New device controls the brain using light

By DUY PHAN
Senior Staff Writer

Optogenetics, is an emerging technique for probing brain function, enabling scientists to control neurons of interest by shining a light on them. Published in the scientific journal Cell, a study from the University of Illinois provides a design for optogenetics that permits wireless control of brain activity.

Optogenetics takes advantage of light-sensitive proteins called opsins, which are often found in microbes. Opsin proteins convert light energy into cellular changes that drive the movement of ions across a cell membrane. As a result, opsins can be genetically engineered to be anchored on a neuron’s cell membrane, rendering the neuron sensitive to light and making it controllable via light pulses.

Traditionally, the light is delivered through a piece of glass called a fiber optic, which is implanted into the brain of the living organism. The fiber optic is then connected to an external light source through wires. Thus, when scientists turn on the light source, the light travels through the wires, passes through the fiber optic and finally is emitted at the opposite end of the fiber optic. The external light source can be programmed so that light is delivered at specific patterns and power output.

Although this wired setup has been widely employed by neuroscience laboratories across the world, it is not ideal for long-term experiments that require animals to be tethered to the wires. Additionally, a wired setup means that a patient may have to frequently visit the clinic to receive the light pulse treatment.

The study’s authors designed a new wireless system in which the implanted light delivery apparatus is connected to a control board. The control board consists of electrical circuits that control when light is turned on and off. Importantly, the control board is wirelessly controlled, eliminating the need to tether the experimental animal or subject to a wire.
In addition to the wireless component of the system, the new device also allows for fluid delivery. This fluid delivery is extremely useful for optogenetics since before the optic fiber can be implanted, it is often necessary to inject viruses so that opsins can be delivered to neurons. As a result, the ability to provide photostimulation along with fluid delivery means that only one surgery is required to set up optogenetics, whereas before two surgeries were needed to inject viruses and to implant the optic fiber. In other words, the new device makes it easier to perform optogenetics by reducing the need for more invasive surgeries.

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