This is indeed an interesting topic. Especially in high numerical aperture objectives incredible things are possible. One can put a diffractive optical element

This is indeed an interesting topic. Especially in high numerical aperture objectives incredible things are possible. One can put a diffractive optical element infront of the sensor and obtain 25 instantaneous images, each at a different depth. http://waf.eps.hw.ac.uk/research/live_cell_imaging.html http://waf.eps.hw.ac.uk/research/live_cell_imaging.html Couple this with high resolution techniques and your at the current research front and could possibly solve the question: What happens in a synapse? It is theoretically possible to image at 40nm resolution with 100fps and therefore see the transport of vesicles. One can expect important discoveries on how the brain works using these techniques.