Scientists find sensor that makes synapses fast

January 17, 2017, Institute of Science and Technology Austria
Synaptotagmin is identified as the calcium sensor in fast synapses. Credit: IST Austria

Synapses, the connections between neurons, come in different flavors, depending on the chemical they use as transmitter. Signal transmitters, or neurotransmitters, are released at the synapse after calcium ions flow into the neuron. The type of synapses that use a signal transmitter called GABA - the GABAergic synapses—stand out because of their speed and precision. But the secret behind their speed was not fully known until now, and neither was the sensor they use to detect the inflowing calcium.

Both questions were solved in a study published today in Cell Reports by Peter Jonas, Professor at the Institute of Science and Technology Austria (IST Austria), together with his group and researchers at the Max Planck Florida Institute for Neuroscience. They find that GABAergic synapses achieve their remarkable signalling speed and reliability partly because of the sensor they use to measure the amount of calcium in the neuron, and that synaptotagmin 2 is the major in this kind of synapses. "We have, for the first time, identified the calcium sensor that triggers neurotransmitter release at an inhibitory synapse", summarizes Peter Jonas.

Interneurons that use GABA as neurotransmitter play a key role in controlling activity in neuronal microcircuits. In all brain regions and species, the hallmark of these GABAergic interneurons is their signalling speed: the delay between stimulation and response lies in the submillisecond range. Peter Jonas and his team asked whether the calcium sensor that triggers contributes to this speed. In their study, they investigate the synapse between basket cells and Purkinje cells. This major inhibitory synapse is located in the cerebellum, a brain region that plays an important role in motor control.

While synaptotagmin 1 is the calcium sensor used at , Peter Jonas and colleagues identify synaptotagmin 2 as the major calcium sensor in inhibitory GABAergic interneurons in the cerebellum. They demonstrate that synaptotagmin 2 triggers a quicker release of neurotransmitter than synaptotagmin 1. At the same time, synaptotagmin 2 also causes a faster refilling of vesicles with neurotransmitter, so that the neuron is ready to send another signal more quickly. This has important consequences for the function of GABAergic interneurons, explains Peter Jonas: "Using synaptotagmin 2 is one reason why GABAergic synapses send signals so fast. Synaptotagmin 2 may control the speed of inhibition in microcircuits, and allow GABAergic to maintain their output by quickly replenishing the pool of ."

Explore further: Loose coupling between calcium channels and sensors

More information: Cell Reports, DOI: 10.1016/j.celrep.2016.12.067

Related Stories

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 ...

Visualization of newly formed synapses with unprecedented resolution

August 11, 2016
The formation of excitatory and inhibitory synapses between neurons during early development gives rise to the neuronal networks that enable sensory and cognitive functions in humans. Inhibitory synapses decrease the likelihood ...

The dopamine advantage

June 20, 2016
The junctions between nerve cells responsible for releasing and receiving dopamine in the brain are a surprising mismatch that gives this chemical a strong competitive advantage.

How excitatory/inhibitory balance is maintained in the brain

December 17, 2015
Just as a thermostat is used to maintain a balanced temperature in a home, different biological processes maintain the balance of almost everything in our bodies, from temperature and oxygen to hormone and blood sugar levels. ...

How neurons talk to each other

September 22, 2016
Neurons are connected to each other through synapses, sites where signals are transmitted in the form of chemical messengers. Reinhard Jahn, Director at the Max Planck Institute for Biophysical Chemistry in Göttingen, has ...

Recommended for you

New technique helps uncover changes in ALS neurons

June 22, 2018
Northwestern Medicine scientists have discovered that some neurons affected by amyotrophic lateral sclerosis (ALS) display hypo-excitability, using a new method to measure electrical activity in cells, according to a study ...

Broken shuttle may interfere with learning in major brain disorders

June 22, 2018
Unable to carry signals based on sights and sounds to the genes that record memories, a broken shuttle protein may hinder learning in patients with intellectual disability, schizophrenia, and autism.

Watching stem cells repair spinal cord in real time

June 22, 2018
Monash University researchers have restored movement and regenerated nerves using stem cells in zebra fish where the spinal cord is severely damaged.

Scientists discover fundamental rule of brain plasticity

June 21, 2018
Our brains are famously flexible, or "plastic," because neurons can do new things by forging new or stronger connections with other neurons. But if some connections strengthen, neuroscientists have reasoned, neurons must ...

Waking up is hard to do: Prefrontal cortex implicated in consciousness

June 21, 2018
Philosophers have pondered the nature of consciousness for thousands of years. In the 21st century, the debate over how the brain gives rise to our everyday experience continues to puzzle scientists. To help, researchers ...

Researchers find mechanism behind choosing alcohol over healthy rewards

June 21, 2018
A new study links molecular changes in the brain to behaviours that are central in addiction, such as choosing a drug over alternative rewards. The researchers have developed a method in which rats learn to get an alcohol ...

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.