First to measure the concerted activity of a neuronal circuit

August 22, 2013
First to measure the concerted activity of a neuronal circuit

Neurobiologists from the Friedrich Miescher Institute for Biomedical Research have been the first to measure the concerted activity of a neuronal circuit in the retina as it extracts information about a moving object. With their novel and powerful approach they can now not only visualize networks of neurons but can also measure functional aspects. These insights are direly needed for a better understanding of the processes in the brain in health and disease.

For many decades and genetics have been the main tools in the toolbox of approaches to study individual neurons in the to understand perception and behavior. In the last five years however, neurobiology has been riding a wave of technological advances that brought unprecedented insights: Optogenetics and genetically encoded activity sensors has allowed scientists to control and measure the activity of clearly defined neurons; the application of rabies viruses enabled the visualization of networks of interconnected . What was still missing, was the link between and monitoring of activity.

Scientists from the Friedrich Miescher Institute for Biomedical Research have now been the first to measure the concerted activity of a neuronal circuit in the as it extracts information about the movement of an object.

In a world defined through eyesight, it is crucial to be able to discern whether something moves towards us, moves away or moves next to us. It comes as no surprise then that in the retina several parallel are reserved for the extraction of information about movement and that most of them are dedicated to the analysis of the direction of motion.

As they report online in Neuron, Keisuke Yonehara and Karl Farrow, two Postdoctoral Fellows in Botond Roska's team at the FMI, have now been able to monitor the activity of all in a motion sensitive retinal circuit at once, and pinpoint the site, at a subcellular level, where the information about the direction of the movement becomes encoded. To achieve this, they used genetically altered rabies viruses expressing calcium sensors developed by the laboratory of Klaus Conzelmann in Munich. The special property of rabies viruses is that they move across connected neurons and therefore are able to deliver the sensors to all circuit elements within a defined neuronal circuit. Simultaneous two-photon imaging allowed them then to monitor activity in every part of the neuronal circuit at once, even in subcellular compartments, such as axons, synapses and dendrites.

"We are extremely thrilled that with this new method, which combines the power of genetically altered rabies viruses with very powerful two-photon microscopy, we are now able to link circuit architecture with activity and ultimately function," comments Yonehara. "We have illustrated the power of the method for a better understanding of the perception of movement and are convinced that the method will allow us to reach a better understanding of many processes in the retina and in other parts of the brain."

Explore further: Switching night vision on or off

More information: Yonehara, K. et al. (2013) The first stage of cardinal direction selectivity is localized to the dendrites of retinal ganglion cells, Neuron.

Tang, J. et al. (2013) A nanobody-based system using fluorescent proteins as scaffolds for cell-specific gene manipulation. Cell 154:928-939. www.ncbi.nlm.nih.gov/pubmed/23953120

Related Stories

Switching night vision on or off

March 27, 2013

Neurobiologists at the Friedrich Miescher Institute have been able to dissect a mechanism in the retina that facilitates our ability to see both in the dark and in the light. They identified a cellular switch that activates ...

Visualizing a memory trace

July 12, 2013

In mammals, a neural pathway called the cortico-basal ganglia circuit is thought to play an important role in the choice of behaviors. However, where and how behavioral programs are written, stored and read out as a memory ...

Researchers map complex motion-detection circuitry in flies

August 7, 2013

Some optical illusions look like they're in motion even though the picture is static. A new map of the fly brain also suggests motion—or at least how the fly sees movement. The new research, published in the August 8 issue ...

Recommended for you

Neuron responsible for alcoholism found

September 2, 2015

Scientists have pinpointed a population of neurons in the brain that influences whether one drink leads to two, which could ultimately lead to a cure for alcoholism and other addictions.

Scientists see motor neurons 'walking' in real time

September 2, 2015

When you're taking a walk around the block, your body is mostly on autopilot—you don't have to consciously think about alternating which leg you step with or which muscles it takes to lift a foot and put it back down. That's ...

Deciphering the olfactory receptor code

August 31, 2015

In animals, numerous behaviors are governed by the olfactory perception of their surrounding world. Whether originating in the nose of a mammal or the antennas of an insect, perception results from the combined activation ...

Neural basis of multitasking identified

September 1, 2015

What makes someone better at switching between different tasks? Looking for the mechanisms behind cognitive flexibility, researchers at the University of Pennsylvania and Germany's Central Institute of Mental Health in Mannheim ...

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.