Monday, December 15, 2014

Proposal: Optogenetic Cochlea Implant

For my very last blog entry, I want to write about a project that I think can potentially become a theme for 20.109 future modules. It capitalizes on the rapidly developing field of optogenetics, which overlaps with both synthetic biology and DNA engineering. The really cool thing about optogenetics is that there are so many open problems to solve and there are many ways we can apply it to address bioengineering challenges. For brevity, I am not citing specific articles but want to acknowledge Dr. Richard Turner from the Engineering Department, University of Cambridge, and Prof. Edward Boyden, from the MIT Media Lab, for the lecture notes and amazing publications on this field.

Background: the way we hear sound relies on an intricate auditory system that can decompose different frequencies and selectively stimulate neurons at specific positions. Concretely, inner hair cells are in control of stimulating neurons aligned at certain positions around cochlea which encodes signal strengths of sound wave with specific frequencies. The loss of inner hair cells (IHCs) is a major cause of deafness and the current cochlea implant solves this problem by bypassing IHCs and directly stimulating neurons according to incoming sound frequency spectrum. The sensitivity of the current technologies is very low because electrodes cross-talk, making perceived sound for people with hearing aid extremely coarse. Light, however, is promising for this application because of its small directed beam width suitable for accurately targeting neurons at millisecond timescale resolution. There are labs at MEEI working on this technology but there hasn’t been papers published yet.

Idea: for the 20.109 labs, we can transfect auditory neurons with light-sensitive proteins and verify that they can be stimulated by light input. We can then align these sensitized neurons and program simulations for selectively stimulating neurons at particular positions (which correspond to perception to particular frequencies of sound) and evaluate how well they work (in terms of spatiotemporal resolution) as compared to electrical stimulation. In fact, to make things simpler, we can even use HEK293 cells instead. We can try to find the optimal light intensity/wavelength as well as the thresholds that can make light stimulation work on mammalian cells.

What’s Cool: open research problem, easy-to-get-on first step experiments, great literature, immediate medical applications, and potential collaboration with Prof. Boyden...

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