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>Sight, hearing, smell, taste, touch: We’re all familiar with the five senses that allow us to experience our surroundings.

>Equally important but much less well known is the sixth sense: “Its job is to collect information from the muscles and joints about our movements, our posture and our position in space, and then pass that on to our central nervous system”, says Dr. Niccolò Zampieri, head of the Development and Function of Neural Circuits Lab at the Max Delbrück Center in Berlin.

>“This sense, known as proprioception, is what allows the central nervous system to send the right signals through motor neurons to muscles so that we can perform a specific movement.”

> 

>The pSN cell bodies are located in the dorsal root ganglia of the spinal cord. They are connected via long nerve fibers to the muscle spindles and Golgi tendon organs that constantly register stretch and tension in every muscle of the body. The pSN send this information to the central nervous system, where it is used to control motor neuron activity so that we can perform movements.

>Using single-cell sequencing, the team investigated which genes in the pSN of the abdominal, back and leg muscles are read and translated into RNA. “And we did find characteristic genes for the pSN connected to each muscle group,” says Dietrich. “We also showed that these genes are already active at the embryonic stage and remain active for at least a while after birth.”

>Dietrich explains that this means there are fixed genetic programs that decide whether a proprioceptor will innervate the abdominal, back or limb muscles.

Nature Communications, 2022. DOI 10.1038/s41467-022-34589-8

I guess I'm a weirdo, cause proprioception for me is mixed in with touch. The only intuitive positioning awareness i have comes from the painful ranges of my joints.

life is pain

Close your eyes, touch your left hand with your right pinky finger, that's proprioception.

Other senses pain, hunger, balance,

Also thermoception, pressure, itch (all are separate from sense of touch), tension sensors (for muscles), stretch receptors (lung, bladder & stomach), chemoreceptors (detects hormones & drugs in the blood), thirst (separate from hunger), magnetorectption (it is really weak) & time

Also the name of pain is nociception & balance is equilibrioception.

We have 18 senses that we know of.

So is this why sobriety tests ask people to close their eyes and touch their nose? If so, is there a connection between being intoxicated pSN? Or would it likely just be that your other senses that feed information into the pSN are impacted?

> time

This can't really be called a sense can it? If sense of time is a biological sense, then so should be sense of distance, or sense of danger, or any other thing we can perceive and roughly calculate.

Does your list include interoception?

Odd that the article says propioception is unconscious. Other papers say there are both conscious and unconscious forms of proprioception:

>Proprioception is the sense of body position that is perceived both at the conscious and unconscious levels.

https://pubmed.ncbi.nlm.nih.gov/18851800/

That involves touch, and conscious motion, that's easy. Ask me to tell you what direction my toes are pointed as i sit here now, and haven't moved my foot consciously in minutes, and be prepared to get a +/- 45° orientation. :D

>DoomGoober

>Odd that the article says propioception is unconscious. Other papers say there are both conscious and unconscious forms of proprioception:

>https://pubmed.ncbi.nlm.nih.gov/18851800/

>J Surg Orthop Adv. 2008 Fall.

An excerpt from Somatosensory 1, last revised December 2013:

>UNCONSCIOUS "PROPRIOCEPTION":

>The sensory information discussed above, which is useful for consciousness, is also useful for unconscious functional control of movement. Therefore:

>• The primary afferent axon, upon entering the spinal cord, will have branches (collaterals) to share the sensory signal with "local reflex" neurons, and

>• To share the signal with the cerebellum (works at unconscious level) by a synapse with spinal cord neurons, whose axons form spinocerebellar tracts.

>http://anat403.class.uic.edu/Lectures/lecture6_09.htm

I think it is its own separate sense as evidenced by the many times I have not set an alarm but somehow, in my sleep without any conscious thinking, my body knows exactly when I need to be awake. Bare in mind I sleep with a light blocking mask in a dead dark room so it isn't light perception either. Just my experience.

It is also a sense that can be messed with - people trapped in dark spaces like underground or sunken ships will often think it's only been a day when in reality they've been there three days.

No it only involves touch once your finger reaches your hand.

The sense of touch is not "reach out and touch someone" it's the sensation you feel when someone touches you.

When you reach out to touch your hand without looking the only way that happens is through your body's innate way of detecting the position of your body and all your limbs in 3D space and coordinating the work of many muscles to make that action occur.

That's the sixth sense of proprioception.

Your body "knows when it needs to be awake" because you've routinely woken at that time and programmed your internal biological clock to wake at that time.

It detects changes in temperature, air pressure etc that occur at that time. That's how it is triggered.

I don't think you're understanding what i'm saying. I'm not suggesting there isn't such a thing as proprioception. What i'm saying is that to me, i infer more about my the positions of my limbs from how they touch my other limbs, or my body, than i do from intuitively knowing. Of course there's feedback loops for moving your limbs - no question. That's what makes it easy to know where my limbs are, actually. When i consciously move something somewhere, i might remember where it was. But if i had to tell you right now whether my foot is toed in or out right now, i'd be guessing. I didn't consciously leave my right foot in any particular orientation, and while proprioception should tell me what its alignment is, i'd literally need to look at it or move it to tell you for certain which direction it's pointed.

> That involves touch, and conscious motion, that's easy

That's actually not easy! You know if you lie on your arm funny and it goes numb, and you're super clumsy moving it around? That's because you've lost your proprioception.

Yeah, yeah, and it all presupposes a functioning GI tract, and that's even more complex, sure. Not the point. The point i was trying to make is that i might be weird in that my intuitive proprioception feels like it mostly doesn't work. I know it's involved in coordinated motions, but that's not what i'm talking about. When we talk about it like a sixth sense - mine must be severely stinted. Like a hard of hearing person's hearing. To the point where i can be laying in bed some time and not know whether my arm is at my side or in front of my belly, so i have to move it to find out which one it is.

But when you go to start moving it, it will instinctively align in the right direction to accommodate without you having to look down and go “ok right foot, rotate 18 degrees to the left before moving.”

This isn’t about your conscious knowledge, it’s about your innate subconscious ability to move relatively accurately through space without having to be explicitly aware of where they are and how they’re oriented. If you didn’t have this 6th sense, it would take multiple attempts and/or visual tracking to do something like closing your eyes and touching your nose with your index finger.

Regardless of how you consciously infer limb position, your body generally know where things are and how to move about.

All of our senses play a big part in the unconscious absorption of the world around us. As with the rest of the senses, each one is connected with many of the others (taste, for example, is a combination of smell and touch, but is also influenced by both sight and sound). Proprioception is intuitively tied to touch, and without touch, the sense is lost.

Think about when you're laying in a recliner. You might cross your legs, or move your arms behind your head, or so on. But no matter what position you're in, the moment you move, your brain already knows where the individual parts need to go without having to input anything. That, specifically, is what proprioception does for us.

Our brains are wired to interpret this information at nearly all times, regardless of whether we're aware of it. I mean, people have actual taste buds on our assholes, but we don't taste it every time we go number 2.

TL;DR:

Our senses are all connected to each other*

^^^* ^^^see ^^^paragraph ^^^1

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How are you typing this?

The real LPT is always in the comments

By consciously manipulating my limbs, I've said as much.

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Yeah, and like i said - my sixth sense is somewhat stinted, i don't think you've misread what i wrote.

Yeah, I've acknowledged the feedback loop in every comment in this thread.

Well, as a bacterial meningitis survivor, my legs have a lot of nerve damage. I have trouble with this sense in them and I never could tell the difference between touch and spatial awareness like I can now. When too idle, it sometimes feels like my legs are asleep. It's an odd feeling to lose a sense you don't even know you have

It's a total game changer, imo

>So is this why sobriety tests ask people to close their eyes and touch their nose?

Not exactly.

>If so, is there a connection between being intoxicated pSN?

No

>Or would it likely just be that your other senses that feed information into the pSN are impacted?

So accurate 3D maneuvering requires at least 2 out of 3 of the following senses working:

• Sight ("eye balance")
• Proprioception ("joint balance")
• vestibular system ("ear balance")

Alcohol messes with how the brain handles system 3 (ear balance) among other things.

Now if you shut off system 1 (eye balance), you can only use proprioception to maneuver in 3D.

1 balance system is not enough to move in 3d accurately so you fail the test.

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Fascinating!

Your body tends to run in circadian (24 hour) and ultradian (90 minute) rhythms/cycles.

There is a bundle of cells known as the suprachiasmatic nucleus that receives light information from the retina. It times those rhythms with sunrise and sunset.

This allows for the proper timing for countless processes within your body.

Cyclic temperature regulation is a good example; in the morning your body cools and in the evening your core body temperature is higher, aiding relaxation and your ability to fall asleep as well as many other things. This is done via these types of rhythmic cycles via the hypothalamus which receives it's timing info from that nucleus (the nucleus is actually a part of the hypothalamus).

REM sleep cycles are another that run on these ultradian rhythms.

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There aren't just 5 senses.

Sight, smell, touch, taste, hearing, temperature, balance, hunger, thirst, itchiness, pressure, pain, proprioception, time, magnetic fields... and more.

Touch is already at least three senses awkwardly bundled together, I have a hard time taking any discussion involving "the five senses" seriously.

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It's not unusual to loose sense of your position if you don't move for a while, but trust me if you can touch your fingers together or touch your nose with your eyes closed then your proprioception is working, you wouldn't be able to do that without looking if it wasn't.

Proprioception is one of the things that makes drawing hands challenging

Sure. Just the way in which it's working there can hardly be called a "sense." It's like calling the secretions of my esophageal mucosal membranes a sense.

It's both. You don't have to be consciously aware of it for it to be engaged, but you can become aware of it more keenly. This is basically what any form of refined motor movement is like a ballerina or a martial artist.

I'd like to see these scientists study drummers and clumsy people.

Guess I forgot one, yeah there are 19.

You sense danger though others senses like sight, smell, touch, hearing and balance. We have internal clocks and some people are really, really good at knowing what time it is without a watch within a few minutes.

How do we know our brains are in our head?

It's as ridiculous as calling the movement of sound waves in your inner ear getting converted to sound signals in the brain a "sense." That's clearly just a body's subconscious mechanical function.

Proprioception isn't about communicating to your conscious mind where your foot is positioned. It's about your cerebellum and CNS working together to coordinate your foot position so it stabilizes you in your current situation without having to consciously think about it.

It's not about you being able to always know where it is but rather trusting that it is keeping you from falling and that you can quickly put it into another position without having to think about it at all.

Not true, you are consciously thinking "type these words" but your unconscious mind coordinates all the various tendon movements needed to actually make the typing happen.

Your conscious mind is delegating the vast majority of the work to the unconscious mind which uses proprioception heavily to carry out the task.

I'm probably being pedantic but proprioception is derived from touch and sight, and not really a sense of its own. In med school I rotated through neuro clinics and frequently tested for diabetics' proprioception. Diabetics lose this in severe diabetes as diabetic retinopathy and/or peripheral neuropathy set in. Your inner ear fluid also factors in (the dizziness you get from spinning) and of course the areas of the brain that process this information.

Similarly I don't think we call depth perception a sense because it's a derived piece of info your brain processes, or sensation of heat/cold because it's derived from touch.

Basically you use sight, your inner ear (I believe it's specifically the positioning of fluid due to gravity), and the feeling of having your feet on the ground, as inputs for your cerebellum to keep your balance.

Loss of 2 of these things will lead you to not have enough information to derive balance. A simple test for peripheral neuropathy in diabetics: have them close their eyes with their feet together, and give them a very slight tap on the shoulders (while ready to immediately catch them). Diabetics with peripheral neuropathy can't balance well if they close their eyes or if their vision is bad enough, because they've lost 2 of the 3 inputs (vision, and sensation in their feet).

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Would pSN be a factor if you have a good sense at catching things you didn’t “see” or having “quick senses” in the quick moments to responds to physical situations?

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So, how is it a sense, then?

No, in very consciously aware of sounds. The tinnitus makes low sounds difficult, but i can consciously tell them apart if i try.

Because they still have 2 of 3...sensation in feet and inner ear fluid...

I can see a very faint image of my arms moving with the eyes closed.