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Archive - Nov 7, 2015

Odometer Neurons: Study of Treadmill-Running Rats Shows That Brain’s Grid Cells Can Encode Time and Distance, As Well As Location in Space

Animals navigate by calculating their current position based on how long and how far they have traveled and a new study on treadmill-running rats reveals how: neurons called grid cells integrate information about time and distance to support memory and spatial navigation, even in the absence of visual landmarks. The findings, published in an open-access article in the November 4, 2015 issue of Neuron, challenge currently held views of the role of grid cells in the brain. The article is titled “During Running in Place, Grid Cells Integrate Elapsed Time and Distance Run.” "Space and time are ever-present dimensions by which events can be organized in memory," says senior study author Howard Eichenbaum, Ph.D., a psychologist and neuroscientist at Boston University. "These findings support the view that memory evolved as a common function in mammals using circuits that organize events in space, time, and potentially many other dimensions of experience." Past research has shown that grid cells receive information from other cells about the direction traveled. But until now, there was no direct evidence showing that grid cells signal distance or time, leaving the role of these variables in path integration merely speculative. In the new study, Dr. Eichenbaum and first author Benjamin Kraus, Ph.D., also of Boston University, and colleagues, addressed this question by placing rats on treadmills while recording the activity of grid cells. The researchers kept either the run duration or run distance fixed, while varying the speed, in order to disentangle the influence of these factors on cell firing. During treadmill running, 92% of grid cells fired at specific moments or distances while the rats ran in place.

Lupski-Led Analysis of Rare Genetic Variants (SNVs and CNVs) in Mendelian Neurogenetic Disorders Identifies Genes That Affect Brain Structure & Function

Like the delicate strokes of the painter’s brush, genes and the epigenetics that regulate them guide the formation of the complicated architecture of the human brain. The result is a marvel of biology, able to learn and to create, while controlling the most basic functions of the body. However, when the genes do not work well or the epigenetic mechanisms are out of alignment, the result is often a devastating genetic disorder, sometimes coupled with a brain malformation. In a news study published in the November 4, 2015 issue of Neuron, an international team of researchers led by James Lupski (photo), M.D., Ph.D., at the Baylor College of Medicine in Houston, Texas, and including a large group of Turkish medical professionals, evaluated the genetics underlying such brain disorders and malformations. The Neuron article is titled “Genes that Affect Brain Structure and Function Identified by Rare Variant Analyses of Mendelian Neurologic Disease.” In their newly reported work, the researchers found variants of genes already known to cause brain disorders and malformations, and they also identified new mutations in genes not previously known to be involved in such problems. In addition, they identified structural deviations such as the duplications or deletions known as copy number variations (CNVs) in different chromosomes. “Human brain development is a precisely orchestrated process requiring multiple genetic and epigenetic events,” said Dr. Lupski, the Cullen Professor of Molecular and Human Genetics at Baylor College of Medicine and the senior and corresponding author of the Neuron article. Dr.

Whole Genome Sequencing of All 14 Known Species of Malassezia Fungi Identifies Multiple Targets for Potential Treatments of Dandruff, Seborrheic Dermatitis, Eczema, and a Form of Skin Cancer

An international team of scientists, led by researchers from A*STAR’s Genome Institute of Singapore (GIS), Institute of Medical Biology (IMB), and Bioinformatics Institute (BII), and Proctor & Gamble, has completed the first comprehensive genomic and biologic study of all known species of Malassezia, one of the top skin disease-causing microbes. The breakthrough study identified multiple potential targets for treating diseases such as seborrheic dermatitis, eczema, and dandruff, all of which can be caused by Malassezia. Malassezia is also associated with skin cancer, the sixth most common cancer in males and the seventh in females in Singapore. These findings improve our understanding of the human skin microbiome, with significant implications for dermatology and immunology. The new study was published online on November 5, 2015 in the November issue of the open-access journal PLOS Genetics, under the title “Genus-Wide Comparative Genomics of Malassezia Delineates Its Phylogeny, Physiology, and Niche Adaptation on Human Skin.” Malassezia is a type of fungus found on the skin of all birds and warm-blooded mammals, including humans. Often, Malassezia simply forms part of our normal skin flora, but, for unknown reasons, it sometimes causes disease. In their article abstract, the authors noted that “Malassezia is a unique lipophilic genus in class Malasseziomycetes in Ustilaginomycotina, (Basidiomycota, fungi) that otherwise consists almost exclusively of plant pathogens. Malassezia are typically isolated from warm-blooded animals, are dominant members of the human skin mycobiome and are associated with common skin disorders.” Two particular species of Malassezia, namely M. restricta and M. globosa, are present on all human scalps and are responsible for common dandruff and seborrheic dermatitis.