psychology & neuroscience
Using Light to Control the Brain
By Lasya Kambhampati
Image ZEISS Microscopy. [CC BY-2.0]
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magine a pendulum swinging back and forth on a string. Your job is to poke it in just the right way so that it stops moving. However, you are given no other information about the movement of the pendulum. You would end up just poking around in the dark, hoping that somehow you will be able to nudge in just the right direction with the right amount of force. This is the analogy that Dr. Andrea Giovannucci, an assistant professor in the Joint UNC-NCSU Department of Biomedical Engineering, uses to describe the current field of neuro-engineering. Scientists are sending signals to neurons (brain cells) hoping that one will eventually cause the reaction they are investigating. At the moment, a prominent approach for artificially connecting with the brain is through the implantation of a chip, such as the NeuraLink technology created by Elon Musk. This chip can then be used to get input from sensory neurons (“read”) and send output to nerves (“write”). However, there are multiple issues with this idea – the implanted needles would corrode, and the chip cannot Dr. Andrea Giovannucci be maintained for long periods. Furthermore, it is difficult to precisely modulate neurons to achieve the desired result. Chips do have positive aspects; for example, the signals to and from the chip can be decoded in real time, which is essential for effective prosthetics. Dr. Giovannucci’s research aims to turn on the light so
that we can accurately and precisely poke specific neurons to elicit a particular reaction. He became interested in this particular topic when he realized that by combining his previous experience with algorithms, artificial intelligence (AI), and prosthetics, he could develop algorithms that would control neuroprosthetics. Instead of using a chip to control neural signals, he elected to use light (holography) to stimulate neurons. Although it is important to mention that, currently the technology is unable to read and modulate brain activity within 30 milliseconds, which is essential to have an effective dialog between input and output. Dr. Giovannucci describes the current relay time as “asking you a question and getting a response 20 minutes later.”1 To do this, two important changes need to be made to the brain’s physiology. Using a genome changing mechanism, the brain can express a gene that encodes a fluorescent protein (Figure 1). This protein activates when the neuron fires, signaling neuronal activity and allowing scientists to “read” the brain’s current state. Past literature has shown that this is possible and effective in the brains of mice and primates. In addition, there needs to be a gene that allows light to change the activity of the neuron. This allows researchers to shine a particular wavelength of light on a neuron and either activate it or suppress its activity. After completing these two Figure 1. Neurons labeled with fluorescent proteins modifications, an optical-
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