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Restoring neural function through neural prosthetic “bypass”
Ziv Williams, MD
Associate Professor in Neurosurgery
Faculty, Harvard-MIT Health Sciences and Technology
Faculty, Harvard Medical School Program in Neuroscience
Massachusetts General Hospital
Harvard Medical School
Boston, MA 02114
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Re-growing disrupted CNS circuits
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Brain-machine-interface
• No need to restore normal physiological continuity• In principal, can be learned very rapidly (hours to
days)• Has the potential for recovering full motor function
(across multiple degrees of freedom)
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Williams, et al. Nature Neurosci. 2003Williams et al. Exp Brain Res. 2005
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Decoding neural activity based on native directional tuning
Vx (t) = a + =-m
n w()n(t ) (t)
Vx position along the x-axis t timet time laga y-interceptn neuronal firing ratew weight for each neuron e residual error
• Model training• Model decoding
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Functional cortical-to-spinal bypass
• Benefit of restoring one’s own paralyzed limb.
• In principal, can be used to functionally connect any proximal and distal neural site.
• Cortical to spinal • Cortical to nerve• Cortical to muscle
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Shanechi M, et al. Nature Neurosci. 2012Shanechi M, et al. Nature Comm. 2014
Brain - Neural recordings
Spinal cord - Neural stimulation
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Restoring other motor functions
• Premotor cortex – planned target of movement
• Primary motor cortex – ongoing trajectory
• Supplementary motor area – movement sequences
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1:1
( | ) ) exp( ( | )( | ) ( 1:12)ck
KcK
k
Ni c i c ik Sp N k iSS
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Shanechi M, et al. Nature Neurosci. 2012
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Motor control based on native neural plasticity?
• In principal, any brain area.
Williams Z, et al. Nature Neurosci. 2006Haroush K & Williams Z. Cell 2015
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Body-to-brain functional bypass (sensation)
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Brain-to-brain information transmission
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Thank you
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• Shanechi M, Hu R, Williams Z. A cortical-spinal neural prosthesis for targeted limb movement in paralyzed primate avatars. Nature Comm. 2014 Feb 18;5:3237.
• Haslinger R, Pipa G, Lewis LD, Nikolić D, Williams Z, Brown E. Encoding through patterns: regression tree-based neuronal population models. Neural Comput. 2013 Aug;25(8):1953-93.
• Shanechi MM, Hu RC, Powers M, Wornell GW, Brown EN, Williams Z. Neural population partitioning and a concurrent brain-machine interface for sequential motor function. Nature Neurosci. 2012 Dec;15(12):1715-22.
• Williams Z, Eskandar EN. Selective enhancement of associative learning by microstimulation of the anterior caudate. Nature Neurosci. 9: 562-8, 2006.
• NIH 1R01 HD059852• NIH 1R01 NS091390• NIH F32N S093769• PECASE
Some references…
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