Saturday, June 18, 2016

Highlights and new discoveries in Neuroscience (May 2016)

In the fifth issue of this monthly digest series you can learn about the neurobiology of love, how long-term marijuana use alters the brain's reward circuit, what nightmares say about your personality, and much more.

The Neurobiology of Love

What is love, anyway? Though often difficult to define, we all know what love is. For most people love involves the development of a strong emotional bond, sexual attraction, and care giving. Even more so, people who are "in love" may experience a range of intense feelings, such as intrusive thoughts, emotional dependency, and increased energy. As involved and intense as love can get, as complex and diverse is the brain activity that goes with it. Love is a complex neurobiological phenomenon, relying on trust, belief, pleasure and reward activities within the brain. Here's what we currently know about the neurobiology of love.

Numerous brain regions, particularly those associated with reward and motivation, are activated by the thought or presence of a romantic partner. These include the hippocampus (involved in memory formation and spatial mapping), hypothalamus (involved in regulating certain metabolic processes and other activities of the autonomous nervous system), and anterior cingulate cortex (ACC) (involved in regulating blood pressure and heart rate). Activation of these areas may serve to inhibit defensive behavior, reduce anxiety, and increase trust in the romantic partner. In addition, other areas such as the amygdala (involved in memory formation, decision-making, and emotional reactions) and the frontal cortex (involved in the processing of reward, attention, short-term memory tasks, planning, and motivation) are deactivated in response to romantic love; a process which may function to reduce the likelihood of negative emotions or judgement of the partner.

A recent study based on the topic "science behind the love" from Rutgers University revealed 3 common stages of love—namely lust, attraction, and attachment. Each stage involves different types of chemical reactions within the body (specifically the brain). Lust is said to be the initial stage of getting involved with love. The feel of lust is basically backed up or instigated by the sexual hormones estrogen and testosterone. Attraction is when a person actually starts to feel the love, and is dominated by adrenaline, dopamine, and serotonin. Finally, attachment is the phase a couple enters when they start "falling in love wholeheartedly", dominated by the "love hormones" oxytocin and vasopressin.

Oxytocin and vasopressin are both produced by the hypothalamus and released by the pituitary gland. Vasopressin is also quickly released in major quantity after sex. Although the brains of women and men are structurally different, they both secrete vasopressin from the pituitary gland. This is a vital role in copulation and partner preference (Hiller, 2004). In particular, oxytocin and vasporessin interact with the dopaminergic reward system and can stimulate dopamine release by the hypothalamus.

The dopaminergic pathways activated during romantic love create a rewarding pleasurable feeling. The pathways are also associated with addictive behavior, consistent with the obsessive behavior and emotional dependency often observed in the initial stages (or "honeymoon phase") of a romantic relationship. In fact, it has been known for a while that social attachment is in many ways similar to behavioral addiction; i.e., individuals become addicted to other because of the returned reward. There is a chemical chain of reaction triggered in our bodies ultimately instigating the feeling of love to strike our minds. Actually, falling in love is getting into a beautiful trap set up by nature, a natural occurrence we cannot fight.

Hence brain activation in response to romantic partners appears to both reward social interaction and impede negative responses. The extent to which the brain is activated during the early stages of a romantic relationship appears to influence both our own well-being and the extent to which the relationship is a success or failure.

Last but not least, love and pleasure ensure the survival of individuals and their species. Love, pleasure, and lust have a stress-reducing and health-promoting potential, since they carry the ability to heal or facilitate beneficial motivation and behavior. After all, love is a joyful and useful activity that encompasses wellness and feelings of well-being.

Perhaps this is the real reason why I am getting married next month. ;-)

Additional source:
Photo Credit: Luisz Esparza Photography (top, middle), Brittney Hannon Photography (bottom).


From 1–5 May, more than 11,000 people attended the Association for Research in Vision and Ophthalmology (ARVO) 2016 Annual Meeting in Seattle, WA. Eye and vision researchers from more than 75 countries presented their current research, discussed emerging technologies, and strategized ways to overcome the current challenges facing ophthalmology and vision science.

One of the highlights was a panel on outbreaks and the threat that Ebola, Zika, and other viruses pose on opthalmology. Moderated by James Chodosh, MD, MPH, (HMS Ophthalmology), and Steven Yeh, MD, (Emory Eye Center), this session focused on emerging infectious diseases, and emphasized the importance of developing a better understanding of disease mechanism and treatments. Speakers addressed the need for improved ophthalmic screening and care as well as the importance of strengthening vision health systems globally. Featured guest speakers included Paul Farmer, MD, PhD, (HMS and Partners in Health); and Ian Crozier, MD, (World Health Organization).

Another expert panel addressed the genetics of vision. Panelists provided critical insight into genetic technologies, monogenic eye diseases, complex eye diseases, and future challenges of vision genetics. The effort to restore vision lost to retinal diseases using stem cells can sound so tantalizing simple. The researcher gets some stem cells, turns them into retinal cells, puts them in the patient's retina to replace lost cells and—voila!—the patient can see again. But the reality is, such a procedure can be mind-blowingly complex, and there is no one-size-fits-all therapy for people with conditions such as age-related macular degeneration (AMD) or retinitis pigmentosa. There are innumerable considerations for researchers developing therapies. Among the speakers were Janey Wiggs, MD, PhD (HMS Ophthalmology); Jay Shendure, MD, PhD, (University of Washington, Genome Sciences); Anneke den Hollander, PhD, (Radboud University Medical Center Ophthalmology and Human Genetics); and Debbie Nickerson, PhD, (University of Washington, Genome Sciences).

ARVO 2017 will take place from 7–11 May in Baltimore, MD, USA.

Sources: ARVO, Harvard Medical School Blog,

How long-term marijuana use alters the brain's reward circuit

In a paper published in Human Brain Mapping, researchers demonstrated for the first time with functional magnetic resonance imaging (fMRI) that long-term marijuana users had more brain activity in the mesocorticolimbic-reward system when presented with cannabis cues than with natural reward cues.

"This study shows that marijuana disrupts the natural reward circuitry of the brain, making marijuana highly salient to those who use it heavily. In essence, these brain alterations could be a marker of transition from recreational marijuana use to problematic use," said Dr. Francesca Filbey, director of Cognitive Neuroscience Research in Addictive Disorders at the Center for BrainHealth and associate professor in the School of Behavioral and Brain Sciences.

The researchers studied 59 adult marijuana users and 70 nonusers, accounting for potential biases such as traumatic brain injury and other drug use. Study participants rated their urge to use marijuana after looking at various visual cannabis cues, such as a pipe, bong, joint or blunt, and self-selected images of preferred fruit, such as a banana, an apple, grapes or an orange. The scientists also collected self-reports from study participants to measure problems associated with marijuana use. On average, marijuana participants had used the drug for 12 years.

When presented with marijuana cues compared to fruit, marijuana users showed enhanced response in the brain regions associated with reward, such as the orbitofrontal cortex, striatum, anterior cingulate gyrus, precuneus and the ventral tegmental area. "We found that this disruption of the reward system correlates with the number of problems, such as family issues, individuals have because of their marijuana use," Filbey said. "Continued marijuana use despite these problems is an indicator of marijuana dependence."

Sources: NeuroscienceNews.

What nightmares say about your personality

The University of Montreal's Center for Advanced Research in Sleep Medicine recently asked people who have at least two nightmares every night to participate in a study. To do so, they had to describe their waking daydreams, answer questionnaires, and complete creativity tests. These individuals also allowed researchers to monitor their brains while they napped.

The results are pretty fascinating (and great news for those who deal with frequent nightmares). "The evidence points towards the idea that, rather than interfering with normal activity, people who are unfortunate in having a lot of nightmares also have a dreaming life that is at least as creative, positive and vivid as it can be distressing and terrifying," lead researcher Michelle Carr wrote in New Scientist. "What's more, this imaginative richness is unlikely to be confined to sleep, but also permeates waking thought and daydreams."

In other words, nightmares lead to creativity, empathy, and even positive thoughts and daydreams.

Sources: New Scientist, HelloGiggles.


Researchers at UC Berkeley have come up with a rough map of the frontal cortex' role in controlling vision. The frontal cortex is often seen as our "thinking cap," the part of the brain scientists associate with thinking and making decisions. But it's not commonly connected with vision. New research now suggests that the frontal cortex is involved in the visual selection of objects, their combination with other sensory cues, and their evaluation to make decision about what you think you saw. (NeuroscienceNews)

Skilled readers can quickly recognize words when they read because the word has been placed in a visual dictionary of sorts, which functions separately from an area that processes the sounds of written words, say Georgetown University Medical Center (GUMC) neuroscientists. The visual dictionary idea rebuts a common theory that our brain needs to "sound out" words each time we see them. (NeuroImage)

Scientists at Heriot-Watt have developed a new 3D printing technique which can produce brain tumor cells that continue to grow rapidly and mimic the growth of real glioma tumors. They plan to 3D print tumor-like constructs to better understand the biology of malignant brain tumors that kill around 5,000 people each year in the UK. (MedicalXpress)

Computer scientists and mathematicians at the CEU Cardenal Herrera University in Valencia have developed a prediction model that can warn epileptic sufferers of an upcoming seizure with 20 minutes notice, giving the patient time to take their medication and nip it in the bud. (NeuroscienceNews)

Researchers at UC San Diego found a self-made cannabinoid-based neuromodulatory mechanism that is directly linked to the formation of both good and bad habits in the brain. This mechanism modulates the flow of information to the orbitofrontal cortex (OFC), potentially blocking the brain's capacity to "break habits" as observed in disorders that affect switching between goal-directed and habitual behaviors. In other words, endocannabinoids act as a brake in the OFC, allowing for habit formation. (PsychologyToday)

Also in the news was a 42-year old man who's spent his whole life unable to visualize anything in his mind. When he thinks about a face, it comes to him as an idea, as an intellectual concept, rather than a mental picture. This newly described condition is called aphantasia and has prompted scientists to reexamine an experience that we so often take for granted—our imagination. (BBC)

Next month

Anything I missed? Sound away in the comment section! Have something of interest or want your discovery to be considered for next month's issue? Let me know via mbeyeler (at) uci (dot) edu.

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