Decoding Neural Activity from an Intracortical Implant in Humans with Tetraplegia Chad E. Bouton Battelle Health and Life Sciences Division

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Decoding Neural Activity from an Intracortical
Implant in Humans with TetraplegiaChad E.
BoutonBattelleHealth and Life Sciences
Division
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Background

• Cyberkinetics (founded in 2001) developed a
  Brain-Computer Interface (BCI) system called
  BrainGate
• At the core of the system was the Utah Electrode
  Array (brain implant)
• Implanted in the Primary Motor Cortex (M1),
  hand/arm area
• Purpose was to allow severely disabled
  individuals to communicate, use their PCs, and
  even control a wheelchair by decoding their
  thoughts

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Background
Time Domain Signals from Electrode Array

• Battelle developed user training methods and
  Neural Decoding Algorithms
• Processed signals from the electrode array (96
  channels)
• Goal isolate and predict arm/hand movements the
  patient is thinking about

Neural Decoding
Elbow Extension
Shoulder Abduction
Wrist Flexion
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Patients

• 54 year old female stroke victim (SCI 3),
  quadriplegic and unable to speak
• 36 year old male, diagnosed with ALS,
  quadriplegic and unable to speak
• Conducted an intended motion survey to look at
  neural modulation (change in neuronal firing
  patterns) for various visually cued movements
• Shoulder Flexion and Extension
• Shoulder Abduction and Adduction
• Elbow Flexion and Extension
• Wrist Flexion and Hyperextension
• Wrist Radial and Ulnar Deviation
• Wrist Pronation and Supination
• Hand Open and Close

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Initial Motion Survey with SCI3
Flexion/extension mixed (dark/med blue)
Zero Units (Neurons) Exhibited Differing Firing
Patterns
(Axes are unit-less and represent the first three
principal components from a principal components
/ eigenvector analysis.)
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Thought-Driven Cursor

• Previous decoding methods (from non-human primate
  work)
• Position based (assumed neural patterns
  correlated to position in space)
• Early demonstration in a human subject BG SCI
  P003 - Center Out - 2006.01.23.wmv
• Marginally stable results - proprioceptive
  feedback is disrupted in a disabled user
• Introduced user training methods - used motion
  demonstration (mirror neuron activation) and
  coaching periods
• Moved away from position-based decoding and
  utilized model-based approaches along with
  support vector machine methods
• Results for Battelle decoding algorithm -
  stabilized cursor motion by isolating 6 intended
  motions rest, four wrist motions, and close
  hand
• SCI P003 8-23-06 Great - excellent motion and
  diagonal.mov

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Increasing Degrees-of-Freedom -12 Motions (6 DOF)
Recognized by Algorithm
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Adaptive Algorithm

• Subject ALS1 exhibited decreased and inconsistent
  performance
• Incorporated performance feedback during training
  (dots/masses on springs)
• Adapted decoding algorithm after each training
  block
• Demonstration ALS1_4DOF_matlab_screen.wmv

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Communicating to Others

• Locked-in syndrome
• 5 imagined movements to move and click cursor
  over virtual keyboard Aug_Communications_Wonderfu
  l_high_quality.wmv

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Wheelchair Control

• Mobility extremely important and can be
  difficult/impossible for certain patients with
  existing interfaces
• As aired on 60 Minutes (Nov. 2, 2008), Cathy
  Hutchinson became the worlds first person to
  control a wheelchair with a brain implant (using
  the Battelle training and decoding methods)
• Stroke Patient - Controlling Wheelchair.wmv

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Acknowledgements

• Cyberkinetics, Inc.
• Dr. John Donoghue
• Dr. Leigh Hochberg
• Mike Fritz
• Almut Branner
• Abe Caplan
• Ammar Shaikhouni
• Oystein Johnsen (Eagle)