Scientists identify brain region in mice that keeps the body from losing its balance

January 30, 2018, Columbia University
A mouse brain that has received an injection of an adeno-associated virus (green) into the LVN. The virus makes a synaptic protein that is tagged with green fluorescent protein, this allows us to follow the projections coming from the LVN through the brain and spinal cord. Credit: Andrew Murray/Jessell Lab/Columbia's Zuckerman Institute

New scientific research has revealed how a small part of the brain singlehandedly steadies the body if it is thrown off balance. The study in mice found that a brain region called the lateral vestibular nucleus, or LVN, accomplishes this feat by moving muscles in a two-step, kneejerk response that first widens the animal's center of gravity, and then strengthens and stabilizes its limb muscles and joints. These findings provide powerful evidence that the LVN is the key to animals' ability to maintain balance, while also offering insight into the mechanics of how animals stay upright when unexpected changes occur beneath their feet.

The study was published today in Cell Reports.

"Whether it's tripping on an uneven patch of sidewalk or negotiating a wobbly balance beam, we can all recall times when we've nearly lost our balance—only to be saved by some quick reflexes," said Thomas M. Jessell, PhD, codirector of Columbia's Mortimer B. Zuckerman Mind Brain Behavior Institute and the paper's senior author. "Today's findings in suggest that reflexes like these may be driven by a predictable process guided by the LVN, a region that appears to be dedicated to one thing: keeping the body on its feet."

Decades of research has shown that multiple brain regions are involved in different aspects of balance. But which regions were involved in the reactive parts of balance—how an animal maintains its stance after experiencing a disturbance—remained unclear.

To get to the root of balance in the brain, the researchers first trained mice to walk across a balance beam, while the beam was nudged at specific intervals. After being momentarily thrown off balance, the mice almost always steadied themselves and continued on their way. Throughout this activity, researchers monitored muscle activity in the animals' limbs.

"Every time we nudged the beam, we observed a predictable pattern of that helped the mice to regain their balance," said Andrew Murray, PhD, the paper's first author who completed the majority of this research while a postdoctoral researcher at Columbia in the Jessell Lab.

That pattern consisted of two movements in sequence: first, the mouse extended its paw, which widened the animal's base of support. Second, the muscles around the animal's limb joints become strong and rigid, which helped the mouse propel itself back over the center of the balance beam. Once they've righted themselves, they continued to walk down the length of the beam.

This reflexive action is something to which nearly everyone can relate.

"If you've ever been standing on a subway train when it moved suddenly, your body may have performed a similar sequence of movements to keep you upright," said Dr. Jessell, who is also the Claire Tow Professor of Motor Neuron Disorders at Columbia University Irving Medical Center and an investigator at the Howard Hughes Medical Institute. "First, you extend your hands or feet outward to widen your base of support. And if you find yourself falling to one side, you may push yourself in the opposite direction to regain your balance."

In a second set of experiments, the researchers sought to identify how the animals' brains made all this possible. By using advanced molecular tools, they traced which brain region directed these specific movements. The data pointed to a tiny region in the brain called the LVN.

To confirm that the LVN was indeed responsible for maintaining balance, the researchers then silenced it. When the mice walked on the ground, they appeared normal. They could even walk on the beam—but when the scientists again nudged the beam, this time they could not steady themselves; they'd lost their ability to regain their balance.

"Intriguingly, the brain had no backup plan; no other part of the brain stepped in to compensate for the LVN," said Dr. Murray, now a Group Leader at the Sainsbury Wellcome Centre, University College London. "This points to the fact that the LVN is orchestrating the movements that keep the body balanced."

Moving forward, the researchers are delving deeper into the brain science of . For example, preliminary research in mice has shown that the LVN appears to perk up when the animal begins walking on something unsteady, such as a . But when it is walking on a more stable surface, such as a treadmill, it remains dormant.

"The brain seems to know that it's about to embark upon a potentially dangerous journey, and therefore needs to be extra aware of its surroundings," said Dr. Jessell. "The precise mechanisms that guide this process are likely complex, involving multiple brain regions. But the LVN may very well be at the center of it all."

This paper is titled "Balance control mediated by vestibular circuits during limb extension or antagonist muscle co-activation."

Explore further: Scientists reveal how patterns of brain activity direct specific body movements

More information: Balance control mediated by vestibular circuits during limb extension or antagonist muscle co-activation, Cell Reports (2018).

Related Stories

Scientists reveal how patterns of brain activity direct specific body movements

July 20, 2017
New research by Columbia scientists offers fresh insight into how the brain tells the body to move, from simple behaviors like walking, to trained movements that may take years to master. The discovery in mice advances knowledge ...

Two left feet? Study looks to demystify why we lose our balance

August 14, 2013
It's always in front of a million people and feels like eternity. You're strolling along when suddenly you've stumbled—the brain realizes you're falling, but your muscles aren't doing anything to stop it.

Better balance at every age

December 4, 2017
(HealthDay)—You probably take balance for granted, but it's a motor skill that benefits from training throughout life.

Genetic 'switch' in animals offers clues to evolutionary origins of fine motor skills

February 9, 2017
Researchers have identified a genetic signature found exclusively in the nerve cells that supply, or innervate, the muscles of an organism's outermost extremities: the hands and feet. This signature, observed in both mice ...

Recommended for you

Convergence of synaptic signals is mediated by a protein critical for learning and memory

July 16, 2018
Inside the brain, is a complex symphony of perfectly coordinated signaling. Hundreds of different molecules amplify, modify and carry information from tiny synaptic compartments all the way through the entire length of a ...

Synapse-specific plasticity governs the identity of overlapping memory traces

July 16, 2018
Memories are formed through long-term changes in synaptic efficacy, a process known as synaptic plasticity, and are stored in the brain in specific neuronal ensembles called engram cells, which are activated during corresponding ...

'Concussion pill' shows promise in pre-clinical pilot study

July 16, 2018
In 2016, funded by a $16 million grant from Scythian, the multidisciplinary Miller School team embarked on a five-year study to examine the effects of combining CBD (a cannabinoid derivative of hemp) with an NMDA antagonist ...

Fetal gene therapy prevents fatal neurodegenerative disease

July 16, 2018
A fatal neurodegenerative condition known as Gaucher disease can be prevented in mice following fetal gene therapy, finds a new study led by UCL, the KK Women's and Children's Hospital and National University Health System ...

Rehabilitating the mind could improve outcomes after spinal cord injury

July 16, 2018
A study led by Heriot-Watt University has explored how individuals with spinal cord injuries perceive the space around them. The findings suggest additions are needed to the rehabilitation programmes adopted post-injury to ...

Study suggests mice and rats, like humans, make poor choices based on 'sunk costs'

July 13, 2018
A team of researchers at the University of Minnesota has found that mice and rats, like humans, tend to make poor decisions based on "sunk costs." In their paper published in the journal Science, the group describes their ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.