Showing posts with label 2014 - Volume 7 - Issue 2. Show all posts
Showing posts with label 2014 - Volume 7 - Issue 2. Show all posts

April 30, 2018

The Ups and Downs of Love: Bridal Weight Changes

For most couples, the wedding is the highlight of their relationship and it is THE big event in many brides' lives. All their friends and relatives are invited and the wedding album will be viewed for years thereafter. It is no wonder that brides aspire to look especially beautiful on this day and they often believe (or are told) that losing weight is absolutely mandatory. But do brides actually succeed in this endeavor? And how lasting are wedding-related weight changes?
From the study of an Australian research team [1], 343 brides-to-be were asked about their weight and related information on average 11 months before their wedding. The brides were questioned again one month pre-wedding (available for 130 women) and six months post-wedding (available for 112 women). Around half of these women reported that they wanted to lose almost 10 kilos before their big day. The authors showed that 47% of the brides did actually lose weight up until one month prior to the wedding - but on average only 3 kg! The remaining, either gained weight of an average of 3 kilos (32%) or did not show any weight changes at all (21%).

For true love, your bridal weight should not matter. via Wikimedia Commons. 

Interestingly, those women who lost a lot of weight prior to the wedding had regained all of it (and more) 6 months after the wedding. The other two groups also gained weight, although significantly less compared to the women with pre-wedding weight loss. On average, women gained over 2 kg in the 6 months after their wedding day, which is probably not at all surprising. Wedding-related stress is reduced and the daily routines step in again, and with them the usual eating habits. Also, to some women the thought might occur that they have now “secured” a man, which might consequently diminish their motivation to work on their bodies.
All in all, one can say that pre-wedding weight loss is very short-lived. Therefore, dear brides and grooms: enjoy your wedding. For true love, a couple of kilos more or less should not matter anyway!


[1] Prichard et al. Body Image 2014

By Ann-Christin Ostwaldt, PhD Alumna Medical Neurosciences (AG Academic Neuroradiology)

February 19, 2018

CNS Newsletter Poll: Mate Selection in Neuroscientists


Who we choose to fall in love and start a family with has gathered considerable interest over the past few decades. The common perception is that men and women prefer different characteristics in their potential mates. The two principal theories contesting these different preferences are based on perspectives drawn from the study of evolution and social structure.

The evolutionary (Darwinistic) perspective assumes that successful mate choice behaviors continue to influence current mate selection because the behavior led to continued existence and prosperity of the human species [1]. Sex differences between men and women have evolved because they have historically faced different environmental and social pressures [2]. The parental investment model proposed by Trivers in 1972 further suggests that this is because men and women differ in the level of parental investment required to ensure the survival of the species. Thus, their mating behaviors evolved accordingly. While women invest extensive physiological resources in producing offspring, men invest more outside resources beyond the act of conception [3].
In contrast, the social structure perspective proposes that sexually differentiated mate selection results from contrasting social positions that men and women have historically occupied within society [2,4]. These types of societal constraints and gender expectations still persist. In an attempt to maximize resources, women who are delegated to roles of less power and resources seek out these characteristics in potential mates. They can offer commodities such as physical beauty, fertility, and sexual pleasure that are desired by men [2,4,5].
Both hypotheses are supported by ample evidence that can be reviewed in Shoemake 2007 [6].
Here, we used a short online poll to investigate possible sex differences and differences associated with career stage regarding mate selection of Berlin neuroscientists.
The survey comprised three questions: 1) ''What is your gender?'' 2) ''What is your position in neuroscience research?'' 3) ''What are the first four qualities you look for in a partner?” Categories were the following: age, cleanliness, ethnicity, financial security, intelligence, kindness, nerdiness, physical attraction, religion, sense of humor, social status, trustworthiness, and other. The survey was prepared on surveymonkey.com and sent to the Berlin Neuroscience community via mailing lists of Medical Neurosciences, Mind and Brain, Bernstein Center for Computational Neuroscience as well as the forum of the staff of the Department of Experimental Neurology. Answers were collected between April 28 and May 2, 2014.
126 responses were collected for the poll. One response had to be excluded since no answers were given to the questions. Out of the 125 answers, 62 participants were male, 61 female, one preferred not to answer and one chose “other”. Of the remaining 125 participants, 23 were students, 58 PhD students, 5 technicians, 20 postdocs, 4 group leaders, 10 professors, and 5 other (Fig. 1).

Fig. 1. Sociodemographic distribution of the participants

Neuroscientists Look for Intelligence, Physical Attraction Rates Only Third
Overall, intelligence (88.6%) was the most frequently reported quality that respondents looked for in their partners, followed by sense of humor (74.0%), physical attraction (68.3%), trustworthiness (60.2%), and kindness (58.5%) (Fig. 2). All other options had less than 10% votes, except for other (11.4%): age (8.1%), social status (7.3%), cleanliness (6.5%), nerdiness (5.7%), religion (3.3%), financial status (2.4%), and ethnicity (1.6%).


Fig. 2. Gender differences in mate selection


Male and Female Neuroscientists Desire Similar Qualities in their Partner
Both male and female participants rated the same top five qualities. The only differences across gender occurred with respect to physical attraction and sense of humor. For men, physical attraction was the second most frequent criterion, whereas only about half of the participating women reported it (80.6 vs. 55.7%, χ²(1, N=123)=8.81, p=0.003). Sense of humor was significantly more preferred by women compared to men (82.0 vs. 66.1%, χ²(1, N=123)=4.01, p=.045).


Neuroscientists Look for the Same Qualities Independent of Career Stage
Due to the low responses from technicians and 'other', we did not include these groups in the analysis. The responses from group leaders and professors were grouped for the same reason. All four groups – students, PhD students, postdocs, group leaders/professors – rated the top five qualities – intelligence, physical attraction, sense of humor, trustworthiness, and kindness – almost equally frequent. The more advanced in their career stage, the more important their partners' intelligence was rated by neuroscientists. Interestingly, postdocs rated physical attraction substantially lower than the other three groups, while they rated kindness substantially higher. Postdocs also had the highest score, even if not as pronounced, for trustworthiness and sense of humor. Only group leaders/professors rated social status as a quality of high importance. A Pearson's chi-squared test was performed and no relationship was found between career stage and any of the mate selection criteria investigated in this study.
Fig. 3. Career stage and mate selection

Discussion
We discovered that male and female neuroscientists have similar mate selection criteria which differ only when it comes to physical attraction. Intelligence was found to be the most frequently reported criterion. A relationship between career stage and mate selection criteria was not found.
In our study, we found intelligence, physical attraction, sense of humor, trustworthiness, and kindness to be the five key attributes both men and women look for in their mate. This goes in line with the immense amount of literature on mate preference that generally indicates a preference for intelligence, emotional stability, honesty and trustworthiness, an exciting overall personality, and – of course – a physically attractive appearance [7].



NEUROSCIENTISTS RATE INTELLIGENCE AS THE MOST IMPORTANT FACTOR IN THEIR PARTNER
 

Interestingly, our study suggests that neuroscientists rate intelligence as the most important factor in their partner – or at least, that is what we would like to believe. According to the matching hypothesis, people are more likely to form and succeed in a relationship with a partner who is equally socially desirable, which often refers to physical attractiveness [8]. On average, women tend to be attracted to men who are taller than they are and vice versa. While men want women with full breasts and lips, low waist-hip ratio, and a young appearance, women prefer men with broad shoulders, narrow waist, V-shaped torso, and masculine facial dimorphism. In addition, both seem to be attracted by a symmetrical face [9-11]. Even when on a purely platonic level, it was shown that people – especially men – tend to be drawn to others that they perceive as similarly attractive [12]. And sure, you probably know one or two successful couples where both partners are not necessarily attractive to the same degree. In this case, the less attractive partner possesses compensating qualities such as status and wealth [13]. Yet, it is not entirely surprising that intelligence is highly ranked. It was previously shown that people unconsciously attribute positive characteristics, e.g. intelligence, to physically attractive people [14]. This association was found to be stronger for men compared to women [15]. Prokosch and colleagues proposed a general fitness factor (f-factor) where intelligence and physical attractiveness are positively correlated because both reflect the quality of the genes and developmental stability [16]. 

NO RELATIONSHIP BETWEEN CAREER STAGE AND MATE SELECTION CRITERIA

Surprisingly, social status was ranked very low in this study, and only group leaders and professors seem to have a preference for it. According to the literature, women have a substantial preference for high social status and wealth [17,18]. In a large US study, men and women were asked how willing they would be to marry someone who possessed a variety of characteristics. While men were significantly less willing than women to marry someone who was “not good looking,” women were significantly less willing than men to marry a partner who was “not likely to hold a steady job” and who “would earn less than you.” However, they showed that both characteristics matter to men and women – just to a different degree [19]. 
We did not find a relationship between career stage and any of the mate selection criteria investigated here. Yet, group leaders and professors tend to pay more attention to social status. We can only speculate that being a neuroscientist or a researcher in academia favors a certain kind of person (which would also explain the lack of gender differences). Why postdocs, in particular, ranked physical attraction much lower than the other groups and tend to value sense of humor, kindness, and trustworthiness more, we'll leave up to your imagination.

What you think your partner should be like and how your beloved turns out to be might be completely different. That’s love! 

Limitations of this Study
This study is greatly limited by the short online poll and low number of respondents. A more detailed study on the mates and reproductive success of Berlin neuroscientists would provide a deeper insight on the actual selection criteria and evolutionary fitness of neuroscientists.

Acknowledgements
We would like to thank Anna Pajkert for helping with the statistical analysis of the data.

[1] Kenrick, Advan Exp Soc Psychol, 1994
[2] Eagly and Wood, Amer Psychol, 1999
[3] Trivers, “Parental investment and sexual selection”, in Campbell, B. (Ed.), Sexual Selection and the Descent of Man (pp. 136-179). Chicago: Aldine, 1972
[4] Howard et al, J Pers Soc Psychol, 1987
[5] Buss and Barnes, J Pers Soc Psychol, 1986
[6] Shoemake, J Scientific Psychol, 2007
[7] Regan, “The Mating Game. A Primer on Love, Sex, and Marriage”, Chapter 1: “Mate Preferences”, 2nd Edition, California State University, Los Angeles, 2008
[8] Feingold, Psychol Bull, 1988
[9] Perrett et al, Nature, 1998
[10] Nettle, Proc Biol Sci, 2002
[11] Glassenberg et al, Arch Sex Behav, 2010
[12] Feingold, J Pers Soc Psychol, 1990
[13] Myers, Social psychology, New York: McGraw-Hill Higher Education, 10th ed., 2009
[14] Dion et al, J Pers Soc Psychol, 1972
[15] Kanazawa, Intelligence, 2011
[16] Prokosch et al, Intelligence, 2005
[17] Buss and Schmitt, Psychol Rev, 1993
[18] Feingold, Psychol Bull, 1992
[19] Sprecher et al, J Pers Soc Psychol, 1994

by Marietta Zille
this article originally appeared 2014 in CNS Volume 7, Issue 2, Neuroscience of Love

February 16, 2018

The Course of True Love Never Did Run Smooth


The Nature of Relationships from a Scientific Perspective

If you peek into your own relationship(s) or those of friends, you might also recognize that there are some differences in behavior depending on the duration of the relationship. And that many of them, unfortunately, do not have a happy ending, as reflected in a divorce rate > 50% of marriages in Western societies [1]. Within this article, we will take a closer look at the different phases of relationships, their neurobiological correlates, and key factors of fulfilling long-term relationships.
               
Phase 1: Falling in love
What is often referred to as the first phase of a relationship is a period characterized by high passion, a rapid rise in intimacy, and increased commitment [2]. Elevated cortisol levels help in overcoming initial neophobia [3] and make this phase a stressful period full of excitement and attachment. As serotonin levels are inversely correlated with those of corticosteroids, serotonin is depleted. Testosterone levels show a gender-specific difference at the beginning of a relationship as they are decreased in men but elevated in women [2]. Reduced activity in different brain areas is observable, for example in the frontal cortex, which explains why people who are in love are not able to judge their partner’s character honestly [4] (see also "Through Rose-Colored Glasses" on pp. 16). This phase usually lasts for half a year.

Phase 2: Passionate love
The second phase is a more settled phase dominated by feelings of safety, calmness, and balance that lasts several years. Passion remains high while intimacy and commitment rise. Testosterone, cortisol, and serotonin levels have returned to normal [2]. The key players of this phase are oxytocin and vasopressin as they are responsible for the formation of strong long-term pair-bonds [2] (see also 'Love is Chemistry', in this issue).

Phase 3: Companionate love
Over the years, intimacy and commitment grow, whereas passion decreases. Compassionate love is a “warm” love that is more similar to intimate friendship than to a couple in the first phase, where physical attraction and desire are more prominent [2]. The essential hormones are also oxytocin and vasopressin, restating and maintaining the pair-bond between a couple [5]. The transition from passionate to compassionate love is a critical point in the course of a relationship; when passion has decreased and intimacy is also low, commitment may be all that is left. This is referred to as “empty love” [6] and is usually not sufficient for the continuation of a relationship.

Breaking up
If a relationship comes to an end, it is usually experienced as an unpleasant event, with increased levels of stress hormones [2]. Recent studies of brain activity patterns found increased activity in areas active during choices for uncertain rewards and delayed responses, reflecting a common feeling of uncertainty about the future [7]. Rejected individuals showed a decreased activity in brain networks involved in the onset of major depression and also showed depressive symptoms, suggesting that the grieving period following a break up might be a major risk factor for clinical depression [8].



Triangular theory of love           
Based on the aforementioned three components “intimacy”, “passion”, and “commitment”, Sternberg postulated the “triangular theory of love” in 2007. Basically, this theory correlates combinations and intensities of the distinct components with different experiences of love (see figure). He hypothesized that love progresses in predictable ways and that all couples experience love in the same patterns [6]. Also, a long-term relationship would be more likely to develop when more than one component is experienced. The complete form of love, also referred to as “consummate love”, thereby arises from a strong expression of all three components and is theorized to be that love associated with the “perfect couple”. According to Sternberg, these couples will continue to have great sex fifteen years or more into the relationship, they cannot imagine themselves happier over the long-term with anyone else, they overcome their difficulties gracefully, and each delights in the relationship with the other. A state that sounds desirable. But Sternberg also points out that maintaining this state is highly dependent on a successful translation of the components into action and that consummate love may not be permanent [6].
All in all, it seems that a fulfilling long-term relationship is not accomplished by just finding “the one”. It is rather a co-operation between two passionate and highly motivated partners working together. If this co-operation is based on trust and respect, if problems are solved diplomatically and if progress is evaluated from time to time, it can result in something really great and satisfying.

[1] Kalmijn, Popul Stud, 2007
[2] De Boer, Neuroscience, 2012
[3] Marazziti, Psycho Endo, 2004
[4] Volz, Curr Opin Neurol, 2006
[5] Starka, Prag Med Rep, 2007
[6] Sternberg, Triangulating Love,2007
[7] Fisher, J Neurophysiol, 2010
[8] Stoessel, Neuropsychobiology, 2011

by Betty Jurek, PhD Student AG Prüß
This article originally appeared 2014 in CNS Volume 7, Issue 2, Neuroscience of Love






February 14, 2018

The Evolution of Love


Let me tell you about the birds and the bees. And the flowers and the trees. And a thing called love…
But hey … what is LOVE, except for the most popular topic of song lyrics?

What is Love?
The urban dictionary gives the following definition: “Love is nature’s way of tricking people into reproducing” [1]. Hm… why didn’t we just continue to be self-copying RNA as described in “The Selfish Gene” by Richard Dawkins, or simply procreate by cell division [2]? The clue is that sexual reproduction brings enormous advantages in terms of fitness: Mutations occur naturally in every organism all the time. Some may be harmful, some without impact and others may be highly beneficial. Maybe a mutation in a structural protein could give a protist sturdier ciliaries, allowing it faster movements and a great advantage in escaping predators. However, only the individual carrying the mutation will benefit from it unless it is shared. And basically, sexual reproduction is nothing else but sharing your genome with someone else. This someone will not benefit in person, but his and your offspring will. Thus sharing is caring. But does caring equal love?

Source

I'm Too Sexy...
In general, mating means higher cost for an individual at first, but pays off with increased fitness of its progeny and gene propagation. But of course, not every individual wants to mate with any other. Hence, mating strategies developed to maximize benefit. Mating strategies vary in complexity: a pretty straightforward strategy is to release attractive molecules to acquire a random partner. However, the more costly the reproduction itself, the more prudence in partner choice is advised. The decision about a partner is usually made by the female, thus males of many animal species have developed specific attributes and/or courtship behaviors that may not serve any practical purpose other than attracting a female’s attention and influencing her choice.
Birds give great examples of this: peacocks grow their beautiful and immense tails to impress females. These have no use other than to signal “I am so fit and healthy, I can afford an entirely useless, giant plumage!” (see also 'You Have Beautiful Eyes, Hundreds of Them'). Similarly, bowerbird males construct little lodges from sticks, grass, and leaves, which they even decorate with flowers, shells, and other colorful and shiny things they collect. If the lodge is impressive enough and the female decides to mate, they entirely abandon the lodge to build a nest suitable for breeding elsewhere.
Humans, too, possess attributes that serve reproductive rather than survival purposes. Compared to other primates, humans have features such as “concealed ovulation, extended female sexuality when not fertile, large visible breasts even when not lactating, large spongy boneless visible pensises relative to body size even when not sexually aroused, relative hairlessness that reveals skin quality, full lips that may mimic female genitalia by exposing skin that simulates mucosal membranes”, as discussed in detail by psychologist Lawrence Josephs [3].

You and Me, Forever
But mating alone does not yet guarantee successful procreation. A lot of further effort needs to be invested by parents to actually ensure the survival of offspring, especially in higher mammals. For humans, this can be up to twenty years! For this purpose, nature developed strategies beyond the "hit and run" approach to make mating partners cooperate until their progeny can survive on its own. Bonding mechanisms cause partners to team up and cooperate until descendants can survive independently [3,4]. This may lead to monogamy (or serial monogamy) as a favored type of relationship.
Nowadays, psychologists discuss compassion, a feeling most of us would also associate with love. Compassion also developed to ensure survival chances for vulnerable offspring because it motivates individuals to join forces and cooperate for the sake of their progeny [5]. Even early evolutionists such as Darwin considered what he called “sympathy” to be one of the strongest human instincts. While all of this totally makes sense, it does not really fit our modern-day definition of “love”.



LOVE IS THE ONLY SOCIALLY ACCEPTED FORM OF MADNESS


Maybe, it is more appropriate to talk about the psychological term “romantic love”. Psychologist James Leonard Park provides a sarcastic explanation of romantic love as a hoax or urban legend [6]. Indeed, considering archeological finds from the beginning of mankind, there is evidence for different forms of courtship behavior and for the concept of marriage, i.e. partnership between man and woman in order to maintain monogamy and raise children. Still today across the globe, people get married for practical reasons only, without any romantic consideration. Where does romance come into play then? Apparently, it is the relatively modern invention of medieval troubadours and minstrels in France [7]. Since then, European culture has spread all over the world, the newly invented concept of romantic love has entered folk psychology and is ubiquitous in songs, novels, television, and movies. Cultural imprinting, one could say.


You Drive Me Crazy
Nonetheless, most of us have experienced romantic love, and it is commonly perceived as an altered state of consciousness or “the only socially accepted form of madness” [8]. Not only because of these definitions, involving consciousness and insanity, psychologists and neurobiologists began to explore what underlies romantic feelings in the brain. Even though research has so far correlated brain regions and autonomous nervous system activity with feelings of love and identified some brain chemistry that elicits affection, science is far from answering the question: What is love?
It's good to know that instead, there are plenty of songs still to come that can tell us the answer.

[1] http://bit.ly/1fTAtUl
[2] Dawkins, "The Selfish Gene", Oxford University Press, New York, 1976
[3] Josephs, Am Acad Psychoanal Dyn Psychiatry, 2010
[4] De Boer, Neuroscience, 2012
[5] Goetz, Keltner and Simon-Thomas, Psychol Bull, 2010
[6] http://bit.ly/1mHJD9x
[7] http://bit.ly/1g2veC6
[8]http://bit.ly/1nnGFXd

by Bettina Schmerl, PhD Student AG Shoichet
This article originally appeared 2014 in CNS Volume 7, Issue 2, Neuroscience of Love

February 12, 2018

You have Beautiful Eyes, Hundreds of Them!

What do people look for in a partner? Many of us would love to know what aspects of our appearance are of most interest to potential mates. Well, we could start by posing the question 'What do people look at in a partner?' After all, what the eye does not see, the heart does not grieve over or in this case throb for.

Avian Eyetracking Shows Peahens Checking Out Males' Train Feathers
This is one of those research questions, however, where straightforward questionnaire data are likely to raise suspicions. How many people are going to admit that they look straight at someone's buttocks or cleavage? Eyetracking, on the other hand, can reveal a great deal about what people attend to, and has delivered such edifying conclusions as: Men seem to like to assess each other's crotches [1]; women check each other out as much as they do men [2]; and men look longer at larger breasts (even when controlling for the larger area of the visual field they occupy) [3].


Picture reproduced with permission from Yorzinski et al, J Exp Biol, 2013

A recent novelty, however, is the application of eyetracking to the romantic interests of birds. And no better bird to begin with than the peacock, famous for its eye-catching train of iridescent feathers, rattled in mating displays. Of course, in the animal kingdom it tends to be the women who do the ogling, so a recent study tracked peahens' eye movements while the males strutted their stuff [4].
The peahens were not especially impressed, spending less than a third of their time even looking at the male at all. Nor were they interested in everything he had to offer. The upper train, where most of the eyes are located, was of relatively little interest. Instead, the females' gaze lingered on the lower train, which they scanned from side to side in a way that suggests they were assessing its symmetry, an important feature in sexual selection [5].
So how can we make sure our next date results in love at first saccade? The authors offer a somewhat disheartening speculation. Briefer viewing times may indicate simply that a trait is much easier to assess. Peahens may look less at train eyes simply because it is very easy to see whether a male has fewer than required, and he may then be rejected without further ado [6]

[1] http://bit.ly/NCem7I
[2] Rupp and Wallen, Horm Behav, 2007
[3] Gervais et al, Sex Roles, 2013
[4] Yorzinski et al, J Exp Biol, 2013
[5] Moller and Thornhill, Amer Nat, 1998
[6] Dakin and Montgomerie, Anim Behav, 2011

by Luke Tudge,
This article originally appeared 2014 in CNS Volume 7, Issue 2, Neuroscience of Love 

February 09, 2018

Mirror Mirror on the Wall - An Insight into Narcissistic Personality Disorder

Having a conversation with a person with an inflated ego is always a very tiresome experience. We are constantly pushed into praising the other person, for criticism is not well received and often disregarded. Narcissism refers to the pursuit of gratification from the egoistic admiration of one’s own physical or mental attributes. 

Narcissistic personality disorder (NPD) is characterized by a lack of empathy as well as a need for admiration and a pervasive pattern of grandiosity [1]. It has prevalence rates of up to 6% in the general population and pathological narcissism is considered a severe mental disorder, associated with significant functional impairments [2].

What Leads to NPD?
Although it is difficult to pinpoint a single cause for the disorder, it is thought to result from extremes in child rearing. On the one hand, it could arise from excessive pampering. On the other, neglect, abuse or trauma inflicted by the parents or other authority figures during childhood could also lead to narcissism, which is usually evident by early adulthood. As a consequence, narcissistic individuals always need people around them, as their entire sense of self-worth is dependent on the admiration of others.


The Neurobiology of Narcissism
From a neurobiological perspective, studies with people suffering from NPD have led to interesting findings. Ritter et al. showed that patients with NPD had severe deficits in emotional empathy although they had intact cognitive empathy.  Emotional empathy requires subjects to rate how much of the emotion in a picture they feel when they view an emotional picture, while cognitive empathy is determined by asking subjects to infer the mental state of a person in the picture [3]. Another study using functional magnetic resonance imaging found that healthy subjects scoring high on a Narcissism Inventory also showed significantly decreased activation during an empathy task, especially in the right anterior insula [4]. Psychotherapy and medication are the currently available treatment options. Identifying the feelings of vulnerability and impaired self-reflection as the core features of the disorder can lead to better psychological treatments.

[1] American Psychiatric Association, 2000
[2] Stinson et al, J Clin Psychiatry, 2008
[3] Ritter et al, Psychiatry Res, 2011
[4] Fan et al, Psychological Medicine, 2011

by Apoorva Rajiv Madipakkam
This article originally appeared 2014 in CNS Volume 7, Issue 2, Neuroscience of Love

December 31, 2017

Head-Turning Asymmetries during Kissing


Did you know that there is a name for the scientific study of kissing? It is called Philematology, from the ancient Greek word philos = earthly love. Scientists found out that we use up to 34 muscles for intensive kissing, that kissing increases levels of endorphins and dopamine, and that we exchange as many as 10 million to 1 billion bacteria during kissing (don't worry, 95% of them are not pathogenic for immunologically competent people). You might be aware of that, but have you ever wondered why you nearly never bump your partner’s nose or head when you kiss?

The Kiss by Auguste Rodin, Musée Rodin, Paris


Onur Güntürkün observed 124 kissing pairs in public spaces in three countries and documented that 65% turned their heads to the right and only 35% to the left, resulting in a 2:1 ratio for right-kissing [1]. Where does this head-turning asymmetry come from? Is it due to brain laterality or due to a motor bias?

Romantic Theory about the Influence of Emotion
One hypothesis is that head-turning asymmetry during kissing is linked to brain laterality. In popular psychology the left hemisphere is often said to be involved in analytical thinking, whereas the right hemisphere processes emotions. At least for posing behavior in portraits, it was shown that the emotional context has an effect on lateralisation bias. In emotive conditions, individuals show the left cheek, i.e. turn the head to the left, whereas when posing for an impassive scientific portrait they show the right cheek [2]. Is head-turning to the right during kissing, like posing behavior, also influenced by the emotional context?
To study the association of right-kissing and emotions, subjects were asked to kiss a life-sized doll head without emotion. The right turning ratio was compared to that of kissing couples. The results showed a similar right turning ratio for both the doll kissers and the couples. As no preferential difference between kissing couples and doll kissers was observed, the emotion theory was dismissed. Kissing the doll does not involve emotions like kissing a partner, but the head-turning ratio was still similar [3].

Reappearance of a Neonatal Right-Side Preference
Another possible explanation for the preference of right-kissing is the persistence of a motor bias seen in neonates: During the final weeks of gestation and during early infancy, most humans have a preference for turning the head to the right. This motor bias persists into adulthood and has effects on various asymmetries. The preferential head turning direction in infants can even be used as prediction for later handedness [4]. However, the prevalence of right-handedness is 8:1 [5]; thus not consistent with the 2:1 kissing ratio for the right side observed by Güntürkün. Thus, the kissing asymmetry is not a simple result of right-handedness. If the asymmetry during kissing is caused by a motor bias, how is it related to handedness and other lateral preferences?
To test whether head-turning preference is related to other lateral preferences, the handedness, footedness, and eye preference of volunteers who were asked to kiss a symmetrical doll face were determined. The study revealed that right-kissers were more likely to be right-handed and right-footed than left-kissers [6]. This relation could not be shown for eye preference, but as the data structure was the same the authors speculate that their questionnaire was not detailed enough. However, the study showed that head-turning preference during kissing is indeed due to a motor bias and related to handedness and footedness.

Dominance of Right-Kissers
As kissing always takes two and both kissers are always influenced by the partner’s head-turning preference, scientists were interested in what happens if a right-turner kisses a left-turner. Therefore Van der Kamp and Canal-Bruland analyzed the consistency of the head-turning bias in kissing by using a doll head rotated in different orientations that were either compatible or incompatible with the participant’s head-turning preference. In the study, right-kissers were more likely to persistently turn their head to the right even if the doll's head was turned as if kissing on the left side [7]. Because the head turning bias among right-kissers is stronger than among left-kissers, two people with different head-turning preferences are more likely to turn their heads to the right during kissing. Furthermore, the results support the hypothesis that behavioral asymmetries are stronger for individuals with a lateral preference pattern for the right than for the left side [8].
In conclusion, the observed asymmetries during kissing can be explained by a motor bias rather than by the emotive context.

[1] Güntürkün, Nature, 2003
[2] Nicholls et al, Proc Biol Sci, 1999
[3] Barrett et al, Laterality, 2006
[4] Michel, Science, 1981
[5] Corballis, Psychol Rev, 1997
[6] Ocklenburg and Güntürkün, Laterality, 2009
[7] Van der Kamp and Canal-Bruland, Laterality, 2011
[8] Searlman and Porac, Brain Cogn, 2003

By Claudia Willmes, PhD Alumni, AG Eickholt and AG Schmitz 

This article originally appeared 2014 in CNS Volume 7, Issue 2, Neuroscience of Love

February 13, 2017

Brain Activity in Love

Is love a mere secretion of chemicals in the brain? And if so, what are the differences between the various forms of it that we experience? Understanding the biological basis of love is a prerequisite to addressing these issues, and recently a lot of scientific research has been directed towards this topic.


Love. Love for God, for wife, for family, for food, for art. The most important aspects of our lives are defined by this strongest of all emotions. Yet we seem unable to define it properly, leading eventually every discussion about it to, at best, a compromise. Is love a mere secretion of chemicals in the brain? And if so, what are the differences between the various forms of it that we experience? Understanding the biological basis of love is a prerequisite to addressing these issues, and recently a lot of scientific research has been directed towards this topic.

The Arrows of Love
As expected, a variety of neurotransmitters are involved in the generation of this unique experience. In particular, waves of dopamine secreted by the hypothalamus flood the brain and recruit certain areas causing a feeling of euphoria and jubilation. At the same time, the neurotransmitter serotonin is depleted, causing the obsessive behavior often described in people who are in love. This association stems from the observation that patients with obsessive-compulsive disorder have similar low serotonin levels. Vasopressin, a hormone associated with aggressive behavior among males, and oxytocin, responsible for the contractions during labor, have also been shown to increase when in love [1]. The above changes have been documented specifically for “romantic” and “maternal” love, indicating a close relation between them and constituting a possible parallel to Freud’s Oedipus complex.

The Coordinates of Love
These hormones and neurotransmitters exert their activity in a plethora of specific brain areas, including the medial insula, anterior cingulate cortex, hippocampus, striatum, and hypothalamus. This activity can be roughly summarized as the activation of the subcortical dopaminergic reward-related system and the areas that it projects to. In a parallel manner, brain areas such as the frontal and prefrontal cortex, amygdala and temporal poles are deactivated [2].
The known functions of most of these areas are consistent with the description of the feelings we experience when in love. For example, the striatum is associated with rewarding feelings and is activated by dopamine - so are the insula and the anterior cingulate gyrus, responsible for mediating emotions and somatosensory integration. On the other hand, the frontal and prefrontal cortex where logical planning and decision making take place are deactivated, partly explaining the irrational behavior and lack of judgment seen in many people that are in love. The parietal cortex and parts of the temporal lobe, linked to negative feelings and depression, are also deactivated [2,3].
On the other hand, the role of the amygdala, a known regulator of fear, is not as simple. Vasopressin and oxytocin seem to exert opposite actions on the activity of the amygdala, increasing and decreasing it respectively, with the effects of the latter prevailing eventually and leading to an experienced lessening of fear [1]. The majority of the above evidence is provided by the results of fMRI studies in which the participants were shown a picture or the name of their beloved partner or of their child.

Are there indeed Different Forms of Love?
Although “romantic” and “maternal” love and sexual arousal share common features in brain activity, there are crucial differences that distinguish them. In the case of maternal love, there is a stronger activation of the brain areas responsible for face recognition, consistent with the need to recognize quickly one's child’s facial expressions and act accordingly. Another region that was found to be activated only in the case of “maternal” love is the periaqueductal gray matter, an area involved in endogenous pain suppression.
Moreover, activation of the same hypothalamic regions has been documented in the case of sexual arousal and “romantic” love, but not in the case of maternal love. In all forms of love, however, the activation of the subcortical dopaminergic reward-related brain system and the deactivation of cortical areas that lead to an impairment in judgment is similar and pronounced, indicating the common aspects they share [3].

The Functional Role of Love
As pragmatic and harsh as it may sound, from an evolutionary point of view, love serves very specific purposes and its intensity as an emotion is totally justifiable. The strong activation of the reward systems that strengthen the bonding between the couple, and between the mother and the child, ensures the unity of the family, increasing their survival chances in a demanding environment [3]. Even the irrational behavior that makes a man defend his partner if a threat is presented, and a mother thoughtlessly sacrifice herself in order to protect her children, could be interpreted in the same way. 

Looking in the Mirror
Although we sometimes regard love as a feeling over which we have no control, fMRI studies suggest otherwise. Cortical areas, such as the angular gyrus, that control complex cognitive behaviors such as social cognition and self-perception are activated even when we are presented with implicit love stimuli, suggesting that love is also a cognitive process.
The mirror neuron system consists of neurons that are activated by the execution and the observation of object-related movements and normally participates in the perception of our surroundings and our actions. This system has been postulated to additionally mediate emotion recognition and social cognition. Located mainly in the insula and anterior cingulate gyrus, areas also activated during the experience of love, it has been suggested that mirror neurons facilitate the understanding of feelings and the prediction of the intentions of others, also providing feedback for the generation of our own feelings [4].

In other words, love is a mutual feeling that gives positive feedback to itself; we need to feel loved in order to feel love in return and vice versa! No matter how logically we try to approach love, using strict scientific terms, in the end love conquers all!


[1] de Boer et al, Neuroscience, 2012
[2] Ortigue, J Sex Med, 2010
[3] Zeki, FEBS Lett, 2007
[4] Ortigue, Med Hypotheses, 2008

By Andreas Antonios Diamantaras, Master's Student Medical Neurosciences
This article originally appeared June 2014 in Vol. 07 - Issue 2 "Neuroscience of Love".  

February 11, 2017

Stockholm Syndrome: A not-quite love story

Fed up with all the love stories you heard in the last days? Here comes a "not-quiet love story" for you:


by EneKiedis via DeviantArt
Love is complicated. While many may spend a sleepless night worrying about finding “the one”, getting together with “the wrong one” can be just as problematic. When taken to the extreme, developing romantic feelings for an inappropriate mate can be confusing, or even dangerous.
Stockholm syndrome is used to define a cluster of symptoms related to inappropriate feelings from a victim towards an aggressor. Within this framework, “positive” actions of the abuser such as withholding abuse are interpreted as signs of love and affection, and the victim begins to develop empathy toward their captor. The name stems from a famous case in the 1970s, a hostage-taking at a Swedish bank in which the victims developed close bonds with their captors and eventually defended them in court [1,2]. Since then, many more cases have been documented, including many linked to forms of domestic and childhood abuse. Though rare, this syndrome has appeared to capture the public imagination [2].



SIMILAR BEHAVIOR MAY BE OBSERVED IN ANIMALS
 


More formally, Stockholm syndrome forms a part of  “Complex post-traumatic stress disorder” [2].Unfortunately, information about its neurobiological correlates is lacking. Evolutionary psychologists have written extensively about Stockholm syndrome, explaining it as an adaptive mechanism to avoid social strife. The story goes like this: a prehistoric woman is kidnapped from her clan, and must survive to protect her children. Making friends, or better yet, a sexual connection with the abductor provides a higher likelihood of survival, and this type of coping strategy is carried on to the next generation. It’s an imperfect story, yet similar types of submissive behavior may be observed in primates or other animals [3,4].



THERE IS STILL SO MUCH TO UNDERSTAND
 


While important for understanding the nature of Stockholm syndrome, these “just so” stories from the animal kingdom are still a long way away from explaining its neurobiological correlates. If nothing else, however, it shows us just how easily (and frighteningly) our feelings may adapt to life-threatening situations. Somewhere between “heart” and “mind”, there is still so much to discover and understand…


[1] Bejerot, “The six-day war in Stockholm”, The New Scientist, 1974
[2] Fitzpatrick, “Stockholm Syndrome”, Time, 2009
[3] Carson and Price, Aust NZ J Psychiatry, 2007
[4] Speckhard et al, Traumatology, 2005

by Constance Holman, PhD Student AG Schmitz
This article originally appeared June 2014 in Vol. 07 - Issue 2 "Neuroscience of Love".