Limits...
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.

Show MeSH

Related in: MedlinePlus

Impact of fluorescence collection through the microprobe walls.A1) Schematics of the coated and uncoated microprobe descents into fluorescent agar. A2) Fluorescence measurements for different penetration depths into fluorescent agar for bare (green) and coated (white) probes (n = 5 probes; 1°<θ <3°)). B) Effect of the coating on the fluorescence DC level when a bare (green) or a coated (black) probe is lowered into cortex and thalamic issue. Arrows show location of fluorescent cells (inset: representation of the probe displacement).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585187&req=5

pone-0057703-g005: Impact of fluorescence collection through the microprobe walls.A1) Schematics of the coated and uncoated microprobe descents into fluorescent agar. A2) Fluorescence measurements for different penetration depths into fluorescent agar for bare (green) and coated (white) probes (n = 5 probes; 1°<θ <3°)). B) Effect of the coating on the fluorescence DC level when a bare (green) or a coated (black) probe is lowered into cortex and thalamic issue. Arrows show location of fluorescent cells (inset: representation of the probe displacement).

Mentions: To ascertain the value of coating the probes with a reflective film, we measured experimentally the impact of fluorescence collection through the microprobe wall. For this, we measured fluorescence collected from coated versus uncoated probes as they were dipped into a uniform fluorescent medium. For uncoated probes, the fluorescence increased as a function of the penetration depth whereas this was not the case for the coated probes (Fig. 5a). Thus Al coating effectively prevents fluorescent signal contamination from the side of the microprobe. We then tested fluorescence changes as the microprobe is advanced through tissue containing individual labeled cells. Transient rise and decay in fluorescence occurred as the probe passed by labeled cells as previously described [2]. These transients were similar with the coated and uncoated probes. However, wall collection caused a gradual shift in the signal DC level with the bare probes (Fig. 5b). In a static protocol, where the probe position is maintained and fluorescence is used to measure functional events such as fluctuations in ionic concentration, wall collection must be considered when choosing the experimental conditions (e.g., labeling volume and sparseness, probe tapering angle). The coating also helps minimize photobleaching and photodamage due to light escaping from the side of the probe. In contrast, the presence of coating does not improve individual cell detection when using the dynamic vertical scanning protocol described previously [2].


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)

Impact of fluorescence collection through the microprobe walls.A1) Schematics of the coated and uncoated microprobe descents into fluorescent agar. A2) Fluorescence measurements for different penetration depths into fluorescent agar for bare (green) and coated (white) probes (n = 5 probes; 1°<θ <3°)). B) Effect of the coating on the fluorescence DC level when a bare (green) or a coated (black) probe is lowered into cortex and thalamic issue. Arrows show location of fluorescent cells (inset: representation of the probe displacement).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0057703-g005: Impact of fluorescence collection through the microprobe walls.A1) Schematics of the coated and uncoated microprobe descents into fluorescent agar. A2) Fluorescence measurements for different penetration depths into fluorescent agar for bare (green) and coated (white) probes (n = 5 probes; 1°<θ <3°)). B) Effect of the coating on the fluorescence DC level when a bare (green) or a coated (black) probe is lowered into cortex and thalamic issue. Arrows show location of fluorescent cells (inset: representation of the probe displacement).
Mentions: To ascertain the value of coating the probes with a reflective film, we measured experimentally the impact of fluorescence collection through the microprobe wall. For this, we measured fluorescence collected from coated versus uncoated probes as they were dipped into a uniform fluorescent medium. For uncoated probes, the fluorescence increased as a function of the penetration depth whereas this was not the case for the coated probes (Fig. 5a). Thus Al coating effectively prevents fluorescent signal contamination from the side of the microprobe. We then tested fluorescence changes as the microprobe is advanced through tissue containing individual labeled cells. Transient rise and decay in fluorescence occurred as the probe passed by labeled cells as previously described [2]. These transients were similar with the coated and uncoated probes. However, wall collection caused a gradual shift in the signal DC level with the bare probes (Fig. 5b). In a static protocol, where the probe position is maintained and fluorescence is used to measure functional events such as fluctuations in ionic concentration, wall collection must be considered when choosing the experimental conditions (e.g., labeling volume and sparseness, probe tapering angle). The coating also helps minimize photobleaching and photodamage due to light escaping from the side of the probe. In contrast, the presence of coating does not improve individual cell detection when using the dynamic vertical scanning protocol described previously [2].

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