AP Biology class blog for discussing current research in Biology

Tag: amygdala

Potent Pot and Potential Problems

Marijuana Joint

Does smoking a little “recreational” Pot now and then really cause health problems? The answer is definitively yes.  Doctor Jodi Gilman of Massachusetts General Hospital- Harvard Center for Addiction Medicine was reviewing some brain scans were she noticed something incredibly alarming.  She found when reviewing brains of 20 pot smokers ages 18 to 25 that the nucleus accumbens of the brain of marijuana smokers were notably denser than normal. Gilman along with other researchers at Harvard University and Northwestern University conducted a study on the effects of smoking marijuana(pot) on the young adult brain.  Moderate marijuana use has been proven effect for use by adults to ease nausea and pain, however in a developing young brain, use could be detrimental.  The study took 40 young adults, non-smokers and smokers ( 7 light smokers, 9 medium smokers- light up 3-5 times per week, and 4 daily smokers) brain scans who had no sign of dependency.  These scans showed that in all smoker brains showed irregularities in the structure of the brain, specifically in the nucleus accumbens.  Similar changes were also seen the amygdala which controls memory, emotional and fear responses in the brain. Gilman concluded that these structural abnormalities indicated long term effects of THC on the brain.  Another point of interest in the influence of marijuana use on the young brain, is that the potency of pot smoked now versus pot smoked year earlier has increased.  According to samples seized by the federal Drug Enforcement Agency show that the concentration of THC, the drugs psychoactive compound, the average potency of THC has risen from 3.75 % in 1995 to 13% in 2013. Some types of marijuana products sold for recreation have been noted to have up to 70% of THC.  High-THC marijuana is associated with paranoia and psychosis according to The New England Journal of Medicine.  Nora D. Volkow stated that “We have seen very,very significant increases in emergency room admissions..It can be explained by the fact that current marijuana has a higher potency.”  Alan J Budney, a researcher and professor at Dartmouth Medical School explained that the higher the potency the more addictive marijuana becomes. A study released in 2012 showed that teenages who were found to be dependant on pot before age 18 and who continued using it into adulthood lost an average of 8 I.Q. points by age 38.  These are some serious facts to consider next time you are at a party and marijuana is present. Lighting up a few times just for the fun of it might wreak havoc on your brain in years to come.

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NYT- Increase of Pot Use in Teenagers


Why do we actually care about celebrities?

Celebrities are a huge facet of many people’s lives. They fill the news and occupy hours of thought from millions of people who don’t even know them on a personal level. Why is there such a huge fascination with celebrities? It turns out that it all links back to our primal nature.

All primates experience the competition for resources within their ecosystem. Granted, some experience this more fiercely than others, but there’s no doubt that it exists in all primates. Let’s look at the savannah baboon, for example. The most defining factor in the life of a savannah baboon is its societal rank in a sex-specific dominance hierarchy. These baboons are constantly observed stealing glances at the most dominant of their pack. Social status is always on their minds. This ranking system is not an anomaly for the savannah baboon. It makes sense. With the hierarchy in place, there’s less fighting, the distribution of food is more orderly, and mates are chosen more easily.

In humans, things get a bit more complex. We simultaneously belong to several hierarchies, valuing most the one we rank highest in. Despite the complexity, the general idea remains the same as that of the savannah baboon. Over the course of our evolution, this hierarchy of social dominance has remained deeply ingrained in our brains. Psychology professor Nicholas Rule found that humans could correctly identify whether a face was of high or low social status in a mere 40 milliseconds. A study by Lotte Thomsen of Harvard shows that ten-month-olds are already accustomed to the idea of dominance and social hierarchy.

To find out more, scientists are looking at brain scans. When subjects evaluate social status from faces, they are using the “fanciest, most recently evolved part of the brain, the frontal cortex.”( Caroline Zink of the Lieber Institute for Brain Development found that if a subject observes two people  flip-flopping in their standing on the social ladder, the amygdala is also activated, which is responsible for processing fear and anxiety.


Looking into the lives of celebrities entrances people because most often, celebrities hit the news because they did something foolish or embarrassing. For that one instant, we feel like we are on even footing with the “alphas” of our society by being able to gossip and joke about them. Caring about celebrities is literally part of our brain, and shows that we have a common ancestor with primates.  As someone who has never taken a big interest in celebrities, maybe it’s time to get my brain checked out.


The Woman who cant be Afraid teaches us about Fear

A lot of people say they aren’t scared of anything, but the reality is every body is scared of something. Everybody, except a woman known as SM.

SM had a rare illness that caused damage to the part of her brain associated with fear. The amygdala “is involved in many of our emotions and motivations, particularly those that are related to survival”.  In the same way that pain is a warning sign in attempt to protect you from danger, fear is a function of protection. Without fear you would constantly place yourself in dangerous situations with out responding to an impulse of survival.

The Amygdala- the area of the brain responsible for fear

The damage to SM’s amygdala caused her to lose the ability to feel fear. Scientists tested her on several simulated and real life situations such as being held up at gunpoint, watching scary movies, watching domestic violence. SM felt no fear what so ever in any of these situations. Scientists naturally would predict that with the loss of a functioning amygdala, SM would never feel fear again.

Yet, one day SM had a panic attack. The panic attack was brought on in an experiment where SM inhaled a small amount of carbon dioxide that created a short feeling of suffocation.

The fact that SM felt fear from a panic attack without an amygdala “illuminates some of the brain’s most fundamental processes and may have practical value in the study of panic attacks.” Additionally, it suggests that there may be an alternative center for fear responding to internal threats- such as suffocation or a heart attack.

This study is particularly fascinating because it shows just how little we know about ourselves and the world around us. It illuminates the flaws in our apparent definitive knowledge and encourages further research and speculation about what we know concerning the brain.


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That’s Disgusting!

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Have you ever watched something so gross you just have to make a face?
Scientists are studying disgust and how it may have helped us evolve into a clean, healthy, and surviving race.

Disgust isn’t just a learned behavior, as I assumed. It begins very early- as you can see on the faces of  these babies who are eating lemons for the first time. And the grammar school taunting of “you have cooties” is a hurtful taunt because the labeling evokes a small sense of disgust in the other children toward the child being teased. It is the disgust, and to a very small degree, the feeling of being shunned that creates the kindergarten tears.

Though teasing puts disgust in a negative light, it has done wonders for the human race.  According to Dr. Valerie Curtis from the London School of Hygiene and Tropical Medicine:

“[Disgust] is in our everyday life. It determines our hygiene behaviors. It determines how close we get to people. It determines who we’re going to kiss, who we’re going to mate with, who we’re going to sit next to. It determines the people that we shun, and that is something that we do a lot of.”

In other words, disgust partially defines who we spend time with, how we maintain ourselves and who we do not spend time with. Because we have a sense of disgust, we humans have kept ourselves clean enough to thrive in this bacteria filled world. Pregnant women are especially sensitive to disgust, especially in the first trimester, when fetal development is most fragile. It is also the time when the mothers immune system is the least strong. For these reasons, the mother’s emotional way of warding off disease — disgust —  is strengthened.

The emotion of disgust stems manly from the insula and amygdala. The insula, a “prune sized,” centrally located “slab of brain tissue,” causes many of the social emotions, including guilt, pride, and humiliation. The amygdala, similarly, is connected to human emotional responses, especially fear and pleasure.

Since disgust has show to be such a key factory in our motivation to stay clean, and healthy, Dr. Valerie Curtis (quoted above) along with other pubic health activists have been “trying to gross people out” in the name of hygiene. Through cartoons and pubic advertisements, the activists are aiming to invoke a sense of disgust in the current, unclean practices. The programs currently exist in Africa, India and England. Who knew disgust could be so helpful?

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