Functional characterization of the response properties of V1 neurons during a perceptual learning task measured by two-photon calcium imaging
Final Report Abstract
The goal of this project was to apply the technique of measuring the activity of neurons in awake animals using optical tools in a non-human primate. This technique has previously been established in mice and the laboratory this work has now been performed in has high expertise in work in non-human primates. The combination of those two aspects has been proven to be a difficult task, as was previously expected. This has not been done before by any other researcher. However progress could be made in several aspects. The AAV delivery system used to label neurons over long periods of time could be improved to generate a more physiological preparation. The surgical procedures and cranial implants required to access the cortex repetitively over weeks has been improved to now enable a optically clearer and sealed chamber. The microscope instrumentation has been improved to have the high sensitivity and optical resolution needed to see small changes in fluorescence on a small spatial scale. And other model systems have been developed to compare and find the right activity sensor suitable for the needs as well as to find biological analogs between mice and macaque monkeys. It is now possible to continuously collect imaging data from an awake non-human primate sitting in a chair ready to perform behavioral task. Labeled neurons can be recorded from over several weeks with several sessions per week. The expression time of those sensor proteins has been reduced from 3 months to 4 weeks. The task remaining now is to find the right calcium indicator protein that serves as our activity reporter. This sensor has to match our needs in sensitivity and signal to noise levels. At this stage we are screening existing sensors and are cloning several novel indicators and preparing AAV vectors, which will all be assesses in our alternative mouse models in the months to come. When we find one sensor that is suitable it should be possible to combine all those progresses made during the funding period to conclude the project and open several other possibilities, both, in the non-human primate as well as the mouse. So far this project has not yet reached the data yielding phase for publications as so many technical aspects had to be improved and modified. However, we are now close to be at the stage where we can obtain data in both, non-human primates as well as mice. As the focus on both is to study the effect learning has on the neuronal interplay, it should be exiting to obtain the first findings for each species, as well as comparing what might make a monkey brain better at learning than a mouse brain.
