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14

There are only three kinds of optical receptors in the eye, but more than 900 kinds of olfactory receptors. Thus you can encode pictures with the three primary colors, but there is no small set of primary scents. To transmit a smell via "primary scents", you'd have to create an artificial nose that monitors the response of each of the olfactory receptors, ...


14

A quick diagram to point out to people who may not know what Eustachian tubes are (#2). In order for the aromatic molecule to reach the olfactory bulb, it would first have to get through the Tympanic Membrane (#22) [a.k.a. - Eardrum]. The Tympanic Membrane is water/airtight unless pierced. So, while it's plausible that an aromatic molecule could travel ...


13

Cats and dogs can both view tv screens & monitors ... though their viewing experience is a little different to ours thanks to differences in cone structure leaving them color blind and giving low acuity. Both species have lower levels of color vision than humans. Cats see slightly more color (in the blue green and yellow end of the spectrum) than dogs ...


10

To quote the University of Sidney site: People often think that other people are staring at them even when they aren't research led by the University of Sydney has found. When in doubt, the human brain is more likely to tell its owner that they're under the gaze of another person, researchers from the University of Sydney and The Vision Centre ...


8

Shampoo contains surfactants, chemicals which cause lipids to emulsify. The cell membrane is composed primarily of phospholipids, which are vulnerable to action by surfactants. In fact, sodium dodecyl sulphate (SDS, often labelled SLS on shampoo bottles), an integral component of many shampoos is also used in the lab (albeit at substantially higher ...


8

In expansion to biocs' excellent answer, I would like to highlight some practical limitations of this. Suppose we did manage to create a huge database of exact chemical mixtures which produce all smells recognisable by humans. You would still meet some complications: The output device (analogous to headphones or screen) would either need to be able to ...


8

Short answer Butterflies can see behind them. Background Merry et al. (2006) have estimated the field of view of the butterfly, by investigating the Orange Sulphur butterfly (Colias eurytheme): Colias eurytheme. Source: Massachusetts Butterfly Club The authors found that this butterfly has a very large visual field, encompassing 93% of the spherical ...


8

Short answer In terms of visual function, the low-tier primary visual cortex and high-tier frontal cortex are inactivated. The activity of the intermediate ventral stream and limbic regions are increased, apparently uncoupling low- and high-level vision processing from the system. Background The sleep stage where visualizations (dreaming) occur is called ...


7

In this instance, I would say your attention has been adjusted, not your ear's ability to perceive sound. Our ears don't have a control setting or a means of adjusting incoming sound levels (though I'm certain when an ambulance with loud siren drives by, we all wish we did). What you are experiencing is a prioritization of the sound by your brain in ...


7

First of all one should tell that one can attribute the activation of certain brain zones with some indepent events only when the activation takes place along the signal input (receptors, sensory pathways towards the cortex and the sensory areas in cortex) or motor action (=output) (along the motox cortex => motor neuron => target organ). Those zones in ...


7

In short, it's because your brain processes external and self-produced stimuli differently. If someone tickles you, you feel that ticklish feeling, but when trying to tickle yourself, there is a reduction in the sensation. When you are tickled by someone, a part of your brain activates causing you to laugh, etc., but it seems that when you trying tickling ...


7

Electrical currents stimulate neurons aspecifically. For example, the BrainPort artificial vision device conveys information through electrical stimuluation of the tongue. Similarly, cochlear implants and retinal implants convey information through electrical stimulation of the inner ear and retina, respectively. The list goes on. Bottom line is, none of ...


6

Short answer Proprioceptic receptors provide a feedback mechanism from the body to the brain, telling the brain what our limbs are doing and where they are with respect to the body without visual feedback being needed. Background Muscles, skin and joints contain proprioceptic receptors. They sense position and movement of our limbs and trunk, they register ...


6

Short answer Echolocating bats have relatively large sensory epithelia in their inner ear, that may correlate with their high upper frequency limit of up to 200 kHz. The basilar membrane is thinner and stiffer, possibly allowing it to decode higher frequencies. Background In terms of the place theory of hearing, the cochlea acts as a frequency transformer, ...


5

Earwax, also called cerumen, is slightly acidic (1), with a pH of about 6, and acidic foods or substances taste sour. The composition of earwax, upon which its taste depends, is related to its functions. Earwax aids in cleaning and lubrication of the ear canal and has an antimicrobial effect. The antimicrobial effect is in part attributed to its acidity, ...


5

@MCM gave a succinct and accurate description of how a healthy and "normal" person will not be able to smell via olfactory sensing trough the Eustachian tube. Here is an interesting concept in which the brain is able to confuse senses, or alternatively, use sensory input as a metaphor for interpretation via another sensory output. This is a condition known ...


5

Short answer Temperature differences of 0.02 degrees Celcius can be distinguished, dependent on various factors including experimental conditions and bodily location. Background The ability to discriminate temperature differences depends on whether it is a cooling or heating pulse, the skin temperature, the duration of the temperature stimulus, age, bodily ...


5

You are right the compounds provoking this burning/tingling sensation is called allyl isothiocyanate. We (human) perceive these compounds in two different ways when ingested, namely via the gustatory and olfactory systems. The molecular receptor sensing isothiocyanates is called the transient receptor channel A1 (TRPA1) [ref]. Here a simplistic view of how ...


4

The dog's ability to smell the world around him and to interpret these odors depends on a complicated chemical sensory system. First of all, it possesses mobile nostrils, that help to determine the direction of the smell. Then comes sniffing, the ability to disrupt the air with a regular pattern of breathing that, through laboratory testing, is structured in ...


4

This paper finds some species can detect as far as 67 meters, but the range varies between species. Note that the bats can actively change their range of detection and trade off range for resolution (low range with high speed resolution for hunting in closed, cluttered spaces or high range with low speed resolution for hunting in open spaces), as explained ...


4

Not all cat predatory behavior is innate. Researchers found that cats predatory behavior for birds vs. mice depends to a significant degree on training by the mother: if the mother taught predatory behavior with birds, the kittens grew up to be better at catching birds than at catching mice and vice versa. Supportive data shows that aside from monkeys and ...


4

Ants follow odor cues in the wind. A study by Wolf and Wehner (2000) manipulated ant antennae and wind direction to show that ants followed odor plumes on the wind. A more recent study by Buehlmann et al. (2014) showed that desert ants of the genus Cataglyphis cued in on linoleic acid, a so-called necromone (death scent) released by dying insects. Here's a ...


4

Butterflies have nearly 360 degree field of vision (see e.g. Belth. Butterflies of Indiana), so they can see you or other predators approaching from behind at the same time as they examine the flower they are feeding from. A large field of vision is common in many animals that are preyed upon, and for instance many birds (e.g. waders) have 360 vision, some ...


4

As far as I know, adaptation of peripheral receptors, including pain receptors, is transient (Giniatullin & Nistri, 2013) Instead, my educated guess is that the increase in subjective pain threshold plays an important role. Pain thresholds differ between the sexes (Chesterton et al., 2003), and depend on disease and physical status (Kosak et al., ...


4

Short answer The main limitation to frequency discrimination is loudness. Background The cochlea is tonotopically organized - it basically acts as a Fourier transformer, where different frequencies are analyzed on a place map (Fig. 1). Frequency tuning of cochlear hair cells is mainly limited by sound intensity. The louder a pure-tone sound stimulus gets, ...


3

It is called a frisson, and actually, there has been a study about it, available here. The frisson is kind of the same you get from cold weather, fear, or... well, other things not suitable to discuss if not knowing how old people reading this might be. Actually, they found that this works best if you include familiarity. In their case, asking study ...


3

With regards to the similar chemicals having similar smells, it does seem that there are trends with smell association and functional group. This wiki article has a good list of compounds and their smells, and some classes definitely give similar types of smells, amines are rotting/fecal smells (hence the names putrescine and cadaverine), while esters are ...


3

Any animal using sound cannot sense color though sonar directly, though these animals are not entirely blind and can probably see colors in the infrared we can't. Even on the darkest night there is some light around and all bats use this. Old World fruit bats have colour vision, which is useful to them as they are often quite active in daytime, roosting ...


3

Is this possible or am I just hallucinating? Certainly possible, but I'd peg the mechanism closer to Sensitization or De-sensitization of the neurons involved so that when you finally ingest some salt the sensation is different. The sodium and chloride levels of the ingested material wouldn't have a direct effect on the level of De-/Sensitization, but ...


3

The short answer is that yes, they will grow back. Cats do regularly shed their whiskers and grow them back in time (reference). The thing is that if damage has been done to the root of the whisker, it may grow back in an irregular manner (reference). Wish for the best and by now I think the whisker should be back just fine.



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