| Zdroj: |
Aachen : Forschungszentrum Jülich, Zentralbibl., Verl., Berichte des Forschungszentrums Jülich 4346, X, 168 S. : Ill., graph. Darst. (2011). = Zugl.: Aachen, Techn. Hochsch., Diss., 2011 |
| Popis: |
Though the study of neuroscience is an advanced field, there remain many questions to be answered about information processing in mesoscale networks of electrogenic cells. This is because such investigations require temporally precise, robust, and non-damaging bi-directional communication with single cell resolution. One possible pair of tools that can be developed towards this end is optogenetic stimulation and extracellular electrode recording. This pair has the complimentary traits of flexible stimulation and spatio-temporal precision of recording, and both fields can benefit from new developments. Improved stability, biocompatibility, and optical clarity make diamond a good candidate for development of new extracellular recording electrodes. This thesis first evaluates the performance of micro electrode arrays made from boron doped nanocrystalline diamond through several design iterations. The devices’ ability to detect cell signals with signal-to-noise ratios comparable to, or better than achieved with metal electrodes is shown. A high signal-to-noise ratio is achieved despite the electrodes not being intentionally microstructured, and having dimensions suitable for single cell resolution recordings. Second, the evaluation of several optogenetic depolarizing proteins from literature, as well as the novel Ch2opt mKATE variant of Channelrhodopsin2 is presented. Ch2opt mKATE is shown to have better viability than several other Channelrhodopsin 2 constructs. Furthermore, Ch2opt mKATE posess channel dynamics that make it suitable for a range of applications. This is in contrast to published variants, which sacrafice performance in one area to be the best in another, such as achieving the highest currents reported at the cost of channel kinetics. Third the use of Ch2opt mKATE is evaluated in two electrogenic cell types. Here it is found that contrary to the oft-discussed on and off kinetics of the channel, or peak currents passed, it is illumination area and dark recovery period that are the critical factors for determining the frequency of maintainable stimulation at the single cell level. Stimulation is shown to be possible with subcellular illumination areas, but would benefit from illumnination not restricted to a small focal volume. The included work shows that a parallel development approach has advanced both the techniques of optical stimulation and MEA recording with new materials. Going forward, integration of these techniques for long term non-invasive interfacing with electrogenic cells requires consolidated optimization. |
