A micro-optrode for simultaneous extracellular electrical and intracellular optical recording from neurons in an intact oscillatory neuronal network

In vivo simultaneous intra- and extracellular potassium recordings using a micro-optrode

“…Although other techniques using small optical fibers exist (Kudo et al, 1992;Nakamura et al, 1999;Duff Davis and Schmidt, 2000;Mottin et al, 2003), our technique, just like the one used by others (Bradley et al, 2008;LeChasseur et al, 2008;Zhang et al, 2009) has the advantage of combining electrical and optical readings. In our case, two electrical sensors have joined the optical fiber.…”

“…We used a technique inspired form targeted bulk-loading (Stosiek et al, 2003;Garaschuk et al, 2006). Similar techniques have been used for in vivo cell loading (Hirase et al, 2004;Wang et al, 2006;Bradley et al, 2008). The potassium indicator PBFI AM (Invitrogen Canada) was first dissolved in dimethyl sulfoxide (DMSO) containing 20% pluronic acid (Invotrogen Canada).…”

“…Our technique is more versatile than others reported so far because it can be easily adapted to various protocols by changing the ionsensitive filling of the extracellular electrode and the fluorescent dye. Another advantage of this technique, if compared to the one proposed by Bradley et al (2008), is that the excitation light is brought to the tissue by the same fiber used for light collection, instead of using a diffuse source to light a large surface of the brain. In our case, the excitation volume is limited to the tip of the fiber because the diameter of the excited area is comparable to the diameter of the optical probe (Dufour et al, 2009), and this considerably reduces the background fluorescence that can be collected by the optical probe.…”

“…In 2006 we proposed the use of tapered waveguides to sense ionic fluctuations and mentioned the possibility to join this technique to electrophysiological measurements in vivo (Dufour et al, 2006). Bradley et al (2008) have recently described a micro-optrode for simultaneous extracellular field potential (FP) and intracellular fluorescent recordings.…”

A glass-coated tungsten microelectrode enclosing optical fibers for optogenetic exploration in primate deep brain structures

“…Fiber-optic fluorescence detection system EYFP expression was examined in vivo by fluorescence measurements via the optical fiber (Bradley et al, 2008;Diester et al, 2011). For the excitation, three of four optical fibers of the optrode were connected to the 473 nm laser system described previously and a train of light pulses was applied (200 ms pulse duration, 0.5 Hz; 110-220 W at input, kept constant during the sessions).…”