June 2019 Research Roundup
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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.
Long-Term Consequences of Zika Virus Infection
Mice exposed to the Zika virus during later stages of gestation present behaviors reminiscent of attention-deficit/hyperactivity disorder, according to a study of genetically diverse animals. The findings, published in JNeurosci, suggest children exposed to the virus during the 2015–16 epidemic may harbor increased risk for developmental disorders.
Microcephaly — a smaller than normal head — is the most well-known and visible consequence of Zika virus exposure. Recent research, however, has found brain and behavior abnormalities in Zika-exposed infants without microcephaly.
Abigail Snyder-Keller and colleagues at the New York State Department of Health and the University of Albany School of Public Health examined these more subtle disruptions in male and female mice of four distinct genetic backgrounds. The public health researchers exposed mice to the virus during a period analogous to the third trimester in humans and report different effects depending on the sex and strain of the mouse. This research provides a first step toward studying the full range of possible outcomes in individuals exposed to the Zika virus in the womb.
Read the manuscript in JNeurosci: Mouse Strain and Sex-Dependent Differences in Long-Term Behavioral Abnormalities and Neuropathologies After Developmental Zika Infection
Noninvasive Electrophysiological Biomarker for Parkinson’s Disease
Novel measures of brain activity associated with Parkinson's disease (PD) can be detected with scalp electrodes, according to a new analysis published in eNeuro. Such a marker of PD — detected using a noninvasive, affordable approach — could improve management of the disease by doctors and patients, particularly in rural areas.
Measuring PD-related brain activity using these novel methods had previously only been demonstrated in patients who have had electrodes surgically implanted deep in their brain. Nicole Swann and colleagues at the University of Oregon and the University of California, San Diego report that similar information can be obtained by recording electrical activity from the surface of the head with electroencephalography (EEG). By analyzing previously published EEG data from PD patients and healthy individuals, the researchers were able to distinguish, between the two groups and within the PD group, when patients were on or off their medication.
These results suggest the shape of beta oscillations is abnormal in PD and may be a promising electrophysiological indicator of disease state. Recording this signal with EEG is straightforward and, after additional validation, could potentially be developed into wearable technology for patients to monitor disease-related brain activity even in patients’ own homes.
Read the manuscript in eNeuro: Characteristics of Waveform Shape in Parkinson's Disease Detected With Scalp Electroencephalography
Broken Brain Cells Repaired in Dementia Mouse Model
Dysfunctional neurons in the hippocampus of adult female mice modeling dementia can be repaired and reconnected to distant parts of the brain, reports a new study published in JNeurosci. The similarity between the mouse model and the human condition underscores the therapeutic potential of targeting these cells in dementia patients.
The hippocampus generates new brain cells throughout life and is implicated in neurodegenerative diseases. María Llorens-Martín and colleagues at the Molecular Biology Center Severo Ochoa (CBMSO) used a mouse model of frontotemporal dementia to investigate the effects of the disease on dentate granule cells.
The researchers observed strikingly similar alterations in newborn neurons from their mouse model and from human brain tissue of patients with frontotemporal dementia, compared to control subjects. In mice, chemically activating the cells and placing animals in a stimulating environment with running wheels and toys reversed the alterations and restored some of the connectivity disrupted by dementia. If translated to humans, these results suggest potential new directions for combating cognitive decline in the elderly.
Read the manuscript in JNeurosci: Activity-Dependent Reconnection of Adult-Born Dentate Granule Cells in a Mouse Model of Frontotemporal Dementia
Diabetes Drug Alleviates Anxiety in Mice
The antidiabetic medication metformin reduces anxiety-like behaviors in male mice by increasing serotonin availability in the brain, according to a study published in JNeurosci. These findings could have implications for the treatment of patients with both metabolic and mental disorders.
People with diabetes have an increased risk for mood disorders such as depression. Although the mechanisms underlying the relationship between insulin resistance — the precursor to diabetes — and depression are not known, studies suggest the neurotransmitter serotonin may be the culprit.
In mice raised on a high-fat diet, Bruno Guiard and colleagues demonstrate that the insulin-sensitizing drug metformin reduces levels of amino acids that impair the entry of tryptophan in the brain and thereby limit its conversion into serotonin. The drug's antidepressant-like effects were accompanied by improved neurotransmission in the hippocampus. The researchers achieved similar effects by reducing the amount of so-called branched chained amino acids in the diet.
Read the manuscript in JNeurosci: Metformin Promotes Anxiolytic and Antidepressant-Like Responses in Insulin-Resistant Mice by Decreasing Circulating Branched-Chain Amino Acids