Brain Studies Advance Neural Mapping, Axon Control

Probing the brain with lasers could not only advance understanding of the organ, but also help heal it.

Researchers at the University of Texas at Arlington have authored two studies on the subject. The first, published in PLOS One (doi: 10.1371/journal.pone.0111488), describes “in-depth non-scanning fiber optic two-photon optogenetic stimulation (FO-TPOS) of neurons in vivo in transgenic mouse models” to manipulate function in specific regions of the brain.

Using near-infrared light rather than a conventional visible beam allows FO-TPOS to penetrate more deeply than a single-photon beam. The new technique also avoids tissue damage; other methods use electrical pulses to map brain circuitry, which can cause damage.

FO-TPOS allows precise and less invasive delivery of stimulation to the brain, which the researchers anticipate will pave the way for a better understanding of neural circuitry.

Professor Dr. Samarendra Mohanty, who leads the Biophysics and Physiology Lab in the University of Texas at Arlington College of Science, is co-author of two neuron-related studies. Courtesy of University of Texas at Arlington.

“Scientists are trying to find out about the connectivity of neuronal circuitry in different regions of the brain, but that information is not sufficient unless we examine how those connections function,” said doctoral candidate Kamal R. Dhakal. “That’s where two-photon optogenetics comes into play.”

In another study, published by the UT Arlington team in Nature Scientific Reports (doi: 10.1038/srep06902), the researchers looked at neuron axon pathfinding. The accuracy of this, as well as the formation of functional neural circuitry, are crucial for processing, storing and retrieving information from internal networks and the environment.

The researchers performed this axon guidance using a noncontact optical method that employs weakly focused NIR laser beams. This allowed “the formation of axonal loops in cortical neurons, which demonstrate that cortical neurons can self-fasciculate (contract) in contrast to self-avoidance,” the researchers wrote in this study.

They said this was the first use of light to cause an axon to loop around on itself. The technique could allow noninvasive guidance of neurons for restoration of impaired neural connections and functions.

“Our innovative approach and expertise in the use of optical tools is making it possible for us to construct, manipulate, transform, modulate and even detect structure and function of neural circuits as never before,” said professor Dr. Samarendra Mohanty. “These publications, along with others this year, chronicle this work and demonstrate the many ways in which our lab is using technical know-how to further research goals.”

The work for both studies was funded by the National Institutes of Health’s National Institute of Neurological Disorders and Strokes.

For more information, visit www.uta.edu.