Innovative fibers can transmit drugs, light and electric signals to the brain

Innovative fibers can transmit drugs, light and electric signals to the brain

The human brain is the most complex organ in the body. This three-pound mass of gray and white matter sits at the center of all human activity—you need it to drive a car, to enjoy a meal, to breathe, to create an artistic masterpiece, and to enjoy everyday activities. In brief, the brain regulates your body’s basic functions; enables you to interpret and respond to everything you experience; and shapes your thoughts, emotions, and behavior. The brain is made up of many parts that all work together as a team. Different parts of the brain are responsible for coordinating and performing specific functions. Drugs can alter important brain areas that are necessary for life-sustaining functions and can drive the compulsive drug abuse that marks addiction.

The brain is a communications center consisting of billions of neurons, or nerve cells. An Innovative multifunctional fiber that could be implanted into the brain or spinal column where it could easily transmit drugs, light, and electrical signals. The human brain's complexity makes it extremely challenging to study ­ not only because of its sheer size, but also because of the variety of signaling methods it uses simultaneously. Conventional neural probes are designed to record a single type of signaling, limiting the data that can be derived from the brain at any point in time. Now researchers at Massachusetts Institute of Technology may have found a way to change that.

By producing complex multimodal fibers that could be less than the width of a hair, they have created a system that could deliver optical signals and drugs directly into the brain, along with simultaneous electrical readout to continuously monitor the effects of the various inputs. The new tech is described in a paper in the journal Nature Biotechnology, written by Polina Anikeeva and ten others. In addition to transmitting different kinds of signals, the new fibers are made of polymers that closely resemble the characteristics of neural tissues, Anikeeva says, allowing them to stay in the body longer without harming the delicate tissues around them.

Christina Tringides, a senior at MIT and member of the research team, holds a sample of the multifunction fiber produced using the group’s new methodology.
Photo credit: Melanie Gonick/MIT

“We're building neural interfaces that will interact with tissues in a more organic way than devices that have been used previously,” says Anikeeva. To do that, her team made use of novel fiber-fabrication technology pioneered by paper co-author Yoel Fink, for use in photonics and other applications.

The result, Anikeeva explains, is the fabrication of polymer fibers “that are soft and flexible and look more like natural nerves.” Devices currently used for neural recording and stimulation, she says, are made of metals, semiconductors, and glass, and can damage nearby tissues during ordinary movement.

“It's a big problem in neural prosthetics,” Anikeeva says. “They are so stiff, so sharp ­ when you take a step and the brain moves with respect to the device, you end up scrambling the tissue.“ The key to the technology is making a larger scale version, called a preform, of the desired arrangement of channels within the fiber: optical waveguides to carry light, hollow tubes to carry drugs, and conductive electrodes to carry electrical signals. These polymer templates, which can have dimensions on the scale of inches, are then heated until they become soft, and drawn into a thin fiber, while retaining the exact arrangement of features within them.

The system can be tailored for a specific research or therapeutic application by creating the exact combination of channels needed for that task. “You can have a really broad palette of devices,” Anikeeva says. While a single preform a few inches long can produce hundreds of feet of fiber, the materials must be carefully selected so they all soften at the same temperature. The fibers could ultimately be used for precision mapping of the responses of different regions of the brain or spinal cord, Anikeeva says, and ultimately may also lead to long-lasting devices for treatment of conditions such as Parkinson's disease. (Article source: MIT)


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