Miniature micro-endoscope

* Custom microendoscopes that were chronically implanted and performed long-term simultaneous bilateral imaging of hippocampal activity in freely moving mice
* More sensitive CMOS sensor in the microscope

* Implanted bilateral microendoscopes in transgenic mice to image the activity of pyramidal neurons in the hippocampus over weeks

* High sensitivity
* Low illumination intensity minimizes damage and allows robust continuous recording of neuronal activity for up to an hour
* Low cost facilitates chronic implants and minimize motion artifacts across days

* Spatial footprint of extracted neurons using microendoscopes can suffer from artifacts arising from changes in firing rates, extraction algorithms, and motion correction artifacts

Gonzalez et al. 2019, Persistence of neuronal representations through time and damage in the hippocampus, Science 365: 821-825

https://science.sciencemag.org/content/365/6455/821.long

https://www.caltech.edu/about/news/how-memories-form-and-fade

* Animals underwent unilateral or bilateral surgeries to implant 1.8 mm GRIN lenses directly dorsal to CA1. The glue covering the GRIN lens was removed and a microendoscope was aligned with the
30 GRIN lens. The miniature microscopes were connected to a portable computer which provided live view of the fluorescence image though the endoscopic lens and guided the final alignment and focal plane of the microscope and lens. The microscope was permanently attached to the implant with dental acrylic and the focal sliding mechanism on the microendoscope was sealed with superglue
* Signal from the microendoscope CMOS sensor was acquired thought a UVC compliant USB analog video to digital converter