Development of a micro-imaging probe for functional brain imaging

Multicellular neuronal activities should be investigated to reveal the dynamics of the neuronal circuit. Optical recording from neuronal populations is suitable for recording multicellular activities. We fabricated the prototype of the micro-imaging probe in combination with a gradient index lens and image fiber. This probe has a smaller diameter than traditional probes. We found an optimal optical configuration for maximizing the efficiency of the imaging probe. Using this optical configuration with the prototype of the imaging probe, the fluorescence images were captured from neurons expressing green fluorescent protein in a cerebellar block preparation, and the calcium-dependent images were sampled in a mouse brain slice preparation. Our optical system would facilitate the in vivo imaging studies with less invasive manners using thinner optic fiber than previously made.

► We developed a micro-imaging probe for multicellular imaging.
► The micro-imaging probe is composed of a gradient index lens and image fiber.
► We found an optimal optical configuration.
► This probe could detect the fluorescence of GFP with high spatial resolution.
► This probe was able to record evoked calcium elevation in putative neurons.