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A multimodal micro-optrode combining field and single unit recording, multispectral detection and photolabeling capabilities.

Dufour S, Lavertu G, Dufour-Beauséjour S, Juneau-Fecteau A, Calakos N, Deschênes M, Vallée R, De Koninck Y - PLoS ONE (2013)

Bottom Line: Here, we describe a, aluminum-coated, fibre optic-based glass microprobe with multiple electrical and optical detection capabilities while retaining tip dimensions that enable single cell measurements (diameter ≤10 µm).It also enables color conversion of photoswitchable fluorescent proteins, which can be used for post-hoc identification of the recorded cells.The extended range of functionalities provided by the same microprobe thus opens several avenues for multidimensional structural and functional interrogation of single cells and their surrounding deep within the intact nervous system.

View Article: PubMed Central - PubMed

Affiliation: Unité de neurosciences cellulaires et moléculaires, Institut universitaire en santé mentale de Québec, Québec, Québec, Canada.

ABSTRACT
Microelectrodes have been very instrumental and minimally invasive for in vivo functional studies from deep brain structures. However they are limited in the amount of information they provide. Here, we describe a, aluminum-coated, fibre optic-based glass microprobe with multiple electrical and optical detection capabilities while retaining tip dimensions that enable single cell measurements (diameter ≤10 µm). 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. While metal coating did not significantly improve the optical separation capabilities of the microprobe, the combination of metal on the outside of the probe and of a hollow core within the fiber yields a microelectrode enabling simultaneous single unit and population field potential recordings. The extended range of functionalities provided by the same microprobe thus opens several avenues for multidimensional structural and functional interrogation of single cells and their surrounding deep within the intact nervous system.

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Related in: MedlinePlus

Optical and electrical microprobes.a) Schematic representation of the probe (left) and a metal coated probe adapted to achieve large field recording through the Al coating (middle: 3D representation, right: transverse cut view). Insets are scanning electron microscopy images of the respective electrode tips (scale bars are 2 µm). b) Experimental setup for multispectral detection showing : (1) 543 nm laser (25-LGR-193-249, Melles Griot), (2) 488 nm laser (FCD488 24 mW, JDS Uniphase Corporation), (3) shutters (LS3,Uniblitz), (4) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (5) multiline dichroic mirror (51015bs, Chroma Technology Corporation), (6) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (7) PMT detectors (H6780-20, Hamamatsu) and bandpass filters (ET520/40M and ET005/52M, Chroma Technology Corporation) and (8) objective (UIS-2 Plan-N, NA = 0.25, Olympus Corporation) and the fibre optic launch system (KT110, Thorlabs Inc.).
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pone-0057703-g001: Optical and electrical microprobes.a) Schematic representation of the probe (left) and a metal coated probe adapted to achieve large field recording through the Al coating (middle: 3D representation, right: transverse cut view). Insets are scanning electron microscopy images of the respective electrode tips (scale bars are 2 µm). b) Experimental setup for multispectral detection showing : (1) 543 nm laser (25-LGR-193-249, Melles Griot), (2) 488 nm laser (FCD488 24 mW, JDS Uniphase Corporation), (3) shutters (LS3,Uniblitz), (4) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (5) multiline dichroic mirror (51015bs, Chroma Technology Corporation), (6) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (7) PMT detectors (H6780-20, Hamamatsu) and bandpass filters (ET520/40M and ET005/52M, Chroma Technology Corporation) and (8) objective (UIS-2 Plan-N, NA = 0.25, Olympus Corporation) and the fibre optic launch system (KT110, Thorlabs Inc.).

Mentions: Probes were made from tapered dual core optical fibre designed in collaboration with the INO (Québec, Canada, http://www.ino.ca). Schematics of the probes are shown in Fig. 1a. and fabrication details were given elsewhere [2]. Briefly, the probe is made from a tapered multimode fibre that combines an optical core for optical illumination and detection as well as a hollow core serving as an electrode Probes tips were cleaved to a diameter of 10 microns, were filled with 2 M NaCl and connected to the optical setup via a relay fibre (Fig. 1b). In some experiments, an aluminum (Al) coating (100 nm) was evaporated on the probe shoulder and shank using a vacuum metal evaporation system. Aluminum was chosen to act both as an optical reflector and an electrical conductor to prevent optical losses through the tapered region and allow electrical recording. Its resistance to oxidation yielded more stable optical and electrical properties. A 100 µm diameter stainless steel wire was attached to the coating with silver epoxy (H2OE, Epoxy Technology). Conductive metallic films were isolated with UV curing adhesive (NOA81, Norland products). Only 100–250 µm at the tip of the probe remained uncovered to serve as an electrode. A dual wavelength detection system was used to differentiate labeled cell types on the basis of their fluorescence spectrum. The optical setup used with the probe and its components is described in Fig. 1b. Photomultiplier tube (PMT) detector outputs were amplified (Gain = 0.5 to 10), filtered (10 Hz low pass, Model 440, Brownlee Precision Co.) and stored on disk.


A multimodal micro-optrode combining field and single unit recording, multispectral detection and photolabeling capabilities.

Dufour S, Lavertu G, Dufour-Beauséjour S, Juneau-Fecteau A, Calakos N, Deschênes M, Vallée R, De Koninck Y - PLoS ONE (2013)

Optical and electrical microprobes.a) Schematic representation of the probe (left) and a metal coated probe adapted to achieve large field recording through the Al coating (middle: 3D representation, right: transverse cut view). Insets are scanning electron microscopy images of the respective electrode tips (scale bars are 2 µm). b) Experimental setup for multispectral detection showing : (1) 543 nm laser (25-LGR-193-249, Melles Griot), (2) 488 nm laser (FCD488 24 mW, JDS Uniphase Corporation), (3) shutters (LS3,Uniblitz), (4) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (5) multiline dichroic mirror (51015bs, Chroma Technology Corporation), (6) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (7) PMT detectors (H6780-20, Hamamatsu) and bandpass filters (ET520/40M and ET005/52M, Chroma Technology Corporation) and (8) objective (UIS-2 Plan-N, NA = 0.25, Olympus Corporation) and the fibre optic launch system (KT110, Thorlabs Inc.).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585187&req=5

pone-0057703-g001: Optical and electrical microprobes.a) Schematic representation of the probe (left) and a metal coated probe adapted to achieve large field recording through the Al coating (middle: 3D representation, right: transverse cut view). Insets are scanning electron microscopy images of the respective electrode tips (scale bars are 2 µm). b) Experimental setup for multispectral detection showing : (1) 543 nm laser (25-LGR-193-249, Melles Griot), (2) 488 nm laser (FCD488 24 mW, JDS Uniphase Corporation), (3) shutters (LS3,Uniblitz), (4) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (5) multiline dichroic mirror (51015bs, Chroma Technology Corporation), (6) 495 nm dichroic mirror (495DCLP, Chroma Technology Corporation), (7) PMT detectors (H6780-20, Hamamatsu) and bandpass filters (ET520/40M and ET005/52M, Chroma Technology Corporation) and (8) objective (UIS-2 Plan-N, NA = 0.25, Olympus Corporation) and the fibre optic launch system (KT110, Thorlabs Inc.).
Mentions: Probes were made from tapered dual core optical fibre designed in collaboration with the INO (Québec, Canada, http://www.ino.ca). Schematics of the probes are shown in Fig. 1a. and fabrication details were given elsewhere [2]. Briefly, the probe is made from a tapered multimode fibre that combines an optical core for optical illumination and detection as well as a hollow core serving as an electrode Probes tips were cleaved to a diameter of 10 microns, were filled with 2 M NaCl and connected to the optical setup via a relay fibre (Fig. 1b). In some experiments, an aluminum (Al) coating (100 nm) was evaporated on the probe shoulder and shank using a vacuum metal evaporation system. Aluminum was chosen to act both as an optical reflector and an electrical conductor to prevent optical losses through the tapered region and allow electrical recording. Its resistance to oxidation yielded more stable optical and electrical properties. A 100 µm diameter stainless steel wire was attached to the coating with silver epoxy (H2OE, Epoxy Technology). Conductive metallic films were isolated with UV curing adhesive (NOA81, Norland products). Only 100–250 µm at the tip of the probe remained uncovered to serve as an electrode. A dual wavelength detection system was used to differentiate labeled cell types on the basis of their fluorescence spectrum. The optical setup used with the probe and its components is described in Fig. 1b. Photomultiplier tube (PMT) detector outputs were amplified (Gain = 0.5 to 10), filtered (10 Hz low pass, Model 440, Brownlee Precision Co.) and stored on disk.

Bottom Line: Here, we describe a, aluminum-coated, fibre optic-based glass microprobe with multiple electrical and optical detection capabilities while retaining tip dimensions that enable single cell measurements (diameter ≤10 µm).It also enables color conversion of photoswitchable fluorescent proteins, which can be used for post-hoc identification of the recorded cells.The extended range of functionalities provided by the same microprobe thus opens several avenues for multidimensional structural and functional interrogation of single cells and their surrounding deep within the intact nervous system.

View Article: PubMed Central - PubMed

Affiliation: Unité de neurosciences cellulaires et moléculaires, Institut universitaire en santé mentale de Québec, Québec, Québec, Canada.

ABSTRACT
Microelectrodes have been very instrumental and minimally invasive for in vivo functional studies from deep brain structures. However they are limited in the amount of information they provide. Here, we describe a, aluminum-coated, fibre optic-based glass microprobe with multiple electrical and optical detection capabilities while retaining tip dimensions that enable single cell measurements (diameter ≤10 µm). 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. While metal coating did not significantly improve the optical separation capabilities of the microprobe, the combination of metal on the outside of the probe and of a hollow core within the fiber yields a microelectrode enabling simultaneous single unit and population field potential recordings. The extended range of functionalities provided by the same microprobe thus opens several avenues for multidimensional structural and functional interrogation of single cells and their surrounding deep within the intact nervous system.

Show MeSH
Related in: MedlinePlus