Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Mice brains shrink during winter, impairing some learning and memory


The brains of one species of mouse actually shrink during the winter, causing the mice to have more difficulty with some types of learning, a new study found.

The results showed that, during the short days of winter, white-footed mice had impaired spatial memory – the mental map that helps them remember important places in their environment. This is one of the first studies to show seasonal changes in the structure and the functioning of brains of mammals, said Randy Nelson, co-author of the study and professor of psychology and neuroscience at Ohio State University . The changes in the brain may help the mice conserve energy to survive during the cold winter season when food is scarce and conditions are harsh. “The brain uses a lot of energy relative to its weight,” Nelson said. “Like many mammals, mice need to reduce their energy costs during winter, and the brain is a good place to do that.”

And while there are obviously many differences between mice and humans, studies like this may one day help researchers gain insight into seasonal brain dysfunctions in humans such as seasonal affective disorder, Nelson said. Nelson conducted the study with Leah Pyter, a graduate student in neuroscience at Ohio State , and Brenda Reader, an undergraduate psychology major at Ohio State . The findings were published in the May 4 issue of the Journal of Neuroscience. In one set of experiments, the researchers used 20 adult male white-footed mice. Using artificial light, some mice were kept in short days – such as they would face in winter – with eight hours of light per day for 13 weeks before the beginning of the study. Other mice were kept in long days, simulating summer, with 16 hours of daylight for 13 weeks.

Their spatial learning and memory were tested using a water maze test in which the mice had to swim to find an escape platform hidden just below the surface of opaque water. They were tested for several days to determine how long it would take them to find the platform, and whether they remembered where the platform was from day to day. Results showed that mice that were kept in short days – simulating winter – took longer and swam farther before they found the hidden platform than did the long-day mice, indicating they had more trouble learning where the platform was. Moreover, they didn’t remember its location as well from one day to the next.

However, other tests showed that nonspatial learning and memory, including sensory abilities, were not affected by short days. “It appears that only specific kinds of brain function are impaired during winter,” Nelson said. In a second experiment, 16 adult male white-footed mice were kept in short or long days for 14 weeks, after which they were sacrificed. The researchers then examined differences in the brains between mice kept in the two differing conditions. These results showed that mice kept in short days had on average a smaller brain mass compared to the other mice, even when taking into account that their overall body mass was smaller, too.

In addition, the researchers found changes in a region of the brain – the hippocampus – that is involved in spatial memory. Mice in short days had a proportionally smaller hippocampus, as well as changes in spine density there that have been associated with spatially related memory and learning performance. “We predicted that when you reduce the size of the hippocampus, it would have an impact on learning, and that’s what we found,” Nelson said. The shrinking of the brain corresponds to a season when the mice may have less need for spatial memory, Nelson said. “They don’t maintain as large a territory in the winter,” he said. Nelson said he and his colleagues believe it may be the hormone melatonin which controls the changes in brain size and function in mammals such as these white-footed mice. Scientists know that levels of melatonin are associated with seasonal changes in daylight.

Melatonin is also found in humans, and that’s one reason why future research on how brain structure changes by season may be applicable to human conditions like seasonal affective disorder. The researchers are continuing work to look at the role of melatonin, and also to examine seasonal changes in brain structures in other types of mammals.

This study was supported by grants from the National Institutes of Health and the National Science Foundation.

: Randy Nelson | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>