May 9, 2024

A Rare Phenomenon of Reversible Brain Shrinkage

Rather of migrating or hibernating to deal with the seasonal difficulty, moles have developed an unanticipated energy-saving method: diminishing their brains.
When the researchers compare moles from various regions, they discover that Dehnels phenomenon is triggered by cold conditions rather than a lack of food alone. Measuring skulls in museum collections, the researchers recorded how two types of mole– the European mole and the Spanish mole– altered throughout seasons. They discovered that the skulls of the European mole diminished by eleven percent in November and regrew by four percent in spring, however those of the Spanish mole didnt alter throughout the year.
“That 3 distantly related groups of mammals can diminish and then regrow bone and brain tissue has huge implications for research into illness such as Alzheimers and osteoporosis,” states Dechmann.

Dehnels phenomenon was first explained in the skulls of shrews, which were discovered to be smaller in the winter and larger in the summer. What these mammals have in typical is a lifestyle that puts them on an energetic knife edge.
Skulls of European moles shrink prior to winter and grow back in spring in a procedure understood as Dehnels phenomenon. Credit: Lara Keicher/ Max Planck Institute of Animal Behavior
” They have incredibly high metabolisms and year-round activity in cold environments,” says Dechmann. “Their small bodies are like turbocharged Porsche engines that burn through energy shops in a matter of hours.”
To the researchers, it was clear that shrinking energetically costly tissue, such as the brain, permits the animals to reduce their energy needs. “We comprehended that Dehnels phenomenon assists these animals endure when times are difficult. But we still didnt understand what were the genuine pressure points, the precise ecological triggers, driving this procedure.”
Now, the group has addressed this by studying a new mammal on the metabolic extreme. Determining skulls in museum collections, the scientists documented how 2 types of mole– the European mole and the Spanish mole– altered throughout seasons. They discovered that the skulls of the European mole shrank by eleven percent in November and regrew by 4 percent in spring, but those of the Spanish mole didnt alter throughout the year.
Because the species reside in greatly different climates, the researchers could determine that weather, not food schedule, was accountable for brain modification. “If it was just a question of food, then we need to see European moles diminishing in winter when food was spanish and scarce moles diminishing in summertime when harsh heat made food scarce,” states Dechmann.
The study findings exceed answering concerns of evolution, using insights into how our bodies can restore after sustaining considerable damage. “That three distantly associated groups of mammals can diminish and after that grow back bone and brain tissue has big ramifications for research study into illness such as Alzheimers and osteoporosis,” says Dechmann. “The more mammals we find with Dehnels, the more pertinent the biological insights become to other mammals, and possibly even to us.”
Reference: “Winter conditions, not resource accessibility alone, might drive reversible seasonal skull size modifications in moles” by Lucie Nováková, Javier Lázaro, Marion Muturi, Christian Dullin and Dina K. N. Dechmann, 7 September 2022, Royal Society Open Science.DOI: 10.1098/ rsos.220652.

European moles diminish their brains by 11% before the winter season and grow them again by 4% by the summer season.
Researchers find another brain-shrinking mammal.
European moles face an existential crisis in the depths of winter. Their high-limit mammal metabolisms need more food than is available during the coldest months. Instead of hibernating or migrating to deal with the seasonal challenge, moles have developed an unanticipated energy-saving strategy: diminishing their brains.
In a recent research study, a group from the Max Planck Institute of Animal Behavior headed by Dina Dechmann discovered that European moles diminish their brains by 11% prior to the winter and grow them back by 4% by summertime. They are a brand-new group of mammals known for reversibly shrinking their brains through a process known as Dehnels phenomenon.
European moles are the current species of mammal known to reversibly diminish their brains prior to winter. Credit: Javier Lázaro
The research, however, does more than simply include another types to the bizarre repertoire of brain-shrinking animals; it looks into the evolutionary puzzle of what presses them down this dangerous course. When the scientists compare moles from various areas, they find that Dehnels phenomenon is triggered by cold conditions instead of an absence of food alone. Decreasing brain tissue helps the animals to use less energy and thus endure the cold.