Craig: I wanted to learn about extra senses, so I talked with Josh Sundquist.

[camera cuts to Craig with Josh]

Josh: Greetings.

C: How are you?

J: Good, man, good to be on the show.

[camera cuts back to Craig]

C: And Hank Green.  Again.

[camera cuts to Craig with Hank]

C: Hello Hank.

Hank: Hello Craig.

C: Now this week, Hank, we're talking about senses.

[cut to Craig and Josh]

C: And one of those things we want to talk about is extra senses.

[cut to Craig and Hank]

C: I hear that there are many more senses other than the basic five.

H: Yeah.  There are thousands of senses.

C: Thousands!?

H: Thousands of senses.

C: I did not hear that.

H: It depends... on how you count.  Some chemists would argue that every smell is a different sense.  We have a chemical receptor for every separate smell you've ever smelled.  This is obviously not the right way to count senses.

C: It's probably a little easier for people to wrap their heads around five senses.

H: Yes.

[Craig and Josh]

J: And the sight, and smelling, and touching, stuff like that.

[Craig and Hank]

H: Which I think Aristotle came up with, and he's- Aristotle was just wrong about everything.  But that's because science hadn't been invented yet.

C: Are there other senses, like..?

H: There are other senses besides the five senses.  The most obvious one is the sense of balance.

[Josh]

J: Equilibrioception is the one in your ears.  That can feel spinning, right, that's what makes you dizzy and it can also feel acceleration.

[Hank]

H: You have a sense of what is up and what is down.  And when you lose that sense it is terrible.

C: What other senses?

H: Um, there's something called proprioception.

C: I've heard of this.

[Josh]

J: Proprioception is the sense of you body in space.  Or another way to say it is...

[Hank]

H: The sense of where your body parts are.  So you can close your eyes and you still know where you nose is. *closes eyes and touches nose*

[Josh]

J: Proprioception is hardwired into your brain, in a sense that if you lose a body part-

[Hank]

H: For example, people who don't have their arm anymore.

[Josh]

J: Your brain is till looking for those proprioceptive nerve signals to come.

[Hank]

H: They still think that it's there.

C: Phantom limb, yeah.

[Josh]

J: A really fun fact to me about phantom limb pain - it's any part of you body.  So people that lose a hand, a nose, an ear, even a private part, let's say, you will still feel that sensation, sensation from that part of your body in your brain.

[cuts to Craig setting camera up]

J: By the way, this is a weird question, can you see that I have one leg? 'Cause I think that that's important, like, credibility factor.

C: I do see that.

[Back to real time]

J: When I was a kid, when I was nine years old I had a rare form of bone cancer called Ewing's Sarcoma.  And I had some chemotherapy, didn't really work, and so my leg was gonna be amputated.  And when that happens, the doctors give you a lot of talks about what you're gonna go through, youknow.  The pain, and the physical therapy and stuff, and one thing they do tell you, is about phantom limb pain.

So you wake up from surgery, and I felt like my leg was sticking like straight up in the air, like perpendicular to my body.  And it was like, it was just the weirdest thing, 'cause it was like, I couldn't move it, it was stuck straight up in the air.  And then, the really frustrating thing about phantom limb pain, of course, is that you feel all this pain in the body part that doesn't exist anymore.

J: For me it felt like a, like thousands of needles suck into the foot on the leg, and you keep like, you close your eyes, and you open them, and there's no leg there. And to this day, I find it, a very bizarre, and almost like, creepy phenomenon, that that happens.

One theory about why people experience phantom limb pain is this.  Let's imagine a building that has like a security camera room, like, where the security guard sits, right.  And he has all these panels, and each panel is connected to one camera in the building. And then let's say that one of those cameras, the chord gets severed.  Then what do we expect on the screen?  Some kind of static signal right? Cause the camera's still there, it's still expecting a signal to come through, but there's no signal coming.  And so, a lot of people think that that's what causes phantom limb pain, is... your brain is hardwired to expect a signal and in my case, from the leg.  The leg gets cut off, the brain's still looking or a signal, but there's no signal there, in other words it gets static because there's just, there's nothing there.

One of the really weird things about phantom limb pain is how on the one hand it can be debilitatingly painful, but there's not a lot that doctors can do for it, although much research has gone into it. Ad it turns out that typically, the most effective treatments turn out to be incredibly..uh, rudimentary. For example, for me, the thing that really, like, changed the game for me is, you know, after I lost my leg, this nine year old kid, sitting in bed just writhing in pain, just couldn't sleep at all.  And what made the difference for me was my mom rubbing my real foot, my right foot that was, that was still there. Because, uhh, and I'm not a neurologist, so I don't understand all the neurology here, but because your brain, uh, it doesn't necessarily always differentiate between which side of your body you're receiving a signal from.  It kind of, can like override the like, the absence of a, of a nerve signal from your left leg.  Now you have this nerve signal from your real, existing leg- my mom rubbing my foot, and all of a sudden it's like *snaps* the pain goes away.

The same deal today, like if I'm lying in bed and I like, can't sleep because I have phantom limb pain, I'll like lift my foot up, and just like rub my foot for a while and all of a sudden it's just poof, the pain goes away.  Not only do I still feel my leg there, but I can sense each individual toe, and I can move my ankle.  Like literally, right now... *closes eyes* I am flexing my ankle.  I don't know if you could see it there...

C: I...

J: It may have been kind of invisible to you.

C: I couldn't see it.

J: But it's like, I close my eyes, and I'm just like, doing like... this *lifts leg and moves ankle* with my ankle like, in my mind, and I can like... takes a little- it's weird, I don't know why but it takes a lot of concentration.  And I can like... yeah I can kind of wiggle the toes, still. Which I just think is so weird, right?  And I don't know why, like I don't even know if... if I'm doing something like muscular, skeletally to do that, or if it's literally just in my brain, sending the normal signal to the ankle, and then my brain thinking, "Oh yeah, that ankle's moving. I can feel it."  Like how weird is that, right?

C: Yeah.

[Craig alone]

C: Thanks Josh and Hank.Up next, we asked you to talk about your sixth sense, and many of you did, and none of you can see dead people, apparantly.  Unless I'm dead.  Am I dead?