Researchers at the University of Illinois have found a new way to image brain cells, observe how they communicate and control their function, all by using light. Future applications in this research could combat mood disorders, sleep abnormalities and obesity.

In the Biophotonics Research Lab, researchers are using “tailored light” to have a more specific control on cell function. This light, called coherent control, has already been used by chemists, but these researchers were the first to use it in a live cell. They have documented this study in the journal Nature Physics.

The procedure by which a scientist can modify a live cell with light is called optogenetics. In this method, scientists genetically modify cells to be sensitive to light. This allows them to be imaged, observed and, to a degree, controlled. Tailored light refines this process because instead of indiscriminately shining light, they are paying attention to color, wavelength and intensity in order to control cells in a more specific way.

“What we found was by changing the light parameters we can now control the output of these neurons,” said Dr. Stephen Boppart, leader of the study and University professor. He explained how changing the color and wavelength of light can change when and how often a neuron can fire.

By tailoring light, they control how much energy the cell has, creating different states of excitation. These different states can cause ion channels to open or close, thus controlling whether the neuron can fire or not. The next step for the researchers is to use these procedures to effectively control large networks of neurons, rather than just a single cell.

“We can develop this framework for being able to know which cells are interconnected and using that as a basis for optical delivery systems,” said Carlos Renteria, graduate student in Engineering. “[When] we know what we are targeting, we know how the network is connected and we can potentially use that as a basis for not just stimulating but potentially controlling those networks.” 

Renteria is developing an algorithm to assess network connectivity in cell cultures and brain tissue. He hopes to integrate it with the optical imaging system to better understand cell networks and how they communicate among themselves.

 “The next step is we’re trying to use coherent control in the retina to see if it also has this effect,” Yuanzhi Liu, postdoctoral research associate in Engineering, said. “People say the eye is the window to the soul, and actually the eye is a pretty good window because it is transparent; you can directly go in to look at the blood vessels or photoreceptors.”

Since the cells in the retina are already sensitive to light, the researchers want to target these cells to see if their tailored light has an effect.

The retina is sensitive to circadian rhythms, the biological clock that regulates the physiological systems of the body. When circadian rhythms are thrown out of order, it can affect metabolism, in turn creating sleep and mood disorders. The hope is that by learning how light can affect the light-sensitive receptors in the retina using tailored light, medical solutions to these types of problems can be investigated.

“The main reason I studied medicine was that I saw many problems in the medical field that could be solved by technical solutions,” Boppart said, highlighting how his research is always concerned with “that interface between medicine and engineering.”

Another possible application of retinal research in the relation to light could be investigating the obesity problem. Boppart noted that some researchers believe that the many screens in modern life could be a factor in the obesity epidemic. Research that focuses on how circadian rhythms, and thus metabolism are affected by different types of light meeting the retina could reveal if these beliefs are true.

Although these possible applications are a long way from being a reality, Yangzhi noted that this research also serves to open avenues and inspire curiosity in this field.

“People still don’t know too many things about the brain. That’s why we feel quite excited — it’s an unexplored field, but we know some evidence,” Liu said. “That is the interest for a researcher, to explore some fundamental questions. They’re unknown fundamental questions, but we have some tools we can develop to solve them.”

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