August 2019 Research Roundup

Did you know? SfN’s journals, JNeurosci and eNeuro, publish high-quality papers on a broad range of neuroscience topics written by scientists around the world. In this Neuronline series, explore some of the research recently published in JNeurosci and eNeuro.

Big Data Clarifies Emotional Circuit Development

Several brain circuits that identify emotions are solidified early in development and include diverse regions beyond the amygdala, according to new research in children, adolescents, and young adults published in JNeurosci.

Previous studies of emotional development have produced conflicting results due to small sample sizes and have often focused only on the amygdala, ignoring other potential regions of interest. To rectify this, Vinod Menon and colleagues at the Stanford University School of Medicine analyzed fMRI data from 1,445 individuals aged 8 to 21 from the Philadelphia Neurodevelopmental Cohort. During the fMRI session, participants were shown images of faces and were asked to categorize the emotion they conveyed as fearful, angry, sad, happy, or neutral.

The research team identified distributed brain areas and circuits involved in identifying emotions and used network stability analysis to disentangle aspects of emotion-related brain circuitry that were stable over development and those that changed with age. They discovered multiple brain circuits that differ among categories of emotion but do not change with age.

These results reveal the power of large sample sizes in the study of emotional development, help to explain inconsistencies in previous small-sample experiments, and highlight the need to examine brain regions and circuits beyond the amygdala.

Read the manuscript in JNeurosci: Development of Human Emotion Circuits Investigated Using a Big-Data Analytic Approach: Stability, Reliability, and Robustness

Impaired Brain Activity in Rats With Family History of Alcohol Abuse

Neural activity that reflects the intention to drink alcohol is observed in the prefrontal cortex and is blunted in rats with a family history of excessive drinking, according to research from eNeuro. This insight could lead to novel treatments for alcohol use disorders.

The prefrontal cortex is a brain region involved in decision-making that becomes active before a behavior is initiated, indicating intention. David Linsenbardt, Nicholas Timme, and Christopher Lapish at Indiana University–Purdue University Indianapolis investigated neural activity in the prefrontal cortex to determine if it encodes the intention to consume alcohol.

Linsenbardt’s team compared activity before and during alcohol consumption in two types of rats. One modeled a family history of alcohol abuse, while the other lacked this family history. The prefrontal cortex was active during consumption in both types of rats, but was only active pre-consumption in the rats without a family history of drinking.

These findings suggest the prefrontal cortex directly encodes the intention to consume alcohol, but less so in those with greater risk of abusing alcohol. Restoring prefrontal cortex activity in individuals with a predisposition to overdrinking could be a new approach for treating alcohol use disorders.

Read the manuscript in eNeuro: Encoding of the Intent to Drink Alcohol by the Prefrontal Cortex Is Blunted in Rats With a Family History of Excessive Drinking

How Deep Space Travel Could Affect the Brain

Exposure to chronic, low dose radiation — the conditions present in deep space — causes neural and behavioral impairments in mice, researchers report in eNeuro. These results highlight the pressing need to develop safety measures to protect the brain from radiation during deep space missions as astronauts prepare to travel to Mars.

Radiation is known to disrupt signaling among other processes in the brain. However, previous experiments used short-term, higher-dose-rate exposures of radiation, which does not accurately reflect the conditions in space.

To investigate how deep space travel could affect the nervous system, Charles Limoli and colleagues at the University of California, Irvine, Stanford University, Colorado State University, and the Eastern Virginia School of Medicine exposed mice to chronic, low-dose radiation for six months. They found that the radiation exposure impaired cellular signaling in the hippocampus and prefrontal cortex, resulting in learning and memory impairments. They also observed increased anxiety behaviors, indicating the radiation also impacted the amygdala.

The researchers predict that during a deep space mission, approximately one in five astronauts would experience anxiety-like behavior, and one in three would experience certain levels of memory impairment. Additionally, the astronauts may struggle with decision-making.

Read the manuscript in eNeuro: New Concerns for Neurocognitive Function During Deep Space Exposures to Chronic, Low Dose Rate, Neutron Radiation

Estrogen Improves Parkinson’s Disease Symptoms

Brain-selective estrogen treatment improves the symptoms of Parkinson’s disease in male mice, according to new research published in JNeurosci. These findings may help explain the sex differences in Parkinson’s disease and could lead to estrogen-based treatments.

Parkinson’s disease is characterized by the death of neurons involved in movement, which may be partially caused by gene mutations for the protein α-synuclein. The mutated, shorter form of the protein clusters in neurons, resulting in their death, while the longer form resists clumping.

Estrogen is thought to protect movement neurons from Parkinson’s disease, but how is unknown. Since the patients more susceptible to Parkinson’s disease — men and post-menopausal women — have low estrogen levels, estrogen treatment might be an effective way to delay and reduce symptoms.

Silke Nuber and colleagues at Harvard Medical School treated mouse models of Parkinson’s disease with brain-selective estrogen and compared the motor performance of males and females before and after treatment. The female mice showed less severe symptoms at a later age, but estrogen still improved their symptoms. In male mice, the estrogen treatment reduced α-synuclein breakdown and buildup and helped with severe symptoms, suggesting that estrogen could be a viable treatment option for Parkinson’s patients with low estrogen levels.

Read the manuscript in JNeurosci: Female Sex and Brain-Selective Estrogen Benefit α-Synuclein Tetramerization and the PD-Like Motor Syndrome in 3K Transgenic Mice