Now diving into the processing and transformation of raw olfactory stimulation of sensory neurons to the output of the olfactory neuropils via projection neurons, see these two papers, one in fly and one in zebrafish. The former shows how PNs respond to the derivative of the input, which is essential for tracking stimuli up a gradient, and the latter shows how the LNs perform a whitening of the olfactory input (to decorrelate the inputs into the otherwise multiply stimulated olfactory receptors and their corresponding sensory neurons) which optimally prepares similar stimuli for separation:

Kim AJ, Lazar AA, Slutskiy YB. Projection neurons in Drosophila antennal lobes signal the acceleration of odor concentrations. Elife. 2015 May 14;4:e06651.
https://elifesciences.org/articles/6651

Wanner AA, Friedrich RW. Whitening of odor representations by the wiring diagram of the olfactory bulb. Nature neuroscience. 2020 Mar;23(3):433-42.
https://www.nature.com/articles/s41593-019-0576-z

4/4

#neuroscience #olfaction #Drosophila #mouse #zebrafish

And in flies in particular, all papers signed by Rachel Wilson as the senior author (now a professor at Harvard Medical School) in the early 2000s are absolutely outstanding, on probing with electrophysiology and genetics the various synapses in the fruit fly olfactory system, e.g., the sensory neuron (ORN or OSN, synonyms) to the projection neurons (PNs), or the local neurons (LNs), or the LNs to each other or to the PNs, and the PNs back to the LNs. She's written a couple of reviews on the subject that are very accessible for the curious student.

Click on "Publications" and expand them, to find the ones published in Current Opinion in Neurobiology or in the Annual Review Neuroscience:
https://neuro.hms.harvard.edu/faculty-staff/rachel-wilson

... like e.g., this one:
Wilson RI. Early olfactory processing in Drosophila: mechanisms and principles. Annual review of neuroscience. 2013 Jul 8;36(1):217-41.
https://www.annualreviews.org/content/journals/10.1146/annurev-neuro-062111-150533

Rachel's more recent work is on neural networks in the fly for spatial navigation.

3/4

#neuroscience #olfaction #Drosophila #mouse #zebrafish

On that, the work from Lucia Prieto-Godino in (then) Richard Benton's lab on "undead" neurons is critical, demonstrating that, beyond the genes encoding olfactory receptors, there is a much larger pool of pseudogenes (genes that aren't normally expressed) that, when rescued, result in additional, distinct yet functional glomeruli in the first-order neuropil for olfaction (the antennal lobe in an insect; the olfactory bulb in a vertebrate).

Prieto-Godino LL, Silbering AF, Khallaf MA, Cruchet S, Bojkowska K, Pradervand S, Hansson BS, Knaden M, Benton R. Functional integration of “undead” neurons in the olfactory system. Science advances. 2020 Mar 11;6(11):eaaz7238.
https://www.science.org/doi/abs/10.1126/sciadv.aaz7238

Lucia is now a lab head at The Crick, studying with comparative connectomics the evolution of olfactory circuits and more, in fruit flies.

2/4

#neuroscience #olfaction #Drosophila #mouse #zebrafish

Very amusing to see how the vertebrate developmental neurobiology field is converging with #Drosophila and insects in general with regard to the mechanisms of brain development:

"Together, these findings suggest a lineage-based mechanism for scalable positional information that complements diffusion-based mechanisms and offers a general framework for tissue patterning."

That sentence has been used for decades to describe fruit fly brain development.

#neurobiology #DevBiol #zebrafish #mouse