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

Up to page 5.

Well written, fulfilling to read. Which has more than made up for the distress of reading about the destruction wrought by alcoholism on the characters introduced.

Let's have a poll about sensory perception and how we experience smells, aromas & scents.

" ... and the smell of wood smoke is articulate in the air." O. Liang

#TheTripToEchoSpring #Olfaction #Smell #Alcoholism

@raulinbonn @foo__ @compoundchem

having meanwhile discovered WP has stubs on old_person_smell and 2-nonenal, I'm really on this one.

decades ago, whilst giving an older person a massage, I noticed their odour, and likened it to that of ham. I had been a vegan for many years at the time.

Since then, I've noticed it in many older people, and now myself occasionally too, though I've not eaten cured meat for 60 years, but do eat tiny amounts of fresh meat now.

Any other opinions on whether "ham" smell is a component of old_person_smell?

beyond the fatty-acid oxidation explanation, gut-wall permeability changes and liver function decrease are factors that seem relevant.

#olfaction #gerentology

@randahl

Smellosophy by A. S. Barwich. 2020

What the Nose Tells the Mind

A pioneering exploration of olfaction that upsets settled notions of how the brain translates sensory information.
Decades of cognition research have shown that external stimuli “spark” neural patterns in particular regions of the brain.

#books
#nonfiction
#smell
#olfaction
#brain
#neuroscience

@randahl re #smell:

Smell by Matthew Cobb, 2020

Our sense of smell—or olfaction as it is technically known—is our most enigmatic sense. It can conjure up memories, taking us back to very specific places and emotions, whilst powerful smells can induce strong feelings of hunger or nausea. In the animal kingdom smell can be used to find food, a mate, or a home; to sense danger; and to send and receive complex messages with other members of a species.

#books
#nonfiction
#olfaction