Does Marijuana Change Young Brains?

Our latest podcast compared the costs of marijuana use to the costs of alcohol use.  A new study in the current issue of The Journal of Neuroscience argues that casual use of marijuana affects the developing brain.  Jason Koebler, writing for Vice, summarizes the findings:

High-resolution MRI scans of the brains of adults between the ages of 18-25 who reported smoking weed at least once a week were structurally different than a control group: They showed greater grey matter density in the left amygdala, an area of the brain associated with addiction and showed alterations in the hypothalamus and subcallosal cortex. The study also notes that marijuana use “may be associated with a disruption of neural organization.” The more weed a person reported smoking, the more altered their brain appeared, according to the Northwestern University and Harvard Medical School study, which was published in the Journal of Neuroscience.

The finding already has the study’s authors calling for states to reconsider legalizing the drugHans Breiter, the lead author, said he’s “developed a severe worry about whether we should be allowing anybody under age 30 to use pot unless they have a terminal illness and need it for pain.

(HT: The Daily Dish)

Brain Trauma in Soccer

Our very first Freakonomics Radio podcast focused on brain trauma among NFL players, and its link to chronic traumatic encephalopathy. Researchers now believe they've identified the first case of C.T.E. in a soccer player; from The New York Times:

Chronic traumatic encephalopathy, the degenerative brain disease linked to repeated blows to the head, has been found posthumously in the brain of a 29-year-old former soccer player, the strongest indication yet that the condition is not limited to athletes who played violent collision sports like football and boxing.

The researchers at Boston University who have diagnosed scores of cases of C.T.E. said Patrick Grange of Albuquerque represents the first named case of C.T.E. in a soccer player. On a four-point scale of severity, his was considered Stage 2.

Messing With Memory: Mouse Edition

We've blogged in the past about how easy it is to create false memories for people. Now scientists at MIT say they've succeeded in creating false memories in mice. From The New York Times:

In the research reported Thursday, Dr. Tonegawa’s team first put mice in one environment and let them get used to it and remember it. They identified and chemically labeled the cells in the animals’ brains where that memory was being formed. The mice were not shocked in that environment.

A day later, in a completely different environment, the researchers delivered an electric shock to the mice at the same time that they stimulated the previously identified brain cells to trigger the earlier memory.

This Is Your Brain on Altruism

We've had a lot to say about altruism, and how economists and others have tried to study it. A group of economists at the University of Zurich now claims to have found a spot in the brain associated with altruistic behavior. From Pacific Standard:

It’s called the right temporoparietal junction (or TPJ for short). Along with many other crucial functions, this neural crossroads gives us the ability to understand the perspectives of others—a prerequisite for empathy.

Swiss scholars report they have found a strong connection between the TPJ and a person’s willingness to engage in selfless acts.

FREAK-est Links

This week, does eating fish reduce the risk of Alzheimer's? How to use Google to pick your baby's name; the brains of psychopaths are structurally different; impatient people have lower credit scores, and an interactive chart of all the money in the world.

Baby Talk: The Benefits of Bilingualism

To all you new parents out there: if you're trying to decide whether to spring for that Mandarin-speaking nanny, the answer is yes. Signing up your child for Chinese language kindergarten classes will be far too late.

A study in the Journal of Phonetics about bilingual learning offers new insight into babies and their relationship to the spoken word. Researchers at the University of Washington's Institute for Learning & Brain Sciences compared the brain functions of babies raised in a monolingual household to those raised in a bilingual household, and found that bilingual babies are more likely to maintain their language learning ability for a longer period of time.

Urban vs. Rural Minds: The Differences in Brain Behavior

The Economist reports that city dwellers are at a significantly increased risk of developing anxiety and mood disorders. Evidence from a new study by Andreas Meyer-Lindenberg, a German psychology professor, might point to why.

Urbanites, it turns out, deal with stress differently than rural residents. Meyer-Lindenberg identified a difference in the activity of the amygdalas, with those living in cities having the highest activity in this area of the brain. The amygdala is responsible for memory storage and emotional events, and scientists believe it's also related to dealing with fear. Meyer-Lindenberg also found that people raised in cities have an off-kilter perigenual anterior cingulate cortex (pACC) amygdala link, a condition also present in schizophrenia.

The Economic Part of Our Brains

Researchers at the University of Pennsylvania have conclusively identified a part of the brain that's necessary for making everyday decisions about value. Previous magnetic imaging studies suggested that the ventromedial frontal cortex, or VMF, plays an evaluative role during decision-making. New research led by Joseph Kable, an assistant professor of psychology in Penn's School of Arts and Sciences, shows that people with damaged VMF's (victims of strokes, aneurysms, or brain tumors) are less able to choose things that are most valuable, and are also less consistent in their choices. The results were published in The Journal of Neuroscience.