California Institute of Technology (Caltech) engineers have developed a robotic device able to act as a brain-computer interface. This is the 'first robotic approach to establishing an interface between computers and the brain by positioning electrodes in neural tissue.' According to the researchers, their approach 'could enhance the performance and longevity of emerging neural prosthetics, which allow paralyzed people to operate computers and robots with their minds.' But read more...
You can see above an earlier version of a prototype of such a system. It "is designed to fit inside a standard laboratory cranial chamber, used for acute experiments in non-human primates, to allow semi-chronic operation. A semi-chronic design has the advantage that the device can be repositioned over a different region with minimal effort and without need for additional surgeries." The device "is capable of positioning four neural electrodes to optimize recordings of action potentials." (Credit: Caltech)
Here is how Wolf describes the project. "Our approach consists of implanting a small robotic device (and accompanying control algorithm) with many individually-motorized electrodes that each autonomously locate, isolate, and track a neuron for long periods of time. To further complicate matters, we wish to find signals only from neurons dedicated ('tuned') to a particular task, say controlling an 'arm reach.' While the primary aim of such technology is for a neural interface for neuroprostheses, such a device may also advance the state-of-the-art experimental techniques for electrophysiology."
Now, let's look at how IEEE Spectrum describes the device. "The Caltech team has designed a system that would make the procedure more predictable by attaching a tiny MEMS-based motor to each electrode on a multichannel electrode array and using an algorithm to direct the electrodes to individual neurons. The MEMS part is still a work in progress, but the software algorithm has been worked out and tested in Caltech neuroscience labs."
And here is how the algorithm makes a neural connection. "As the electrodes are driven into the tissue, the software starts taking sample recordings to detect spikes of electrical activity at the electrode tip. When the software detects spikes, it moves forward in small increments and tracks how the signals change. After determining whether the signal has improved or gotten worse, it the algorithm moves the electrode to a new position and does more recording and comparing, driving the electrode in further if necessary until it finds the best signal. If the signal wanes, the algorithm will automatically adjust the electrode position to improve the signal."
The researchers say that they've designed their neuron-tracking algorithm by looking at software used by the U.S. military to track planes. They also say that even if it hasn't been done before, their "robotic interface could increase the life span of neural prosthetics."
This research work will be presented tomorrow at the 2008 IEEE International Conference on Robotics and Automation (ICRA 2008) currently held in Pasadena, California (May 19-23, 2008) during a session focused on "Bio-Inspired and Biomedical Robotics" under the name "A Miniature Robot for Isolating and Tracking Neurons in Extracellular Cortical Recordings."
Here is a link to the abstract. "This paper presents a miniature robot device and control algorithm that can autonomously position electrodes in cortical tissue for isolation and tracking of extracellular signals of individual neurons. Autonomous electrode positioning can significantly enhance the efficiency and quality of acute electrophysiolgical experiments aimed at basic understanding of the nervous system. Future miniaturized systems of this sort could also overcome some of the inherent difficulties in estabilishing long-lasting neural interfaces that are needed for practical realization of neural prostheses. The paper describes the robot's design and summarizes the overall structure of the control system that governs the electrode positioning process. We present a new sequential clustering algorithm that is key to improving our system's performance, and which may have other applications in robotics. Experimental results in macaque cortex demonstrate the validity of our approach."
The Caltech team has already given talks at previous ICRA conferences. Here is a link to a presentation given during ICRA 2005, "A miniature robot that autonomously optimizes and maintains extracellular neural action potential recordings" (PDF format, 8 pages, 816 KB). The above figure has been extracted from this presentation.
Sources: Morgen E. Peck, for IEEE Spectrum Online, May 20, 2008; and various websites
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