Are Oreos the New Cocaine?

We have all found ourselves reaching for that second delicious, crunchy Oreo (or maybe the German variant, Neo) after we finished the first one all too soon. But just because we do not stop with one cookie, does this mean we are addicted to them? Can Oreos be compared to drugs of abuse? Maybe. At least in rats.  

Source

Researchers at the University of Connecticut made headlines with their discovery that rats spent as much time in a chamber where they got Oreos as in one where they got a shot of cocaine or morphine. In other words, when rats had to pick between two chambers – one with a boring, bland, rice cake and one with an Oreo cookie – they preferred the Oreo chamber. And when given the choice between a shot of saline and a shot of morphine, they picked the morphine chamber. The researchers also found that eating cookies activated more neurons in the brain's nucleus accumbens than exposure to drugs of abuse [1]. 

EATING AN OREO GIVES US PLEASURE

Can we conclude that Oreos are as addictive as drugs of abuse? No! Here is a fatal flaw in the experiment: the researchers never directly compared Oreos to cocaine. They performed two independent experiments in two different groups of animals comparing rice cakes to Oreos and cocaine to saline. What the study does show is that eating an Oreo produces pleasure. But this is nothing new! In order to really find out if Oreos are as addictive as cocaine, we have to compare how hard a rat will work (for example, how often they press a lever) to get either an Oreo or a dose of cocaine [2]. Junk foods can create addictive-like tendencies [4] – this idea is neither new nor wrong. But the conclusions of this particular study certainly are [3].

How addictive are high fat/high sugar foods? Read the upcoming article to find the answer before checking into the treatment center for your addiction just yet!

[1] http://bit.ly/1KrTRTG
[2] http://bit.ly/1er5Fdp
[3] http://bit.ly/1MuWaIS
[4] Avena et al., Method Mol Biol, 2012


by Apoorva Rajiv Madipakkam
This article originally appeared 2015 in CNS Volume 8, Issue 3, Food for Thought.

Conference Report - FENS 2012

The 11th FENS Forum of Neuroscience (FENS 2018, http://www.forum2018.fens.org/), will take place in Berlin, Germany from 7-11 July, 2018. Early registration and abstract submission opens today. One of our students attended the FENS in 2012, read her impressions here.


The Federation of European Neurosciences Societies (FENS) held its 8th Forum of Neuroscience in Barcelona, Spain, from July 14th to 18th 2012. Organized every two years since 1998, the FENS Forum is the largest meeting for neuroscientists in Europe. This year, it gathered more than 6500 scientists from all over the world, who were able to present, share and learn from the latest and most important advances in brain research, in fields like learning and memory, synaptic plasticity, neurodegeneration, neurodevelopment, behavior and emotion, psychiatric disorders, genetics, epigenetics, etc.

The program was very attractive, with a combination of plenary lectures, parallel symposia, technical workshops and special lectures every day. Poster presentations played a very big role, with four sessions each day and more than 2500 posters displayed during the whole event.
One of the special lectures held at the FENS Forum was dedicated to the winners of the Brain Prize in its inaugural 2011 edition. The Brain Prize is awarded by the Grete Lundbeck European Brain Research Foundation to one or more scientists who have contributed to European neuroscience advance with an outstanding and relevant research. Although nominees can be of any nationality, the prize is aimed at researchers whose work has been carried out in Europe or in collaboration with neuroscientists in Europe.

The prize, consisting in € 1 million, was awarded in Copenhagen, Denmark, on May 2nd, 2011, to Péter Somogyi (Oxford University, UK), Tamás Freund (Institute of Experimental Medicine, Budapest, Hungary) and György Buzsáki (Rutgers University, New Jersey, USA) 'for their wide-ranging, technically and conceptually brilliant research on the functional organization of neuronal circuits in the cerebral cortex, especially in the hippocampus, a region that is crucial for certain forms of memory' [1].
The three awarded researchers are native Hungarians. The prize therefore seeks to also recognize the recent contribution of Hungarians to neuroscience that follows the tradition already started by scientists like Károly Schaffer (who gave name to ´Schaffer collaterals´) or Mihály Lenhossék (who introduced the term ´astrocyte´). Somogyi, Freund and Buzsáki have worked together, as reflected in several collaborations and joint publications, with their research focused on the structure and function of complex circuits of nerve cells, particularly in the hippocampus, as unravelling these is important for the understanding of information processing.

During the FENS lecture, Peter Somogyi explained his concept of the unity of time and space in the brain, an idea he has termed ´chronocircuitry´. He presented his latest work aiming at understanding the functional organization of the brain by identifying the specific neuronal subtypes that make up a given neuronal circuit, their morphology, the particular expression of certain neurotransmitters and receptors and their input-output relationships.

In his talk, Tamás Freund presented how different types of interneurons modulate neuronal oscillation in the cortex and hippocampus and the role of endocannabinoid signaling. To explain it, Freund used a comic, yet very didactic video of an octopus: In the animation the octopus represented the interneuron, holding in its tentacles several swimmers (pyramidal cells) under the water. When the octopus releases the swimmers, they all go and reach the surface of the water at the same time to catch their breath, therefore, representing the role of interneurons in synchronizing pyramidal cells to fire at the same time and frequency. In the same way, release of endocannabinoids by a pyramidal cell inhibits GABA release by the interneuron onto them - thus, avoiding synchronization. This was shown in the video as a Bob Marley-looking swimmer who, by smoking marijuana (the analogue to endocannabinoid release), had escaped from the octopus tentacles and could thus breathe at his own rate.

Finally, György Buzsáki presented his recent work on how brain rhythms coordinate cell assemblies - transiently active ensembles of neurons- to allow them to perform operations like encoding memories or reasoning. The idea behind his research is that hierarchical organization of cell assemblies can be seen as a ´neural syntax´, i.e. as a mean of an ordered language construction in the brain.
In addition to the scientific program, a number of social and special events were organized, such as 'Cooking with the brain' about the evolution of food perception, 'Meet the expert' and 'Build your career', giving scientists and industrial partners the chance to meet other scientists in a more informal environment or the 'Jump the FENS Party'. Finally, participants had the opportunity to visit several touristic attractions in the city as well as museums, such as the Museum of Natural Sciences, located next to the FENS venue.

The Forum took place at the International Convention Center of Barcelona (CCIB), right in front of the beach, by the Mediterranean sea, an ideal location to allow everyone to enjoy the warm temperatures and sunshine weather before, in-between and after the daily sessions.


[1] Soltesz I, Trends in Neurosciences, 2011
The Brain Prize: http://www.thebrainprize.org/flx/the_brain_prize/



By Violeta Castelo Szekely, MSc Student Medical Neurosciences
This article originally appeared 2012 in CNS Volume 5, Issue 3, Engineering the Brain

Tracing the Roots of Aggression

Many evolutionary theories explain the development of human aggression as a necessary trait for survival. However, aggression rarely has practical use in contemporary society. When exhibited, it is often in a violent and illegal context and therefore it is incriminated. Sometimes, it can even be considered part of someone’s temperament.

Aggression is thought to be the result of a complex corticolimbic interaction between subcortical neural systems, decision-making circuits, and frontoparietal regions [1]. Strong genetic and hormonal influences, in addition to the various environmental stimuli, seem to regulate these networks. This raises questions regarding the degree of responsibility that violent people bear.

Aggression Is a Male Phenomenon
According to statistics, the ratio of crimes committed by males compared to females is greater than 10:1. The more aggressive behavior of males starts to manifest itself even before adolescence, with boys being more likely to be involved in some kind of antisocial conduct [2].
Hormones are among the first suspects for male aggression. Exposure to androgens in the early stages of adolescence is thought to constitute a possible cause. However, according to a recent meta-analysis, the association between testosterone levels and antisocial behavior is weak [3]. Next is the stress hormone cortisol, whose action is regulated through the hypothalamus and adrenal axis. Lower cortisol concentration was found in the saliva of males with antisocial conduct [4]. Finally, low levels of the serotonin metabolite 5-HIAA and low blood sugar are other messengers implicated in the regulation of aggressive behavior.

Is It You Y?
More than four decades have passed since males with XYY syndrome, known also as supermales, were associated with criminal behavior. A higher percentage of XYY men was found in prisons and in institutions for criminally insane people than was found among the normal population. This hypothesis has been significantly weakened after the publication of epidemiological studies that suggested otherwise [5], although it has not been totally refuted as emerging evidence still supports the initial claim [6].
Taking a closer look at the genes, recent knockout studies in mice have excluded any contribution of the Y-linked loci to aggression [7]. Nevertheless, the investigation of other chromosome loci revealed genes that might explain the sex-related difference in aggression and should be interpreted along with the hormone hypothesis. A shorter GAG repeat in the Androgen receptor in Swedish and Indian males accused of aggressive behavior has been associated with it [8]. Certain polymorphisms of the monoamine oxidase (MAOA, MAOB)-coding genes have been linked with functional differences in expression. A plethora of enzyme-coding genes (COMT, dopamine-β-hydroxylase and tryptophan hydroxylase) has been linked to male aggressive behavior [9].

Environmental Interactions
Stressful events, especially in the first years of life, confer a higher risk for manifesting antisocial conduct. Interestingly, it seems that stress triggers aggressive behavior in males with a “vulnerable” genetic background and more specifically a low-activity polymorphism in the MAOA gene. The causality in this case is not clear yet, as evidence suggests that an initial stressful event down-regulated the activity of the MAOA genes later on [2].

The Role of Recreational Substances
Substance use is closely related to offending behavior in both sexes, with alcohol being the most common culprit. It is not only widespread alcohol use, but also its high correlation with violent behavior that make it one of the most significant perpetrators of aggression. Drug users on the other hand, rarely exhibit such behavior, with cocaine users being the only exception [10]. 
Aggressive behavior, like every behavior, is difficult to approach and explain with molecular and genetic mechanisms. However, there seems to be a notable interaction between the environment and one's genetic background. This requires further investigation, as the potential implications for preventing the development of an aggressive behavior, even in a small portion of the population, could improve dramatically the fabric of our societies.

[1] Coccaro et al, Biol Psychiatry, 2011
[2] Craig and Halton, Hum Genet, 2009
[3] Book et al, Aggress Violent Behav, 2001
[4] Shirtcliff et al, Dev Psychopathol, 2005
[5] Noël et al, Clin Genet, 1974
[6] Stochholm et al, BMJ Open, 2012
[7] Gatewook et al, J Neurosci, 2006
[8] Rajender et al, Int J Legal Med, 2008
[9] Pavlov et al, J Appl Genetics, 2012
[10] Lammers et al, Tijdschr Psychiatr, 2014

by Andreas A. Diamantaras, MSc student
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture

Can You Raise Your Kids Gay?

Over the years, the controversy of the nature versus nurture debate has extended beyond childhood behavior to intelligence and also sexual preference. Today's article aims at uncovering the roots of male homosexuality.

digitalart / FreeDigitalPhotos.net

On July 16th 1993, the Daily Mail ran the headline: "Abortion hopes after the 'gay genes' findings". The author, Jason Lewis, claimed that, thanks to recent advances, it might soon be possible to predict the sexual orientation of a baby and give parents the option of abortion. Irrespective of the intentions of the author and possible implications of this article, let us first consider whether this will ever be possible. Since male homosexuality is much more common in nature than female homosexuality, most of the research on sexual orientation concerns only male homosexuality. Years into research on the topic, scientists cannot give a conclusive answer to the question of reasons for our sexual orientation. Simply put, it does not exist.

The Evolutionary Mystery
Homosexual behavior is natural in the animal world, with over 1500 species practising it [1]. Does this give us a first clue that biological factors play a crucial role in establishing sexual orientation? Possibly. In 1991, a twin study conducted by Michael Bailey and Richard Pillard showed that among monozygotic male twins, one gay brother increased the probability of the second being gay by up to 52% [2]. In contrast, this percentage was as low as 22% for dizygotic twins and 11% for adoptive brothers. Hamer and colleagues proposed that an Xq28 allele influences sexual orientation, as its sharing between gay brothers was 64%, not 50% as would be expected by chance [3].

Over 1500 species practice homosexual behaviors

Yet, evolution would intuitively not promote a gene that is anti-reproductive. Why would it then survive in our population at all? The hypothesis here is simple and elegant – the gene that in males promotes homosexuality, in females contributes to their fecundity. Families with homosexual members have been shown to reproduce more than those without  [1]. We must, however, note that genetic studies conducted on a large group of participants showed that the genetic changes can explain only a small fraction of the occurrence of homosexuality [4].

If Not Genes, Then What?
If genes do not explain 100% of homosexuality, there must be some additional factors. Interestingly, a fraction of male homosexuality might be explained by immunology. A phenomenon called the fraternal birth order effect shows that homosexual males have a higher number of older brothers. To put it differently, having a son increases the probability of the next male child being homosexual.
This is explained by the maternal immunity hypothesis. It states that male offspring immunize the mother to male cells, thus producing anti-male antibodies during the next pregnancy with a male. The theory posits that those antibodies cross the placenta and blood-brain barrier, changing the brain’s development. This, in turn, may cause diverted sexual attraction and sexual orientation in the male offspring [5]. This phenomenon is the most thoroughly established factor in the field of human homosexuality [1]. However, we cannot forget that more than half of homosexual males have no older brothers [1].

The Neuroscience of Homosexuality
Concerning the ‘homosexual brain’, a number of brain regions have been shown to be, either functionally or anatomically, different in homosexuals compared to heterosexuals. Research has shown that brain regions such as the interstitial nuclei of the anterior hypothalamus show similar anatomy in homosexual men as in heterosexual women, that is clearly different from heterosexual men [6]. Yet it must be noted that even if homosexual males’ brains are similar to those of heterosexual women, it is not clear whether those changes precede the development of homosexuality, or whether attraction to males has elicited changes in the brain.

Environment and Sexual Orientation
In his paper, John Bancroft argues that homosexuality is caused by environmental factors [1]. He starts with an argument that homosexual males usually experience sexual attraction earlier than heterosexuals. They might therefore develop same-sex attraction because at this point of time, boys spend most of their time with other boys. This is, however, only a speculation.
He goes further and says that homosexuality is often just a phase in human development and that the final phase is heterosexuality. To support his hypothesis, Bancroft gives an example of a people in Papua New Guinea: Young boys around the age of ten are taken to all-male dormitories. They are told to fellate older boys and swallow their semen (in a belief that it is crucial for their proper development). At a particular age, they leave the dormitories and lead a heterosexual life that leads to marriage. He claims that this proves his argument of homosexuality being just a phase. Yet, the author fails to mention that activities performed in all-male dormitories might be merely a cultural concept and that in no way are they a proof of homosexuality.
Additionally, nurture theorists claim to have identified characteristic familial patterns that are supposedly related to children’s homosexuality. Those include low paternal presence or high maternal cues in the case of male homosexuality. However, this can be easily reversed – perhaps those familial patterns were caused by the homosexuality of children [1].

Homosexuality is multifaceted and extremely complicated

Clearly, homosexuality is a multifaceted and extremely complicated phenomenon. But why do we even think about it? The Daily Mail headline from 1993 seems unnecessarily harsh and, at least now, incorrect. We are investigating the basis of homosexuality, but can it have detrimental outcomes? Being able to predict one's sexual preferences might mean denying the right to live. So maybe, we should just let it go and try to accept that people are different no matter where this difference comes from.

[1] Jannini et al, J Sex Med, 2010
[2] Bailey and Pillard, Arch Gen Psychiatry, 1991
[3] Hamer et al, Science, 1993
[4] Mustanski et al, Hum Genet, 2005
[5] Blanchard and Bogaert, Am J Psychiatry, 1996
[6] LeVay, Science, 1991

by Filip Morys, PhD student Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture 

The Origins of Intelligence

The intelligence quotient (IQ) is the best predictor of success in academia and at work. It also serves as a reliable indicator of longevity [1], making the origin of intelligence and the possibility of enhancing it a most interesting research topic.

The theory of multiple intelligences proposed by Howard Wagner in 1983 outlines nine types [2]. Some of them, such as bodily-kinesthetic intelligence (“body smart”) would be hard to assess using a written test. Yet, it has been shown that people who performed well on any single test section, such as linguistic intelligence, also score high on other areas [2].

Source

Big Brains Mean More Intellect
Intelligence positively correlates with the size of the whole brain [1]. However, brain size is limited by skull size and the skull has to pass the birth canal. Complications are hence more likely during the birth of naturally intelligent babies, possibly lowering their survival chances. Moreover, the individual volumes of brain areas are highly heritable [1,3], supporting the theory that nature is more influential on intelligence than nurture. Thus, not surprisingly, in diseases that cause dementia, brain cells are lost and the brain effectively shrinks.

Genes for Smartness and Intellectual Disability
Intelligence is a polygenetic trait. This year, the University of Edinburgh announced the discovery of the first intelligence gene. A highly active NPTN gene allows adolescents to score higher on intelligence tests [4]. The gene codes for a neuronal synapse protein that plays a role in brain development and neuronal signaling. Surprisingly, the NPTN gene explains only about 0.5% of the variability in intelligence. Conversely, candidate gene studies have revealed over 282 genes associated with intellectual deficits (formerly known as mental retardation).

“The measure of intelligence is the ability to change.” – Albert Einstein

Results pooled from a number of studies conducted during the last century on human intelligence research indicate that genetic factors are responsible for up to 50% of differences in intelligence between individuals [1,5].

Race over Education or Education over Race?
The philosophy of race superiority suggests that some ‘types’ of humans are superior from birth because of their lineage. Fortunately, this has largely been unpopular since the abolishment of slavery in America (1865) and the defeat of Nazi Germany (1945). Following each of these events, the Caucasian and Afro-American races began to mingle. With the establishment of racially integrated schools, it became apparent that Afro-Americans showed a lower cognitive ability compared to their white peers [5]. This result was partly attributed to their lower socioeconomic status [5], but may have fueled racism in Europe.

Intelligence is an indicator for success

A post-World War II study in Germany looked at the “occupation babies” of Afro-American and Caucasian American soldiers with German mothers. The IQ of the mixed-race children was 96.5 compared to 97 in Caucasian children [6]. This suggested that inheritance of culture, education, and equal opportunity (rather than race) influence IQ.

Dirty Minds at Age 5 Associated with Lower IQ
A study published this year showed that the exposure of pregnant women to air pollution released by the burning of fossil fuels can cause birth defects and lower the IQ of their offspring by about 3.8 points at age 5 [7]. This result persisted even after the scientists accounted for the level of parental education and several other factors that might influence child IQ. Similar studies have shown that pollution is a cause of birth defects, childhood behavioral disorders, and rare cancers [7].

The Recipe for Raising a Genius Is Continuous Practice
In 1993, K. Anders Ericsson presented evidence showing that violinists who practiced more than 10,000 hours before their 20^th birthday were likely to become professionals [6,8]. This was applied to the mastery of other skills and eventually became known as the 10,000 hours rule. Talent plays a lesser role.
A standard IQ test provides no or unreliable results for half of the intelligence types known so far. Intrapersonal intelligence, for example, contributes to good teamwork, stress management, and leadership. However, there is no comprehensive and standardised measure for it [9].
It requires four hours of practice (with coaching and reinforcement), for six days a week, for fifty weeks a year, over ten years will help you master anything! It's no wonder, really. But honestly, how many of us would volunteer to undergo such rigorous training?

[1] Gardner, The Nine Types of Intelligence, http://bit.ly/19kchVz
[2] Deary et al, Eur J Hum Genet, 2006
[3] Science Daily, 2007, http://bit.ly/1s8kvcf
[4] Desrivières et al, Mol Psychiatry, 2014
[5] Dickens, Future Child, 2005
[6] Blech, Spiegel Online, 2010, bit.ly/1pVTiEV
[7] Perera et al, J Public Health Policy, 2014
[8] Ericsson et al, Psychol Rev, 1993
[9] Arora et al, Med Educ, 2010

by Rick Cornell Hellmann, PhD student AG Schwab
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture 

Open positions for PhD and Master students in Neuroscience research in Berlin

The working group "Neural Regeneration and Plasticity" at the Department of Neurology (Charité Campus Mitte) is looking for a student (m/f), who is interested in a Master’s Thesis about the interrelation of Alzheimer’s disease and Type 2 Diabetes in a mouse model.

Focus:
- behavioral tests in mice
- histology (preparation and staining of brain tissue)
- microscopy

Contact:
Stefanie Schreyer (AG Steiner)
stefanie.schreyer@charite.de

How Much of Ourselves Are We Born With?

Today is Universal Children's Day, which was established in 1954 to promote international togetherness and awareness among children worldwide. In today's article we are revisiting the nature versus nurture debate.

The phrase ‘nature versus nurture’ is derived from early studies on the effects of parenting on childhood development. Researchers sought to determine the relative contributions of an individual’s innate qualities, determined by one’s genes (nature), and parenting or personal experiences (nurture) on the psychological and behavioral traits of children. If a child shows aggressive behavior, was he or she genetically ‘programmed’ to behave in such a way, or is it the product of his or her upbringing or environment? Consider if one of the child’s parents is also aggressive. Did the child acquire this behavioral trait through exposure to his or her parent's behavior or through inheritance?
No concept is as pervasive in the study of health and disease as distinguishing the effects of internal and external stimuli on bodily function. Since Claude Bernard elegantly introduced the idea, it has not only formed the basis of modern physiology but has also helped us understand numerous pathological states in terms of the interaction between inherited and environmental factors.
Over the years, the controversy has extended beyond childhood behavior to intelligence, sexual preference, and the propensity for certain diseases (see ''The Origin of Intelligence'' and ''Can You Raise Your Kids Gay?''). Despite being heavily researched, at least two problems make the nature versus nature debate a major challenge facing modern biology. The diseases and traits being investigated, particularly those to do with the brain, are themselves complex and often hard to characterize. Moreover, as our understanding of biology progresses, separating the consequences of intrinsic and extrinsic factors on a certain physiological or pathological state becomes increasingly difficult (see here).

Shedding Light on the Issue Using Twin Studies
Separating the effects of genes and environment on childhood development and the pathogenesis of diseases can be achieved by performing adoption and twin studies. Francis Galton first proposed this approach in 1875. It gained impetus at the beginning of the 20^th century when Gregor Mendel’s insights into the mechanism of heredity became widely known. Identifying differences in specific traits by studying monozygotic twins, who share identical genetic information, over portions of their lives gives us insights into the contribution of the environment in developing these characteristics.
In terms of psychological traits, separated twins usually grow up to be very similar even when brought up in substantially different environments. In the landmark Minnesota Twin Study, which began in 1979, researchers studied more than 100 sets of twins or triplets that had been separated in infancy and raised apart from one another. They found that genetics can explain up to 70% of the variability in personality, intelligence, and temperament between the twins [1].

Implications Beyond Medicine
Investigating the relative contributions of innate and acquired factors in human psychology and health can have far-reaching consequences. Not surprisingly, the nature versus nurture debate has also made its way to the courtrooms. Many experts believe that criminality, for example, is a trait that is predominantly inherited. Thus, defense lawyers sometimes argue (with varying degrees of success) that, in certain cases, people accused of committing crimes cannot be held responsible for their actions because they cannot be held accountable for their DNA.
The discovery of rare mutations that strongly predispose to aggression, such as that of the monoamine oxidase type A gene, has helped encourage the acceptance of such legal arguments [2] (see also ''Tracing the Roots of Aggression"). Biologists and physicians often oppose legal battles that attempt to make use of such a defense. They believe that the public often poorly understands the link between genes and behavior, which is a complex issue.

Is the Debate Obsolete?
Over the past few decades, we have made some astounding discoveries regarding how our genetic material is controlled. We now know that DNA is not the rigid, unchanging blueprint of our entire lives that it was once thought to be. Gene expression is a flexible (yet tightly regulated) process that is modulated continuously in health and disease.
Epigenetics (meaning ‘in addition to’ genetics) is the field of biology that deals with the alterations in gene expression that occur in the absence of changes to the DNA sequence. These changes can persist over long periods of time and, perhaps most interestingly, can be inherited from one generation to the other. The signals that trigger epigenetic changes can come from within the organism itself or from the surroundings (see "Lamarck's Last Laugh" on p.4).
The more we learn about epigenetics, the smaller the distinction between nature and nurture becomes. Consider an example. Exposing an individual to stress can alter the expression of proteins involved in the pathogenesis of mood disorders [3]. This altered expression can persist not only throughout the individual’s lifetime, but can also be transmitted to his or her offspring. If one of this individual’s children eventually develops depression, is the contribution of the exposure of the child’s parent to stress inherited or environmental? The simple answer is both. It thus comes as no surprise that, nowadays, many experts consider the debate obsolete.

Although we should not insist on drawing a line where boundaries are becoming less and less clear, making a distinction between the effects of nature and nurture aids our understanding of complex biological processes.

[1] Bouchard TJ Jr et al, Science, 1990
[2] Brunner, Nelen et al, Am J Hum Genet, 1993
[3] Murgatroyd, Nat Neurosci, 2009

by Ahmed Khalil
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture