Towards a Man-Machine MeldA more profound and intensive area of research for neuroscientists has been the development of brain-computer interfaces (BCI). Conceptually, a brain-computer interface is a system where a computer can directly receive and interpret information from a subject’s brain, seamlessly bridging the gap between man and machine. The technology to enable this futuristic advance has been the work of countless laboratories and millions of dollars in funding.The first step in constructing a BCI is to create a physical interface between the neurons of the brain and the copper of the computer. Three main approaches have been taken, which vary in the amount of physical penetration into the brain.One approach is a direct descendent of Delgado’s and Georgopoulos’ wire insertions: using an invasive field of pins called Utah arrays to cleanly capture the signals of hundreds of neurons at once. These arrays, which lie snugly against individual neurons, can capture the changing electrical signals with unprecedented fidelity, making it one of the least error-prone techniques currently available. Researchers in Japan used one of these arrays on a monkey, allowing it to remotely control a robotic arm. However, the quality of the extracted signal is not enough to compensate for the complications associated with open-brain surgery as well as the tissue damage from the pin insertions. Thus, although technology is unceasingly refining and improving the design of these arrays, they are currently relegated to experimentation on rats and monkeys.At the same time, an alternative approach has been researched in parallel. Known as electroencephalography (EEG), this technology takes a fundamentally different approach from invasive electrode arrays. By applying very sensitive electrodes on the scalp, faint electrical residues emanating from neurons near the surface of the brain could be skimmed off and recorded. By observing large-scale fluctuations in the location and intensity of distinctive parts of the brain, the observed signal could be used by machines. Currently, noninvasive EEG-based devices are used by quadriplegics and individuals suffering from locked-in syndrome, a disease characterized by the complete inability to elicit movement in any part of the body, to communicate through a computer. BCIs act as a detour around the damage and offer these patients the ability to interact with the outside world. This system interprets EEG signals to help the patient input letters in a computer, allowing them to communicate with others.Finally, recent research has offered yet more methods of signal acquisition that have yet been commercialized. One is a compromise between the tissue-damaging but high-fidelity recordings from electrode arrays and the noninvasive but noisy EEG. Known as electrocorticography (ECoG), this sensor system functions as a plate of EEG-like noninvasive sensors that sits atop the surface of the brain. By sitting much closer to the brain, it offers much higher-fidelity signals than EEG, but without the damage created from the sharp pins of the electrode array. Even as these techniques are commercialized, new and more advanced techniques are being developed that offer higher resolution, better signal fidelity, and larger recording field. For example, Eugenio Culurciello, Associate Professor of Electrical Engineering, and Vincent Pieribone, Associate Professor of Physiology and Neurobiology, developed a system called NeuroView, a novel approach for very fast and noninvasive optical recording of neurons in experimental animals that use fluorescent neurons to track activity. His approach will allow for recording of neurons over a hundred times faster than EEG and on the spatial resolution of individual neurons to rival an electrode array.
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