Breakthrough in Mind Control: Caltech’s Revolutionary Brain-Machine Interface Utilizing Ultrasound
The latest advancements in Brain-Machine Interfaces (BMIs) have introduced functional ultrasound (fUS), a non-invasive technique for monitoring brain activity. This groundbreaking innovation shows promising results in enabling precise control of electronic devices with minimal delay, eliminating the need for frequent recalibration.
Functional ultrasound (fUS) represents a significant leap forward in Brain-Machine Interface technology, providing a less invasive approach to interpreting brain activity for the purpose of controlling electronic devices.
BMIs are devices designed to read brain activity and translate it into commands for electronic devices, such as prosthetic limbs or computer cursors. They hold the potential to empower individuals with paralysis to manipulate prosthetic devices using their thoughts.
Traditional BMIs often necessitate invasive surgical procedures to implant electrodes directly into the brain to capture neural activity. However, in 2021, researchers at Caltech introduced a novel method for monitoring brain activity utilizing functional ultrasound (fUS), a far less invasive technique.
Functional Ultrasound: Transforming BMIs
A recent study serves as a proof-of-concept that fUS technology could underpin an “online” BMI. Such a BMI would not only read brain activity but also decode its significance through machine learning algorithms, subsequently controlling a computer with minimal delay while accurately predicting movements.
Ultrasound technology is employed to create two-dimensional brain images, which can then be stacked together to generate a three-dimensional representation. This approach, which is transparent to the skull, involves no implantation into the brain itself, reducing the risk of infection and preserving the integrity of brain tissue and its protective covering, the dura.
Understanding Ultrasound Imaging
Ultrasound imaging functions by emitting high-frequency sound pulses and measuring how these vibrations propagate through various substances, such as human body tissues. Sound waves travel at distinct speeds within these tissues and reflect at their boundaries. This technique is commonly used for diagnostic imaging, including fetal imaging during pregnancy.
Since sound waves cannot penetrate the skull, a transparent “window” must be installed in the skull to facilitate brain imaging with ultrasound. The key to functional ultrasound lies in monitoring changes in blood flow within specific brain regions. As neural activity fluctuates, so does the utilization of metabolic resources like oxygen, which are replenished through the bloodstream. This study utilized ultrasound to measure alterations in blood flow, enabling the simultaneous monitoring of the activity of small neural populations, some consisting of just 60 neurons, spread throughout the brain.
Unlocking Mobility: Empowering Paralyzed Individuals through Thought-Controlled Computers and Robotic Limbs
Innovative Application in Non-Human Primates
Researchers applied functional ultrasound to monitor brain activity within the posterior parietal cortex (PPC) of non-human primates. This region governs the planning and execution of movements and has been extensively studied by the Andersen lab using various techniques.
The animals were trained to perform two tasks that required them to plan movements either with their hands to control a cursor on a screen or with their eyes to focus on a specific part of the screen. Remarkably, they only needed to think about performing the task, as the BMI interpreted the planning activity in their PPC.
Promising Outcomes and Future Prospects
Real-time ultrasound data was transmitted to a decoder that had been trained to interpret this data using machine learning. Subsequently, the decoder generated control signals to move a cursor to the intended location as conceived by the animal. This BMI achieved successful control over eight radial targets, with mean errors of less than 40 degrees.
Notably, this technique obviates the need for daily recalibration, setting it apart from other BMIs. In contrast, envision a scenario where one needs to recalibrate their computer mouse for up to 15 minutes each day before use.
Next Steps: Human Studies and Enhanced Imaging
The research team’s future endeavors involve investigating the performance of BMIs based on ultrasound technology in humans and refining fUS technology to enable three-dimensional imaging for enhanced precision.
This study, titled “Decoding motor plans using a closed-loop ultrasonic brain–machine interface,” was published in the journal Nature Neuroscience on November 30, 2023.
Reference: “Decoding motor plans using a closed-loop ultrasonic brain–machine interface” by Whitney S. Griggs, Sumner L. Norman, Thomas Deffieux, Florian Segura, Bruno-Félix Osmanski, Geeling Chau, Vasileios Christopoulos, Charles Liu, Mickael Tanter, Mikhail G. Shapiro and Richard A. Andersen, 30 November 2023, Nature Neuroscience.
Whitney Griggs (PhD ’23), a UCLA-Caltech MD/PhD student, and Sumner Norman, a former postdoctoral scholar now affiliated with Forest Neurotech, are the study’s primary authors. Alongside Griggs, Norman, and Andersen, other Caltech coauthors include graduate student Geeling Chau and Vasileios Christopoulos, a visiting associate in biology and biological engineering. Additional coauthors include Charles Liu from USC, and Mickael Tanter, Thomas Deffieux, and Florian Segura from INSERM in Paris, France. Funding for the research was provided by the National Eye Institute, a Josephine de Karman Fellowship, the UCLA-Caltech MSTP, the Della Martin Foundation, the National Institute of Neurological Disorders and Stroke, the National Institutes of Health, the T&C Chen Brain-Machine Interface Center, and the Boswell Foundation.
Frequently Asked Questions (FAQs) about Ultrasound Brain-Machine Interface
What is functional ultrasound (fUS) technology?
Functional ultrasound (fUS) is a non-invasive technique for monitoring brain activity, allowing precise control of electronic devices by interpreting neural signals.
How do traditional Brain-Machine Interfaces (BMIs) differ from fUS-based BMIs?
Traditional BMIs often require invasive surgeries to implant electrodes into the brain, while fUS-based BMIs use ultrasound to monitor brain activity without the need for implantation.
What advantages does fUS technology offer?
Functional ultrasound is less invasive than traditional brain implants, doesn’t require frequent recalibration, and allows for monitoring activity in multiple brain regions simultaneously.
How does ultrasound imaging work in this context?
Ultrasound emits high-frequency sound pulses, measuring how they propagate through tissues. Changes in blood flow, linked to neural activity, are detected by the Doppler effect, enabling precise monitoring.
What are the potential applications of this technology?
This technology could empower paralyzed individuals to control prosthetic devices or computers with their thoughts, offering newfound mobility and independence.
Are there plans to test this technology in humans?
Yes, the research team plans to study how fUS-based BMIs perform in humans, potentially bringing this innovation to a broader audience.
More about Ultrasound Brain-Machine Interface
- Nature Neuroscience Paper
- Caltech Brain–Machine Interface Center
- Functional Ultrasound (fUS) Overview
- Ultrasound Imaging in Medicine
- Brain-Machine Interfaces for Paralyzed Individuals