Blending electrophysiology with optical techniques like optogenetics, fiber photometry, or fluorescence microscope's calcium imaging provides sub-second temporal resolution and much-needed cell-type specificity for neuron's electrical activity not possible with either method alone. This technique, called Optoelectrophysiology or Oephys for short, explores the activity of labeled neurons within the nervous system by recording their electrical activity with adjacent electrodes and enables neuron's optogenetic manipulation, imaging, or fluorescence monitoring under light brought upon them via implanted optical fibers, rod lenses or else. It requires not only light signal delivery to the point of interest within the neural tissue but detecting and processing electrical spikes and light bursts from neuronal activity. In vitro or in vivo head-fixed experiments use optoelectric probes. In contrast, experiments with behaving animals use chronically implanted optoelectric cannulas with tethered or wireless headstage options.
The optoelectric probe for acute single-unit recordings is an optical fiber with an additional hollow core in its cladding that becomes an electrode when filled with electrolyte. These probes are tapered to 10 µm diameter tips to ensure optical measurement or manipulation at a single-unit or, in other words, a single-cell level.
The optoelectric probe for acute multi-unit in-vivo head-fixed recordings features a replaceable probe tip that combines a multimode optical fiber with a wire electrode alongside the fiber.
To integrate chronic electrophysiology recordings with optical techniques like optogenetic manipulations and fiber photometry, Doric Lenses offers implantable optoelectric cannulas, a combination of microelectrodes and optical fibers for long-term experiments with freely moving animals. The electrodes connect to a headstage where the analog recorded signal is amplified and converted to a digital signal. From the headstage, the digital signal is sent to an electrophysiology console via a tether or wirelessly, leading to two distinctly different systems, i.e., Tethered Recording System and Fiberless & Wireless (Fi-Wi) Recording System.
- A tether consists of a tiny electrical cable and an optical fiber patch cord for optogenetics or fiber photometry.
- A wireless option has optical fiber directly connected to a LED within the optoelectronic cannula, allowing triggered optogenetic stimulation with selected intensity and time patterns. The electrical activity recording and LED illumination draw power from the headstage battery. The wireless link between the headstage and console is over RF antennas (FiWi system).
|doric Optoelectrophysiology systems|
|System Type||Acute single-cell||Acute multi-units||Tethered||Wireless
|Number of optical fiber
||1||1||1 or 2||1|
|Number of electrodes||1||1 to 8||1 to 16||1 to 4|
|Suitable for "freely moving"||no||no||yes||yes|
|Combines with Optogenetics||yes||yes||yes||yes|
|Combines with Fiber photometry||yes||yes||yes||no|
|Combines with Miniature fluorescence microscopy
1. Scanziani, M., Häusser, M. Electrophysiology in the age of light.
Nature 461, 930–939 (2009).
2. LeChasseur Y, et al., A microprobe for parallel optical and electrical recordings from single neurons in vivo.
Nature Methods 8, 319–325 (2011)
3. Dufour S, et al., A Multimodal Micro-Optrode Combining Field and Single Unit Recording, Multispectral Detection and Photolabeling Capabilities.
PLoS ONE 8, e57703 (2013).
4. Ameli R, et al., A wireless and batteryless neural headstage with optical stimulation and electrophysiological recording.
Conf Proc IEEE Eng Med Biol Soc. 5662-5 (2013).
5. Gagnon-Turcotte G. et al., A wireless optogenetic headstage with multichannel electrophysiological recording capability.
Sensors 15, 22776-22797 (2015).