When the brain forms a memory of a new experience, neurons called engram cells encode the details of the memory and are later reactivated whenever we recall it. A new MIT study reveals that this process is controlled by large-scale remodeling of cells’ chromatin.

This remodeling, which allows specific genes involved in storing memories to become more active, takes place in multiple stages spread out over several days. Changes to the density and arrangement of chromatin, a highly compressed structure consisting of DNA and proteins called histones, can control how active specific genes are within a given cell.

“This paper is the first to really reveal this very mysterious process of how different waves of genes become activated, and what is the epigenetic mechanism underlying these different waves of gene expression,” says Li-Huei Tsai, the director of MIT’s Picower Institute for Learning and Memory and the senior author of the study.

A new, rare genetic form of dementia has been discovered by a team of Penn Medicine researchers. This discovery also sheds light on a new pathway that leads to protein build up in the brain—which causes this newly discovered disease, as well as related neurodegenerative diseases like Alzheimer’s Disease—that could be targeted for new therapies. The study was published today in Science.

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by a buildup of proteins, called tau proteins, in certain parts of the brain. Following an examination of human brain tissue samples from a deceased donor with an unknown neurodegenerative disease, researchers discovered a novel mutation in the Valosin-containing protein (VCP) gene in the brain, a buildup of tau proteins in areas that were degenerating, and neurons with empty holes in them, called vacuoles. The team named the newly discovered disease Vacuolar Tauopathy (VT)—a neurodegenerative disease now characterized by the accumulation of neuronal vacuoles and tau protein aggregates.

“Within a cell, you have proteins coming together, and you need a process to also be able to pull them apart, because otherwise everything kind of gets gummed up and doesn’t work. VCP is often involved in those cases where it finds proteins in an aggregate and pulls them apart,” Edward Lee, MD, Ph.D., an assistant professor of Pathology and Laboratory Medicine in the Perelman School of Medicine at the University of Pennsylvania. “We think that the mutation impairs the proteins’ normal ability to break aggregates apart.”

Researchers at Rockefeller University have just released findings from a new study, done in mice, which identifies a gene that is critical for short-term memory but functions in a part of the brain not traditionally associated with memory. Classical models for short-term memory typically assume that all neuronal activity is contained within the prefrontal cortex (PFC), yet, data from this new study suggests that a G-protein coupled receptor in the thalamus may play a large role. Data from the study was published recently in Cell through an article titled “A Thalamic Orphan Receptor Drives Variability in Short Term Memory.”

Interestingly, in order to discover new genes and brain circuits that are important for short-term memory, the researchers turned to studying genetically diverse mice, rather than inbred mice commonly used in research.

“We needed a population that is diverse enough to be able to answer the question of what genetic differences might account for variation in short-term memory,” explained co-senior study investigator Praveen Sethupathy, PhD, an associate professor of biomedical sciences in Cornell’s College of Veterinary Medicine and director of the Cornell Center for Vertebrate Genomics.

Some people are at higher risk of developing obesity because they possess genetic variants that affect how the brain processes sensory information and regulates feeding and behavior. The findings from scientists at the University of Copenhagen support a growing body of evidence that obesity is a disease whose roots are in the brain.

Over the past decade, scientists have identified hundreds of different genetic variants that increase a person’s risk of developing obesity. But a lot of work remains to understand how these variants translate into obesity. Now scientists at the University of Copenhagen have identified populations of cells in the body that play a role in the development of the disease—and they are all in the brain.

“Our results provide evidence that biological processes outside the traditional organs investigated in obesity research, such as fat cells, play a key role in human obesity,” says Associate Professor Tune H Pers from the Novo Nordisk Foundation Center for Basic Metabolic Research (CBMR), at the University of Copenhagen, who published his team’s findings in the internationally-recognized journal eLife.