However some technical challenges still need to be taken to make the technology more accessible and usable to its full potential: gaining selective and comprehensive genetic access to the neurons of interest, controlling variation in the expression of the optogenetic tools (when using viruses) and its precise localization (
axon vs. presynaptic terminals), tailoring light - delivery system signals to individual cells in a population rather than the population
as a whole, developing observation techniques which have the
same spatial and temporal resolution
as those tools... to cite only a few of them.