Tag Archives: fiberoptics

A multimodal micro-optrode

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

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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

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