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

Re-growing disrupted CNS circuits

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)

Williams, et al. Nature Neurosci. 2003Williams et al. Exp Brain Res. 2005

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

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

Shanechi M, et al. Nature Neurosci. 2012Shanechi M, et al. Nature Comm. 2014

Brain - Neural recordings

Spinal cord - Neural stimulation

Restoring other motor functions

• Premotor cortex – planned target of movement

• Primary motor cortex – ongoing trajectory

• Supplementary motor area – movement sequences

1:1

( | ) ) exp( ( | )( | ) ( 1:12)ck

KcK

k

Ni c i c ik Sp N k iSS

Shanechi M, et al. Nature Neurosci. 2012

Motor control based on native neural plasticity?

• In principal, any brain area.

Williams Z, et al. Nature Neurosci. 2006Haroush K & Williams Z. Cell 2015

Body-to-brain functional bypass (sensation)

Brain-to-brain information transmission

Thank you

• 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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