Dr Beverly Chen
Research | Current
A Fully Implantable Optogenetic System for Chronic Animal Studies
Optogenetics uses light to manipulate neural activity that has several advantages over conventional electrical stimulation approach including specific cell-type targeting with precise temporal precision, simultaneous stimulation using different wavelengths of light and is relatively harmless to targeted tissue.
In optogenetic experiments, targeted neurons are transfected with photo-sensitive proteins (opsins) for subsequent exciting or silencing neurons with pulses of visible light. The most commonly used to excite neural activity and alter behaviour in freely moving animals is Channelrhodopsin-2 (ChR). ChR2 is obtained from green algae named Chlamydomonas reinhardtii, which serves as sensory photoreceptors in the green algae. ChR2 can be activated with pulses of blue light (wavelength of ~470nm) to depolarize target neurons and evoke an action potential response. The development of inhibitory opsins called Halorhodopsin (NpHR), is obtained from archaebacterial named Natronomonas pharaonis. NpHR is an ion pump driven by red light (625nm), which can hyperpolarize neurons and therefore inhibit neural activity.
Optogenetic stimulation offers the prospect of treating lifetime conditions; however, current optogenetics available commercially are mainly connected with wires coming out of the head of the animal which brings a risk of infection and is vulnerable to damage from chewing or scratching. Also, current light stimulation systems are generally not suitable for chronic use due to the risk of infection associated with components located outside the brain. This study aims to investigate the technical feasibility of implementing a fully implantable optogenetics system supporting long-term light stimulation as well as for feasibility of wireless transmission of recorded signals outwards.
A fully implantable optogenetic system has been developed for wavelengths of 470nm (blue) and 625nm (red). Blue light is suitable for exciting the ChR2 opsin and red light is suitable for inhibiting the NpHR opsin.
At the end of the project, we want to show that the fully implantable optogenetic system can improve neurological disorders such as Parkinson’s disease in an animal model after continuous light stimulation. This preliminary study will enable its use to be transferred from research to clinical studies.
- Pulse-Width Modulation of Optogenetic Photo-Stimulation Intensity for Application to Full-Implantable Light Sources. Published in: IEEE Transactions on Biomedical Circuits and Systems ( Volume: 11, Issue: 1, Feb. 2017 ) http://ieeexplore.ieee.org/document/7546908/
- Neural stimulation from an implantable optogenetics system
Selected publications and creative works (Research Outputs)
- Chen, F. Y. B., Budgett, D. M., Sun, Y., Malpas, S., McCormick, D., & Freestone, P. S. (2017). Pulse-width modulation of optogenetic photo-stimulation intensity for application to full-implantable light sources. IEEE Transactions on Biomedical Circuits and Systems, 11 (1), 28-34. 10.1109/TBCAS.2016.2577042
Other University of Auckland co-authors: Peter Freestone, David Budgett, Daniel McCormick, Simon Malpas
- Hu, A. P., You, Y. W., Chen, F. Y. B., McCormick, D., & Budgett, D. (2016). Wireless power supply for ICP devices with hybrid supercapacitor and battery storage. IEEE Journal of Emerging and Selected Topics in Power Electronics, 4 (1), 273-279. 10.1109/JESTPE.2015.2489226
Other University of Auckland co-authors: Aiguo Patrick Hu, David Budgett, Daniel McCormick
- Chen, F. B., Freestone, P. S., Malpas, S., McCormick, D., & Budgett, D. (2015). Feasibility of Implantable Optogenetics System. Paper presented at IUPESM World Congress on Medical Physics and Biomedical Engineering, Toronto, Canada. 7 June - 12 June 2015. Related URL.
Other University of Auckland co-authors: Peter Freestone, Simon Malpas, Daniel McCormick, David Budgett
- Li, Y.-T., Wickens, J. R., Huang, Y.-L., Pan, W. H., Chen, F.-Y. B., & Chen, J.-J. J. (2013). Integrated wireless fast-scan cyclic voltammetry recording and electrical stimulation for reward-predictive learning in awake, freely moving rats. Journal of Neural Engineering, 10 (4)10.1088/1741-2560/10/4/046007
- Chen, F.-Y. B., Wang, B., Hu, A. P., & Budgett, D. (2013). Zero voltage switching operation of a push-pull resonant converter with slow feedback loop and online communication. 2013 IEEE International Conference on Industrial Technology (ICIT), 644-649. Cape Town, South Africa: IEEE. 10.1109/ICIT.2013.6505747
Other University of Auckland co-authors: Aiguo Patrick Hu, David Budgett