DOW-UAP-D130, AAWSAP DIRD, Technological Approaches to Controlling External Devices, March 2010

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Technological Approaches to Controlling External Devices in the Absence of Limb-Operated Interfaces Prepared by: Acquisition Support Division (DW0-3) Defense Warning Office Directorate for Analysis Defense Intelligence Agency AAP Person 73 Administrative Note COPYRIGHT WARN ING: Further dissemination of the photographs in this publication is not authorized. This product is one in a series of advanced technology reports produced in FY 2009 under the Defense Intelligence Agency, Defense Warning Office's Advanced Aerospace Weapon System Applications (AAWSA) Program. Comments or questions pertaining to this document should be addressed to !AAP Person 1 AAWSA Program Manager, Defense Intelligence Agency, ATTN: CLAR/DWO-3, Bldg 6000, Washington,

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Direct Neural Signals.............................................................................................. 1 Indirect Neuronal Signals - The BOLD Effect.......................................................... 3 Control of External Devices .................................................................................... 4 MRI and fMRI ..................................................................................................... 9 Invasive Technologies.......................................................................................... 10 Open-Loop Direct Cortical Array Algorithm Modeling ....................................... 11 Closed-Loop Peripheral Arrays Utilizing Visual Feedback ................................. 13 MEMS, ECoG, and PSoC Circuitry ...................................................................... 14 Chronic Neural Implants and fMRI ................................................................... 16 New Electrode Designs..................................................................................... 18 Hybrid Neuro-Robotic Systems for True Closed-Loop BMI ................................ 20 Trials Using Human Subjects............................................................................ 22 Optical Stimulation of Action Potentials ........................................................... 23 Noninvasive Electrical Devices ......................................................................... 24 Noninvasive BOLD-Based devices..................................................................... 25 Noninvasive Magnetic Devices ......................................................................... 26 Invasive Technologies - General, Optical, and Ex-Vivo Engineering................. 26 Implantable Chips, Ladders, and Arrays........................................................... 27

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Figure 2. The General Layout of a Closed-Loop Control Interface........................... 5 Figure 3. Two Commercially Available EEG Sensors................................................ 8 Figure 4. Experimental Overview of Brain-Controlled Robot in a Closed Loop With Visual Feedback Experiment ......................................................... 13 Figure Schematic of the Neurochip Functional Blocks ...................................... 15 Figure 7. Histology and Electrode Tracks ............................................................. 17 Figure 8. The Michigan Electrodes........................................................................ 18 Figure 9. Image Distortion and Custom Microwire Electrode Assembly to Improve It............................................................................................. 19 Figure 11. T2 Value Analysis Summary of T2 Values in All the Image Slices That Spanned the Electrode Arrays in All Animals ....................................... 20

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Technological Approaches to Controlling External Devices in the Absence of Limb-Operated Interfaces Since the advent of modern interactive control of computers, technologies have been sought to directly connect the biological and the physical to form a seamless entity. While science fiction explores the possibilities of shared consciousness between brains and mainframes, real-life scientists work toward an equally fantastic but more pedestrian goal of eliminating required electromechanical human-machine interfaces (HMis). Such technologies promise integration of thought and computer-controlled action, without the need for a limb-operated device to translate intent from physiological networks to physical circuits. This paper first briefly reviews underlying neural structure, function, and activity to provide background on the type of signals and the scale of temporal changes that arise from conscious control within the nervous system. A short primer on brain-machine interfaces (BMis) is included at the end of the background material. This is followed by a survey of the state-of-the-art detection and stimulation technologies available utilizing noninvasive and invasive methods, including several studies that exemplify research paths currently being undertaken. Discussion brings together elements of the technology survey, application limitations, a timeline for useful commercial deployment, and predicted future research directions. Two technology research paths are highlighted as the most probable to produce functionally useful devices (defined as nearly equal or even superior to the control capabilities of current HMis) in the near and far term. The technology endpoint this paper seeks is thought-based operation of remote machinery during normal human activities without mechanical device interaction-that is, control of external devices without the need to go to a specified location, such as a shielded room; without the need to remain perfectly motionless to reduce signal noise; and without the need for interaction with a normal electro-mechanical device, such as an i-Phone or other handheld device with buttons and trackballs. Data transfer rates are sought to exceed 5-10 bits/second to be useful for operation of complex devices; this rate range and above is referred to as high-bandwidth BMis. Response time for a 1-of-N selection of commands is targeted at 300 milliseconds or less. These are the operational parameters assumed for final implementation unless some limitation or supercapability is described. The paper concludes that noninvasive electrical monitoring of neural activity, primarily reading combined action of muscles and neurons, is the most promising commercial technology in the near term. Inherent limitations in the noninvasive electrical approach require future development of different research paths. The paper argues, mainly by eliminating other approaches, that the most probable technology in the long term involves invasive single­ neuron-based direct cortical connections to form a network of high-bandwidth duplex communication pathways. Currently the most promising technologies

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for robust construction of such an interface are optical stimulation, gating, and sensory devices, and chip-based electrode arrays that have been encased in ex-vivo-engineered neural tissue.

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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 BMI. 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 Figure 1. Simplified Rendering of a Neuron. The arrows indicate t he direction in which signals are conveyed. The single axon conducts signals away from the cell body, while the multiple dendrites receive