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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.
“The Times”18 pages
UNCLASSIFIED/ ,SF&lil: 8FFI1il.t.lt '11815 8HI£?/ Direct Neural Signals The human nervous system has two classes of cells, neurons and glia. Based on all research to date, it is believed that signals within the network of neurons constitute the whole of information processing, with glial cells playing a purely supporting role. This neural doctrine has dominated research in BMI until recently and still constitutes the only major research path in direct technologies. Furthermore, all technologies directly measuring human neuronal action rely on detecting or influencing electrical activity of these cells; no current in situ research selectively affects neurotransmitter activity between local cells for the purpose of information exchange. Therefore, the focus for the foreseeable future will be on the electrical activity of neurons as the primary target of BM!. Neurons consist of four parts: axon, dendrites, cell body or soma, and pre-synaptic terminals. Electrical information is transmitted to the neuron through the dendrites, proceeds through the cell body, and leaves the cell through the axon at one or more pre-synaptic terminals. Neurons have one axon and from one to tens of thousands of dendrites. ,:, •,. '1 ,,, .. ,' '. -, " '.. • '-" ' !, • • ' ' . ' • ' • Figure 1. Simplified Rendering of a Neuron. The arrows indicate the direction 1n which signals are conveyed. The single axon conducts signals away from the cell body, while the multiple dendrites receive signals from the axons of other neurons. The nerve terminals end on the dendrites or cell body of other neurons or on other cell types, such as muscle or gland cells. (Reference 1) Chemical details of how the action potentials travel through the cell or are transmitted across the synapse are not important to the current treatise, other than the distinction that in these biologically based electrical networks, ions of sodium, potassium, and chlorine move through the cell membranes perpendicular to the propagation of the action potential down the axon. This allows information to be transmitted faster than ions could flow down the axon. The propagation of information is similar to a wave traveling down a garden hose: quickly move one end of the hose back and forth with sufficient force, and a wave will travel to the other end of the hose; however, any part of the hose structure has only moved (nominally) perpendicular to the direction of wave propagation. In a similar fashion, ions flow through channels across the axon's cell membrane, changing the local membrane potential and thus propagating the electrical signal down the axon. 1 UNCLASSIFIED/1«F81i1: 8FFI&l1ltk I l&'i ADIi X
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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.