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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 23 March 2010, was produced under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It surveys invasive and noninvasive brain-machine interface technologies for controlling external devices without limb-operated interfaces. The technologies covered include EEG, MEG, fMRI, NIRS, and implanted electrode arrays. It concludes that noninvasive electrical monitoring is the most promising near-term approach. In the long term, it favors invasive single-neuron cortical connections that use optical stimulation or chip-based arrays.
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UNCLASSIFIED/ /PIHi: 8fflll.t.k YE&i 811L>C based on skin movement using technology similar to the operation of GPS. This system would have the same inherent problem of signal conduction through tissue from all directions. The key indicator of a future advance in EEG technology would be a study showing noninvasive spiking or ERP signal detection from a coherent group of less than 10,000 neurons. Until progress in localization on this order is demonstrated, EEG-only devices will remain low bit rate application technologies. EEG-only sensor control of devices has been pursued with the supposition that signal transmission directly from the motor cortex will outperform conventional mechanical operation because the signal transmission delay between the neocortex and muscles in the extremities will be augmented via a physical circuit. While this is true, the inherent assumption that complex mechanical interface operation can be replaced with a 1 bit/second low-delay control pathway is incorrect for naturalistic environments. The millions of channels of two-way communication between the extremities and the brain naturally present will control naturalistic mechanical devices far better, and provides the ability to react to an ever-changing environment. Adding significant computer control and relegating the motor cortex to a supervisory role of low data bandwidth could have benefits and is a possible path to real-world improved reaction time application. Also beneficial to reaction time is the combined EMG EEG devices mentioned above since the pathways between the brain and facial muscles are far shorter than those to the extremities. NONINVASIVE BOLD-BASED DEVICES The detection resolution of hemodynamic responses using fMRI and NIRS type technologies is expected to improve in the near, medium, and far terms. NIRS has been deployed in naturalistic experiments, specifically, automobile driving, and it is reasonable to envision such systems becoming small enough to wear in the medium to far term. The limiting issue with BOLD technologies is that the detectable response is delayed several seconds from neuronal firing, greatly limiting the cognitive control applications available to these technologies. Progress in localization to below 0.5 mm 3 in a mobile device could indicate the possibility of high bit transfer rates with the use of state vector machines, albeit with the inherent delay of the physiology. Until the localization and portability issues are addressed in tandem, BOLD-only devices are unlikely to be used for commercial cognitive control interfaces. The vast majority of experiments in fMRI utilize the General Linear Model (GLM) and something akin to a canonical hemodynamic response. There exists significant physiological noise in these data analyses that are traditionally filtered out. The differential results from Independent Component Analysis (ICA) and GLM analysis of the same data sets indicate that there may be additional circulatory response mechanisms with faster onsets than typical BOLD. Future studies indicating that filtering or analysis methods may be ignoring important detectable signals that have inherently faster response times would provide a breakthrough path for hemodynamic response technologies. The current research to monitor on this matter is the technology known as Inverse MRI which can capture high temporal resolution (100 frames a second for single slices) T2* variations. 25 UNCLASSIFIED,'~P8"1 8PPll!l"'I! l!l!il! 8111!¥
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Report, from the dia collection. The PDF is mirrored here; the original link is under it. 36 pages are in the text index: search them above, or from the library's search.