Bioimaging, optical stimulation enable real-time observation of brain circuits

In a study using multiphoton microscopy and stimulation via light flashes along optical fibers, a team of researchers at McGill University (Montreal, QC, Canada) has shown—in real time—how the brain re-wires and fine-tunes its connections differently depending on the relative timing of sensory stimuli. The ability to observe this activity is promising for treatment of nervous system injuries and human brain disorders.

Related: High-resolution serial two-photon tomography images whole brains fast

By using multiphoton microscopy to observe cells in the brains of intact animals, the researchers discovered that asynchronous firing, or “firing out of sync,” not only caused brain cells to lose their ability to make other cells fire, but unexpectedly also caused them to dramatically increase their elaboration of new branches in search of better matched partners.

“The surprising and entirely unexpected finding is that even though nerve circuit remodeling from asynchronous stimulation actively weakens connections, there is a 60-percent increase in axon branches that are exploring the environment, but these exploratory branches are not long-lived,” says Dr. Edward Ruthazer, senior investigator on the study at the Montreal Neurological Institute and Hospital –The Neuro at McGill University and the McGill University Health Centre.

Dr. Ruthazer’s lab charts the formation of brain circuitry during development in the hopes of better understanding the rules that control healthy brain wiring and of advancing treatments for injuries to the nervous system and therapies for neurodevelopmental disorders such as autism and schizophrenia.

In the developing brain, initially imprecise connections between nerve cells are gradually pruned away, leaving connections that are stronger and more specific. This refinement occurs in response to patterned stimulation from the environment. “The way we perceive the world as adults is directly impacted by what we saw when we were younger,” says Dr. Ruthazer.

Dr. Ruthazer’s team studies brain development in Xenopus tadpoles, which have the distinct advantage of being transparent, enabling the team to clearly see the nervous system inside. They have developed a model that allows them to watch nerve cell remodeling in vivo, in real time, and to measure the efficacy of connections between cells. Optical fibers were used to stimulate the eyes of the tadpoles with different light patterns while imaging and recording nerve cell branch formation. Asynchronous stimulation involved light flashes presented to each eye at different times, while synchronous stimulation involved simultaneous stimulation of both eyes.

Importantly, Dr. Ruthazer’s group also has begun to identify the molecular mechanisms underlying these changes in the nervous system. They show that the stabilization of the retinal nerve cell branches caused by synchronous firing involves signaling downstream of the synaptic activation of a neurotransmitter receptor called the N-methyl-D-aspartate receptor. In contrast, the enhanced exploratory growth that occurs with asynchronous activity does not appear to require the activation of this receptor.

Full details of the work appear in the journal Science; for more information, please visit http://www.sciencemag.org/content/344/6186/904.long.

-----

Don't miss Strategies in Biophotonics, a conference and exhibition dedicated to development and commercialization of bio-optics and biophotonics technologies!

Follow us on Twitter, 'like' us on Facebook, and join our group on LinkedIn

Subscribe now to BioOptics World magazine; it's free!

Get All the BioOptics World News Delivered to Your Inbox

Subscribe to BioOptics World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now
Related Articles

FDA authorizes emergency use of Zika virus molecular detection assay

The xMAP MultiFLEX Zika RNA assay combines optofluidics and digital signal processing to detect Zika virus in vitro.

Merz acquires laser tattoo removal device maker ON Light Sciences

Merz North America has acquired ON Light Sciences, which develops technologies to enhance laser-based dermatology procedures.

Shortwave-infrared device could improve ear infection diagnosis

An otoscope-like device that could improve ear infection diagnosis uses shortwave-infrared light instead of visible light.

Laser therapy extracts rare tumor that grew human hair, skin in boy's skull

About four years ago, a tumor comprised of human skin, hair, bone and cartilage was fast-growing inside a Ramsey, MN, 10-year-old youth's brain.
BLOGS

Neuro15 exhibitors meet exacting demands: Part 2

Increasingly, neuroscientists are working with researchers in disciplines such as chemistry and p...

Why be free?

A successful career contributed to keeping OpticalRayTracer—an optical design software program—fr...

LASER Munich 2015 is bio-bent

LASER World of Photonics 2015 included the European Conferences on Biomedical Optics among its si...

White Papers

Understanding Optical Filters

Optical filters can be used to attenuate or enhance an image, transmit or reflect specific wavele...

How can I find the right digital camera for my microscopy application?

Nowadays, image processing is found in a wide range of optical microscopy applications. Examples ...

CONNECT WITH US

            

Twitter- BioOptics World

Copyright © 2007-2016. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS