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Tag Archives: Optrodes
The ability to wirelessly control neural circuitry has been a long-standing goal in neuroscience. Recent advances have put this goal in site using optogenetic approaches. In 2011, multiple groups presented the first attempts at making wireless light delivery application for optogenetics (Iwai et al., 2011; Wentz et al., 2011). These advances, however, were constrained to particular environments or apparatuses to power the devices. The radiofrequency power scavenging approach presented in Kim et al., 2013 frees the experimenter from these constraints. In the recent report, the Bruchas (Washington University at St. Louis) and Rogers (University of Illinois at Urbana-Champaign) labs present ultrathin, microscale optoelectronics and sensors that can be used for the optogenetic manipulations. Unlike other wireless approaches this system can be used with any behavioral apparatus or paradigm, which should allow researchers to explore more complex behaviors while perturbing neural circuitry.
The wireless µILED devices can incorporate wired cellular-scale components that can all be inserted into the brain using a combination of a silk-based biodissolvable adhesive (Kim et al., 2010) and an injection needle similar in concept to electrode delivery presented previously (Kozai and Kipke, 2009). These components include, but are presumably not limited to, temperature sensors, electrodes for … Continue reading
Simultaneously recording and perturbing neural circuits with millisecond-scale temporal precision is a cornerstone of optogenetics research, but the methods for doing so are not always easily accessible. A variety of labs have come up with ad hoc ways to incorpoate fiber optic cables into existing multielectrode implant designs. Very few of these solutions have been documented or published, even though this is becoming an increasingly popular technique. Fortunately, the Moore Lab at Brown University recently published a manuscript on their “flexDrive,” a lightweight implant that can hold multiple fiber optic cables and 16 electrodes (Voigts et al., 2013).
The basic concept is similar to the designs from Matt Wilson’s lab involving a ring of electrodes, each driven by its own screw (Kloosterman et al., 2009). But it introduces a novel spring-based drive mechanism that significantly reduces both the weight of the implant and the time it takes to build. In contrast to previously published designs (Anikeeva et al., 2011), each of the electrodes on the flexDrive can be moved independently—a feature that is essential for maximizing the number of well-isolated single units that can be recorded.
The authors have put a lot of effort into making their designs as accessible … Continue reading
Microelectrodes are powerful tools for in vivo functional studies. However they are limited in the number of information they provide. In January 2011, LeChasseur and colleagues (Nature Methods 8(4), 319-325, 2011) developed a glass microelectrode which was integrating an optical micro-channel for light delivery and fluorescence collection. The probe serves for specific cellular fluorescence optical detection and activation/inhibition. In a recent issue of PLOS ONE, Dufour et al. extended the multimodal aspect of this micro-optrode. They introduce a, aluminum-coated, fibre optic-based glass microprobe (diameter ≤ 10 μm) with multiple electrical and optical detection capabilities. The probe enables optical separation from individual cells in transgenic mice expressing multiple fluorescent proteins in distinct populations of neurons within the same deep brain nucleus. It also enables color conversion of photoswitchable fluorescent proteins, which can be used for post-hoc identification of the recorded cells and finally it enables dual electrical recordings. Figure 1 shows a representation of the microp-optrode and the modalities described in this paper.
These modalities are in addition to the calcium monitoring and optogenetic cellular activation previously reported (Nature Methods 8(4), 319-325, 2011). In this study, two different excitation sources and detection pathways were used simultaneously to differentiate two different populations … Continue reading
The optopatcher: an electrode holder allowing the insertion of an optical fiber into a patch pipette
In order to perform simultaneous intracellular recording and light stimulation of a single neuron, two separate positioning systems are often needed (one to position the recording electrode, one to position a waveguide near the recorded neuron). More sophisticated solutions for single neuron photostimulation involve light patterning techniques which are not suited for deep in vivo recordings. Katz et al. came up with a simple and affordable solution for this problem, by designing a patch pipette holder containing an additional port for the insertion of an optical fiber into the pipette.
This device, which they called “OptoPatcher” allows whole cell patch-clamp recording simultaneously with direct projection of light from the recording pipette. The holder spares the use of an additional manipulator and, importantly, enables accurate, stable and reproducible illumination. Moreover, the presence of the bare fiber within an aqueous solution instead of the brain can prevent tissue damage due to heating of the brain. In addition, replacement of standard pipettes is done as easily as with the available commercial holders.
The OptoPatcher was used successfully in vivo for intracellular recordings from different cortical layers in the motor cortex of transgenic mice expressing channelrhodopsin-2 under the Thy1 promoter and it was also … Continue reading
Wen Li’s group at Michigan State University recently presented preliminary results on the development of an epidural micro-electrocorticogram (μECoG) array combining microelectrodes and light emitting diodes (LEDs) for optical neural stimulation. This work follows-up on a new line of research aiming at providing μECoG arrays with versatile optical stimulation capabilities (see for example the work of Ledochowitsch et al). The “Opto-μECoG” arrays developped in Wen Li’s group were especially designed to address three major limitations of current designs, in particular the limited cortical area and spatial resolution available for optical stimulation. The key features of these Opto-μECoG arrays are the following:
Untethered system: integration of surface mounted μ-LED light sources (220 × 270 ×50 μm3, wavelength peak at 460nm, Cree® TR2227TM) on the Opto-μECoG array allows the possibility to achieve a truly untethered system. Maximized target cortical area available for optical stimulation: optically transparent indium tin oxide (ITO)  epidural electrodes of the Opto-μECoG array allow maximum exposure of the target cortical area for optical stimulation. Maximized spatial resolution of optical stimulation: the embedded light sources, placed on top of the ITO electrodes, were preciously arranged based on a recent study of the optimal spacing of subdural, epidural, and scalp … Continue reading
As optogenetic neuronal control strategies develop and get widely adopted in neurobiology labs, the demand for devices allowing combined light delivery and electrophysiological recording is growing. These devices, commonly called opto-electrodes or optrodes, already exist under a wide variety of forms, from the simple home made single optical fiber + single electrode to more complex microfabricated multi-fiber/multi-electrode systems. In the past years, Zhang et al. integrated an optical fibre in a Utah Array, and NeuroNexus assembled an optical fiber on their standard silicon shaft. Other groups implemented waveguides directly into the optrode fabrication process: Cho et al. integrated a microstructured SU-8 waveguide on the shaft of a Michigan Probe and the group of Ed Boyden integrated 12 silicon oxynitride waveguides on silicon shafts (paper1, paper2). Royer et al. in the Buszaki lab managed to establish silicon based shaft arrays with integrated optical fibers.
In a recent paper published in “Lab on a Chip”, the Stieglitz and Lüthi labs introduced a novel optrode which also comprises a microfluidic channel for liquid delivery at the tip of the probe. This channel can be used for example to inject a solution containing a virus right under the waveguide tip and around the electrical … Continue reading
Sending light and recording electrical activity in deep brain structures using optrodes
When optogenetic tools for controlling neural activity came into play in the late 2000s, it became obvious that hybrid probes for delivering light into the brain and recording photoevoked activity simultaneously would become a basic component of the optogenetic toolkit. And this for at least two reasons. First, microelectrode recordings are still the golden standard for measuring neuronal firing, surpassing by far optical sensors at least at the single cell resolution and millisecond time scale. And second, electrical recordings are and will probably remain the ultimate readout of the efficiency of optogenetic activation and inactivation protocols. In other words, the only way to show that your optogenetic activator or silencer does the job is to directly record its effects on neuronal firing.
Various types of optical⁄electrical probes for deep brain photostimulation and recording. Top left: An optical⁄electrical probe having single optical fiber and single electrode. Bottom: Three types of single optical fiber–multiple electrode combination. Bottom left – wire-wound tetrodes are combined with an optical fiber. Bottom center – “Michigan probe” integrated with an optical fiber. Bottom right – “Utah” multi-electrode array combined with a tapered optical … Continue reading
The Frank lab and Deisseroth lab came out with a smart design for a movable optical fiber + tetrode (“optetrode”) drive. The design and fabrication of the drive, which can be assembled in less than 3 hours once you have all the parts, are exposed in a Nature Neuroscience technical report and will soon be posted here on OpenOptogenetics. The drive’s essential features are the following: compact, robust, lightweight (2 g) and low-cost. Stay tuned!