Neurochips and Neural Telemedicine
Jaideep Mavoori
University of Washington (currently at Neurovista)
Collaborators:Andy Jackson+, Eb Fetz (Biophysics and Neurophysiology)Tom Daniel (Biology)Chris Diorio (Computer Science)
+Currently at Newcastle University
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Neural Telemedicine
Acquire
Monitor
Single neuronsLocal field potentialsECoGEEG
EMG
Detect abnormalities & their evolution
Diagnose
Issue alerts
Initiate curative actions
Track pathological waveforms
Trigger repair mechanisms
Drug delivery
Electrical stimulation
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Biological Motor Control
Photo courtesy of UW PWB program
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Conventional neurophysiology of restrained primates
Filters + Amplifiers
Recording
Stimulator
Analog to Digital Converter
Spike discriminator
Analysis
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Option 1 - Telemetry systems:
• high power consumption• limited range• transmission delays
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Option 2 - Implantable microelectronics:
• autonomous operation• low power• limited processing capability
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Primate Brain Computer Interface
50μm diametertungsten wire
Polyamideguide-tubes
Connector
Skull
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Neurochip BCI User interfaces:
PDA (Lyme)
PC (MatLab)
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Two Cypress Programmable System-on-Chips (PSoCs)
Front-end signal processing (filtering, DC offset + amplification)
Neural signal sampled at 12ksp/s
2 EMG signals sampled at 2.7ksp/s
Real-time spike discrimination
Spike rate and mean rectified EMG compiled for user-defined timebins
2 x 8Mb non-volatile FLASH memory
Biphasic, constant-current stimulator
(±15V, ~100μA)
Infra-red link to PC or PDA
Architecture of the neurochip
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M1 and muscle activity during natural behaviour:
IEEE TNSRE, 2006
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M1 and muscle activity during natural behaviour:
IEEE TNSRE, 2006
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M1 and muscle activity during natural behaviour:
IEEE TNSRE, 2006
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Long-term recording of cell activity: Continuous recording of a single M1 neuron for 2 weeks.
J. Neurophysiol. 2007
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MI-Motor Model
System properties?
Corticalactivity
Muscle output
How time-invariant is this system ?
How does the model compare in task and free behaviours ?
Can we alter the system properties ?
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Motor Pathway Modeling
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Motor Pathway Modeling
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MI-Motor Model
Findings: Over several neurons and muscles, aspects of the system are linear and time-invariant. The relationships translate from task to free-behaviour as well as from day to day.
Advantageous for neural prosthetics:Parameters for limb mechanics can possibly be learnt during a training segment and applied during a wide range of daily activities.
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Neurons that fire together, wire together.
Induce correlated firing between neighboring sites
Long-lasting changes in biological wiring
Altering system properties:Cortical remapping with the Neurochip
Nature 2006
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Neurons that fire together, wire together.
Induce correlated firing between neighboring sites
Long-lasting changes in biological wiring
Nature 2006
Altering system properties:Cortical remapping with the Neurochip
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Neurochip conditioning
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Neurochip conditioning
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Motor cortex plasticity induced by Neurochip conditioning
Movements evoked from the recording site changed to resemble those evoked from the stimulation site.
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Motor cortex plasticity induced by Neurochip conditioning
Additional findings: Timing from spike to stimulation is critical. Delay of 20 ms produced strongest conditioning effect.
Conditioning effects last for several days.
Useful for repairing damage caused by spinal chord injury or neural disorder.
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RepairMonitor Detect early onset Diagnose
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RepairMonitor Detect early onset Diagnose
Early stages of neural telemedicine
Early stages of neural disorders
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Miniature chips for insect flight studies
1cm x 3cm x 0.5cm1.47g (without battery)
(top)
(bottom)
1st Generation
1cm x 1.9cm x 0.4cm0.85g (without battery)
2nd Generation
(top)
(bottom)
3rd Generation
(top)
(bottom)
1cm x 1.25cm x 0.25cm0.25g (without battery)
4th
Generation
0.9cm x 1cm0.6g (no battery)
5th Generation
(top)
(bottom)
1cm x 1.27cm0.42g (no battery)
1cm 1cm
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Acknowledgements:
Supported by NIH, ONR,UW Royalty Research Fund, Packard Foundation.
Chris Diorio Tom Daniel
Andy JacksonEb Fetz
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