AAWSAP DIRD, Technological Approaches to Controlling External Devices, March 2010

This Defense Intelligence Reference Document was produced by the Defense Intelligence Agency's Defense Warning Office under the Advanced Aerospace Weapon System Applications program and dated 23 March 2010. It surveys noninvasive and invasive brain-machine interface technologies, including EEG, MEG, fMRI, NIRS and implanted electrode arrays, that could control external devices without limb-operated interfaces. It concludes that noninvasive electrical monitoring is the most promising near-term approach. For the long term it favors invasive single-neuron cortical connections.

From the source:Release of 2026-09-18 Incident: 3/23/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys brain-machine interface technologies intended to allow users to control external devices without conventional manual controls, and it evaluates both noninvasive and invasive approaches for turning neural or related physiological signals into usable commands. The report reviews the underlying neural signals, distinguishes between open- and closed-loop control systems, and examines technologies including scalp-based electrical recording, magnetic and imaging-based methods, and implanted cortical interfaces, with particular attention to bandwidth, response time, signal quality, and practical usability. It concludes that, in the near term, the most practical systems are likely to be noninvasive electrical approaches that draw heavily on muscle and neural signals, while longer-term high-bandwidth control would likely require more advanced invasive interfaces capable of robust two-way communication with individual neurons. The document presents thought-based control of external devices as a research field with plausible assistive and specialized applications, while emphasizing that naturalistic, high-performance control remained constrained by major technical and physiological limits.

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NEW ELECTRODE DESIGNS
Building upon studies like Parikh et al., designs look toward invasive systems capable of
pinpointing cortical regions and monitoring their neural activity at or near single neuron
resolution. Clement et al. employed microwire neural implants to combine fMRI and
intracortical recordings to yield important information about metabolic mechanisms that
correlate with neural activity. While modeling studies have been conducted in numerous
experiments, they served as a baseline to understand the potential dangers associated
with the strong static magnetic field alone or while exposed to typical MRI protocols on
the surrounding tissue and the design of an MRI compatible electrical array (References
48, 49). On the surface this may seem a trivial task, however the study shows this is
not only a challenging design detail, but decisive in the resulting recorded data of
neural activity. Examples of the electrode designs are shown in Figure 8.
Figure 8. The Michigan Electrodes. Left: A variety of different silicon probes have been placed on the back of a
U.S . penny . The copper scaffold in the background is the array of columns on the Lincoln Memorial. Right: Four 64-
site probes have been assembled into a three -dime nsional structure. (Reference 49)
Previous work addressed important issues related to short-term compatibility of silicon
microelectrodes. In that report, identification and replacement of appropriate
components of a silicon microelectrode system resulted in virtually artifact-free MR
images and stable recordings of motor unit activity, although chronic studies were not
performed (Reference 50). By utilizing this knowledge the authors designed a microwire
electrode array capable of surviving the strong magnetic fluctuations exhibited from an
fMRI. Figure 9 shows the device and its related connective components (Reference 51).
Figure 10 shows the before and after MR images when connectors and structural screws
compatible with MR are employed as well as the compatible electrodes.
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