If we want to understand how the brain creates memories, and how genetic disorders distort the brain’s machinery, then the fragile X gene is an ideal place to start. That’s why the Stephen T. Warren Memorial Symposium, taking place November 28-29 at Emory, will be a significant event for those interested in neuroscience and genetics.
Stephen T. Warren, 1953-2021
Warren, the founding chair of Emory’s Department of Human Genetics, led an international team that discovered Read more
At a time when COVID-19 appears to be receding in much of Georgia, it’s worth revisiting the start of the pandemic in early 2020. Emory virologist Anne Piantadosi and colleagues have a paper in Viral Evolution on the earliest SARS-CoV-2 genetic sequences detected in Georgia.
Analyzing relationships between those virus sequences and samples from other states and countries can give us an idea about where the first COVID-19 infections in Georgia came from. We can draw Read more
We can’t read Emory neuroscientist Shannon Gourley’s papers on social isolation in adolescent mice, without thinking about how the COVID-19 pandemic is affecting children and teenagers. Much of the experimental work was completed before the pandemic began. Still, in the future, researchers will be studying the effects of the pandemic on children, in terms of depression and anxiety, or effects on relationships and education. They could look to neuroscience studies such as Gourley’s for insights into brain mechanisms.
In the brain, social isolation interferes with the pruning of dendritic spines, the structures that underly connections between neurons. One might think that more dendritic spines are good, but the brain is like a sculpture taking shape – the spines represent processes that are refined as humans and animals mature.
Mice with a history of social isolation have higher spine densities in regions of the brain relevant to decision-making, such as the prefrontal cortex, the Emory researchers found.
In a recently published review, Gourley and her co-authors, former graduate student Elizabeth Hinton and current MD/PhD Dan Li, say that more research is needed on whether non-social enrichment, such as frequent introduction of new toys, can compensate for or attenuate the effects of social isolation.
This research is part of an effort to view adolescent mental health problems, such as depression, obesity or substance abuse, through the prism of decision-making. The experiments distinguish between goal-oriented behaviors and habits. For humans, this might suggest choices about work/school, food, or maybe personal hygiene. But in a mouse context, this consists of having them poke their noses in places that will get them tasty food pellets, while they decode the information they have been given about what to expect.
The researchers examined neurons in the orbitofrontal cortex, a region of the brain thought to be important for â€œlinking reward to hedonic experience.â€ It was known that stimulants such as cocaine can cause the loss of dendritic spines: small protrusions that are critical for communication and interaction between neurons.
â€œTo make an analogy, itâ€™s like a tree losing some of its leaves,â€ Gourley writes. â€œLaurenâ€™s work shows for the first time that if cocaine is given in adolescence, it can cause the loss of dendrite arbors â€“ as if entire branches are being cut from the tree.â€
The mice are exposed to cocaine over the course of five days in early adolescence, and then their behavior is studied in adulthood. This level of cocaine exposure leads to impairments in instrumental task reversal, a test where mice need to change their habits (which chamber they poke their noses into) to continue receiving food pellets.
A new study using brain imaging to study teen behavior indicates that adolescents who engage in dangerous activities have frontal white matter tracts that are more adult in form than their more conservative peers.
The brain goes through a course of maturation during adolescence and does not reach its adult form until the mid-twenties. A long-standing theory of adolescent behavior has assumed that this delayed brain maturation is the cause of impulsive and dangerous decisions in adolescence. The new study, using a new form of brain imaging, calls into question this theory.
In order to better understand the relationship between high risk-taking and the brain’s development, Emory University and Emory School of Medicine neuroscientists used a form of magnetic resonance imaging (MRI) called diffusion tensor imaging (DTI) to measure structural changes in white matter in the brain. The study’s findings are published in the Aug. 26, 2009 PLoS ONE.
“In the past, studies have focused on the pattern of gray matter density from childhood to early adulthood, says Gregory Berns, MD, PhD, principal investigator and professor of Psychiatry and Neuroeconomics at Emory University and director of the Center for Neuropolicy. “With new technology, we were able to develop the first study looking at how development of white matter relates to activities in the real world.”
Gray matter is the part of the brain made up of neurons, while white matter connects neurons to each other. As the brain matures, white matter becomes denser and more organized. Gray matter and white matter follow different trajectories. Both are important for understanding brain function.
Berns suggests that doing adult-like activities requires sophisticated skills.
“Society is a lot different now than it was 100 years ago when teens were expected to go to work and raise a family,” says Berns. “Now, adolescents aren’t expected to act like adults until they are in their twenties, when they have finished their education and found a career. Listen to Berns discuss the changing definition of adulthood.