Summary
A bioRxiv preprint describes iFLiP, a low-cost fiber photometry system using off-the-shelf components to measure fluorescence lifetime. The researchers report demonstrations tracking protein kinase A activity in cells and mice, including measurements over multiple days.
Researchers at Oregon Health & Science University describe iFLiP, a fiber photometry system designed to make fluorescence-lifetime measurements simpler and less expensive for neuroscience research. In a bioRxiv preprint, they report that the system uses off-the-shelf components, comes with software for routine operation and can track lifetime changes at rates of up to 5,000 Hz over periods of days.
The team used iFLiP to monitor protein kinase A (PKA) activity in laboratory experiments and in mice. They report that locomotion was associated with distinct PKA dynamics in different striatal subregions and cell types. Continuous, multi-day measurements in the basal forebrain also revealed PKA activity associated with sleep and wakefulness.
Measuring fluorescence lifetime
Fiber photometry collects fluorescent signals through an optical fiber placed near the tissue of interest. Many systems quantify changes in brightness. Lifetime photometry instead measures how long fluorescence persists after a molecule is excited. For sensors designed to change this lifetime with a biological signal, the measurement can help quantify ongoing activity and track changes over time—two challenges the researchers identify for intensity-based methods.
The distinction matters when interpreting iFLiP’s biological demonstrations: PKA is an intracellular signaling enzyme, so these measurements follow molecular signaling rather than directly recording electrical spikes from neurons. The reported locomotion and sleep/wake findings are associations with PKA activity, not evidence that PKA caused those behaviours.
What the system demonstrated
The preprint describes iFLiP as a system that can be assembled without specialised expertise, alongside software intended to make operation straightforward. Its reported measurement rate and multi-day operation are relevant to experiments that need to follow biochemical signals over time, rather than capture only brief changes. The abstract reports demonstrations in vitro and in vivo, but does not state animal counts, detailed protocols or numerical effect estimates.
The work is a preprint. Its authors also disclose that Haining Zhong founded Lake Photon PDX LLC, which is licensed by OHSU to produce a commercial version of iFLiP; the disclosure says OHSU manages this interest.