Weir Biomechatronics Development Laboratory

Bidirectional Optogenetic Peripheral Nerve Interface

Optogenetics

Interfacing with the nervous system and using optics for neuromodulation.

Spatially selective photo-stimulation

Optogenetics

Interfacing with the nervous system and using optics for neuromodulation.

Abstract

Optogenetic Interfacing with Nerves
Bidirectional Optogenetic Peripheral Nerve Interface
Figure 1: System diagram of our proposed optogenetic neural interface. We seek to develop a fiber coupled miniature two-photon microscope attached via a flexible GRIN lens to the vagus nerve of a live animal model. Our goal is an optical nerve interface that can record from and stimulate individual axons of the vagus nerve for closed loop optogenetic modulation of vagus nerve. With an optically based system we achieve: Axon level specificity; Organ level selectivity; Non-invasive interfacing.
Ted for your Head Talk
Why talk to nerves using light?

To communicate with nerves, precision and non-invasiveness are key.  Light can be focused precisely to both activate and read activity within a nerve with specificity not attainable with electrode-based approaches.  These traditional electrode approaches usually deliver relatively broad and indiscriminate stimulation while also being invasive to the nerve.  By using optical nerve cuff systems, we are working  on non-tissue damaging chronic implantable devices to ‘talk’ to specific pathways within the nerve.

How can we use light to interact with nerves?

Novel Methods to ‘Talk’ to Peripheral Nerves – Our laboratory studies and develops novel techniques for interfacing with peripheral nerves, with the goal of stimulating and reading-out highly specific neural activity for rehabilitative and therapeutic purposes.  We focus on optical (optogenetic) approaches which enable axon-level control of intervention with genetic targeting and spatially selective photostimulation.  This research includes the engineering of implantable nerve devices, along with in vivo studies investigating the effect of targeted neural stimulation on organ function for disease therapies as well as prosthesis control.  We are particularly interested in the therapeutic potential of the vagus nerve, which innervates the thoracic and abdominal organs.  Photomodulation nerve cuff devices are in development to enable chronic studies in animal models for the investigation of systemic inflammation and post-traumatic stress disorder (PTSD) treatment.  Recent applications also include the optical stimulation of pathways to modulate cardiac indices and pancreas endocrine function. To facilitate the interfacing of nerves with multi-photon microscopes we utilize an optical relay lens (GRIN-lens) incorporated nerve cuff. 

3D-Printable Vagus Nerve Device for Chronic Photostimulation – This device will facilitate visible light illumination of the in vivo vagus nerve for optogenetic stimulation of select neural pathways.  Current experiments include the targeting of cholinergic and glutamatergic pathways in the nerve to study how these neural pathways may be therapeutically beneficial in reducing systemic inflammation and treating PTSD.    

3D Printing Optogenetic Interface – 3D printers allow for the rapid iteration of different nerve cuff designs and allow for the customization of the nerve cuff for specific anatomies. Check out more about this project here.

Figure 2: 3D Printed Neuromodulation Interfaces, or Nerve Cuffs, in PEGDA (Left: Self-Securing Optical Probe (Littich, 2020), Center: Passive Nerve Cuff, Right: Pull-Through Nerve Cuff)

Modulation of the Heart – Studies utilize transgenic rodent models as well as retrograde adeno-associated virus (AAV) delivered in the heart to specifically infect cardiac fibers of the upstream vagus nerve with light-sensitive opsin proteins.  Stimulation of these vagal pathways, using both one-photon excitation and two-photon holographic excitation enable the perturbation of heart rate, ECG parameters and cardiorespiratory reflexes.1

Infection of light-sensitive opsins
Figure 3: Light-sensitive proteins were virally delivered to pathways in the vagus nerve and subsequently stimulated with light through a custom GRIN-lens integrated nerve cuff device leading to physiological changes including cardiac modulation.1

GRIN-Lens Nerve Cuff – A silicone pressure-molded nerve cuff was fabricated in 3D-printed maraging steel molds.  The cuff incorporated a ratcheted strap mechanism to fix the nerve within the device.  A GRIN lens provides an optical relay to interface the nerve with microscopes and other laser sources.  

Nerve cuff fabrication and implantation
Figure 4: (A) 3D-Printed maraging steel molds for device fabrication. Progress made in nerve cuff manufacturing. (B) Diagram of the finished cuff in situ on the vagus nerve and next to a penny for scale. (C) Imaging of fluorescently labeled axons in the vagus nerve in vivo. After 83 days, it is still possible to image axons through the implanted GRIN.
Video 1: Strapping mechanism of the silicone pressure-molded vagus nerve cuff with GRIN lens.

Modulation of the Pancreas – We study whether optical activation of defined nerve pathways to the pancreas stimulates therapeutically beneficial effects on insulin and glycemic control.  Our studies have demonstrated the stimulation of insulin secretion along with reduction in blood glucose levels by targeting cholinergic pathways2 – an effect not observed with electrical vagus nerve stimulation.  

Optogenetic photosimulation
Figure 5: Optogenetic photostimulation of cholinergic fibers in the pancreas (top) and in the cervical vagus nerve (bottom) may be effective in reducing blood sugar by stimulating insulin secretion.2
Optical Measurement of Neural Activity In Vivo: 
In vivo GCaMP6s transients
Figure 6: In Vivo GCaMP6s transients from vagus nerve axons in ChAT-GCaMP6s mice. (a) Two-photon optical section within the vagus nerve and activity-dependent calcium transients recorded in three axons (ROI1, ROI2, ROI3) in response to a 2-second electrical stimulation of 50 Hz and 70 Hz (black bar). A graded response to stimulus frequency is observed in two of the three responsive axons. (b) Activity-dependent calcium transient recorded in a separate mouse in response to a 10-action potential burst (mean of 3 axonal responses). (c-e) Spontaneous calcium transients recorded with no stimulation present.3
Selective Photostimulation with Spatial Light Modulation:
Spatially selective photo-stimulation
Figure 7: In Vivo GCaMP6s transients from vagus nerve axons in ChAT-GCaMP6s mice. (a) Two-photon optical section within the vagus nerve and activity-dependent calcium transients recorded in three axons (ROI1, ROI2, ROI3) in response to a 2-second electrical stimulation of 50 Hz and 70 Hz (black bar). A graded response to stimulus frequency is observed in two of the three responsive axons. (b) Activity-dependent calcium transient recorded in a separate mouse in response to a 10-action potential burst (mean of 3 axonal responses). (c-e) Spontaneous calcium transients recorded with no stimulation present.3

People

Weir Biomechatronics Development Laboratory

  • R. F. ff. Weir, PhD
  • AK Fontaine, PhD
  • Michael O’Donnell
  • Kathryn Mirandette
  • Tyler Currie

Previous

  • Aiden Roemer

Collaborations

Bioengineering Department, University of Colorado, Denver | Anschutz Medical Campus

Gibson Labs:

  • Emily A Gibson, PhD
  • Greg L Futia, PhD
  • Tarah Welton, MS

Department of Physiology, University of Colorado| Anschutz Medical Campus

  • John H Caldwell, PhD
  • Deigo Restrepo, PhD

University of Colorado | Boulder

  • Juliet Gopinath, PhD, EECS
  • Robert McLeod, PhD, EECS
  • Victor Bright, PhD, ME

Posters & Conference Presentations

  1. Futia, G. L., Fontaine, A. K., Littich, S., McCullough, C., Restrepo, D., Weir, R. F .ff., Caldwell, J. & Gibson, E. A. In vivo holographic photo-stimulation and two photon GCaMP6 imaging of vagus nerve axons using a GRIN lens integrated nerve cuff. in Proceedings of SPIE: Optogenetics and Optical Manipulation 2019 28 (2019). doi:10.1117/12.2521830
  2. Gibson E. A, Weir, R. F .ff., Caldwell, J. H., Restrepo D., Bright, V.M., Gopinath J.T., McLeod R., Bidirectional Minimally Invasive Optogenetic Peripheral Nerve Interface, 11th Congress of the International Society for Autonomic Neuroscience, Los Angeles, CA  (2019).
  3. Fontaine, A. K., Futia, G. L., Littich S., McCullough C., Restrepo D., Weir, R. F .ff., Caldwell, J. H., Gibson E. A., In vivo holographic photo-stimulation and two photon GCaMP6 imaging of vagus nerve axons using a GRIN lens integrated nerve cuff. Neuroscience 2019, Chicago IL.
  4. Futia G.L., Fontaine A.K., Littich S., McCullough C., Restrepo D., Weir, R. F .ff., Caldwell J., Gibson E.A., In vivo holographic photo- stimulation and two photon GCaMP6 imaging of vagus nerve axons using a GRIN lens integrated nerve cuff.  2019 Colorado Neuroscience Symposium (CNS), Aurora CO.
  5. Fontaine, A. K., Segil, J. L., Caldwell, J. H. & Weir, R. F .ff., Real-Time Prosthetic Digit Actuation by Optical Read-out of Activity-Dependent Calcium Signals in an Ex Vivo Peripheral Nerve. in 9th International IEEE EMBS Conference on Neural Engineering (2019).
  6. Fontaine, A. K., Kirchner, M. S., Caldwell, J. H., Weir, R. F.ff., & Gibson, E. A. Deep-Tissue Two-Photon Imaging in Brain and Peripheral Nerve with a Compact High-Pulse Energy Ytterbium Fiber Laser. SPIE BiOS Opt. Interact. with Tissue Cells XXIX 1049217, (2018). doi: 10.1117/12.2309490

Publications

  1. Fontaine, A. K., Futia, G. L., Rajendran, P. S., Littich, S. F., Mizoguchi, N., Shivkumar, K., Ardell, J. L., Restrepo, D., Caldwell, J. H., Gibson, E. A. & Weir, R. F. Optical vagus nerve modulation of heart and respiration via heart ‑ injected retrograde AAV. Sci. Rep. 1–12 (2021). doi:10.1038/s41598-021-83280-3
  2. Fontaine, A. K., Ramirez, D. G., Littich, S. F., Piscopio, R. A., Kravets, V., Schleicher, W. E., Mizoguchi, N., Caldwell, J. H., Weir, R. F. & Benninger, R. K. P. Optogenetic stimulation of cholinergic fibers for the modulation of insulin and glycemia. Sci. Rep. 1–9 (2021). doi:10.1038/s41598-021-83361-3
  3. Fontaine, A. K., Gibson, E. A., Caldwell, J. H. & Weir, R. F. Optical Read-out of Neural Activity in Mammalian Peripheral Axons: Calcium Signaling at Nodes of Ranvier. Sci. Rep. 7:4744, (2017). doi:10.1038/s41598-017-03541-y
  4. Anderson, H. E., Fontaine, A. K., Caldwell, J. H. & Weir, R. F. Imaging of electrical activity in small diameter fibers of the murine peripheral nerve with GCaMP6f. Sci. Rep. 2–10 (2017). doi:10.1038/s41598-018-21528-1
  5. Fontaine, A. K., Anderson, H. E., Caldwell, J. H. & Weir, R. F. Optical read-out and modulation of peripheral nerve activity. Neural Regen. Res. 13, 58 (2018). doi: 10.4103/1673-5374.224364
  6. Weir, R.F.ff. (2008). Prostheses: Human Limbs and Their Artificial Replacements. In The Engineering Handbook of Smart Technology for Aging, Disability, and Independence (eds A.(. Helal, M. Mokhtari and B. Abdulrazak). doi:10.1002/9780470379424.ch22
  7. Weir, R.F.ff. and Sensinger, J.A., (2009): The Design of Artificial Arms and Hands for Prosthetic Applications. Chapter 20, in Biomedical Engineering & Design Handbook, Volumes I and II, Myer Kutz (Editor), McGraw-Hill, pp. 537-598.
  8. Weir, R.F.ff. (2012): The Design of Advanced Prosthetic Limb Systems. Chapter 1, Grasping the Future: Advances in Powered Upper Limb Prosthetics, V. Parenti-Castelli & M. Troncossi (Eds.) Bentham Science Publishers – Open Access e-book (http://www.benthamscience.com/ebooks/9781608054398/index.htm). 1st Edition, pp1-14.
  9. Kethman, W. Weir, R.F.ff. (2021): Human-Machine Integration and the Evolution of Neuroprostheses. Chapter in “Digital Surgery”, Sam Atallah, Ed., Springer Nature Switzerland AG 2021, pp.275-284. https://doi.org/10.1007/978-3-030-49100-0
  10. R. F. ff. Weir (2017): Extrapolation of Emerging Technologies and Their Long-Term Implications for Myoelectric versus Body-Powered Prostheses: An Engineering Perspective, JPO: Journal of Prosthetics and Orthotics. 29(4S) Supplement 1 4S, P63-P74, October 2017. http://journals.lww.com/jpojournal/toc/2017/10001
  11. Farina, D., Vujaklija, I., Brånemark, R., Bull , A. M. J., Dietl , H., Graimann, B., Hargrove, L., Hoffmann, K., Huang, H., Ingvarsson, T., Janusson, H. B., Kristjánsson, K., Kuiken, T., Micera, S., Stieglitz, T., Sturma, A., Tyler, D., Weir, R.F.ff., and Aszmann , O. C., (2021): Toward higher-performance bionic limbs for wider clinical use. Nature Biomedical Engineering, 31 May 2021, DOI: 10.1038/s41551-021-00732-x. URL: https://www.nature.com/articles/s41551-021-00732-x
  12. Anderson, H. E., and Weir, R. F. ff., (2019): On the development of optical peripheral nerve interfaces. Neural Regeneration Research, 14(3)425-436, March 2019. doi:10.4103/1673-5374.245461
  13. Anderson, H. E., Schaller, K.L., Caldwell, J.H., Weir, R. F. ff., (2019): Intravascular injections of adenoassociated viral vector serotypes rh10 and PHP.B transduce murine sciatic nerve axons. Neuroscience Letters 2019 Jul 27;706:51-55. doi: 10.1016/j.neulet.2019.05.010. Epub 2019 May 9.PMID: 31078676.
  14. Anderson, H. E., and Weir, R. F. ff., (2021): The future of adenoassociated viral vectors for optogenetic peripheral nerve interfaces. Neural Regen Res. 2021 Jul;16(7):1446-1447. doi: 10.4103/1673-5374.301017. PubMed PMID: 33318448
  15. Fontaine, A., Caldwell, J., Gibson, E., Weir, R. F. ff., (2015): Toward an Optogenetic Peripheral Nerve Interface for Control of Advanced Prosthesis. Keystone Symposia Conference, C5: Optogenetics, March 12 – March 16, 2015, Westin Downtown Denver, Denver, Colorado.
  16. Weir, R. F. ff., Caldwell, J., Fontaine, A., Anderson H., (2016): Optogenetics as a Means of Achieving a Non-Invasive Peripheral Nerve Interface with Neuron Level Specificity. Proceedings from the First International Symposium on Innovations in Amputation Surgery and Prosthetic Technologies, Chicago, IL, May 12-13, 2016, pp. 24-25.
  17. Futia, G.L., Fontaine, A.K., McCullough, C., Ozbay, B.N., George, N.M., Caldwell, J.H., Restrepo, D., Weir, R. F. ff., Gibson, E.A., (2018): Measurement of wavefront aberrations in cortex and peripheral nerve using a two-photon excitation guidestar, Proc. SPIE 10502, Adaptive Optics and Wavefront Control for Biological Systems IV, 105020J (23 February 2018). http://dx.doi.org/10.1117/12.2309492.
  18. Futia, G.L., Fontaine, A.K., Littich, S., McCullough, C., Restrepo, D., Weir, R. F. ff., Caldwell, J.H., Gibson, E.A., (2019): In vivo holographic photo-stimulation and two photon GCaMP6 imaging of vagus nerve axons using a GRIN lens integrated nerve cuff. Proc. SPIE 10866, Optogenetics and Optical Manipulation 2019, 108660K (22 February 2019); SPIE BiOS, 2019, San Francisco, California. doi: 10.1117/12.2521830
  19. Littich, S. A., Fontaine, A. K., Futia, G. L., Arevalo, N. L., Caldwell, J. H., Gibson, E. A., Restrepo, D., & Weir, R. F .ff., (2019): Next generation neural interfaces for biophotonic medicine. Poster presented at; 41st Annual Conference for the Association of the Chemoreception Sciences; 2019 April 14-17; Bonita Springs, FL.
  20. Weir, R. F. ff., (2019): Myoelectric to Optogenetic Neural Interfaces for Advanced Prosthesis Control. Invited talk at the Peripheral Neuroprosthetics and Rehabilitation. 9th International IEEE EMBS Conference On Neural Engineering (NER’19) to be held at the Hilton Union Square Hotel, San Francisco, CA – USA from 20-23 March 2019.
  21. Fontaine, A. K., Segil, J., Caldwell, J., Weir, R. F .ff., (2019): Real-Time Prosthetic Digit Actuation by Optical Read-out of Activity-Dependent Calcium Signals in an Ex Vivo Peripheral Nerve. 9th International IEEE EMBS Conference On Neural Engineering (NER’19), Hilton Union Square Hotel, San Francisco, CA – USA, 20-23 March 2019, , pp. 143–146.
  22. Weir, R. F .ff., Fontaine, A. K., Segil, J., Caldwell, J. (2019): Real-Time Prosthetic Digit Actuation by Optical Read-out of Activity-Dependent Calcium Signals in an Ex Vivo Peripheral Nerve, Proceedings from the Second International Symposium on Innovations in Amputation Surgery and Prosthetic Technologies, Vienna, Austria, May 12-13, 2019.
  23. Weir, R. F .ff., Fontaine, A.K., , Segil, J.L., Caldwell J., “Demonstration of an Optogenetic Neuronal Control Interface”, in the MEC Symposium Conference, July 2020
  24. Fontaine, A.K., Weir, R. F .ff., Gibson, E.A. (2015, October). Deep-Tissue Two-Photon Imaging in Brain and Peripheral Nerve with a Compact High-Pulse Energy (Ytterbium) Fiber Laser. Colorado Photonics Industry Association Symposium, Boulder, CO.
  25. Fontaine, A.K., Caldwell, J., Gibson, E., Weir, R. F. ff., (2015): Toward an Optogenetic Peripheral Nerve Interface for Control of Advanced Prosthesis. Keystone Symposia Conference, C5: Optogenetics, Poster Number: 1012, March 12 – March 16, 2015, Westin Downtown Denver, Denver, Colorado.
  26. Fontaine, A.K., Futia, G. L., Littich, S., McCullough, C., Restrepo, D.,  Weir, R. F .ff., Caldwell, J., Gibson, E. (2019): In Vivo Holographic Photo-Stimulation and Two Photon GCaMP6 Imaging of Vagus Nerve Axons Using a GRIN Lens Integrated Nerve Cuff. Society for Neuroscience 2019, Chicago, IL, October 19-23.
  27. Weir, R. F .ff., (2019): Myoelectric to Optogenetic Neural Interfaces for Advanced Prosthesis Control. Talk MS Modern Human Anatomy Program Seminar, Anschutz Medical Campus, October 24th, 2019.

Funding

Current

NIH NINDS R01 NS118188-01 (Weir, Gibson, Caldwell): Optimization of a Minimally-Invasive Bidirectional Optogenetic Peripheral Nerve Interface with Single Axon Read-in & Read-out Specificity (09/30/2020 – 07/31/2025).

Previous

NIH NINDS 1R21 NS124313-01 (Weir, Fontaine): A 3D-Printed Nerve Cuff for 1-Photon Optogenetic Vagal Stimulation (07/01/2021 – 06/30/2023).

VA ORD RR&D 1I21RX003894-01 (Fontaine, Weir): Investigation of an Optogenetic Vagus Nerve Stimulation Device in an Animal Model of Post-Traumatic Stress Disorder (10/01/2021 – 09/30/2023)

NIH SPARC 3 OT2 OD023852-01S4 (Weir, Gibson, Caldwell, Gopinath): Development of a Bidirectional Optogenetic Minimally Invasive Peripheral Nerve Interface with single axon read-in & read-out specificity (09/24/2016 – 02/28/2020).

Patents

Gopinath, J. T., Gibson, E. A., Bright, V. M., Weir, R. F. ff., D. Restrepo, D., (2014): Optical Imaging Devices and Electrowetting Lens Elements, and Methods for Using Them. Application No. 61/930,349. US Provisional Patent. Filed on 22 Jan. 2014. International Application # PCT/US2015/012539 filed on 22 Jan. 2015.

News & Media

References

  1. Fontaine, A. K., Futia, G. L., Rajendran, P. S., Littich, S. F., Mizoguchi, N., Shivkumar, K., Ardell, J. L., Restrepo, D., Caldwell, J. H., Gibson, E. A. & Weir, R. F. Optical vagus nerve modulation of heart and respiration via heart ‑ injected retrograde AAV. Sci. Rep. 1–12 (2021). doi:10.1038/s41598-021-83280-3
  2. Fontaine, A. K., Ramirez, D. G., Littich, S. F., Piscopio, R. A., Kravets, V., Schleicher, W. E., Mizoguchi, N., Caldwell, J. H., Weir, R. F. & Benninger, R. K. P. Optogenetic stimulation of cholinergic fibers for the modulation of insulin and glycemia. Sci. Rep. 1–9 (2021). doi:10.1038/s41598-021-83361-3
  3. Futia, G. L., Fontaine, A., Littich, S., McCullough, C., Restrepo, D., Weir, R., Caldwell, J. & Gibson, E. A. In vivo holographic photo-stimulation and two photon GCaMP6 imaging of vagus nerve axons using a GRIN lens integrated nerve cuff. in Proceedings of SPIE: Optogenetics and Optical Manipulation 2019 28 (2019). doi:10.1117/12.2521830

Check out the projects we are currently working on!

Implanted nerve cuff on the vagus nerve of a mouse.

3D Printing Nerve Cuffs

3D printed silicone nerve interfaces for inflammation

Spiralized nerve interface

Spiralized Nerve Cuffs

Rolled silicone nerve interfaces for inflammation

DRG cell bodies and axons expressing GFP

Novel Adeno-Associated Vectors (AAVs)

Using AAVs to target nerve cells for the restoration of sensory feedback

Our Collaborations

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