Menu
Scientific developments
NASA's WISE Mission Captures Black Hole's Wildly Flaring Jet

Climatic Fluctuations Drove Key Events in Human Evolution, Researchers Find

Researchers Discover How 'Promiscuous Parasites' Hijack Host Immune Cells

Using Human Genomes to Illuminate the Mysteries of Early Human History

Carnivorous Plant Inspires Coating That Resists Just About Any Liquids

From the Comfort of Home, Web Users May Have Found New Planets

Aquarium Fishes Are More Aggressive in Reduced Environments, New Study Finds

Bioengineers Reprogram Muscles to Combat Degeneration

Asia Was Settled in Multiple Waves of Migration, DNA Study Suggests

Some Brain Wiring Continues to Develop Well Into Our 20s

Evolutionary Tree of Life for Mammals Greatly Improved

Nitrate Levels Rising in Northwestern Pacific Ocean

Nanoscale Nonlinear Light Source Optical Device Can Be Controlled Electronically

Cloaking Magnetic Fields: First Antimagnet Developed

Nature Offers Key Lessons On Harvesting Solar Power, Say Chemists

Monkeys Also Reason Through Analogy, Study Shows

Invasion of Genomic Parasites Triggered Modern Mammalian Pregnancy, Study Finds

Jumping Gene Enabled Key Step in Corn Domestication

Salty Water and Gas Sucked Into Earth's Interior Helps Unravel Planetary Evolution

People Learn While They Sleep, Study Suggests

New Technique Maps Twin Faces of Smallest Janus Nanoparticles

New 'FeTRAM' Is Promising Computer Memory Technology

Hide-And-Seek: Altered HIV Can't Evade Immune System

Scientists Reveal Molecular Sculptor of Memories

Correcting Sickle Cell Disease With Stem Cells

Scientists Reveal Molecular Sculptor of Memories
Researchers working with adult mice have discovered that learning and memory were profoundly affected when they altered the amounts of a certain protein in specific parts of the mammals' brains.

The protein, called kibra, was linked in previous studies in humans to memory and protection against late-onset Alzheimer's disease. The new work in mice, reported in the Sept. 22 issue of Neuron, shows that kibra is an essential part of a complex of proteins that control the sculpting of brain circuitry, a process that encodes memory.

"There are populations of humans who are slightly smarter and have better memory recall than others, and these traits have been mapped to the gene that codes for the kibra protein" says Richard L. Huganir, Ph.D., professor and director of the Solomon H. Snyder Department of Neuroscience at the Johns Hopkins University School of Medicine, and a Howard Hughes Medical Institute investigator. "Our studies in mice show that this same gene is involved in the operation of synapses, through which neurons communicate, and in brain plasticity, suggesting that's what its role might be in humans too."

In their lab, Huganir and neuroscience graduate student Lauren Makuch isolated kibra from mouse brain cells and confirmed by standard biochemical tests that it interacted with a neurotransmitter receptor in the brain known as the AMPA receptor.

They then determined that kibra regulated the delivery of AMPA receptors from inside the brain's nerve cells out to the synapses by first growing live brain cells from embryonic mice in a dish for two weeks and then genetically altering some of those cells to produce less kibra protein. Next, they placed the live neurons in an imaging chamber and recorded the activity of the AMPA receptors once a minute for 60 minutes. Results showed that AMPA receptors moved faster in the cells with less kibra than in control cells with normal amounts of the protein demonstrating that kibra regulates how receptors are delivered to the surface of brain cells.

The work affirms that the addition of AMPA receptors to synapses serves to strengthen connections in the brain, Huganir says, noting that most forms of learning involve the strengthening of some synapses and the weakening of others, a phenomenon known as plasticity, which is responsible for sculpting circuits in the brain that encode memory. Without kibra, this process doesn't function properly; as a result, learning and memory are compromised. Huganir hypothesizes that kibra specifically helps create a pool of receptors that is used to add receptors to synapses during learning.

Later in their study, using slices of brain from mice with or without kibra, postdoctoral fellow Lenora Volk recorded and measured electrical activity and synaptic plasticity in nerve cells, noting that mice lacking kibra showed less plasticity, a phenomenon that translates into a reduced ability to learn and recall new information, Makuch explains.

Finally, the Hopkins researchers conducted a series of behavioral studies using adult mice to compare the learning and memory of normal mice with those that made much less kibra protein. They used a well-established fear-conditioning task by placing the mice in a training chamber and exposing them to a tone and subsequent shock. After two days of training, the animals' rates of "freezing" in place -- a normal rodent response to fear -- were measured. Kibra-deficient mice took longer to learn to associate the tone with the shock than it did the others. On day three of the experiment, upon simply being placed back into the training chamber, the normal mice had a high rate of freezing, while the kibra-deficient mice had a very low rate, indicating impairments in contextual fear response and therefore, memory.

"Our work in the mammalian brain shows that kibra, required for normal brain function and associated with learning and memory, is important for regulating the trafficking of AMPA receptors," Huganir says. "In addition, as kibra has been associated with protection against early onset Alzheimer's disease, these studies may help define novel therapeutic targets for the treatment of age-related memory disorders."

This study was funded by the National Institutes of Health and the Howard Hughes Medical Institute.

Authors on the paper, in addition to Huganir, Makuch and Volk are Victor Anggono, Richard C. Johnson, and Yilin Yu, all of Johns Hopkins.

Other authors are Kerstin Duning and Joachim Kremerskothen, University Hospital Münster, Germany; Jun Xia, The Hong Kong University of Science and Technology, China; and Kogo Takamiya, University of Miyazaki, Japan.


First Comet Found With Ocean-Like Water

Laser Light Used to Cool Object to Quantum Ground State

Biologists Find 'Surprising' Number of Unknown Viruses in Sewage

Long-Lost Lake Agassiz Offers Clues to Climate Change

Series of Bumps Sent Uranus Into Its Sideways Spin, New Research Suggests

Venus Has an Ozone Layer Too, Space Probe Discovers

Supersaturated Water Vapor in Martian Atmosphere

Is Chivalry the Norm for Insects?

Crab Pulsar Beams Most Energetic Gamma Rays Ever Detected from a Pulsar

Subtly Shaded Map of Moon Reveals Titanium Treasure Troves

Ancient Climate Change Has Left a Strong Imprint On Modern Ecosystems

Astrophysics and Extinctions: News About Planet-Threatening Events

Giant 'Kraken' Lair Discovered: Cunning Sea Monster That Preyed On Ichthyosaurs

file transfer software for mac

Menu
Easily Embarrassed? Study Finds People Will Trust You More

Stardust Discovered in Far-Off Planetary Systems

Galaxy Caught Blowing Bubbles

Sharks Are in Trouble, New Analysis Confirms

Engineers 'Cook' Promising New Heat-Harvesting Nanomaterials in Microwave Oven

NASA Space Telescope Finds Fewer Asteroids Near Earth

Scientists Release Most Accurate Simulation of the Universe to Date

'Superfast' Muscles Responsible for Bat Echolocation

Space Telescopes Reveal Secrets of Turbulent Black Hole

'Alarm Clock' Gene Explains Wake-Up Function of Biological Clock

Mechanism Uncovered for the Establishment of Vertebrate Leftright Asymmetry

Astronomers Reveal Supernova Factory

Reefs Recovered Faster After Mass Extinction Than First Thought

Gravitational Waves That Are 'Sounds of the Universe'

Decline and Recovery of Coral Reefs Linked to 700 Years of Human and Environmental Activities

Unprecedented Arctic Ozone Loss Last Winter

'Mirage-Effect' Helps Researchers Hide Objects

Electricity from the Nose: Engineers Make Power from Human Respiration

Natural Compound Helps Reverse Diabetes in Mice

Physicists Move One Step Closer to Quantum Computer

Pumice Proposed as Home to the First Life Forms

Arctic Sea Ice Continues Decline, Hits Second-Lowest Level

Sociability May Depend Upon Brain Cells Generated in Adolescence

Last Universal Common Ancestor More Complex Than Previously Thought

Monkeys 'Move and Feel' Virtual Objects Using Only Their Brains