Gateway to the Brain

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Science Translational Medicine  04 May 2011:
Vol. 3, Issue 81, pp. 81ec66
DOI: 10.1126/scitranslmed.3002572

Although it sounds like science fiction, direct transmission of information between the human brain and external devices is possible. Through brain-computer interface (BCI) technology, individuals with motor or communication disabilities can control assistive devices such as computers and prosthetic limbs by using just their own brain activity. The core of this technology is a neural interface, which must be able to detect brain activity reliably at high spatial and temporal resolution over long periods of time. A recent pilot clinical trial of a BCI system called BrainGate shows the long-term reliability and feasibility of intracortical recording with microelectrode arrays.

Microelectrodes can detect activity of individual neurons in the cortex, offering high spatial and temporal resolution. Nevertheless, their long-term reliability for BCI applications has been questioned. The main concern is that implanted electrodes will trigger the brain to form scar-like tissue around them, degrading neural recording quality. The new study examined this question. A 4-by-4-mm microelectrode array with 100 1.5-mm-long electrodes was implanted in the motor cortex of an individual with tetraplegia caused by a brain stem stroke. Approximately 1000 days after implantation, neural activity was recorded for 5 days by the microelectrode array and mathematically translated into control signals in real time. With these brain activity signals, the subject could direct the movement of a two-dimensional computer cursor and click on desired targets, with an average success rate of 94%. Thus, cortical activity recorded by the implanted electrode array could be effectively used for real-time BCI control almost 3 years after the initial implantation. Although only approximately 20 to 30 neurons were monitored by the microelectrode array, they carried sufficient information for cursor control. Although studies of this type require substantial interdisciplinary collaboration, regulatory and clinical resources, and devoted participants, it will be important to validate the results in additional participants. Nevertheless, these initial results will raise interest in conducting translational human studies to move BCI technology from scientific achievement to clinical practice.

J. D. Simeral et al., Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array. J. Neural Eng. 8, 025027 (2011). [PubMed]

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