The control of robotic prosthesis via signals from the nervous system has reached an impressive level in recent years. However, the feedback of signals from the prosthesis back into the nervous system, e.g., to provide touch sensation, remains a much more challenging problem. Could methods of optogenetics provide an alternative interface in this context?
Dear Alejandro,
Yes it could: in fact there's an application to restore vision in some forms of blindness, mostly retinitis pigmentosa (progressive degeneration of photoreceptors) using virally delivered channelrhodopsin combined with special goggles. Papers from mice have already been published (from Botond Roska and others), and I heard a recent talk that showed very promising preliminary results pointing towards human applications - so I am very optimistic :-) Here are some links to papers and news pages:
http://www.nature.com/neuro/journal/v11/n6/abs/nn.2117.html
http://www.jneurosci.org/content/30/26/8745.full.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3129568/
http://scienceblogs.com/neurophilosophy/2008/05/27/channelrhodopsin-restores-vision/
http://www.nature.com/news/2008/080425/full/news.2008.781.html
http://www.gensight-biologics.com/optogenetic
Dear Jochen,
It seems that the answer of that question is in the selective expression of channelrhodopsin (CRho) in the damaged primary afferents (i.e., A-beta nerve fiber), which in the current time, with the current molecular tools, could be done by local virus injection to transfect the targeted nerve cells. The optical excitation of CRho might mimic the receptor potential, and then the communication between the prosthesis and the nerve cell can be stablished. However the efficiency of the communication may depend on the CRho kinetics and its expression level. I guess that this kind of approach has to be validated in laboratory animals before to be tried in humans.
Best
AP
Dear Alejandro,
thanks for your answer. I am excited to hear that this approach could actually work!
Cheers,
Jochen
Dear Alejandro,
Yes it could: in fact there's an application to restore vision in some forms of blindness, mostly retinitis pigmentosa (progressive degeneration of photoreceptors) using virally delivered channelrhodopsin combined with special goggles. Papers from mice have already been published (from Botond Roska and others), and I heard a recent talk that showed very promising preliminary results pointing towards human applications - so I am very optimistic :-) Here are some links to papers and news pages:
http://www.nature.com/neuro/journal/v11/n6/abs/nn.2117.html
http://www.jneurosci.org/content/30/26/8745.full.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3129568/
http://scienceblogs.com/neurophilosophy/2008/05/27/channelrhodopsin-restores-vision/
http://www.nature.com/news/2008/080425/full/news.2008.781.html
http://www.gensight-biologics.com/optogenetic
Indeed optogenetics can be used in feedback modular designs embedded in brain-computer interface. Optogenetics has been used recently to control the onset of seizure in mice using a simple feedback loop which modulates brain activity 'specifically' to epileptic neurons (or networks that connect to them). Optogenetics is successful in this feedback engineering due to the incoorporation of EEG detectors in the optical stimulation circuitry.
http://www.nature.com/ncomms/journal/v4/n1/full/ncomms2376.html
Optogenetics technology will continue to evolve with higher resolution on molecular and genetic level of channel protein engineering and targeting (which is crucial for temporal specificity, think of it as time-varying microstates in an ensemble of neuronal states). The limiting factor currently for transitioning to humans is the optical stimulation protocol. We need to non-invasively apply photon pulses to neurons, once that happens, optogenentics will be most-likely not only a brain-connectome tool but a therapeutic tool as well, which can be way more efficient than small molecules.
Optogenetics is definitely the heart of future of interdisciplinary sciences from physics to social engineering :-)
I think it's a great question. In addition to the already mentioned selectivity of expression or spatial resolution, it seems that the precise deciphering of information-carrying signals afferent to the damaged region would need to be done (there may be models out there?). The transmission of the sensations of touch, pressure and/or pain consist of neuronal activities including but not limited to firing and oscillating by a variety of cells and cell-types. For this to work naturally, one would have to accurately decipher the information-carrying signals, and then appropriately replicate them in the subject/patient in order to transmit the precise signal that the brain would interpret as sensation.
Dear Elwood Siagian,
I wonder to which degree the plasticity of the brain could be sufficient to re-learn new sensation signals / patterns in order to avoid the exact replication of previously existing signals / patterns.
Cheers,
Jochen
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