AP Biology class blog for discussing current research in Biology

Tag: Dopamine

Tickle, Tickle! : Great Apes Demonstrate Playful Teasing

Marco the chimpanzee at the Center for Great Apes

Researchers from the University of California Los Angeles (UCLA), the Max Planck Institute of Animal Behavior (MPI-AB), Indiana University (IU), and the University of California San Diego (UCSD) have identified playful teasing behavior in four species of great apes. This behavior shares similarities with joking in humans, characterized by its provocative, persistent nature, and inclusion of play elements. The presence of playful teasing across all four great ape species suggests its evolutionary roots in the human lineage at least 13 million years ago.

Playful teasing, similar to joking, emerges in humans as early as eight months of age. Infants engage in repetitive provocations, such as offering and withdrawing objects as well as disrupting activities. In a study published in the Proceedings of the Royal Society B, researchers examined spontaneous social interactions among orangutans, chimpanzees, bonobos, and gorillas to identify teasing behaviors.

The study involved analyzing teasing actions, bodily movements, facial expressions, and responses from the targets of teasing. Teasers exhibited intentional provocative behaviors, often accompanied by playful characteristics. The researchers identified 18 distinct teasing behaviors, such as waving or swinging objects in the target’s field of vision, poking or hitting, and disrupting movements.

Although playful teasing shares similarities with play, it differs in several aspects. Teasing tends to be one-sided, initiated primarily by the teaser and rarely reciprocated. Additionally, apes almost never use play signals like the primate ‘playface’ or ‘hold’ gestures. Teasing occurs in relaxed contexts and involves repetition and elements of surprise, similar to teasing in human children.

To offer an explanation for this teasing behavior among animals, oxytocin (love hormone) may play a role in doing so as well as promoting positive social interactions. Oxytocin goes into effects by binding to specific oxytocin receptors in the brain such as G protein-coupled receptors (as learned in AP Biology). Oxytocin receptors then activates the primary signaling pathways, involving the phosphoinositide 3-kinase (PI3K) pathway. Activation of PI3K leads to the production of second messengers, which regulate various cellular processes that contributes to the warm and fuzzy feeling we get due to oxytocin.

The presence of playful teasing in great apes, resembling behaviors in human infants, suggests its existence in our common ancestor over 13 million years ago. This study sheds light on the importance of understanding the evolutionary origins of behavior and the need for conservation efforts to protect these endangered animals.

Personally, I can definitely attest to the evolutionary pass-down of these playful teasings as I still find myself engaging in the same behaviors, oftentimes scorned and unreciprocated.

What are your thoughts on these findings?

Can Science Explain Love?

Sometimes it’s the greatest feeling in the world. Sometimes it hurts. Although we may never derive a fundamental recipe for it, much of love can be explained by chemistry and biology.

The brain (not the heart!) is responsible for romantic love, which, according to Dr. Helen Fisher at Rutgers University and Katherine Wu at Harvard University, can be broken down into three categories: lust, attraction, and attachment.

Credit: “Hearts” by eflon on Flickr.

Lust is our yearning for “sexual gratification.” This facet of love is grounded in our evolutionary, inherent need to reproduce. Lust is stimulated when the hypothalamus releases “sex hormones (testosterone and estrogen) from the testes and ovaries.”

Whereas lust concerns merely “sexual gratification,” another aspect of love, attraction, encompasses a variety of emotions with regard to a specific person. Attraction leads to the release of the chemicals dopamine and norepinephrine. As anyone whose ever been attracted knows, these chemicals make us “giddy, energetic, and euphoric.” Attraction also stimulates the brain’s reward center, which fires “like crazy when people are shown a photo of someone they are intensely attracted to.” Another hormone, serotonin, is found in low levels in both people with obsessive-compulsive disorder and people those who are experiencing attraction. As a result, scientists have theorized that attraction, and the ensuing low level of serotonin, is responsible for the obsessive infatuation so common in love.

The third aspect of love, attachment, is responsible for intimacy, is a key factor in long-term relationships, and is, of course, mediated by hormones.  The two hormones responsible for attachment, oxytocin and vasopressin, “are found in large quantities during sex, breastfeeding and childbirth,” all activities that are “precursors to bonding.” From this, it is easier to understand the concept of three different aspects of love: the “love” parents feel towards their children is merely the attachment aspect of it, but neither the lust nor the attraction aspect.

Although science can give us a biological basis for it, love, and all of its intricacies, can never be fully explained.

Don’t BEE Hating on BEES (Bees and Emotion)

Have you ever stepped on a bee or crushed it out of anger because it was bothering you?  Little did you probably realize that there is scientific evidence that bees, do in fact, experience emotion.  Biologist Clint Perry, University of London demonstrated this phenomenon in his bee experiment.  In order to see if bees really did experience emotion he ran a test with a blue flower and a green flower.  The blue flower had a 30 percent sugar solution, ultimately causing the bees to associate blue flowers with a sweet treat.

After this he created another experiment in which 50% of his bees were given sugar water and the other half were not.  He set up colored flowers and in his experiment found that the bees given a 60% sugar water solution to drink flew more quickly to the flower they were trained to go to (in this case the blue one), compared to the bees that were not given sugar water.  This sugar seemed to have “amped up the bees into a positive emotional state, making them more optimistic that the flower would contain a sugary treat.”  The author of this article compared this to humans and how after eating a sweat treat are in a better emotional state and feel happy.  Another experiment done was with a drug that disrupted receptors of dopamine, causing the preference and motivation to disappear.  This proves the importance of the chemical dopamine in the brain.  Dopamine is ultimately what is giving the bees emotion.  It is important to understand that biologist Clint Perry did not prove that bees have feelings, because feelings are different than emotion. “Emotions are the body’s adaptive response to external events or stimuli.  Feelings are subjective to experience of them.”  In this experiment emotions were tested because it tested the bees response to something rather than past experience.

Now that we know bees have emotion is it possible that eventually they may acquire feelings?  Maybe you will think twice the next time you swat a bee away!

Other helpful links

Sorry I’m So Lazy, Blame It On My Pre-Motor Cortex.

Scientists at the University of Oxford revealed in MRI scans of forty people that people of different levels of motivation show different brain responses to motion. Before people act, the pre-motor cortex activates prior to the parts of the brain which control movement. The brain’s of lazy people proved to light up more than the brains of industrious people.

Scientists believe that the brain connections between decisions and action are less effective in the lazy. Consequently, it requires more effort for this people to take actions. This leads scientists to believe that laziness is biology rather than concerning attitude.


Scientists at the University of Oxford caution that this finding most likely does not explain all conditions of laziness, but state that, by giving us more information about the brain processes underlying normal motivation, it helps us understand better how we might find a treatment for those pathological conditions of extreme apathy” (Robert Roy Britt, Laziness: Blame it on the Brain).

A previous study in 2012 suggests that laziness is related to the level and location of dopamine in the brain. “While high levels in some brain regions were associated with high work ethic, a spike in seemed to indicate just the opposite–a person more likely to slack off” (Jennifer Welsh, Slacker or Go-Getter? Brain Chemical May Tell).  Similar to the recent study in 2015, this study in 2012 suggests a similar point: laziness is most attributable to biology.

So readers, what do you think? Do you think there are some people who are just lazy no matter how much effort they put in? Should lazy people be taking antidepressants, which increase the level of dopamine?

For addition information…

Just Because My D1 Neurons Are Excited, Doesn’t Mean My Risk of Alcoholism Increases…Does it?!

Alcoholism can now not only be studied and analyzed at the psychological level, but also at the molecular level, thanks to researchers at the Texas A&M Health Science Center College of Medicine. They recently conducted a study that found how alcohol influences the dorsomedial striatum, the part of the brain that participates in decision-making and goal-driven behaviors.

The dorsomedial striatum is composed of medium spiny neurons, neurons that have many branches, or spines, protruding off their dendrites.


Spiny neurons have receptors for dopamine, which is further categorized into dopamine D1 and D2 neurotransmitters. D1 neurons have receptors for D1 neurotransmitters. They send excitatory postsynaptic potentials and encourage the action potential/signal to continue. D2 neurons counteract D1 neurons; they send inhibitory postsynaptic potentials and discourage further actions. In this study, D1 neurons prove to be a major part of alcoholism and addiction.

High consumption of alcohol, scientists learned, excites D1 neurons. The more excited they become, the more compelled one feels to perform an action…in this case, the action is drinking another alcoholic beverage.

More drinking induces more D1 neuron excitement, which leads to even more drinking.

Not only does it affect a D1 neuron’s excitability, alcohol also makes physical changes to the neuron itself at the molecular level, and consequently affects the neuron’s function.

In their study, researchers divided their test subjects into two groups: one that’s exposed to alcohol and one that’s not. Analyzing their spiny neurons, scientists saw that though the number of spines in the neurons of the individuals of each group didn’t change, the ratio of the difference between mature and immature spines was dramatic. The subjects that drank alcohol had notably longer branches and a high number of mature mushroom-shaped spines. The abstainers’ neurons had shorter branches and more immature mushroom-shaped spines. Mature, mushroom-shaped spines are involved in long-term memory; activation of long-term memory through alcohol underlies addiction.

However, there’s promising news! The study also showed results that blocking, or at least partially blocking, D1 receptors via a drug can inhibit and reduce the desire for consumption of another drink.

This is a huge step towards finding a cure for alcoholism. Alcoholism is a disease that affects not only the individual, but also his or her family, relatives, friends, etc…With this study, the scientific community has more of an understanding of how to go about creating new drugs and combating alcoholism.

If we suppress this activity, we’re able to suppress alcohol consumption. This is the major finding. Perhaps in the future, researchers can use these findings to develop a specific treatment targeting these neurons.

-Jun Wang, M.D., Ph.D., the lead author on the paper and an assistant professor in the Department of Neuroscience and Experimental Therapeutics at the Texas A&M College of Medicine.

What do you think? Do you think this study promotes a viable option towards curing alcoholism and addiction, or is there another method out there that we should be pursuing? Leave a comment below!


Original Article

Epigenetics and Dopamine Activity

Researchers at the University of California in Irvine have correlated erratic dopamine activity as an underlying cause of complex neuropsychiatric disorders, specifically because of the epigenetic alterations caused by low levels of dopamine. This study, overseen by Emiliana Borelli, a UCI professor of microbiology & molecular genetics, provides clues to the possible causes of complicated disorders like schizophrenia.

Dopamine is a neurotransmitter (and hormone) that fuels our daily life, acting as our prime motivator and pleasure inducer, while also being linked to memory, and cognitive function. Many addictive drugs increase the amounts of dopamine released to exhausting levels, eventually wearing out the neurotransmitters notwithstanding the negative effects of the drugs themselves. High dopamine levels can also be achieved via everyday pleasures like exercise or sex, which can also spur addiction.


Dopamine, therefore, has an irrefutable role in our everyday lives, and according to Borelli, “Genes previously linked to schizophrenia seem to be dependent on the controlled release of dopamine at specific locations in the brain. Interestingly, this study shows that altered dopamine levels can modify gene activity through epigenetic mechanisms despite the absence of genetic mutations of the DNA.”

In short, it is quite likely that Dopamine is an epigenetic hub of sorts, that can cause powerful changes in gene regulation when functioning in a disrupted or excessive manner. Borelli, knowing the consequences of excess dopamine release, tested the opposite effect on mice, hindering dopamine release by turning off mid brain dopamine receptors in rats, leading to mild dopamine synthesis. The results were profound, as Borelli found there to be decreased expression in approximately 2,000 genes in the prefrontal cortex. This epigenetic surge of decrease in genetic expression was reinforced by the increase in change of DNA proteins called histones, which are associated with reduced gene activity. The now mutated mice suffered from ranging psychotic behavior and episodes, and were then treated with dopamine activators for a duration of time before seeing their behavior normalize.

Borelli’s and others’ work will provide useful clues for understanding these complex neurological disorders, while serving to reinforce the newfound importance of comprehending gene regulation and expression. These studies seem to point to a new era in which it is not just your genetic make up that determines your future, but also the regulation of your genes.



Don’t Blame Me, Blame the Involuntary Remodeling of My Brain!

Credit: Susánica Tam

How many of you have found yourself doing something stupid, knowing that there will be major consequences for this action but doing it anyway? And how many of those people have found themselves getting yelled at by an adult for these actions? What those adults don’t know is that none of this is really your fault. Of course a teenager has to take responsibility for their decisions, but the fact that we are teenagers automatically makes us more inclined to take risks and get that adrenaline rush. So really, does the teen deserve to be blamed?

As reported in recent studies, according to an N.I.H. (National Institutes of Health) project, the brain reaches 90% of its full size by the time a person is six years old, and goes through intensive rewiring and remodeling between the ages of 15 and 25. What is happening during that time period, or adolescence, is that the brain’s axons gradually become more insulated with myelin. But that’s not all that’s happening. Dendrites are becoming thinner and heavily used synapses are becoming stronger (the rarely-used synapses become gray matter). That all happens to make your brain faster and more sophisticated.

How many times have you heard that “making mistakes are a part of growing up”? Well, it’s true! And (as I’m sure you are very well aware) learning from your mistakes is a BIG part of adolescence. In the brain, stronger links between the hippocampus and frontal areas are developing. The result from this type of remodeling is that teenagers become better at incorporating past experiences (or mistakes) into their future decisions.

At the same time, our frontal areas are developing greater speed and richer connections. This gives a teen the ability to balance out impulse, desire, goals, self-interest, rules, and ethics on a day-to-day basis. However, our brains are just getting used to this rewiring, so the average teenager can only help but slip up every now and again.

As if all this rewiring wasn’t enough, risk-taking and a need for excitement reaches a peak at around age 15. This can best be explained through two factors. One, teenagers are more receptive to dopamine and oxytocin; chemicals that make us LOVE winning and HATE losing, as well as make us prone that feeling of excitement when we are with all our friends and other kids our age. Two, it’s not that teenagers don’t understand how much damage a certain action will cause, it’s just that teenagers weigh the reward of completing this action much more heavily than the consequences if things go awry. The high levels of dopamine also explain why some teenage boy can’t seem to handle losing his soccer game, and why some 15-year-old girl becomes inconsolable after not being invited to that party.

So the next time you get in trouble for speeding down 25A, remember that you’re just a teenager and you’re going to make mistakes, due to the changes in your myelinated axons and high levels of dopamine and oxytocin. So everyone relax, because teenagers aren’t young adults, we’re just works in progress!


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