Northwestern University researchers have developed a wireless device that utilizes light to send information straight into the brain, marking a significant advancement in neurobiology and bioelectronics. Instead of using the body's conventional sensory pathways, the technology sends impulses directly to neurons.

The soft, flexible device rests on the head and fits under the scalp. From this position, it activates particular groups of neurons across the cortex by sending precisely regulated light patterns through the bone.

Light-Based Brain Signals in Animal Models

In order to excite specific populations of neurons deep within the brains of mice models, researchers employed small, precisely timed bursts of light. (These neurons have been genetically altered to react to light.) The mice rapidly acquired the ability to decipher specific patterns as significant indicators. According to Science Daily, the animals used the incoming information to make decisions and successfully complete behavioral tasks even in the absence of voice, sight, or touch.

Numerous medical applications may be supported by this technology in the future. Potential applications include manipulating robotic limbs, delivering artificial inputs for future hearing or vision prosthesis, aiding rehabilitation following injury or stroke, and altering pain perception without the need for medication.

Creating New Brain Signals With Micro-LED Technology

"Our brains are constantly turning electrical activity into experiences, and this technology gives us a way to tap into that process directly," said Northwestern neurobiologist Yevgenia Kozorovitskiy, who led the experimental portion of the study. "This platform lets us create entirely new signals and see how the brain learns to use them. It brings us just a little bit closer to restoring lost senses after injuries or disease while offering a window into the basic principles that allow us to perceive the world."

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John A. Rogers, a leading figure in bioelectronics and head of the technology development, said, "Developing this device required rethinking how to deliver patterned stimulation to the brain in a format that is both minimally invasive and fully implantable. By integrating a soft, conformable array of micro-LEDs -- each as small as a single strand of human hair -- with a wirelessly powered control module, we created a system that can be programmed in real time while remaining completely beneath the skin, without any measurable effect on natural behaviors of the animals. It represents a significant step forward in building devices that can interface with the brain without the need for burdensome wires or bulky external hardware. It's valuable both in the immediate term for basic neuroscience research and in the longer term for addressing health challenges in humans."

Training the Brain to Recognize Synthetic Patterns

The team used mice with light-responsive neurons in their cortex to test the device. The animals were trained to link a specific stimulation pattern to a reward, which is typically found at a designated port in a testing chamber.

The implant worked like tapping a coded message straight into the brain by delivering a predetermined pattern across four cortical regions during a series of studies. Among a variety of options, the mice were trained to recognize this target pattern. They found the right artificial signal and navigated to the right port to be rewarded.

"By consistently selecting the correct port, the animal showed that it received the message," Wu said. "They can't use language to tell us what they sense, so they communicate through their behavior."

Future Development and Wider Applications

The team intends to test increasingly complex patterns and find out how many different signals the brain can consistently learn now that they have shown that the brain can interpret patterned light stimulation as meaningful information. Future iterations of the gadget might include more LEDs, closer spacing between them, larger arrays that cover more cortex, and light wavelengths that reach deeper into tissue.