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

Messing up With Mendel - Genetic Imprinting and Its Effect on Your Life

It was on a summer’s day in the year 1822 when Johann Mendel saw the light of day. He inherited 50% of his genes from his father Anton and 50% from his mother Rosina. But contrary to his postulated rules, the expression of some genes was altered in a parent-of-origin specific manner: Depending on whether the origin of a gene copy is maternal or parental, the gene is active or non-active. This phenomenon is called “genetic imprinting” or “genomic imprinting” [1].

Methylation Is Key to Genetic Imprinting
Helen Course described a “parent-of-origin effect” for the first time in 1960. Experiments with mice in 1980 revealed the first proof of parent-dependent inheritance of some genes. They used nuclear transplantation in mouse embryos with either maternal or parental chromosomes. The embryos could not develop normally, despite a diploid genome [2].
Since this discovery, researchers have tried to answer questions on how imprinting is facilitated, what the evolutionary advantages are, and which diseases are correlated with imprinting. In principle, imprinting is an epigenetic process that leads to monoallelic expression without altering the DNA sequence – a process known as methylation that leads to inactivation of gene expression (see also "Lamarck's Last Laugh" ). In contrast to mutation, imprinting is reversible. During gametogenesis, the imprinting status in germ cells is erased and re-programmed according to the sex of the individual [3].

Mendel’s studies with pea plants established many rules of heredity, known as
"rules or principles of Mendelian inheritance":
1. Segregation: In diploid organisms, chromosome pairs are separated into individual gametes to transmit genetic information to offspring.
2. Independent Assortment: Alleles on different chromosomes are distributed randomly to individual gametes.
3. Dominance: A dominant allele completely masks the effects of a recessive allele. A dominant allele produces the same phenotype in heterozygotes and in homozygotes.

A Parental Tug-of-War
As genetic imprinting diminishes the advantages of a diploid genome, it is unclear why genetic imprinting occurs. The most favored hypothesis is the “parental conflict theory”. It states that genomic imprinting reflects the differing strategies of parents regarding the proliferation of their genes [4].
A classic example is the regulation of fetal growth in mice by imprinting of the insulin-like growth factor 2 gene (Igf2) and the receptor gene Igf2r. Igf2 is a paternally expressed growth factor that enhances fetal and placental growth when it binds to the receptor Igfr1. Therefore, paternal strategy lies in extracting more resources to improve the fitness of their offspring [2].
The maternally expressed receptor Igf2r also binds Igf2 which leads to degradation of the paternally expressed protein. This antagonistic mechanism counterbalances the paternal effect and ensures an equal distribution of nutrients among the offspring [2]. Loss of genetic imprinting in Igf2- or Igf2r-locus in mice leads to either fetal overgrowth (e.g., biallelic expression of Igf2) or reduced fetal growth.

The Shady Side of Genetic Imprinting
In humans, less than 1% of the human genome is modified by parental imprinting [4]. The majority of these genes are related to growth and neuronal development of the embryo [4]. By affecting neurodevelopmental processes, genetic imprinting influences brain function and behavior. This leads to severe dysfunctions if the non-imprinted gene copy is malfunctional.

ACTIVATION OF IMPRINTED GENES IS ORIGIN-DEPENDENT

 
The ubiquitin-protein ligase E3A (UBE3A), for example, is only imprinted in brain tissue where the paternal copy is silenced. This enzyme is a key player in ubiquitin-mediated protein degradation. Children with a malfunctional maternal copy suffer from Angelman’s syndrome, characterized by developmental delay, epilepsy, movement disorders, and a perpetually smiling facial expression.
Other genes located near the UBE3A locus, like the genes SNRPN and NDN, are maternally imprinted. A malfunctional paternal copy leads to Prader-Willi syndrome, characterized by intellectual delay, hypogonadism, and hypotonia [4]. The risk of some neuropsychiatric disorders such as autism spectrum disorders, schizophrenia, Tourette syndrome, and bipolar disorders has also been related to genetic imprinting [4].
It seems that genetic imprinting can influence many aspects of our lives. Further investigation will bring us a better understanding of development, pathologies, and genetic fitness. And though it contradicts with Mendel’s postulated rules, he would probably be fascinated by the strange paths evolution may take.

[1] http://www.genetics.edu.au
[2] Reik and Walter, Nat Rev Genet, 2001
[3] Philips, Lobo, Nature Edu, 2008
[4] Wilkinson et al, Nat Rev Neurosci, 2007

by Betty Jurek, PhD student AG Prüß
This article originally appeared 2014 in CNS Volume 7, Issue 3, Nature vs Nurture

How Different Cultures View Early Life and Death

The students of MedNeuro are multinational and so diverse are their ways of celebrating easter and other festivities. Betty Jurek had a look of how beginning and end of life are celebrated around the globe.

The Beginning…
When a baby is born, parents are usually overwhelmed with emotions, and only want the best for their child. But the interpretation of what “the best” is also depends on the parents’ nationality and can be somewhat, let’s say, "unique".

Baptism by keskieve via pixabay

Sifudu Smoke
This ritual is practiced in Nigeria and means “passing baby through smoke”. Between the third and fourteenth day after birth, leaves from a Sifudu tree are burnt, causing a pungent smoke that is irritating to the mouth and eyes. The baby is held head downwards into this smoke several times, in the belief that this prevents the child from being frightened, timid or shy [1].

Precious Saliva
An interesting way to give blessings to a baby is practiced by the Wolof people in Mauritania. They believe that saliva can retain words so the women spit into the baby’s face while men spit into the baby’s ear. To ensure that the blessing works, they rub the saliva all over its head [1].

Recycled Wedding Cake
In comparison to applying saliva onto Mauritanian babies, Irish babies seem to have better luck. Couples freeze the top tier of their wedding cake and re-use it for the christening of their first baby. Some crumbs are sprinkled over the baby’s head and if the couples have leftovers from their wedding champagne, this will also be used to wet the baby’s head for good luck [1]. Cheers!

Placenta Power
In contrast to many animal species, eating up the placenta following delivery is a somewhat unusual practice for humans. Proponents of human placentophagy claim that eating their own placenta results in better mood, increased energy and lactation although there is no study that gives evidence for a causal effect. Dried placenta is also commonly used in Chinese traditional medicine to treat infertility, impotence and other conditions [2].

Lithuanian Baby Race
Every year on International Children’s Day (June 1^st), Lithuanian toddlers compete in a race where they have to crawl a 5-meter carpet to their mothers as fast as they can. All participants seem to have great fun, and the winner this year crawled the distance within 11 seconds [3].

Toddler Tossing
This ritual may be the scariest one for outsiders. At an annual festival in India, babies and toddlers are tossed from a 15-meter high tower, right onto a landing sheet. Despite appearing to be a traumatic experience for the babies, it is supposed to give luck, health and prosperity to the child [4].

…And The End
Depending on our spiritual or religious backgrounds, we see death as either the end of life or as some sort of transition. Every people has its own way of dealing with death and grief. Some of them seem very creative, others more disturbing.

 fantasy coffin by Regula Tschumi via Wikimedia Commons

Fantasy Coffins
This interesting tradition from southern Ghana is based on the belief that life continues after death the same way as it was before. Therefore, people make individual, colorful coffins that often reflect the dead person’s profession or passion, which is thought to allow them to start the afterlife as conveniently as possible [5]. From a boat to a piano to a pack of cigarettes, everything is possible.

Death Beads
Space in graveyards in South Korea is running out, so a law was passed in 2000 mandating that people who get buried need to be removed 60 years later. This crisis led to an invention which has gained popularity during the last decade: Death beads. These turquoise beads are generated by melting the cremated ashes at ultrahigh temperatures [6]. In this way, the beloved one can be kept at home “forever”.

Consuming Grief
As an act of compassion, some tribes in South America, Africa and India used to eat their deceased family members. As a part of the grieving process, the Wari’ people in Brazil ate the complete corpse whereas other tribes, like the Amahuaca Indians, made some sort of gruel out of the ground bones and corn [7].

Death is Not the End
In contrast to Western culture, members of the Toraja ethnic group in Indonesia are buried weeks, months or even years after they pass away. For the Toraja, death is a gradual process toward the afterlife. Therefore, the deceased is wrapped in several layers of cloth and kept in a special room in the family’s home. They are still part of family life, are symbolically fed and taken out every once in a while. At the actual funeral, the social status of the deceased is reflected in the numbers of sacrificed chickens and water buffaloes [8].

Sky Burial
This special form of funeral is practiced in different regions of Asia (e.g., Tibet, Mongolia), where people practice Vajrayna Buddhism. A monk or a rogyapas (body-breaker) prepares the dead body (by taking out the organs) and places it on a mountaintop to return the body to nature. Most of the time, this means that the dead body will be devoured by vultures to the bone. The bones are then ground with a special sort of flour and given to crows and hawks that wait until the vultures have departed [9]. This way, the deceased merges with the wind.

[1] http://glblctzn.me/2ewEsaT                               
[2] http://bit.ly/2ewE5Ng           
[3] http://bit.ly/2ewEtLS                             
[4] http://dailym.ai/2eo6Wbq                   
[5] http://bit.ly/2ewFl39                              
[6] http://lat.ms/2eo69Ho
[7] http://bit.ly/2ewEfo0                             
[8] http://bit.ly/2enT6Wx           
[9] http://bit.ly/2eo70I6

by Betty Jurek, PhD Student AG Prüß
This article originally appeared 2016 in CNS Volume 9, Issue 4, From Cradle to Grave in the Brain