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Article Overview "Reach and grasp by people with tetraplegia using a neurally controlled robotic...
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Reach and grasp by people with tetraplegia using a neurally controlled robotic arm Ilya Kuzovkin 11 April 2014, Tartu Leigh R. Hochberg et al. Nature, 17 May 2012 Paper overview
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Transcript of Article Overview "Reach and grasp by people with tetraplegia using a neurally controlled robotic...
Reach and grasp by people with tetraplegia using a neurally controlled robotic arm
Ilya Kuzovkin
11 April 2014, Tartu
Leigh R. Hochberg et al.
Nature, 17 May 2012
Paper overview
etc…
etc…
How it works?
2012 Reach and grasp by people with tetraplegia using a neurally controlled robotic arm
2011
Efficient Decoding With Steady-State Kalman Filter in Neural Interface Systems
Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array
Point-and-Click Cursor Control With an Intracortical Neural Interface System by Humans With Tetraplegia
2010 Neural control of computer cursor velocity by decoding motor cortical spiking activity in humans with tetraplegia
2006
Neuronal ensemble control of prosthetic devices by a human with tetraplegia
Bayesian Population Decoding of Motor Cortical Activity using a Kalman Filter
2012 Reach and grasp by people with tetraplegia using a neurally controlled robotic arm
2011
Efficient Decoding With Steady-State Kalman Filter in Neural Interface Systems
Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array
Point-and-Click Cursor Control With an Intracortical Neural Interface System by Humans With Tetraplegia
2010 Neural control of computer cursor velocity by decoding motor cortical spiking activity in humans with tetraplegia
2006
Neuronal ensemble control of prosthetic devices by a human with tetraplegia
Bayesian Population Decoding of Motor Cortical Activity using a Kalman Filter
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
Hypothesis (hand motion)
Evidence (sequence of observed firing rates)
Posterior probability Prior probabilityLikelihood
Marginal likelihood (can be ignored since it is the same
for all hypothesis)
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
“Likelihood term models the probability of firing rates given a particular hand motion”
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
“Likelihood term models the probability of firing rates given a particular hand motion”
“linear Gaussian model could be used to approximate this likelihood and could be readily learned from a small amount of training data”
“… uses Bayesian inference techniques to estimate hand motion from the firing rates of
multiple neurons.”
“Likelihood term models the probability of firing rates given a particular hand motion”
“linear Gaussian model could be used to approximate this likelihood and could be readily learned from a small amount of training data”
“The prior term defines a probabilistic model of hand
kinematics and was also taken to be a linear Gaussian model.”
Neural Coding
Neural Coding of Hand Kinematics
Neural Coding of Hand Kinematics
Neural Coding of Hand Kinematics
Neural Coding of Hand Kinematics
Experiment 1: 23/25 neurons are correctly described by equations (4) and (5) !Experiment 2: 39/42 neurons correctly described by (4) and (5)
Neural Coding of Hand Kinematics
Experiment 1: 23/25 neurons are correctly described by equations (4) and (5) !Experiment 2: 39/42 neurons correctly described by (4) and (5)
The relationship between the kinematics of the arm and the
behavior of the neurons is strong
Learning the model
Detour: Multivariate normal distribution
Detour: Multivariate normal distribution
Detour: Multivariate normal distribution
Why covariance matrix and not just a vector of variances?
Definitions
Definitions
Parameters of the model
Parameters of the model
H is the relation between the firing rates of each of the neurons and states of the arm
Q is covariance matrix of the noise
Parameters of the model
H is the relation between the firing rates of each of the neurons and states of the arm
Q is covariance matrix of the noise
A is the relation between the state at time k+1 and the state at time k
W is covariance matrix of the noise
Parameters of the model
H is the relation between the firing rates of each of the neurons and states of the arm
Q is covariance matrix of the noise
A is the relation between the state at time k+1 and the state at time k
W is covariance matrix of the noise
Matrices A, H, Q, W is what we want to learn from the training data
The Learning
Decoding
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
Note that now x and z and everything else refer to the test data
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
The probability that the hand can move in
the way it did
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
The probability that the hand can move in
the way it did
The probability that hand can end up in the state where it
was in time k-1
“… the Kalman filter operates recursively on streams of noisy input data to produce a statistically optimal estimate of the underlying system
state.” (Wikipedia)
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
“Decoding was performed using a Kalman filter which gives an efficient recursive method for
Bayesian inference …”
Results
2012 Reach and grasp by people with tetraplegia using a neurally controlled robotic arm
2011
Efficient Decoding With Steady-State Kalman Filter in Neural Interface Systems
Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array
Point-and-Click Cursor Control With an Intracortical Neural Interface System by Humans With Tetraplegia
2010 Neural control of computer cursor velocity by decoding motor cortical spiking activity in humans with tetraplegia
2006
Neuronal ensemble control of prosthetic devices by a human with tetraplegia
Bayesian Population Decoding of Motor Cortical Activity using a Kalman Filter
2006 2010
20112013
The steady-state Kalman filter significantly increases the computational efficiency for even relatively simple neural spiking data sets from a human NIS. <…> The decoding complexity is reduced dramatically by the SSKF, resulting in approximately seven-fold reduction in the execution time for decoding a typical neuronal firing rate signal.
Summary
http://braingate2.org/publications.asp
