I had COVID for the first time the other week. Was totally fine other than I lost my sense of smell.
Never realised how much I use it!
- Cleaning the bathroom. I did not realise I was inhaling bleach until my sinuses started burning painfully.
- My wife came home and said "it kinda smells in here"... I was mortified! Usually I crack open windows for fresh air, but I couldn't smell anything so didn't bother.
- I couldn't sniff-test clothes to see if they needed a wash.
- Sanding. You know how sometimes the paper gets worn/clogged and doesn't sand as well? I usually smell a bit of sawdust as I'm sanding, which signals to me it's sanding OK.
- Are these leftovers ok ...?
- My cat made a fart noise next to me. Did it fart? Not sure. Was I breathing in concentrated cat-fart gas unknowingly?
- Taste! Everything tasted bland. I tested this by eating a tablespoon of horse radish and a whole chilli. Nothing!
- Sometimes the neighbour's chimney blows smoke directly onto our house. When I smell it I close the windows. I couldn't smell it, so the whole house filled with smoke before I realised!
- Didn't know my toast was burning.
- I avoided painting things because I wouldn't know if I were inhaling harmful fumes (a signal to adjust my mask or move my face away from what I'm painting).
My sense of smell did return after a week or so though.
An upside was that I was unbothered when my morning walk coincided with the garbage truck doing its weekly route.
I also did enjoy intentionally putting pungent things up to my nose and exclaiming to my wife "Look! I can't smell this!!!" She got sick of that pretty quickly.
"Every molecule will activate a combination of receptors. To give a hypothetical example, vanillin may activate receptors 73, 115 and 299, the activation of the receptor combination 73, 115, 299 therefore signals to the brain that vanillin molecules are being encountered. This is known as the “combinatorial code” of olfaction: each type of odor molecule activates several receptors, and each receptor is activated by several types of odor molecules, resulting in a unique combination of activated receptors for each type of odor molecule."
I thoroughly enjoyed the article, but I do tire of the “hundreds of olfactory receptors Vs JUST THREE colour receptors” trope. Perception of EMR is fundamentally simpler (just two receptors could do it, one at either end of the spectrum).
Smell is fundamentally more complex, which is, I suppose, the point, but I feel that the naked repetition of the trope harms articles such as these, where acknowledging the physical complexity directly, without the trope, might better serve.
What I take from that was the interesting point that you can take a principled approach about what "correct colour perception" means. But there's no such stable basis for deciding that with olfaction given that it seems like an ad-hoc jumble of molecules to sense and there's such a wide and, seemingly random, variety of gene variants in the gene pool.
I believe that it was meant that each of the 2 receptors is not tuned to a single frequency, but its spectral transfer function must have an approximately triangular shape, with the peak at the nominal frequency, and the slope of the spectral transfer function must be such that the transfer function does not become null before reaching the nominal frequency of the second receptor.
In such a case, it is possible to determine both the amplitude and the frequency of any electromagnetic radiation, e.g. light, with a frequency intermediate between the 2 peak frequencies of the receptors, from the 2 values provided by the 2 receptors.
However spectral transfer functions of such a shape can be approximated only in a narrow bandwidth. Therefore both in animal vision and in artificial vision, a larger number of receptors must be used to cover a large bandwidth, with approximately equal spacings between their peak frequencies, in order to be able to determine not only the intensity but also the color (i.e. the frequency) of incoming light.
>In such a case, it is possible to determine both the amplitude and the frequency of any electromagnetic radiation, e.g. light, with a frequency intermediate between the 2 peak frequencies of the receptors, from the 2 values provided by the 2 receptors.
Is it? How would you distinguish between monospectral illumination at a frequency between the two peaks and lower amplitude polyspectral illumination at each of the peaks? That ambiguity is essentially the basis of rgb displays.
Ah, I lost sense of smell last week due to Covid. And it only bothered me yesterday while frying onion and garlic and not being able to smell. Though food turned out alright and tasted fine. It's still weird on not being able to smell and knowing how it should have smelled.
I never realized this until I first took a break, but regular coffee intake has severely blunted my sense of smell. After about three days of abstinence, everything has an attention-grabbing smell in a way I never realized I had been missing out on for years.
Fascinating...perfumeries will often have coffee beans for people to "cleanse their palate" before smelling another perfume. I'm not sure how it works, I guess I'd assume you'd have better smell after having coffee, but I really know very little about biochem and will trust your anecdote until I hear otherwise :-)
I suspect it's due to the chemical properties of caffeine and not the smell of coffee. There are plenty of reports like mine for all kinds of stimulants.
Never realised how much I use it!
My sense of smell did return after a week or so though.An upside was that I was unbothered when my morning walk coincided with the garbage truck doing its weekly route.
I also did enjoy intentionally putting pungent things up to my nose and exclaiming to my wife "Look! I can't smell this!!!" She got sick of that pretty quickly.