MAPT and tauopathy: Human tau isoform-specific phenotypes in vivo have been described mostly in Drosophila tauopathy models by assessing neuronal function (including axonal transport, locomotor behavior, synaptic function, olfactory learning and memory) [20,21,22] and cell loss/toxicity during development (photoreceptor neuron and mushroom body neuron loss), or in adult animals (elevated oxidative stress, shortened lifespan) [22,23,24].