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SummaryAccurately predicting an outcome requires that animals learn supporting and conflicting evidence from sequential experience. In mammals and invertebrates, learned fear responses can be suppressed by experiencing predictive cues without punishment, a process called memory extinction. Here, we show that extinction of aversive memories in Drosophila requires specific dopaminergic neurons, which indicate that omission of punishment is remembered as a positive experience. Functional imaging revealed co-existence of intracellular calcium traces in different places in the mushroom body output neuron network for both the original aversive memory and a new appetitive extinction memory. Light and ultrastructural anatomy are consistent with parallel competing memories being combined within mushroom body output neurons that direct avoidance. Indeed, extinction-evoked plasticity in a pair of these neurons neutralizes the potentiated odor response imposed in the network by aversive learning. Therefore, flies track the accuracy of learned expectations by accumulating and integrating memories of conflicting events.

MINFLUX offers a breakthrough in single molecule localization precision, but is limited in fieldof-view. Here, we combine centroid estimation and illumination pattern induced photon count variations in a conventional widefield imaging setup to extract position information over a typical micron sized field-of-view. We show a near twofold improvement in precision over standard localization with the same photon count on DNA-origami nano-structures and tubulin in cells, using DNA-PAINT and STORM imaging. Single-molecule localization microscopy 1,2,3 circumvents the diffraction limit using centroid estimation of sparsely activated, stochastically switching, single-molecule fluorescence images. Improvement over state-of-the-art image resolutions of around 20 nm towards values below 5 nm is desired for truly imaging at the molecular scale. This needs improvements in labelling strategy to reduce linker sizes 4,5,6,7 and methods to overcome low labelling density such as data fusion 8 , but also a step in localization precision. Efforts so far have targeted an increase in the number of detected photons N by chemical engineering of brighter fluorophores 9 , or by avoiding photo-bleaching via e.g. cryogenic techniques 10,11,12. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Single-particle imaging in budding yeast demonstrates that mRNP export is fast (∼200 ms) and that mRNPs are retained at NPCs and undergo retrograde transport in a mex67-5 mutant, proving an essential role for Mex67p in directional mRNP transport.