Brain noise found to nurture synapses

May 7, 2014
This is a developing Drosophila synapse superimposed over electrophysiology recordings of minis. Credit: Lab of Brian McCabe, PhD/ Columbia University Medical Center

A study has shown that a long-overlooked form of neuron-to-neuron communication called miniature neurotransmission plays an essential role in the development of synapses, the regions where nerve impulses are transmitted and received. The findings, made in fruit flies, raise the possibility that abnormalities in miniature neurotransmission may contribute to neurodevelopmental diseases. The findings, by researchers at Columbia University Medical Center (CUMC), were published today in the online edition of the journal Neuron.

The primary way in which neurons communicate with each another is through "evoked neurotransmission." This process begins when an electrical signal, or action potential, is transmitted along a long, cable-like extension of the neuron called an axon. Upon reaching the axon's terminus, the signal triggers the release of chemicals called neurotransmitters across the synapse. Finally, the neurotransmitters bind to and activate receptors of the neuron on the other side of the synapse. Neurotransmitters are packaged together into vesicles, which are released by the hundreds, if not thousands, with each action potential. Evoked neurotransmission was first characterized in the 1950s by Sir Bernard Katz and two other researchers, who were awarded the 1970 Nobel Prize in Physiology or Medicine for their efforts.

"Dr. Katz also found that even without action potentials, lone vesicles are released now and then at the synapse," said study leader Brian D. McCabe, PhD, assistant professor of pathology and cell biology and of neuroscience in the Motor Neuron Center. "These miniature events—or minis—have been found at every type of synapse that has been studied. However, since minis don't induce neurons to fire, people assumed they were inconsequential, just background noise."

Recent cell-culture studies, however, have suggested that minis do have some function and even their own regulatory mechanisms. "This led us to wonder why there would be such complicated mechanisms for regulating something that was just noise," said Dr. McCabe.

To learn more about minis, the CUMC team devised new genetic tools to selectively up- or down-regulate evoked and miniature neurotransmission in (a commonly used model organism for neuronal function and development). This was the first study to identify a unique role for minis in an animal model.

The researchers found that when both types of neurotransmission were blocked, synapse development was abnormal. However, inhibiting or stimulating evoked alone had no effect on synaptic development. "But when we blocked minis, synapses failed to develop," said Dr. McCabe, "and when we stimulated the release of more minis, got bigger."

The study also showed that minis regulate synapse development by activating a signaling pathway in neurons involving Trio and Rac1 proteins in presynaptic neurons. These proteins are also found in humans.

It remains to be seen exactly how minis are exerting their effects. "Parallel communication occurs in computer networks," Dr. McCabe said. "Computers communicate primarily by sending bursts of data bundled into packets. But individual computers also send out pings, or tiny electronic queries, to determine if there is a connection to other computers. Similarly, neurons may be using minis to ping connected neurons, saying in effect, 'We are connected and I am ready to communicate.'"

The researchers are currently looking into whether minis have a functional role in the mature nervous system. If so, it's possible that defects in minis could contribute to neurodegenerative disease.

Explore further: Sensing gravity with acid: Scientists discover a role for protons in neurotransmission

More information: The paper is titled, "Miniature Neurotransmission Regulates Drosophila Synaptic Structural Maturation."

Related Stories

Sensing gravity with acid: Scientists discover a role for protons in neurotransmission

March 25, 2014
While probing how organisms sense gravity and acceleration, scientists at the Marine Biological Laboratory (MBL) and the University of Utah uncovered evidence that acid (proton concentration) plays a key role in communication ...

Amplifying communication between neurons

January 17, 2014
Neurons send signals to each other across small junctions called synapses. Some of these signals involve the flow of potassium, calcium and sodium ions through channel proteins that are embedded within the membranes of neurons. ...

Nobel Prize winner reports new model for neurotransmitter release

October 10, 2013
In a Neuron article published online October 10th, recent Nobel Laureate Thomas C. Südhof challenges long-standing ideas on how neurotransmitter gets released at neuronal synapses. On October 7th, Südhof won the Nobel Prize ...

Seeking the causes of hyperactivity

April 25, 2014
The 60 trillion cells that comprise our bodies communicate constantly. Information travels when chemical compounds released by some cells are received by receptors in the membrane of another cell. In a paper published in ...

Eavesdropping on brain cell chatter: Novel tools learn how astrocytes listen in on neurons

April 16, 2014
Everything we do—all of our movements, thoughts and feelings – are the result of neurons talking with one another, and recent studies have suggested that some of the conversations might not be all that private. Brain ...

Loose coupling between calcium channels and sensors

February 6, 2014
In research published in this week's online edition of Science, postdoc Nicholas Vyleta and Professor Peter Jonas of the Institute of Science and Technology Austria uncover the existence of loose coupling between calcium ...

Recommended for you

Brain stimulation may improve cognitive performance in people with schizophrenia

July 24, 2017
Brain stimulation could be used to treat cognitive deficits frequently associated with schizophrenia, according to a new study from King's College London.

New map may lead to drug development for complex brain disorders, researcher says

July 24, 2017
Just as parents are not the root of all their children's problems, a single gene mutation can't be blamed for complex brain disorders like autism, according to a Keck School of Medicine of USC neuroscientist.

Bird songs provide insight into how developing brain forms memories

July 24, 2017
Researchers at the University of Chicago have demonstrated, for the first time, that a key protein complex in the brain is linked to the ability of young animals to learn behavioral patterns from adults.

Working around spinal injuries: Rehabilitation, drug treatment lets rats recover some involuntary movement

July 24, 2017
A new study in rats shows that changes in the brain after spinal cord injury are necessary to restore at least some function to lower limbs. The work was published recently in the journal eLife.

Scientists capture first image of major brain receptor in action

July 24, 2017
Columbia University Medical Center (CUMC) researchers have captured the first three-dimensional snapshots of the AMPA-subtype glutamate receptor in action. The receptor, which regulates most electrical signaling in the brain, ...

Research identifies new brain death pathway in Alzheimer's disease

July 24, 2017
Alzheimer's disease tragically ravages the brains, memories and ultimately, personalities of its victims. Now affecting 5 million Americans, Alzheimer's disease is the sixth leading cause of death in the U.S., and a cure ...

3 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

RobertKarlStonjek
not rated yet May 08, 2014
"and when we stimulated the release of more minis, synapses got bigger."

And when they stop, the synapse will get smaller and perhaps disappear altogether. This would be a logical mechanism for synapse maintenance, perhaps even a method for detecting death of the neuron forming the synapse and breaking the connection sooner, that synaptic bud then free to form a synapse with some other neuron.

Maybe...
thingumbobesquire
not rated yet May 08, 2014
The physical brain may be crudely modeled on fruit fly and computer mechanics. But the principle of the historically developing mind of humanity writ large will never be made to fit into an arithmetic "base" of symbolic logic as Kurt Godel so devastatingly proved. The well tempered contrapuntal musical development of J.S. Bach and his epigones which is part and parcel of this uniquely human higher cognitive principle of "mind" will forever elude such crude reductionists' comprehension.
http://thingumbob...ain.html
alfie_null
not rated yet May 11, 2014
The physical brain may be crudely modeled on fruit fly and computer mechanics. But the principle of the historically developing mind of humanity writ large will never be made to fit into an arithmetic "base" of symbolic logic as Kurt Godel so devastatingly proved.

I sense your fear.

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.