Neurochips and Neural Telemedicine

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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