby recent research. Animals and humans are capable of experiencing emotions even when thecortex has been damaged or removed. For purposes of this paper and the NBML, we willassume that emotions emerge from these primary systems.Each of these emotional systems controls distinct but specific types of behaviorassociated with many overlapping physiological changes; stimulating intense emotional feelings,memories, and thoughts about what is happening in our lives. Figure 1 (Adapted from Panksepp,2012) illustrates these primary emotional systems (affective circuits) and the secondary feelingsand tertiary processes that emerge in higher regions of the brain. These basic affective circuitsare ancient and give rise to “higher feelings”, second order processing of primary emotionswithin the limbic system. Primary emotions are driven by hormones that arise within our bodiesas we respond to environmental stimuli. These primary emotions in turn stimulate our limbicsystem to produce “Secondary” feelings such as pride, blame, shame, confidence, trust, disgust,dominance, empathy and guilt. They are the result of the limbic system interacting with theenvironment in which we live and interact. Tertiary processes are what we typically think of as“mind” and occur in the neocortext; that is, how we think about primary emotions that have beenconverted into feelings within the environment context in which the person is living. TheseSecondary feelings and Tertiary processes are influenced by the cultural and immediateinterpersonal context as we live our lives, and are at least in part learned.4

Brain in LoveFigure 1Often emotions are not under willful control of our higher mind (neocortext) but ratherare programmed by our lower mind (primary emotional systems) in conjunction with our earlylearning (Narvaez, D., Panksepp, J., Schore, A., & Gleason, T., 2012). In sum, our dailyexperience of life is instinct (lower brain) moderated by life experience (higher brain). As ourhigher brain thinks and reflects on our day to day experiences, our lower brain influences ourthoughts although we are not consciously aware of those influences. Primary process emotional5

Brain in Lovesystems are raw affects that automatically make important decisions for us. Our consciousprocesses create a narrative to explain what is happening. At times that narrative interprets ourraw affects in irrational ways because we are not consciously aware of our primary emotions butneed to invent a story that helps us make sense of the world in which we are living. Partners inclose relationships at times disagree because their individual interpretations of shared lifeexperiences differ; that is, their individual primary emotional processes interact with their pastlearning to produce personal narratives that disagree. Couples seen by marital therapists andthose involved in our study demonstrate this phenomenon regularly.Of the seven primary emotional systems, SEEKING/EXPECTANCY is the mostpervasive and plays a supportive role for all other emotions. Its activation is necessary tomotivate any mammal including humans to want to do anything. If this system is notfunctioning well, a person may appear, and may indeed be, depressed. If this system is activated,the person is motivated to enthusiastically explore, seek out resources, and euphoricallyanticipate a reward. In fact, anticipation of a reward is the primary motivation that drives us todo something. Actually receiving the reward: food, water, sex is pleasurable because it returnsour body to homeostasis (satiation), but anticipating the reward is the true motivation.Consequently calling the SEEKING/EXPECTANCY system the “reward system” is misleading.Unfortunately reward system is still often used by individuals who are not aware of recentresearch.6

Brain in LoveThe SEEKING/EXPECTATION circuit runs from the ventral tegmental area (VTA) tothree destinations: the medial forebrain bundle and lateral hypothalamus (MFB-LH), nucleusaccumbens, and medial prefrontal cortex following the mesolimbic and mesocortical dopaminepathways. In sum, the VTA receives messages from other parts of the brain as to how efficientlybasic human needs (e.g., sex, companionship) are being met. If needs are being satisfied,dopamine neurons alert the nucleus accumbens; dopamine levels increase, enhancing pleasurablefeelings and thereby "rewarding" the behaviors through which the basic needs are met. Themedial frontal cortex and MFB-LH help devise strategies to get what we want out of life andavoid problems. Raw emotions connect to pleasure producing portions of the brain that areinformed by our “thinking” brain so we follow the most productive course of action. We7

Brain in Lovehumans become motivated to seek a relationship with other people when theSEEKING/EXPECTANCY system, the PANIC/GRIEF and the LUST/SEXUALITY systemsare all activated. This occurs when we desire to have other people in our lives to keep our bodiesin a state of homeostasis. To feel comfortable we need other people to fulfill our desires for loveand attachment. When we have been without food or water for a long period we feel hungry andthirsty. When we do not have someone to fill our social needs we become lonely. When we donot have a sexual partner, we become sexually aroused. Consequently when we are lonely oranxious because we don’t have a loved one or partner close, several of our primary emotionalsystems become activated to reestablish homeostasis; that is, feel comfortable.8

Brain in LoveLustFisher’s first stage of love, the Lust or Sex Drive is characterized by a craving for sexualgratification. This should come as no surprise because humans, like all mammals, are driven toreproduce. Panksepp’s LUST/SEXUALITY system and PANIC/GRIEF systems are activated ashumans initially approach each other seeking a mate. Our SEEKING/EXPECTANCY systemmotivates us to seek another person to fulfill this desire.9

Brain in LoveHumans, like other animals, display a rich assortment of “courting” behavior. We flirt ina particular sequence. She smiles and lifts her eyebrows, raises her shoulders, arches her back,tosses her hair. He walks up to her, arches his back, and thrusts his upper body in her direction(Fisher, 2016). Such instinctive behaviors are common among mammals (Sapolsky, 2017). Theauthor’s observations of human mating behavior in 27 different cultures and baboons in Kenyahave shown similar recurring tendencies. All these behaviors are generated by the primaryemotional systems described by Panksepp; largely outside of our conscious behavior. Trainedactors, anthropologists, and relationship therapists are aware of these behavioral tendencies anduse them in their professional work.We are usually unaware that such behavior is due to our genes, hormones, and nervoussystem driving us to reproduce. We may find someone attractive, interesting, and find ourselvespursuing them. When we interact with a potential love interest, phenyl ethylamine (PEA) in theventral tegmental area (VTA) of our brain stimulates dopamine neurons that in turn increase10

Brain in Lovedopamine levels in the nucleus accumbens (NA); an important brain area in forming memoriesinvolving salient environmental stimuli, both positive and negative. In sum, the rise of dopaminelevels in the nucleus accumbens helps us remember what environmental stimuli increase pleasureand what stimuli cause discomfort. Consequently, we seek a mate who we perceive to be asource of pleasure and avoid individuals who we perceive as causing pain. The same person canbe seen as a source of pleasure (when courting) and a source of pain (when considering adivorce).Phenyl ethylamine also helps to stimulate the production of beta-endorphins(endogenous opioids), which are our brain’s ‘feel-good’ hormones. This process acts likeamphetamine. Some scientists believe that PEA is responsible for the giddy, intoxicating feelingwe experience when falling in love (Fisher, 2016).We are not aware of the activation of our lust brain circuit, the flow of testosterone andestrogen through our blood stream and glands, or of the increase of dopamine in theSEEKING/EXPECTANCY, reward circuit of our brain. None the less, our bodies are aware inthe sense that the “feeling” center of our brain, the limbic system, is strongly activated andpushing us to engage in behavior that the rational part of our brain, the prefrontal cortex, may notperceive as rational. We all smile when we see lovers engaging in behavior that may seemcharming, provocative, or silly to an observer. We engage in such behavior because our bodiesare designed to do what is needed to reproduce. An amusing example of these behaviors is thetelevision show, The Orville, a quirky science fiction parody of the Star Trek series in which thecaptain, a man, is attempting to deal with his first officer, a woman who happens to be his exwife. They are sexually attracted to one another so struggle to overcome their history as a couple.11

Brain in LoveWhen the lust system is activated, it produces feelings of sexual arousal; thoughts orientedtoward sexual fulfillment, and urge us to engage in sexual activity. The evolutionary advantageof having a lust system is to motivate organisms to reproduce.Lust stems predominantly from the hypothalamus, a region of the brain that also controlsbasic desires such as hunger and thirst. The hypothalamus is closely tied to the autonomicnervous system that controls our heart rate and how fast we breathe. When we fall in love withsomeone our initial lustful feelings are enhanced by dopamine, a neurohormone produced byseveral areas of the brain including the ventral tegmental area and the hypothalamus. Once inour bloodstream, dopamine triggers the release of testosterone from our gonads, the hormonethat drives sexual desire. Specific receptors on the hypothalamus for testosterone result in astrong drive for reproduction in both men and women. In effect, dopamine feeds back to thehypothalamus in the form of testosterone which in turn stimulates more dopamine release. Aswe fall in love we experience a highly sexual urge that is very pleasurable if we find the rightpartner. The lust system “jump starts” our relationship and sets the stage for the activation ofother brain systems important to relationship development.Men and women have somewhat different sexual neuro-circuitry that helps explaindifferences in sexual behavior. Our sexual interests and behavior as adults is the result ofdifferent experiences in our mother’s womb. All fetuses start as anatomically female but boybabies change structurally because of greater influence by testosterone during fetal development.Male fetuses have more testosterone receptors especially in the hypothalamus (specifically theanterior, front part, the preoptic area). This makes males very susceptible to surges oftestosterone during fetal development and again during puberty. Testosterone also activatesvasopressin and nitric oxide. Vasopressin promotes sexual ardor, sexual bonding, inter-male12

Brain in Loveaggression, and possibly jealousy; tends to make males more “pushy and competitive” (Tayloret. al., 2000). Males have twice as much vasopressin as females. Nitric oxide heightens sexualeagerness and “offensive” aggression. This hormonal cocktail also promotes social dominance.Testosterone also sensitizes the RAGE/ANGER circuit. No wonder adolescent males at timesengage in fierce competition for female attention.Female fetuses are more influenced by estrogen which enhances oxytocin neural systems inthe female brain while testosterone increases vasopressin in males. Oxytocin calms the brain andappears to facilitate positive social bonding in both men and women. Women have far moreestrogen than males. From an evolutionary perspective, greater estrogen production in femalesleading to social bonding with children and other women makes sense. When estrogen iscombined with oxytocin, female typical nurturing attitudes are enhanced, the tendency “to trendand befriend” (Taylor et.al. 2000). For hundreds of thousands of years proto-humans andmodern humans survived in migrating small bands or clans with the woman and children stayingclose to one another while men at times hunted. Not until the rise of agriculture approximately11,000 years ago did that pattern change, a small period time from an evolutionary standpoint.Women are neurologically wired to work together to raise children.Like males female sexual receptivity is governed by the hypothalamus, specifically theventromedial hypothalamus (upper middle area). Human females do not produce muchtestosterone so their hypothalamus is more influenced by estrogen and progesterone. Femaletestosterone is produced by the adrenal gland and has some influence on sexual receptivityespecially when estrogen and progesterone levels are high during ovulation. The greaterinfluence of estrogen and progesterone is governed by the pituitary gland, an extension under thehypothalamus that secretes gonadotropin releasing hormone (GnRH) during the menstrual cycle.13

Brain in LoveGnRH causes the ovaries to ripen and release eggs as well as produce more estrogen andprogesterone. These hormones in turn promote the release of oxytocin and make females’hypothalamus more receptive to oxytocin. This hormonal mix in turn makes females moretrusting of and emotionally receptive to suitors.At a primary emotional level attractiveness between the sexes is also neurologicallyprogramed. Men respond to a 0.73 waist to hip ratio, the classic hourglass figure, a sign offertility recognized by wiring in the male visual system. At a primal level human females likeother primates are attracted to confident, dominant males with resources. Dominant, resourcerich males increase the likelihood that a female’s children will be protected and have enough toeat. At times human females can also be affected by testosterone as evidenced by mothers’fierce protection of their children and anger with other women who attempt to seduce theirmates. Social context and learning can modify our primal tendencies at a secondary (feeling)and tertiary (thought) level. Men may learn to treat women respectfully at a behavioral level andthink of them as their equal even though their primal urge may push them to be sexuallydominant. Human females tend to exhibit more discernment than other primates so may chooseto not enter a relationship with a socially dominant, powerful, self-centered male even though hemay offer social status and wealth. To paraphrase Edgar Rice Boroughs, the author of theTarzan series of books, men and women are restrained by a “thin veil of civilization.”Sexually driven courting behavior is especially pronounced during adolescence becauseof the flood of sex hormones invading the bodies of young humans. Although the intensity ofthe lust circuit’s influence on our behavior diminishes with age, it never goes away. Even the“elderly” couples we have studied show activation of the lust circuit especially if they are14

Brain in Lovebeginning a relationship. Their bodies still want to reproduce even though they are notphysically capable of doing so.Attempting to suppress the sex drive of adolescents is usually a futile effort because thelust circuit is activated much of the time. The best we can hope for is to channel their sex drivein a productive direction by providing age appropriate sex education including training regardingrelationship development; sexual activity when appropriate as a relationship develops rather thanan end in itself.The LUST/SEXUALITY circuit stimulates sexual activity and social bonding because abonded pair has each other to gratify sexual desire and to provide social support, which in turnstimulates beta-endorphin and oxytocin production. This process makes us feel calm and loved.However, oxytocin may not act alone but in a context of pleasant social interaction that enhancesendogenous opioids (endorphins), the comfort and joy hormones. Feeling calm, loved, andcomfortable with our partner leads to a satisfying sex life. A satisfying sex life promotes acompetent immune system and increases our life span just like exercise; in fact, a satisfyingsexual encounter is exercise. Well bonded, loving couples live longer because their bodiesremain healthy longer. Sexual enrichment programs that emphasize couple closeness andsexually satisfying interaction enhance this effect (Joanning, H. & Keoughan, P., 2005; Nathan,E. & Joanning, H., 1985).Limbic System The stages of love and the brain systems involved with love aremoderated by the limbic system, a part of the brain that evolved after the primary emotionalsystems identified by Panksepp and before the neocortex.15

Brain in LoveThe limbic system affects mood, memory and hormone production. A primary part of thelimbic system, the hypothalamus, controls the endocrine system and regulates temperature,hunger, thirst, sexual arousal, stress, and the sleep/wake cycle.Another part of the limbic system, the amygdala senses ambiguity in environment and isthe source of curiosity. If ambiguity is perceived as dangerous, the amygdala signals thehypothalamus to trigger the fight/anger or flight/fear response. These responses are involvedwith two of the brain systems identified by Panksepp, RAGE/ANGER and FEAR/ANXIETYthat will be described in more detail when we discuss stress responses during relationships,especially when couples move toward divorce or have a spouse die. If the amygdala comparesnew stimuli being perceived from the environment and senses no danger, it can lead us tobecome curious; an experience we will explore in more detail when we examine the AttractionStage of love.The amygdala attempts to make emotional experience (feelings) congruent with andappropriate to the context of the event experienced. Ambiguity takes away our sense of securityand predictability. Ambiguity is perceived as fearful so the amygdala calls for more informationby “turning up the volume” of hearing and increasing sensitivity of all senses; it compares newstimuli to memories stored in the brain. If the ambiguity is resolved, we remember similarevents that were not dangerous, the amygdala stays calm. If the ambiguity is not resolved, theamygdala alerts the hypothalamus to take action to protect us from danger. The amygdala’sdefault reaction is fear. For love to emerge, danger must not be sensed.The amygdala is the “watchdog” of our brain and nervous system. It reacts to theexternal and internal environment before our neocortex (“thinking brain”) has time to react. A16

Brain in Loveprimary function of the amygdala is to keep us alive until we can “think through” what ishappening to us.An additional part of the limbic system that is involved in love is the hippocampus, abrain structure that influences memory formation, spatial memory, navigation and remembersprior sexual arousal especially in males. This is the first part of the brain to be damaged byAlzheimer’s disease causing the victim to be unable to form new memories. The hippocampusprocesses our experience of dealing with our partner and is critically involved in helping us“learn” how to relate to our partner. When an organism is highly stressed, this brain structuredoes not function properly making it difficult to process relationship issues. Relationshipproblems can be sufficiently stressful to lessen hippocampus functioning; at times causing onespouse to complain that the other is not remembering important relationship issues.The hypothalamus controls the endocrine system; ductless glands that release hormones thatdirect our body to respond to changes in our bodies and the environment. When we fall in love,the hypothalamus is actively influencing our thoughts and behavior by releasing dopamine thatenhances testosterone from testes, ovaries, and adrenal glands and promotes basic reproductiondrive in both sexes.Attraction Fisher’s second stage of love, Attraction, begins shortly after or concurrent withthe Lust stage. Attraction is characterized by increased energy, intrusive thinking about andcraving for emotional union with a mate. In sum, our body is involved in an addiction likeprocess that takes over the SEEKING/EXPECTANCY system in the brain and occursconcurrently with activation of Panksepp’s PLAY/JOY circuits.17

Brain in LoveAs we continue to fall in love and the dopamine rush subsides, our love is maintained byoxytocin and vasopressin, the same bonding, calming hormones that are secreted by thehypothalamus to promote lust. Some scientists point to a progression in a relationship. First lust(he or she is cute or sexy), then romance (I'll profess my love), then marriage (calmer andcozier). Sex, romance, and affection may dwindle but continue to interact.If the amygdala compares what we are experiencing in the here and now to memories storedin our brain and no ambiguity (danger) is sensed, it remains calm. The hypothalamus proceedsto instruct our endocrine glands to release hormones that produce pleasure (endorphins), bonding(oxytocin), and sexual desire (testosterone) in response to our interaction with a potential lover.During attraction, we become curious about our new partner and want to learn moreabout them. This curiosity is handled by Panksepp’s SEEKING/EXPECTANCY system. Whenthis system is active, people experience curiosity, interest, anticipation, craving, expectancy,engagement, excitement, eagerness, and directed purpose. It leads people to energeticallyexplore their world and seek resources. It produces an invigorated feeling of anticipation weexperience when actively seeking accomplishments and rewards. TheSEEKING/EXPECTANCY system is driven by dopamine, a hormone that causes a pleasurablefeeling. From an evolutionary perspective this system motivates us to learn, to give us effectiveagency in the world. While falling in love, we use this system to learn all we can about ourpartner and we feel vigorously motivated to do so. We experience a “love high.”At the same time the SEEKING/EXPECTANCY system is activated, another systemimportant to developing a love relationship is activated, the PLAY/JOY System. This systemtriggers the urge to vigorously and spontaneously interact with others. The accompanying18

Brain in Loveemotions can be characterized by joy or delight, and associated thoughts are generally positive.From an evolutionary perspective, the play systems triggers the release of hormones (oxytocinand vasopressin) that promote social belonging; in combination with theSEEKING/EXPECTANCY system, the PLAY/JOY system motivates creativity andexperimentation; and releases intrinsic healing properties of hormones (endorphins) that make usfeel better.During the attraction stage of love, we experience intense positive feelings within ourbodies and are drawn toward our partner because our relationship with him or her is the stimulustriggering our bodies to have these emotions that in turn stimulate feelings such as joy andenthusiasm. We seek our new partner like a drug addict seeks their desired drug. Fortunatelyour bodies are designed to have a “love high” and we do not do physical damage to ourselveslike we do when using street drugs to get high.Hormones Before moving to the Attachment stage of love it will be helpful to describe therole of hormones in relationship development. Hormones are crucial to the function of brainsystems and our bodies in general. Hormones come in a variety of flavors and functions. Thefollowing is a brief summary of the hormones already mentioned that are involved in sexualfunctioning, the key component of the Lust (Romance) stage of love and some additionalhormones that are also important to the maintenance of relationships during the later stages oflove.Testosterone contributes to motivation to action and sexual urges (libido) so is critical to thesex drive of men and women although men have much more of it than women; thus theperception that men are more interested in having sex. However, interest in sexual expression is19

Brain in Lovealso moderated by age, health, quality of the relationship, stress levels, and attitudes aboutsexuality. The popular notion that men are more sexual than women is not supported byscientific studies. Although young men may have a strong desire to have sex, that does not makethem more sexual than women, simply more aroused in part due to high levels of testosterone intheir systems. The picture changes as men and women age (Joanning & Keoughan, 2005).Estrogen regulates reproduction cycles, menstruation, promotes wellbeing, keeps femalegenital tissues healthy, and promotes sperm production in males. Consequently, it is essential tokeeping women’s bodies sexually functional and able to become pregnant before menopause.Estrogen supplementation may be necessary to maintain that functionality later in life. Althoughsome concern exists regarding estrogen supplementation increasing the risk of breast cancer,recent research has modified that concern. Progesterone along with estrogen is needed to keepwomen’s bodies fertile and facilitates enjoyment of sex.Oxytocin is a hormone secreted by the pituitary gland to reinforce attachment and trust, aswell as to promote breastfeeding and child birth. Oxytocin is referred to as the “cuddlehormone” because it strongly promotes bonding. It is expressed during nursing and surgesduring orgasm. It makes us feel bonded to our babies or to the person with whom we are havingsex. It also is expressed if we hold or are held by a lover, parent, or caregiver. A German study,(Scheele, et. al., 2013) found that male volunteers shown pictures of their female partner whilebeing scanned by an fMRI after intranasal oxytocin was administered showed preference fortheir partner over other women friends and women they did not know as indicated by VTA andnucleus accumbens activation (award regions of the brain). It was hypothesized that oxytocincontributes to romantic bonds by enhancing partner attractiveness and reward value compared toother women.20

Brain in LoveVasopressin is a hormone similar to oxytocin that facilitates and coordinates reward circuitscrucial for bonding. This hormone helps coordinate the closeness felt due to oxytocin with thegood feelings generated by dopamine and endorphins.Oxytocin and vasopressin are synthesized in the hypothalamus and secreted into the blood bythe pituitary gland, a gland attached to the hypothalamus. These hormones are exclusive tomonogamous pair bonded species as an evolutionary adaption for the long-term care of helplessinfants. In short, we fall in love because our children need us! We will explore this notion whenwe describe parenting.21

Brain in LoveEndorphins are endogenous opioids that reduce pain sensation, increase feelings of pleasureand surge with exercise, orgasm, and love. Non-endogenous opioids (str

The Neurobiology of Love Harvey Joanning, Ph.D. University of South Alabama Iowa State University . Brain in Love 2 Falling in love and attempting to stay in love is a time honored human tradition. Why we are driven to be in love, and how we behave during the process has been the subject of e